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Opportunity Updates

M I S S I O N     M A N A G E R S   
Scott Lever, Mission manager Mike Seibert, Mission manager Al Herrera, Mission manager
Scott Lever Mike Seibert Al Herrera
P R E V I O U S    M I S S I O N    M A N A G E R S
Matt Keuneke, Mission Manager Cindy Oda, Mission Manager Rich Morris, Mission Manager Bill Nelson, Mission manager
Matt Keuneke Cindy Oda Richard Morris Bill Nelson
Byron Jones, Mission Manager Mark Adler, Mission Manager Leo Bister, Mission manager Beth Dewell, Mission Manager
Byron Jones Mark Adler Leo Bister Beth Dewell
Emily Eelkema, Mission Manager Jeff Favretto, Mission Manager Soina Ghandchi, Mission Manager Andy Mishkin, Mission Manager
Emily Eelkema Jeff Favretto Saina Ghandchi Andy Mishkin
Art Thompson, Mission Manager Rick Welch, Mission Manager Colette Lohr, Mission Manager Dan Gaines, Mission Manager
Art Thompson Rick Welch Colette Lohr Dan Gaines

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sol 1749-1755, December 24-30, 2008: Looking Down and Looking Up

Opportunity has been investigating an area called "Crete," where both bedrock and soil targets are within reach of instruments on the rover's robotic arm. Achieving this position is another testament to the skills of rover drivers on Earth, who have been able to use the robotic arm even though Opportunity lost use of the shoulder azimuth joint. On sol 1751 (Dec. 26, 2008), Opportunity used both the microscopic imager and the alpha-particle X-ray spectometer to study the bedrock. Following that, on sol 1755 (Dec. 30, 2008), the rover acquired microscopic images and alpha-particle X-ray measurements of soil.

Also of note this week, Opportunity recorded a transit of Mars' moon Phobos across the Sun. The rover used the panoramic camera to capture a series of images of the event.

Opportunity is healthy and all subsystems are performing as expected as of sol 1755 (Dec. 30, 2008). Tau has risen slightly, going up to 0.71 on sol 1755, meaning the atmosphere is somewhat more opaque with suspended dust particles. Even so, with the arrival of spring in Mars' southern hemisphere, the Sun is in the sky longer, helping to keep solar energy up. Solar energy available on sol 1755 was 586 watt-hours.

Sol-by-sol summary

In addition to monitoring daily dust-related changes in atmospheric clarity with the panoramic camera, Opportunity completed the following activities:

Sol 1749 (Dec. 24, 2008): Opportunity studied the mineralogy of Santorini with the Mössbauer spectrometer.

Sol 1750: Opportunity finished studying the mineralogy of Santorini with the Mössbauer spectrometer.

Sol 1751: Opportunity acquired panoramic-camera images of the rover's tracks and stereo (three-dimensional), microscopic images of Santorini. The rover placed the alpha-particle X-ray spectrometer on Santorini, paused for a communications link with NASA's Odyssey orbiter, and then used the spectrometer to study the rock's elemental composition.

Sol 1752: In the morning, Opportunity acquired six, time-lapse movie frames in search of clouds with the navigation camera; monitored dust accumulation on the rover mast; and took spot images of the sky for calibration purposes with the panoramic camera. Opportunity then acquired panoramic-camera images of Santorini, relayed data to NASA's Odyssey orbiter for transmission to Earth, and studied the elemental makeup of Santorini with the alpha-particle X-ray spectrometer.

Sol 1753: First thing in the morning, Opportunity measured surface reflectivity, or albedo, with the panoramic camera. After that, Opportunity acquired stereo microscopic images of Santorini; moved the robotic arm to a new position on the same rock; and acquired more stereo microscopic images. The rover then placed the alpha-particle X-ray spectrometer on the new target, relayed data to Odyssey, and used the spectrometer to look for changes in the rock's elemental composition.

Sol 1754: Opportunity placed the alpha-particle X-ray spectrometer on a rock nicknamed "Candia; used all 13 filters of the panoramic camera to acquire full-color images of the external magnets and the spacecraft deck; and used the panoramic camera to take thumbnail images of the sky. After relaying data to NASA's Odyssey orbiter for transmission to Earth, Opportunity studied the elemental makeup of Candia with the alpha-particle X-ray spectrometer.

Sol 1755 (Dec. 30, 2008): In the morning, Opportunity took spot images of the sky for calibration purposes and surveyed the horizon with the panoramic camera. The rover acquired image mosaics with the navigation and panoramic cameras and stereo microscopic images of a soil target nicknamed "Minos." After relaying data to Odyssey for transmission to Earth, Opportunity studied soil composition with the alpha-particle X-ray spectrometer. Plans for the following morning called for the rover to monitor dust on the panoramic-camera mast assembly.

Odometry

As of sol 1755 (Dec. 30, 2008), Opportunity's total odometry was 13,617.33 meters (8.46 miles).



sol 1743-1748, December 18-23, 2008: Taking a Close Look at "Santorini"

Opportunity spent the past week using instruments in the rover's scientific toolkit to study the composition of the cobble known as "Santorini." These included the Mössbauer spectrometer, which analyzes the mineralogy of iron-bearing minerals; the alpha-particle X-ray spectrometer, which analyzes chemical elements in the rock; and the microscopic imager, which takes magnified images of the surface of the rock. The rover then moved the robotic arm to a second spot on Santorini and took alpha-particle X-ray spectrometer measurements and microscopic images to determine whether or not the rock's composition varies.

On sol 1748 (Dec. 23, 2008), Opportunity moved a short distance to study a new area, informally named "Crete," where both bedrock and adjacent soil will be within reach of the rover's robotic arm. This will enable the rover to study the rock and the soil using the microscopic imager, alpha-particle X-ray spectrometer, and Mössbauer spectrometer.

Opportunity is healthy and all subsystems are nominal as of the downlink of information on Sol 1748. Atmospheric opacity caused by dust, known as tau, has risen slightly during this period, with tau at 0.65 on sol 1748. Meanwhile, solar-array energy has slightly decreased to 576 watt-hours on sol 1748. Opportunity successfully relayed data collected during solar conjunction to Earth, emptying out the large number of data products that had accumulated during the two-week period. The rover now has a healthy amount of onboard storage available for more science observations.

Sol-by-sol summary

In addition to monitoring daily dust-related changes in atmospheric clarity with the panoramic camera, Opportunity completed the following activities:

Sol 1743 (Dec. 18, 2008): Opportunity studied the mineralogy of Santorini with the Mössbauer spectrometer.

Sol 1744: Opportunity finished studies of the mineralogy of Santorini with the Mössbauer spectrometer.

Sol 1745: Opportunity acquired panoramic-camera images of the rover's tracks and stereo (three-dimensional), microscopic images of Santorini. The rover placed the alpha-particle X-ray spectrometer on Santorini, paused for a communications link with NASA's Odyssey orbiter, and then used the spectrometer to study the rock's elemental composition.

Sol 1746: In the morning, Opportunity acquired six, time-lapse movie frames in search of clouds with the navigation camera; monitored dust accumulation on the rover mast; and took spot images of the sky for calibration purposes with the panoramic camera. Opportunity then acquired panoramic-camera images of Santorini, relayed data to NASA's Odyssey orbiter for transmission to Earth, and studied the elemental makeup of Santorini with the alpha-particle X-ray spectrometer.

Sol 1747: First thing in the morning, Opportunity measured surface reflectivity, or albedo, with the panoramic camera. After that, Opportunity acquired stereo microscopic images of Santorini; moved the robotic arm to a new position on top of the same rock; and acquired more stereo microscopic images. The rover then placed the alpha-particle X-ray spectrometer on the new position, paused to relay data to Odyssey, and used the spectrometer to look for changes in the rock's elemental composition.

Sol 1748 (Dec. 23, 2008): Opportunity started the day with a photo session to acquire early-morning, full-color, panoramic-camera images of a new study area nicknamed "Crete." The rover drove a short distance to get there, stopping midway to acquire full-color, panoramic-camera images of Santorini. After the drive, Opportunity acquired navigation-camera images of the new location. Opportunity relayed data to Odyssey and measured argon gas in the atmosphere with the alpha-particle X-ray spectrometer.

Odometry

As of sol 1748 (Dec. 23, 2008), Opportunity's total odometry was 13,617.33 meters (8.46 miles).


sol 1716-1742, November 20 - December 17, 2008: Post-Solar Conjunction Hangover

As soon as Opportunity came out of solar conjunction - a period when the Sun passes between Earth and Mars and prohibits communication - engineers discovered that the rover's computer memory was a bit too full for comfort. They spent the first two days after conjunction minimizing data generation on Mars and planned to spend another two days doing the same. The purpose of the slowdown was to give Opportunity a chance to empty out some of the large number of "sent" data products.

In this case, the memory situation involved the data product limit, not the data volume limit. In the event of an excess of data volume, the rover automatically deletes data. An excess number of data products, on the other hand, can cause a rover fault. Such a fault occurred on Spirit, Opportunity's twin on the opposite side of Mars, shortly after landing. The potential for such a fault becomes a concern whenever the number of on-board data products is greater than 6,000. After solar conjunction, on sol 1740 (Dec. 15, 2008), the number of data products in Opportunity's computer memory was 6,448.

To prevent a potential fault, engineers postponed more scientific studies and adopted a plan to minimize data products. These plans permitted only one measurement per sol of atmospheric opacity or "tau" (atmospheric darkness caused by dust) and an overnight measurement of atmospheric argon. The rover science team expects a pending deletion of about 3,000 "sent" data products on sol 1743 (Dec. 18, 2008) to alleviate the memory overload.

As soon as engineers confirm deletion of a sufficient number of data products from the rover's flash memory, Opportunity will resume studying the cobble nicknamed "Santorini." The name Santorini comes from a Greek isle once known as Thera that 3,600 years ago was the site of one of the most powerful volcanic eruptions ever seen. Remaining observations will include taking microscopic images and measuring elemental composition with the alpha-particle X-ray spectrometer.

Opportunity is healthy and all subsystems are performing as expected as of the downlink of data on sol 1742 (Dec. 17, 2008). Energy was around 594 watt-hours (almost enough to light a 100-watt bulb for six hours). Tau, a measure of the amount of sunlight blocked by dust in the atmosphere, was 0.622, and the dust factor, a measure of the amount of sunlight penetrating dust on the solar arrays, was 0.6536.

Sol-by-sol summary

Before, during, and after solar conjunction, Opportunity completed the following activities:

Sols 1716-1720: With only a few days left before solar conjunction, Opportunity scrambled to get as much interactive work done as possible. Having successfully placed the robotic arm on Santorini, Opportunity began studying the mineralogy of Santorini with the Mössbauer spectrometer and acquired images of the rock with the panoramic camera. Opportunity also used the panoramic camera to acquire a 360-degree panorama, take images of the rover's tracks, and monitor dust-related changes in the atmosphere. In addition, the rover surveyed the horizon, acquired time-lapse movie frames of the sky in search of clouds with the navigation camera, and measured argon gas in the atmosphere with the alpha-particle X-ray spectrometer.

Sols 1721-1722: Opportunity switched over to the master sequence of commands to be followed during the two weeks of solar conjunction. Plans called for Opportunity to study the mineralogy of Santorini using the Mössbauer spectrometer on all but two Martian days - sols 1726 (Dec. 1, 2008) and 1736 (Dec. 11, 2008) - when the rover was to measure argon gas in the atmosphere with the alpha-particle X-ray spectrometer. During conjunction, Opportunity was also to complete a photon-transfer measurement on each of the rover's cameras.

Sols 1723-1740 (Nov. 28-Dec. 15, 2008): While out of contact with Earth, Opportunity studied Santorini's mineralogy with the Mössbauer spectrometer, measured argon gas in the atmosphere with the alpha-particle X-ray spectrometer, and made remote-sensing observations. On sol 1725 (Nov. 30, 2008), approximately 0.93 megabits of data transmitted to Earth was lost to solar interference. The following day, sol 1726 (Dec. 1, 2008), at least a third of the expected data volume from Mars was lost. After that, virtually all data was lost while the Sun blocked communications.

Sol 1741 (Dec. 16, 2008): Opportunity relayed data to Earth via NASA's Mars Odyssey orbiter, measured dust-related changes in atmospheric clarity with the panoramic camera, and measured argon gas in the atmosphere using the alpha-particle X-ray spectrometer.

Sol 1742 (Dec. 17, 2008): Opportunity measured dust-related changes in atmospheric clarity with the panoramic camera and recharged the batteries.

Odometry

As of sol 1742 (Dec. 17, 2008), Opportunity's total odometry was 13,616.47 meters (8.46 miles).


sol 1709-1715, November 13-19, 2008: Opportunity Prepares for Two Weeks of Independent Study

Opportunity is getting ready for solar conjunction, the time when the Sun is in the line of sight between Earth and Mars. During this two-week period, from Nov. 30, 2008 to Dec. 13, 2008, the mission team will not send new commands to the rover. The science team plans to position Opportunity on a rock outcrop, possibly near a cobble the rover can study with the Mössbauer spectrometer, during this time interval.

Opportunity began the week with a 93-meter (310-foot) drive on Sol 1709 (Nov. 13, 2008). The drive allowed the rover to reach a large expanse of bare outcrop. Another drive on Sol 1710 (Nov. 14, 2008), covering 17 meters (56 feet), placed the rover near potential targets of scientific interest. A candidate target, a cobble about 8 meters (30 feet) away, became the objective of the drive on Sol 1713 (Nov. 17, 2008). The 8-meter drive positioned the cobble, now nicknamed "Santorini", within the work volume of the science instruments on Opportunity's robotic arm.

The challenge for the team was the placement of the science instruments on Santorini using only 4 degrees of freedom of the robotic arm instead of the usual 6. The rover is not able to change the azimuth of the shoulder joint, that is, move it from side to side, because the shoulder azimuth joint (Joint 1) is disabled due to degraded performance.

On Sol 1714 (Nov. 18, 2008), Opportunity successfully placed the Mössbauer spectrometer on a faceted surface of the cobble. The contact switches on the instrument confirmed that the spectrometer had touched the surface. An analysis by the spectrometer is now under way. Rover operators plan to have Opportunity integrate Mössbauer measurements of Santorini for the two-week period of solar conjunction.

Opportunity is acquiring a panorama of images using multiple filters of the panoramic camera and making daily observations of atmospheric dust as well as measuring atmospheric argon using the alpha-particle X-ray spectrometer APXS. The rover is creating occasional, time-lapse movies of clouds with the navigation camera.

This coming weekend, engineers plan another attempt to remove dust from the miniature thermal emission spectrometer mirror by shaking it.

As of Sol 1715 (Nov. 29, 2008), the solar array energy was 565 watt-hours (100 watt-hours is the amount of energy needed to light a 100-watt bulb for one hour). The atmospheric opacity (tau) was 0.747 and the dust factor (a measure of sunlight-blocking dust on the solar arrays) was 0.694.

Sol-by-sol summary

In addition to measuring dust-related changes in atmospheric clarity with the panoramic camera and relaying data from Mars to NASA's Odyssey orbiter for transmission to Earth, Opportunity completed the following activities:

Sol 1709 (Nov. 13, 2008): Opportunity drove 93 meters (300 feet) toward outcrop, made atmospheric observations with the panoramic camera, acquired targeted images with the panoramic and navigation cameras, and measured argon gas in the atmosphere with the alpha-particle X-ray spectrometer.

Sol 1710: Opportunity drove 17 meters (56 feet) on outcrop, made atmospheric observations with the panoramic camera, acquired targeted images with the panoramic and navigation cameras, and measured argon gas in the atmosphere with the alpha-particle X-ray spectrometer.

Sol 1711: Opportunity completed atmospheric observations with the panoramic camera, acquired targeted images with the panoramic camera, and measured atmospheric argon with the alpha-particle X-ray spectrometer.

Sol 1712: Opportunity completed atmospheric observations with the panoramic camera, measured atmospheric argon with the alpha-particle X-ray spectrometer, and acquired navigation-camera images for a time-lapse movie in search of clouds.

Sol 1713: Opportunity drove 8 meters (30 feet) toward Santorini, made atmospheric observations with the panoramic camera, and acquired navigation-camera images for a time-lapse movie in search of clouds.

Sol 1714: Opportunity placed the Mössbauer spectrometer on Santorini, integrated measurements of the cobble with the spectrometer, and acquired targeted images and studied the atmosphere with the panoramic camera.

Sol 1715 (Nov. 19, 2008): Opportunity continued the integration of data from Santorini with the alpha-particle X-ray spectrometer, acquired panoramic-camera images of multiple targets, and used the camera to make atmospheric observations.

Odometry

As of sol 1715 (Nov. 19, 2008), Opportunity's total odometry was 13,616.47 meters (8.46 miles).


sol 1702-1708, November 06-12, 2008: Science Instrument Gets A Shaking

For more than a year, Opportunity's miniature thermal emission spectrometer, which identifies minerals from a distance based on thermal radiation, has not been able to take successful measurements. Scientists suspect that dust on one of the instrument's mirrors, likely deposited by the dust storms of summer 2007, is interfering with measurements.

After giving the problem a great deal of thought, engineers decided it might be possible to shake off the dust by running motors in the panoramic-camera mast assembly at a setting that would vibrate the mirror. (The mirror in question is inside the mast that carries the panoramic and navigation cameras, along with related optical equipment.) When the first attempt did not produce a noticeable improvement, engineers decided to perform the shake multiple times. On sol 1705 (Nov. 9, 2008), they performed the shake twice. So as not to interfere with driving or other rover activities, they waited until sol 1708 (Nov. 12, 2008) to take follow-up measurements to see if the shake test had improved the performance of the miniature thermal emission spectrometer. They are analyzing the results.

Meanwhile, Opportunity continued to drive across the Plains of Meridiani toward Endeavour Crater, progressing an additional 238 meters (781 feet) since the last report. Near-term plans are to drive the rover about 120 meters to a location where Opportunity will spend solar conjunction, when the Sun will block communications between Earth and Mars. In high-resolution images taken from orbit by the High-Resolution Imaging Science Experiment on board the Mars Reconnaissance Orbiter, the area appears to have extensive outcrops of layered rock.

Opportunity is healthy, with all subsystems performing as expected as of the rover's 1,707th Martian day, or sol, of exploration (Nov. 11, 2008). Energy is around 574 watt-hours (100 watt-hours is the amount of energy necessary to light a 100-watt bulb for 1 hour.) Tau, a measure of sunlight-blocking dust in the atmosphere, increased from 0.478 to 0.602. The dust factor, a measure of the fraction of sunlight penetrating dust on the solar arrays, decreased only slightly to 0.7108.

Sol-by-sol summary

In addition to measuring dust-related changes in atmospheric clarity with the panoramic camera and relaying data from Mars to NASA's Odyssey orbiter for transmission to Earth, Opportunity completed the following activities:

Sol 1702 (Nov. 6, 2008): Before driving, Opportunity took panoramic-camera images of the rover's tracks. Opportunity then resumed driving, taking images at the end of the drive with the panoramic and navigation cameras. After relaying data to Odyssey, Opportunity went into a deep sleep.

Sol 1703: Opportunity took panoramic-camera images of albedo (surface reflectivity) and had another good night's sleep.

Sol 1704: In the morning, Opportunity surveyed the horizon with the panoramic camera. The rover took images of surface ripples and looked for pearl-shaped mineral deposits known as "blueberries" with the panoramic camera. Opportunity resumed driving and acquired images at the end of the drive with the panoramic and navigation cameras. After talking to Odyssey, it was time for a deep sleep.

Sol 1705: Tosol was the day Opportunity shook the miniature thermal emission spectrometer in an effort to remove dust from one of its mirrors. Before the shake test, the rover took images to document conditions with the navigation camera and looked at the sky with the spectrometer for later comparison. After sending data to Odyssey, Opportunity measured atmospheric argon with the alpha-particle X-ray spectrometer. The rover went into a deep sleep.

Sol 1706: Opportunity continued to measure atmospheric argon. Afterward, the rover went into a deep sleep.

Sol 1707: Tosol was another day of driving and acquiring image panels at the end of the drive with the navigation and panoramic cameras. After finishing the day's activities, Opportunity went into another deep sleep.

Sol 1708 (Nov. 12, 2008): In the morning, Opportunity completed a horizon survey with the panoramic camera and monitored dust accumulation on the panoramic-camera mast assembly. The rover surveyed the sky at high Sun with the panoramic camera. Opportunity acquired post-shake images of the sky and ground with the miniature thermal emission spectrometer as well as navigation-camera images to document conditions. Plans for the following morning called for Opportunity to acquire spot images of the sky for calibration purposes with the panoramic camera as well as a six-frame, time-lapse movie in search of clouds with the navigation camera.

Odometry

As of sol 1707 (Nov. 11, 2008), Opportunity's total odometry was 13,493.85 meters (8.38 miles).


sol 1695-1701, October 30 - November 05, 2008: Opportunity Cleans the Chalkboard

During solar conjunction, Opportunity will not be able to clean the chalkboard, so to speak, after each day's lesson. That's because the Sun will be between Mars and Earth, blocking communications for 16 days beginning Nov. 30. To have room for engineering and science observations during that time, the rover needs a clean slate. To that end, Opportunity is clearing the rover's on-board computer memory as much as possible.

At the beginning of the past week Opportunity's memory was brimming with data. To prevent the rover's computer from filling up with new data as fast as the rover could send it to Earth, engineers directed Opportunity to eliminate most science observations as well as auto-navigation drives.

"Autonav" is one of two ways the rover can drive. The other way is called a "blind drive" because the rover doesn't have any say in the route selection. During a blind drive, rover drivers on Earth tell the rover where to go using three-dimensional maps and images of Mars. During "autonav," the rover gets to choose its own path using on-board computer smarts. Engineers permit autonav only where terrain is fairly predictable. Opportunity recently achieved near-record drive distances by using autonav drives at the end of blind drives. The greater distances came at a price, however, because the autonav drives generated a lot of data.

Opportunity is now doing only blind drives, resulting in some decrease in overall distance while reducing data volume to necessary levels. The rover continues to make good distance, driving 254 meters (more than two football fields lined up end to end) since the last report.

Near-term plans include more of the same. Opportunity will continue to perform blind drives and add autonav drives only where and when appropriate. The goal is to achieve as much distance as possible while keeping an eye on data volume.

Opportunity is healthy, with all subsystems performing as expected as of Martian day, or sol, 1701 (Nov. 5, 2008). Power is about 596 watt-hours (almost enough energy to light a 100-watt bulb for six hours.) Tau, a measure of darkness caused by atmospheric dust, has increased to 0.478. The dust factor, a measure of the fraction of sunlight penetrating dust on the solar arrays, has remained relatively stable at 0.7151.

Sol-by-sol summary

In addition to making daily measurements of dust-related changes in atmospheric clarity with the panoramic camera, Opportunity completed the following activities:

Sol 1695 (Oct. 30, 2008): Opportunity drove approximately 60 meters (200 feet), made a "quick fine attitude" adjustment to pinpoint the rover's precise position relative to the Sun, and took post-drive images with the navigation and panoramic cameras. The rover went into a deep sleep.

Sol 1696: After relaying data to NASA's Odyssey orbiter for transmission to Earth, Opportunity spent 7 hours measuring argon gas in the Martian atmosphere with the alpha-particle X-ray spectrometer. Opportunity enjoyed another deep sleep.

Sol 1697: Prior to the day's drive, Opportunity took rearward-looking images with the navigation camera. The rover continued driving toward Endeavour Crater, acquiring images just before and after ending the drive with the navigation and panoramic cameras. Before sleeping deeply, Opportunity relayed data to Odyssey.

Sol 1698: In the morning, Opportunity monitored dust accumulation on the panoramic-camera mast assembly. After sending data to Odyssey, Opportunity measured atmospheric argon with the alpha-particle X-ray spectrometer. The rover went into a deep sleep.

Sol 1699: Besides meaasuring atmospheric opacity caused by dust, known as Tau, Opportunity recharged the batteries and went into a deep sleep.

Sol 1700: Today was another sol of driving and acquiring image mosaics with the navigation and panoramic cameras. Before sleeping deeply, Opportunity relayed data from Mars to Odyssey.

Sol 1701 (Nov. 5, 2008): In the morning, Opportunity took offset, thumbnail images of the sky with the panoramic camera. In addition to measuring atmospheric dust, Opportunity recharged the batteries. Plans for the following morning called for Opportunity to take spot images of the sky for calibration purposes with the panoramic camera.

Odometry

As of sol 1701 (Nov. 5, 2008), Opportunity's total odometry was 13,256.27 meters (8.24 miles).


sol 1688-1694, October 23-29, 2008: Putting the Pedal to the Metal

Thanks to relatively plentiful solar energy, Opportunity was able to drive for 5.5 hours in one Martian day! In fact, Opportunity came close to breaking the distance record for a single sol of driving. On sol 1691 (Oct. 26, 2008), the rover drove 216.29 meters (709.61 feet)! That distance was just a tad shy of Opportunity's previous distance record of 219.89 meters (721.42 feet), established back on sol 410 (March 19, 2005).

The material surrounding "Victoria Crater," known as the annulus, is great terrain for driving. The annulus is a ring of material ejected from the crater that has eroded away, leaving behind a thin layer of relatively dense, coarse spherules of the mineral hematite. This material forms a fairly smooth surface when compared to the ripple fields beyond the annulus and has enabled Opportunity to make significant progress.

For example, on sol 1634 (Aug. 28, 2008), when Opportunity first exited Victoria Crater, the rover's odometry was 11,781.51 meters (7.32 miles). By sol 1683 (Oct. 18, 2008), Opportunity had completed the science campaign on the southern rim of Victoria Crater and driven a total distance of 12,410.50 meters (7.71 miles). By sol 1693 (Oct. 28, 2008), Opportunity had completed several long drives toward Endeavour Crater and the rover's odometry was 13,002.55 meters (8.08 miles). Since exiting Victoria Crater, Opportunity has driven 1.22 kilometers (0.76 miles)!

Opportunity is healthy, with all subsystems performing as expected as of Martian day, or sol, 1694 (Oct. 29, 2008). Power went back up to about 603 watt-hours during the past week (that's enough energy to light a 100-watt bulb for six hours each day.) Tau, a measure of atmospheric dust, was 0.359. The dust factor, a measure of the fraction of sunlight penetrating dust on the solar arrays, was 0.7116.

Sol-by-sol summary

In addition to measuring daily, dust-related changes in atmospheric clarity with the panoramic camera, Opportunity completed the following activities:

Sol 1688 (Oct. 23, 2008): Opportunity surveyed the sky at high Sun with the panoramic camera and recharged the batteries.

Sol 1689: In the morning, Opportunity used the panoramic camera to take thumbnail images of the sky. Opportunity also used the panoramic camera to document albedo (surface reflectivity) and complete a survey of rock clasts. After relaying data to NASA's Odyssey orbiter for transmission to Earth, Opportunity measured argon gas in the Martian atmosphere with the alpha-particle X-ray spectrometer.

Sol 1690: In the morning, Opportunity took spot images of the sky for calibration purposes with the panoramic camera and acquired six, time-lapse movie frames in search of clouds with the navigation camera. The rover surveyed the sky at high Sun with the panoramic camera and, after the usual afternoon measurement of atmospheric dust, relayed data to Odyssey.

Sol 1691: Opportunity took morning spot images of the sky with the panoramic camera, then resumed driving toward Endeavour Crater. Opportunity drove 216.29 meters (709.61 feet) toward Endeavour Crater and just before and after ending the drive, acquired image mosaics with the navigation and panoramic cameras.

Sol 1692: In the morning, Opportunity surveyed the Martian horizon with the panoramic camera and acquired six, time-lapse images in search of clouds with the navigation camera. The rover surveyed rock clasts with the panoramic camera and acquired a 7-by-1 panel of post-drive, rearward-looking images with the navigation camera.

Sol 1693: Opportunity took offset, thumbnail images of the sky with the panoramic camera and made another long-distance drive in the direction of Endeavour Crater. Opportunity completed a "quick fine attitude" check to pinpoint the rover's precise position relative to the Sun. Opportunity acquired post-drive image mosaics with the navigation and panoramic cameras.

Sol 1694 (Oct. 29, 2008): Besides measuring atmospheric dust throughout the day, Opportunity recharged the batteries.

Odometry

As of sol 1693 (Oct. 28, 2008), Opportunity's total odometry was 13,002.55 meters (8.08 miles).


sol 1681-1687, October 15-21, 2008: Farewell, Victoria, and on to Endeavour!

Opportunity took the last images of "Victoria Crater" before beginning the journey to Endeavour Crater. The final focus of the rover's cameras was a cliff at the edge of Victoria nicknamed "Cape Victory." After spending more than two years investigating this spectacular crater, Opportunity took parting images as Victoria disappeared into the distance. The rover first arrived at the rim of Victoria on sol 952 (September 28, 2006), at the top of a sloping alcove known as "Duck Bay."

Opportunity has made good progress, driving more than 314 meters (1,030 feet)! Near the end of that leg of the journey, Opportunity began to see small ripples about 10 centimeters (4 inches) high.

Opportunity completed work on images of the miniature thermal emission spectrometer after the shake test performed on Sol 1680 (Oct. 14, 2008). That's when the rover shook the instrument's pointing mirror for 3 seconds to try to shake dust off the mirror. In the end, images did not show a measurable improvement, but rover planners aim to try again in the near future.

Other remote sensing highlights for the week included panoramic-camera imaging of some boulder tracks within Victoria, along with the usual observations of the sky, clouds, atmospheric dust, and dust accumulation on the rover itself.

Opportunity is healthy, with all subsystems performing as expected as of Martian day, or sol, 1687 (Oct. 22, 2008). Power has been averaging 589 watt-hours during the past week (100 watt-hours is the amount of energy needed to light a 100-watt bulb for one hour.) This is a slight decrease from the week before and is the result of slightly elevated dust levels in the atmosphere and a change in the orientation of Opportunity's solar panels.

Sol-by-sol summary

In addition to measuring daily, dust-related changes in atmospheric clarity with the panoramic camera and sending regular updates to Earth by relaying data to NASA's Odyssey orbiter, Opportunity completed the following activities:

Sol 1681 (Oct. 15, 2008): Opportunity acquired images of boulder tracks inside Victoria Crater and surveyed the sky at high Sun with the panoramic camera. The rover checked for drift (changes with time) in the miniature thermal emission spectrometer, conducted a utility test of the instrument as well as a post-shake test calibration of observations of the ground and sky.

Sol 1682: In the morning, Opportunity used the panoramic camera to take super-resolution images of Cape Victory, a 3-by-1 panel of frames of the area around Cape Victory, and thumbnail images of the sky for calibration purposes. The rover searched for morning clouds with the navigation camera. Before driving, Opportunity took a 3-by-1 panel of panoramic-camera images of a target known as "Iceland," then moved a short distance for a long-baseline, stereo panorama. Opportunity acquired post-drive images with the panoramic and navigation cameras, including a 7-by-1 panel of rearward-looking images.

Sol 1683: In the morning, Opportunity took spot images of the sky for calibration purposes and surveyed the horizon with the panoramic camera. The rover then acquired part 2 of the long-baseline, stereo panorama begun the day before. Opportunity acquired post-drive images with the panoramic and navigation cameras.

Sol 1684: Opportunity took thumbnail images of the sky with the panoramic camera in the morning. The rover measured argon gas in the Martian atmosphere with the alpha-particle X-ray spectrometer.

Sol 1685: Opportunity began the day by surveying the horizon with the panoramic camera and searching for morning clouds with the navigation camera. At midday, Opportunity took images measuring albedo (surface reflectivity) with the panoramic camera.

Sol 1686: Opportunity took morning, spot images of the sky and full-color, systematic, foreground images with the panoramic camera. Opportunity completed the day's drive and performed a "get quick fine attitude" to determine the rover's precise position relative to the Sun. After the drive, Opportunity acquired image mosaics with the navigation and panoramic cameras.

Sol 1687 (Oct. 21, 2008): Opportunity started the day by surveying the horizon with panoramic camera, searching for clouds with the navigation (which involves taking six time-lapse movie frames), and monitoring dust on the panoramic-camera mast assembly. The rover then continued driving and acquired images just before and after completing the drive with the navigation and panoramic cameras. Plans for the following day called for Opportunity to take spot images of the sky and make the usual measurements of atmospheric dust.

Odometry

As of sol 1687 (Oct. 21, 2008), Opportunity's total odometry was 12,677.65 meters (7.88 miles).


sol 1674-1680, October 08-14, 2008: Shake, Rattle, and Ready to Roll

Opportunity got some good vibrations going this week while trying to remove dust from the mirror of the miniature thermal emission spectrometer, an instrument that measures temperatures and detects minerals from a distance. Using low-level motor commands on the rover's 1,680th sol, or Martian day of exploration (Oct. 14, 2008), Opportunity created a short vibration to shake the instrument's external scan mirror. It was the first time Opportunity attempted such a feat, and scientists are analyzing the results.

Opportunity also got into position for the final imaging campaign at "Victoria Crater," driving onto a promontory known as "Cape Agulhas." From here, the rover acquired images of rocks exposed in a promontory known as "Cape Victory."

Other remote-sensing highlights of the week included measurements of argon gas in the atmosphere on sols 1675, 1677 and 1680 (Oct. 9, 11, and 14, 2008) and color images of an area of bedrock in front of the rover nickamed "Savu Sea" on sol 1676 (Oct. 10, 2008). Opportunity took images of a weathered rock exposure known as "Dauphin," surveyed the horizon, and took spot images of the sky for calibration purposes. The rover monitored dust on the panoramic-camera mast assembly, searched for clouds, and studied the atmosphere.

Opportunity remains healthy, with all subsystems performing as expected as of Martian day, or sol, 1680 (Oct. 14, 2008). Power has been averaging 616 watt-hours during the past week (100 watt-hours is the amount of energy needed to light a 100-watt bulb for one hour.)

Sol-by-sol summary

Besides measuring daily, dust-related changes in atmospheric clarity with the panoramic camera, Opportunity completed the following activities:

Sol 1674 (Oct. 8, 2008): During the day's drive, Opportunity acquired a 2-by-1 panel of images with the navigation camera. After the drive, Opportunity acquired a 5-by-1 tier of navigation-camera images, a 4-by-1 tier of forward-looking, panoramic-camera images, and a 5-by-1 tier of rearward-looking, navigation-camera images.

Sol 1675: In the morning, Opportunity surveyed the horizon with the panoramic camera. The rover took thumbnail images of the sky for calibration purposes with the panoramic camera and scanned the sky for clouds by acquiring four time-lapse images with the navigation camera. After relaying data to NASA's Odyssey orbiter to be transmitted to Earth, Opportunity measured atmospheric argon with the alpha-particle X-ray spectrometer.

Sol 1676: Opportunity acquired full-color images, using all 13 filters of the panoramic camera, of Savu Sea. The rover continued driving, acquiring a 2-by-1 panel of forward-looking images along the way with the navigation camera. After the day's drive, Opportunity took a 5-by-1 tier of images with the navigation camera, a 4-by-1 panel of images of the road ahead with the panoramic camera, and a 5-by-1 tier of rearward-looking images with the navigation camera.

Sol 1677: In the morning, Opportunity monitored dust accumulation on the rover mast. After sending data to Odyssey, Opportunity integrated measurements of atmospheric argon with the alpha-particle X-ray spectrometer.

Sol 1678: Opportunity acquired systematic, full-color images of the foreground with the panoramic camera. The rover spent much of the day recharging the battery.

Sol 1679: Opportunity took morning spot images of the sky for calibration purposes and a 2-by-1 panel of pre-drive images of Dauphin with the panoramic camera. The rover drove to the next imaging location on Cape Agulhas, acquiring a 2-by-1 panel of forward-looking images before ending the drive with the navigation camera. After the drive, Opportunity acquired a 3-by-1 standard tier and a 7-by-1 rearward-looking tier of images with the navigation camera. The rover transmitted data to Odyssey.

Sol 1680 (Oct. 14, 2008): Opportunity took spot images of the sky with the panoramic camera and searched for morning clouds with the navigation camera by pointing it skyward and acquiring a six-frame, time-lapse movie. Opportunity acquired a 3-by-1 panel of color images of Cape Victory with the panoramic camera and a high-resolution view of the rover deck with the navigation camera. The rover acquired images with the navigation camera to provide context for measurements by the miniature thermal emission spectrometer. Before shaking the spectrometer's mirror, Opportunity checked for drift (changes with time) in the instrument, conducted an operational test, and surveyed the ground and sky with the instrument for comparison purposes. Finally, Opportunity conducted the shake test, operating the motor in such a way as to vibrate the mirror in an effort to shake off dust. After sending test results and other data to Odyssey, Opportunity measured argon gas in the atmosphere with the alpha-particle X-ray spectrometer.

Odometry

As of sol 1679 (Oct. 13, 2008), Opportunity's corrected total odometry was 12,362.95 meters (7.68 miles).


sol 1669-1673, October 03-07, 2008: Preparing for the Road Trip of a Lifetime

Like a motorist preparing for a road trip, NASA's Opportunity rover is studying a "road atlas" of Mars, using details provided by a powerful camera in orbit above the red planet. Opportunity's road crew is poring over every detail of the landscape in images from the High-Resolution Imaging Science Experiment on board the Mars Reconnaissance Orbiter. Team members will use the data to select a route to "Endeavour Crater" 12 kilometers (7.5 miles) away.

Meanwhile, Opportunity continues traveling south around the rim of "Victoria Crater," stopping for photo shoots at selected locations along the way. During the past week, Opportunity drove a distance of 143 meters -- more than twice the wingspan of two Boeing 747's parked side by side. The rover acquired images of a promontory inside the crater known as "Cape Pillar" and began driving to another vantage point for taking images of a promontory known as "Cape Victory." Opportunity also studied the atmosphere, searched for Martian clouds, and scanned the rover's external dust-collection magnets.

Opportunity is healthy, with all subsystems performing as expected as of Martian day, or sol, 1673 (Oct. 7, 2008). Power has been superb, averaging 652 watt-hours during the past week (100 watt-hours is the amount of energy needed to light a 100-watt bulb for one hour.)

Sol-by-sol summary:

Besides measuring daily, dust-related changes in atmospheric clarity with the panoramic camera, Opportunity completed the following activities:

Sol 1669 (Oct. 3, 2008): Opportunity surveyed the sky at high Sun and worked on a systematic survey of the rover's surroundings using all 13 filters of the panoramic camera. The rover acquired a six-frame, time-lapse movie in search of clouds with the navigation camera. Before relaying data to NASA's Odyssey orbiter for transmission to Earth, Opportunity measured atmospheric dust with both the panoramic and navigation cameras.

Sol 1670: Opportunity searched for morning clouds by acquiring a six-frame, time-lapse movie with the navigation camera. The rover took thumbnail images of the morning sky for calibration purposes with the panoramic camera. Before starting the day's drive, Opportunity acquired a 4-by-1 panel of images with the panoramic camera. After the drive, the rover acquired a 2-by-1 and a 3-by-1 panel of images with the navigation camera.

Sol 1671: In the morning, Opportunity acquired a 6-by-1 tier of images of the terrain, overlapping the frames to compensate for dust on the lens of the panoramic camera. Using all 13 color filters of the panoramic camera, the rover conducted a systematic survey and acquired images of particles on the external magnets. After sending data to Odyssey, Opportunity measured atmospheric argon with the alpha-particle X-ray spectrometer.

Sol 1672: Opportunity acquired thumbnail images of the sky for calibration purposes with the panoramic camera and searched for morning clouds by acquiring six, time-lapse movie frames with the navigation camera. Opportunity surveyed the sky at high Sun with the panoramic camera, made another six-frame movie in search of clouds with the panoramic camera, and took more thumbnail images of the sky with the panoramic camera.

Sol 1673 (Oct. 7, 2008): Opportunity took thumbnail images of the morning sky for calibration purposes with the panoramic camera and produced a six-frame movie in search of clouds with the navigation camera. Opportunity continued driving south and completed a "get fine attitude" procedure to determine the rover's exact position relative to the Sun. After the drive and before sending data to Odyssey, Opportunity took a 2-by-1 and 5-by-1 panel of forward-looking images with the navigation camera, a 4-by-1 panel of images with the panoramic camera, and a rearward-looking, 5-by-1 mosaic of images with the navigation camera. Opportunity acquired a 3-by-1 and a 7-by-1 post-drive tier of images with the navigation camera as well as a 4-by-1 panel of images with the panoramic camera. Plans for the following day called for the rover to take thumbnail images of the sky with the panoramic camera and look for clouds with the navigation camera.

Odometry:

As of sol 1673 (Oct. 7, 2008), Opportunity's total odometry was 12,292.15 meters (7.64 miles).


sol 1661-1668, September 25 - October 02, 2008: Opportunity Takes a Victory Lap

A journey of 7.5 miles began with a partial victory lap around "Victoria Crater," as Opportunity headed south toward enormous "Endeavour Crater." Partway around the circuit, Opportunity passed the 7.5-mile mark of the mission. In metric terms, the rover began a 12,000-meter, cross-country trek by ending a similar 12,000-meter journey across uncharted terrain and in and out of craters.

Opportunity also chalked up the second-longest drive of the mission on sol 1663 (Sept. 27, 2008), advancing 153 meters (500 feet). Three days later, Opportunity drove another 129 meters (423 feet), on sol 1666 (Sept. 30, 2008).

Along the way, the rover took advantage of opportunities to explore rock layers and other features visible from the rim of Victoria Crater. The first drive of the trek on Martian day, or sol, 1661 (Sept. 25, 2008) included a drive-by photo shoot with the camera pointed at a small crater known as "Sputnik Crater" on the edge of Victoria. That drive covered 27 meters (89 feet).

Drive performance has been excellent, with very little wheel slippage on this terrain. As a result, Opportunity is now in position to approach Victoria Crater again. This time, the rover's itinerary will take it onto a promontory called "Cape Victory" for a photo shoot of rock layers visible in a neighboring promontory known as "Cape Pillar."

On its journey to the southeast, Opportunity will have route-planning assistance from super high-resolution images taken by the Mars Reconnaissance Orbiter. Rover operators will use the images, which reveal details as small as individual boulders, to plot the safest path.

Opportunity remains healthy, with all subsystems performing as expected as of Martian day, or sol, 1666 (Sept. 30, 2008). Power continues to improve, with sunlight generating 654 watt-hours of solar energy -- enough to light a 100-watt bulb for 6.5 hours (100 watt-hours is the amount of energy needed to light a 100-watt bulb for one hour.)

Sol-by-sol summary:

Besides measuring daily, dust-related changes in atmospheric clarity with the panoramic camera, Opportunity completed the following activities:

Sol 1661 (Sept. 25, 2008): Midway through the sol's drive, Opportunity acquired a 3-by-1 panel of images of Sputnik using the navigation camera. The rover acquired a 2-by-1 panel of forward-looking images with the navigation camera. Before relaying data to NASA's Odyssey orbiter for transmission to Earth, Opportunity took several tiers of post-drive images, including a 4-by-1 tier with the panoramic camera as well as 3-by-1 and 7-by-1 tiers with the navigation camera.

Sol 1662: In the morning, Opportunity took thumbnail images of the sky for calibration purposes with the panoramic camera. After sending data to Odyssey, Opportunity measured argon gas in the Martian atmosphere using the alpha-particle X-ray spectrometer.

Sol 1663: Opportunity searched for morning clouds by acquiring six, freeze-frame images to be stitched together into a movie. Before the day's drive, Opportunity acquired a 3-by-1 mosaic of images of Sputnik, an image of another small crater nicknamed "Gauss," and a ripple profile with the panoramic camera. Opportunity made the second-longest, single-day drive of the mission, traveling a distance of 152 meters (449 feet). The rover acquired rearward-looking images of the ground near its wheels with the hazard-avoidance cameras and relayed data to Odyssey.

Sol 1664: Opportunity searched for morning clouds by acquiring six movie frames with the navigation camera. The rover acquired a 2-by-1 panel of forward-looking images with the navigation camera. After driving another 129 meters (423 feet), Opportunity acquired a 3-by-1 tier of navigation-camera images and a 7-by-1 and 6-by-1 tier of panoramic-camera images. Using all 13 color filters of the panoramic camera, Opportunity completed a systematic survey and took images of the external magnets. After sending data to Odyssey, the rover measured atmospheric argon.

Sol 1665: In the morning, Opportunity took spot images of the sky for calibration purposes with the panoramic camera. The rover surveyed the sky at high Sun and also measured albedo -- surface brightness -- with the panoramic camera. After relaying data to Odyssey, Opportunity measured argon gas in the atmosphere with the alpha-particle X-ray spectrometer.

Sol 1666: Opportunity took morning thumbnail images of the sky for calibration purposes with the panoramic camera. In conjunction with the day's drive, the rover took a 2-by-1 panel of forward-looking images with the navigation camera. Opportunity acquired a 3-by-1 and a 7-by-1 post-drive tier of images with the navigation camera as well as a 4-by-1 panel of images with the panoramic camera. After sending data to Odyssey, Opportunity measured atmospheric argon. Plans for the following day called for the rover to take spot images of the sky with the panoramic camera, monitor dust accumulation on the rover mast, and acquire a six-frame movie in search of Martian clouds.

Sol 1667: Plans called for Opportunity to continue monitoring atmospheric dust, complete a systematic survey with the panoramic camera, and send data to Odyssey.

Sol 1668 (Oct. 2, 2008): Plans called for Opportunity to survey the horizon and acquire forward-looking images with the panoramic camera, drive toward the north end of Cape Victory, acquire a 2-by-1 and two 5-by-1 tiers of post-drive images with the navigation camera, measure atmospheric dust at sunset, and send data to Odyssey. The following morning, the rover was to monitor atmospheric dust with the panoramic camera, supplement those measurements with monitoring by the navigation camera, and take thumbnail images of the sky with the panoramic camera.

Odometry:

As of sol 1666 (Sept. 30, 2008), Opportunity's total odometry was 12,188.15 meters (7.53 miles).


sol 1655-1660, September 19-24, 2008: Road Trip Gets Under Way

Opportunity has embarked on the next great challenge -- a journey of 12 kilometers (7.5 miles) southeast to a huge hole in the ground nicknamed "Endeavour Crater." Measuring 22 kilometers (14 miles) from rim to rim and plunging 300 meters (1,000 feet) below the surface, Endeavour Crater is significantly larger than "Victoria Crater," which is 730 meters (almost half a mile) wide and 70 meters (200 feet) deep. Because it is so much deeper, Endeavour promises to expose even more rock layers going further back in time.

Opportunity's trek began on sol 1659 (Sept. 23, 2008), as the rover backed away from a slippery ripple and advanced 10 meters (30 feet) toward its destination. The journey to Endeavour will be long. Opportunity is sure to encounter many interesting science opportunities along the way.

During the previous week, Opportunity's wheels slipped excessively while trying to cross a ripple to reach a patch of dust on the ripple's downwind side. After two tries on sols 1652 (Sept. 16, 2008) and 1654 (Sept. 18, 2008), rover operators decided to resume driving and look for other deposits of Martian dust in more accessible locations.

Opportunity remains healthy. All subsystems are performing as expected as of Martian day, or sol, 1660 (Sept. 24, 2008). Power is on the rise, with sunlight generating 623 watt-hours of solar energy -- enough to light a 100-watt bulb for more than 6 hours (100 watt-hours is the amount of energy needed to light a 100-watt bulb for one hour.)

Sol-by-sol summary:

Besides measuring daily, dust-related changes in atmospheric clarity with the panoramic camera, Opportunity completed the following activities:

Sol 1655 (Sept. 19, 2008): Opportunity acquired full-color images, using all 13 filters of the panoramic camera, of a target dubbed "Velvet." Opportunity took images of the tracks made by the rover's wheels with the navigation camera.

Sol 1656: Opportunity acquired a 5-by-1 panel of images with the navigation camera and a 10-by-1 panel of images with the panoramic camera. After relaying data to NASA's Odyssey orbiter as it passed overhead for transmission to Earth, Opportunity measured atmospheric dust at sunset with the panoramic camera. The rover measured argon gas in the Martian atmosphere with the alpha-particle X-ray spectrometer.

Sol 1657: In the morning, Opportunity monitored dust on the panoramic-camera mast assembly. The rover took panoramic-camera images of its tracks and, after sending data to Odyssey, measured atmospheric argon with the alpha-particle X-ray spectrometer.

Sol 1658: Following several measurements of atmospheric dust at different times of day, Opportunity relayed data to Odyssey and used the alpha-particle X-ray spectrometer to determine the amount of atmospheric argon.

Sol 1659: In the morning, Opportunity took thumbnail images as well as spot images of the sky for calibration purposes with the panoramic camera. Opportunity then began the trek to Endeavour, driving almost 10.5 meters (34 feet). The rover acquired images of the surrounding terrain with the navigation camera just before and just after ending the drive. After sending data to Odyssey, the rover measured atmospheric argon.

Sol 1660 (Sept. 24, 2008): Opportunity surveyed the morning horizon with the panoramic camera and acquired six, time-lapse movie frames in search of clouds with the navigation camera. At high Sun, Opportunity surveyed the sky with the panoramic camera. Before relaying data to Odyssey, Opportunity took images of the rover's wheel tracks with the panoramic camera.

Odometry:

As of sol 1659 (Sept. 23, 2008), Opportunity's total odometry was 11,808.39 meters (7.34 miles).


sol 1648-1654, September 12-18, 2008: Slipping Like a Dune Buggy

During the past week, Opportunity has been trying to reach a patch of dust between two crests of the ridge surrounding "Victoria Crater." The rover approached the ridge from the west, driving on flat ground, on Martian days, or sols, 1648 and 1650 (Sept. 12 and Sept. 14, 2008). Then, after reaching a staging position, Opportunity began to climb the ridge. That's when the rover's wheels began slipping excessively on the sandy slope.

Rover drivers decided to give Opportunity another chance to make it up the slope by loosening the slip constraints. This allowed Opportunity to keep trying to climb the slope with a higher rate of wheel slippage. If the attempt to do this as planned on sol 1654 (Sept. 18, 2008) is not successful, rover drivers may try a different approach or abandon the effort.

After the dust patch campaign, plans call for Opportunity to drive south toward a 20-kilometer-wide (12-mile-wide) crater 12 kilometers (7.5 miles) away.

Opportunity is healthy, and all subsystems are performing as expected. Based on the latest data from sol 1653 (Sept. 17, 2008), the rover has 582 watt-hours of solar power available each day. (One hundred watt-hours is the amount of energy needed to light a 100-watt bulb for one hour.)

Sol-by-sol summary:

In addition to measuring dust-related changes in atmospheric clarity each day with the panoramic camera, Opportunity completed the following activities:

Sol 1648 (Sept. 12, 2008): Opportunity stowed the robotic arm and began driving toward the dust patch. Just before and after ending the drive, Opportunity took images with the hazard-avoidance and navigation cameras, respectively. The rover acquired a 4-by-1 panel of images, called the "Bagnold mosaic," with the panoramic camera.

Sol 1649: Opportunity took full-color images, using all 13 filters of the panoramic camera, of a target nicknamed "Drummond." After relaying data to NASA's Odyssey orbiter for transmission to Earth, Opportunity measured argon gas in the Martian atmosphere with the alpha-particle X-ray spectrometer.

Sol 1650: In the morning, Opportunity took thumbnail images of the sky with the panoramic camera. The rover continued driving toward the dust patch and documented progress before and after ending the drive by taking images with the engineering cameras. Opportunity acquired another 4-by-1 panel of images for the Bagnold mosaic before sending data to Odyssey.

Sol 1651: Opportunity searched for morning clouds in the Martian sky by taking six time-lapse, movie frames with the navigation camera. The rover took spot images of the sky for calibration purposes, surveyed the horizon, and surveyed the sky at low Sun with the panoramic camera.

Sol 1652: In the morning, Opportunity searched for clouds passing overhead by taking six time-lapse, movie frames with the navigation camera. The rover checked for drift -- changes with time -- in the miniature thermal emission spectrometer and also conducted a test of the instrument. Before beginning the day's drive, Opportunity used the spectrometer to study a target dubbed "Velvet" and survey the sky and ground at different elevations. The rover then attempted to drive up the ridge to the dust patch, acquiring images along the way with the hazard-avoidance and navigation cameras. Opportunity sent data to Odyssey for transmission to Earth.

Sol 1653: Opportunity acquired a 3-by-1 mosaic of westward-looking images with the navigation camera and took images in total darkness with the panoramic camera for calibration purposes.

Sol 1654 (Sept. 18, 2008): Upon rising, Opportunity took more "dark current" images with the panoramic camera for calibration purposes. The rover tried once more to drive to the dust patch, taking images before and after ending the drive with the hazard-avoidance and navigation cameras. Before proceeding with plans to measure atmospheric argon, Opportunity transmitted data to Odyssey for relay to Earth.

Odometry:

As of sol 1653 (Sept. 17, 2008), Opportunity's total odometry was 11,796.22 meters (7.33 miles).


sol 1641-1647, September 04-11, 2008: Playing in the Sand

During the past week, Opportunity performed several tests of the robotic arm to learn how to use it with a disabled shoulder joint. Having successfully completed those tests, Opportunity is moving on to investigate some bright patches of dust. Scientists hope to ascertain if the patches contain material not thoroughly analyzed in the past.

On sol (Martian day) 1641 (Sept. 4, 2008), Opportunity homed in on an area of sand that appeared to contain a high concentration of dust. For the next several days, sols 1642-1647 (Sept. 5-11, 2008), the rover tested the robotic arm's ability to place scientific instruments on specific targets in the sand. These instruments included the Mössbauer spectrometer, microscopic imager, and alpha-particle X-ray spectrometer. Tests revealed that the robotic arm placed the instruments in position with very little error in spite of the disabled shoulder joint. Because the dust was not pure enough to yield the desired scientific results, engineers decided on sol 1648 (Sept. 12, 2008) to drive the rover north to a more promising area of apparent dust patches.

On sol 1644 (Sept. 7, 2009), Opportunity relayed data at UHF frequencies to NASA's Mars Reconnaisance Orbiter (MRO). Typically, the rover sends data to NASA's Odyssey orbiter for transmission to Earth. Once a month, Opportunity is relaying data to the Mars Reconnaissance Orbiter in preparation for using it more in the future.

Opportunity is healthy, with all subsystems performing as expected as of the most recent transfer of information from NASA's Odyssey orbiter on sol 1647 (Sept. 11, 2008). Power rose to 652 watt-hours (enough energy to light a 100-watt bulb for a tad longer than 6.5 hours).

Sol-by-sol summary:

Each Martian day, or sol, Opportunity measured dust-related changes in atmospheric clarity with the panoramic camera. In addition, Opportunity completed the following activities:

Sol 1641 (Sept. 4, 2008): Before driving, Opportunity acquired a 3-by-1 panel of panoramic-camera images looking north. The rover then nudged toward a bright patch and, after stopping, acquired images of the ground near its wheels and the area directly ahead with the hazard-avoidance and navigation cameras, respectively. The rover relayed data to Odyssey.

Sol 1642: In the morning, Opportunity took thumbnail images and spot images of the sky for calibration purposes with the panoramic camera. Next, the rover tested movement and placement of the Mössbauer spectrometer, taking images near the ground with the hazard-avoidance cameras and images from above with the panoramic camera. Opportunity then used the Mössbauer spectrometer to acquire compositional data from a sand dune on the rim of "Victoria Crater." After relaying data to Odyssey, Opportunity went into a mini-deep sleep.

Sol 1643: Opportunity acquired six, time-lapse movie frames in search of morning clouds with the navigation camera. Opportunity continued to acquire data from the sand dune at the rim of Victoria Crater with the Mössbauer spectrometer. Opportunity took full-color images, using all 13 color filters of the panoramic camera, of the rover's tracks. After sending data to Odyssey, Opportunity went into a mini-deep sleep.

Sol 1644: Opportunity acquired six, time-lapse movie frames in search of clouds. The rover continued to collect data from the dune on the rim of Victoria Crater using the Mössbauer spectrometer. Before communicating with Odyssey, Opportunity relayed data to the Mars Reconnaissance Orbiter for transmission to Earth. After sending data to Odyssey, the rover went into a mini-deep sleep.

Sol 1645: In the morning, Opportunity acquired six, time-lapse movie frames in search of clouds with the navigation camera. Opportunity acquired a 1-by-3-by-15 stack of microscopic images of ripple soil. The rover restarted the Mössbauer spectrometer and began collecting data from the soil in the ripples. After transmitting data to Odysssey, Opportunity acquired a 3-by-1 panel of images of a target dubbed "Schuchert."

Sol 1646: Opportunity monitored dust accumulation on the panoramic-camera mast assembly and restarted the Mössbauer spectrometer for collecting data on the ripple soil. The rover used the miniature thermal emission spectrometer to complete a mini-survey of the sky and ground. Before sending data to Odyssey, Opportunity used the spectrometer to characterize the external calibration target.

Sol 1647 (Sept. 11, 2008): Opportunity acquired more time-lapse, movie frames to document potential clouds passing overhead. The rover took a 3-by-1 panel of images of Schuchert with the panoramic camera and a time-lapse movie in search of clouds. Opportunity placed the alpha-particle X-ray spectrometer on the ripple soil and, after sending data to Odyssey, acquired compositional data. Plans for the following morning called for the rover to study a cobble field, acquiring a 4-by-1 panel of images with the panoramic camera.

Odometry:

As of sol 1647 (Sept. 11, 2008), Opportunity's total odometry was 11,782.10 meters (7.32 miles).


sol 1634-1640, August 28-September 03, 2008: Farewell, "Victoria"!

Opportunity has completed one of the most fantastic scientific campaigns of the Mars Exploration Rover mission -- the interior investigation of "Victoria Crater." After spending more than 340 Martian days, known as sols -- almost one Earth year -- inside the crater, Opportunity climbed back out on sol 1634 (Aug. 28, 2008). To do so, Opportunity retraced the wheel tracks the robotic geologist had made while crossing a large sand ripple and entering Victoria on the slopes of an alcove known as "Duck Bay."

From the crater rim, Opportunity gave a final salute to Victoria, raising its robotic arm on sol 1639 (Sept. 2, 2008) and taking a snapshot of its shadow with the front hazard-avoidance cameras. The rover completed the salute by swinging the arm at its elbow joint back to the starting position.

Opportunity then got into position to practice using an ailing shoulder joint on the robotic arm. The shoulder joint had begun showing signs of degradation on sol 1502 (April 15, 2008). Rover operators selected the large sand ripple at the lip of Victoria Crater as an opportune target. There, the rover will practice learning to use the arm again.

Remote sensing highlights of the week included taking images of the tracks Opportunity left behind on the plains more than a year ago as well as color images of a nearby cobble called "Isle Royale." The rover also acquired images of a planned study area known as "Bright Spot" because of the large amount of sunlight reflected from its surface. Along the way, Opportunity continued to study the Martian atmosphere and clouds.

Opportunity is healthy, with all subsystems performing as expected as of the most recent transfer of information from NASA's Odyssey orbiter on sol 1640 (Sept. 3, 2008). Power has been excellent throughout this period, averaging about 621 watt-hours (enough energy to light a 100-watt bulb for more than 6 hours).

Sol-by-sol summary:

Each Martian day, or sol, Opportunity measured dust-related changes in atmospheric clarity with the panoramic camera. In addition, Opportunity completed the following activities:

Sol 1634 (Aug. 28, 2008): While driving, Opportunity took snapshots of its journey. After the day's drive, the rover acquired images of the surrounding terrain and the surface near its wheels with the navigation and hazard-avoidance cameras. After relaying data to the Odyssey orbiter for transmission to Earth, Opportunity measured argon gas in the Martian atmosphere with the alpha-particle X-ray spectrometer.

Sol 1635: Opportunity searched for morning clouds with the navigation camera, acquiring six, time-lapse frames for a movie.

Sol 1636: Upon awakening, Opportunity acquired another six-frame, time-lapse movie in search of clouds with the navigation camera. The rover monitored dust accumulation on the panoramic-camera mast assembly and took images of the ripple at the lip of Victoria Crater with the panoramic camera. Opportunity took full-color images of Isle Royale, using all 13 color filters of the panoramic camera. After relaying data to Odyssey, Opportunity spent 5 hours and 20 minutes measuring argon gas in the atmosphere using the alpha-particle X-ray spectrometer.

Sol 1637: After the day's drive, Opportunity completed a "get fine attitude," during which the rover compared its precise location relative to the Sun with the position indicated by the on-board, inertial measurement unit. Following the drive, Opportunity took images with the hazard-avoidance and navigation cameras. The rover acquired a full, 360-degree panorama of the area with the navigation camera. After communicating with Odyssey, Opportunity went into a deep sleep.

Sol 1638: In the morning, Opportunity surveyed the horizon with the panoramic camera. After sending data to Odyssey, the rover went into a deep sleep.

Sol 1639: Before beginning the day's drive, Opportunity took images of "Bright Patch Two" with the panoramic camera. Opportunity approached the large sand ripple on the rim of Victoria and took post-drive images with the hazard-avoidance and navigation cameras. After relaying data to Odyssey, the rover measured atmospheric argon with the alpha-particle X-ray spectrometer. Opportunity then went into a mini-deep sleep.

Sol 1640 (Sept. 3, 2008): Opportunity acquired more images of Bright Patch Two as well as a 360-degree panorama of the area with the navigation camera. After sending data to Odyssey, the rover went into a deep sleep.

Odometry:

As of sol 1639 (Sept. 2, 2008), Opportunity's estimated total odometry was 11,781.51 meters (7.32 miles).


sol 1627-1633, August 21-27, 2008: Poised to Exit "Victoria"

During the past week, Opportunity traversed almost 15 meters (49 feet) of upward-sloping, alternately rocky and sandy terrain on the way out of "Victoria Crater." The drive put Opportunity in position to make one last push over the final obstacle -- a ripple surrounding the alcove known as "Duck Bay."

Remote-sensing highlights included panoramic-camera images of weathered rock exposures known as "Barghoorn," "Dawson," and "Eugster." Other achievements were two surveys of the sky at high Sun and one survey of the horizon. Opportunity shot several time-lapse movies in search of clouds and rounded out the week's activities with a variety of atmospheric observations.

Opportunity is healthy, with all subsystems performing as expected as of the latest downlink from NASA's Odyssey orbiter on sol 1633 (Aug. 27, 2008). Power has been excellent throughout this period, averaging about 613 watt-hours (enough energy to light a 100-watt bulb for more than 6 hours).

Sol-by-sol summary:

Each Martian day, or sol, Opportunity measured dust-related changes in atmospheric clarity with the panoramic camera. Opportunity also completed the following activities:

Sol 1627 (Aug. 21, 2008): Opportunity implemented the "runout" portion of an earlier master sequence of commands following a glitch in transmissions from Earth.

Sol 1628: Opportunity surveyed the sky at high Sun and acquired a 2-by-1 image mosaic of Barghoorn with the panoramic camera.

Sol 1629: After relaying data to NASA's Odyssey orbiter for transmission to Earth, Opportunity integrated measurements of argon gas in the Martian atmosphere using the alpha-particle X-ray spectrometer.

Sol 1630: Opportunity completed a morning survey of the horizon with the panoramic camera. After driving closer to the rim of Victoria Crater, Opportunity took images of the ground near the rover's wheels and the area in front of the rover with the hazard-avoidance and navigation cameras, respectively. The rover acquired a 5-panel image mosaic of the local scenery with the navigation camera.

Sol 1631: In the morning, Opportunity took spot images of the sky for calibration purposes with the panoramic camera. Opportunity surveyed the sky at high Sun and acquired a 2-by-1 panel of images of Dawson as well as a 2-by-1 panel of Eugster with the panoramic camera. The rover relayed data to Odyssey.

Sol 1632: Upon greeting the rising Sun, Opportunity surveyed the sky with the panoramic camera. Opportunity then searched for morning clouds by acquiring six, time-lapse movie frames with the navigation camera. Midway through the day's drive, Opportunity paused to take a navigation-camera image of the terrain ahead. At the end of the drive, the rover took images of the ground near its wheels and the terrain ahead with the hazard-avoidance and navigation cameras, respectively. Opportunity compiled a 3-by-1, post-drive mosaic of images of the rover's surroundings. Anticipating a large tilt in the rover's new parking space, Opportunity made sure the panoramic camera was not pointed above the horizon. After relaying data to Odyssey, Opportunity went into a deep sleep.

Sol 1633 (Aug. 27, 2008): Opportunity produced another time-lapse movie in search of morning clouds with the navigation camera. The rover completed a systematic survey of the ground in full color with the panoramic camera. Anticipating a large tilt in-between activities, the rover made sure the panoramic camera was not pointed above the horizon. After sharing the latest news from Mars with Odyssey, Opportunity went into a deep sleep. Plans for the following sol called for the rover to produce a six-frame, time-lapse movie in search of clouds immediately upon wakening.

Odometry:

As of sol 1632 (Aug. 26, 2008), Opportunity's estimated total odometry was 11,770.38 meters (7.30 miles).


sol 1621-1626, August 15-20, 2008: On the Exit Ramp

Opportunity is now about 12.5 meters (41.0 feet) from the place where engineers plan to drive the rover out of "Victoria Crater." During the past week, Opportunity traveled about 17 meters (56 feet), successfully crossing about 10 meters (30 feet) of sandy terrain and a portion of rocky outcrop. Once the rover reaches the exit point, Opportunity will still need to cross the ripple surrounding the inward-sloping alcove known as "Duck Bay.

Power has been excellent, averaging more than 510 watt-hours (on Earth, that's enough energy to light a 100-watt bulb for 5 hours and 6 minutes).

Science observations during the past week included taking images of weathered rock exposures nicknamed "du Toit" and "Logan" as well as full-color images of the cobble known as "Jin" with the panoramic camera. Opportunity measured trace amounts of argon gas in the Martian atmosphere on sol 1623 (Aug. 17, 2008) using the alpha-particle X-ray spectrometer and surveyed rock clasts on sol 1626 (Aug. 20, 2008) using the panoramic camera.

Opportunity is healthy, with all subsystems performing as expected as of the latest downlink from NASA's Odyssey orbiter on sol 1626 (Aug. 20, 2008).

Sol-by-sol summary:

Each sol, Opportunity measured dust-related changes in atmospheric clarity with the panoramic camera. In addition, Opportunity completed the following activities:

Sol 1621 (Aug. 15, 2008): Just before and after ending the day's drive, Opportunity took images of the Martian surface near the rover's wheels with the hazard-avoidance cameras. After the drive, Opportunity took three image mosaics of the surrounding terrain -- two looking ahead and one looking back -- with the navigation camera.

Sol 1622: Upon wakening, Opportunity took spot images of the sky for calibration purposes with the panoramic camera. Opportunity next measured atmospheric opacity (known as tau) with both the navigation and panoramic cameras. Then, Opportunity surveyed the sky at high Sun and acquired thumbnail images of the sky with the panoramic camera.

Sol 1623: Opportunity started the day by taking six, freeze-frame images with the navigation camera for a movie in search of clouds. After acquiring panoramic-camera images of the rock target nicknamed Logan, Opportunity went for a drive. Just before and after ending the drive, the rover took hazard-avoidance-camera images of the surface next to its wheels. Following the drive, Opportunity also acquired two image mosaics of surrounding terrain with the navigation camera. After relaying data to Odyssey to be transmitted to Earth, Opportunity measured atmospheric argon with the alpha-particle X-ray spectrometer.

Sol 1624: Opportunity surveyed the horizon in the morning and surveyed the sky at high Sun with the panoramic camera.

Sol 1625: First thing in the Martian morning, Opportunity took spot images of the sky with the panoramic camera and acquired six, time-lapse movie frames in search of clouds with the navigation camera. Opportunity then began the day's drive. Upon reaching the end of the drive, Opportunity acquired two image mosaics of the surrounding terrain with the navigation camera. The rover also inspected the surface near its wheels with the hazard-avoidance cameras.

Sol 1626 (Aug. 20, 2008): Opportunity was about 12.5 meters (41.0 feet) from the rover's exit point out of Victoria Crater. Early in the morning, Opportunity took spot images of the sky for calibration purposes with the panoramic camera and monitored dust accumulation on the rover mast. Using all 13 color filters of the panoramic camera, Opportunity completed a systematic ground survey, took images of Jin and completed a survey of nearby rock clasts. Plans for the following morning called for Opportunity to survey the horizon with the panoramic camera.

Odometry:

As of sol 1626 (Aug. 20, 2008), Opportunity's total odometry was 11,755.61 meters (7.30 miles).


sol 1614-1620, August 8-14, 2008: Opportunity Eyes Challenges Ahead

Opportunity faces several challenges on the way out of "Victoria Crater" but continues to make steady progress. The first of these is a traverse of approximately 10 meters (30 feet, a little longer than a double-decker bus) across a sandy, 17-degree slope. Opportunity is more than halfway through that part of the journey. The next is a drive across 30 to 50 meters (100 to 160 feet), depending on the route taken, of rocky outcrop. The final leg of the climb will require Opportunity to cross the ripple surrounding the alcove known as "Duck Bay."

Because Opportunity is facing the threat of a drive-motor failure on the left front wheel, the engineering team has been working on pseudo-"Mars time" for the past week to take advantage of extra drive opportunities.

Opportunity remains healthy, with all subsystems performing as expected as of the downlink of information from NASA's Odyssey orbiter on sol 1620 (Aug. 14, 2008).

Sol-by-sol summary:

In addition to measuring daily, dust-related changes in atmospheric clarity with the panoramic camera, Opportunity completed the following activities:

Sol 1614 (Aug. 8, 2008): Opportunity took offset, thumbnail images of the sky with the panoramic camera for calibration purposes. With the navigation camera, Opportunity acquired images and six, time-lapse, movie frames in search of clouds. Just before and after ending the day's drive, Opportunity took rearward-looking images with the hazard-avoidance cameras. The rover relayed data to NASA's Odyssey orbiter for transmission to Earth.

Sol 1615: In the morning, Opportunity took six, time-lapse, movie frames in search of clouds with the navigation camera and monitored dust on the rover mast. Opportunity acquired image mosaics of targets dubbed "Dawson" and "Barrell" using the panoramic camera. The rover relayed data to Odyssey to be transmitted to Earth.

Sol 1616: Opportunity drove 3.05 meters (10.0 feet), stopping mid-drive to acquire images with the navigation camera. The rover acquired images of the surface next to its wheels with the hazard-avoidance cameras as well as two post-drive image mosaics -- a 2-by-1 and 5-by-1 panel -- of its surroundings with the navigation camera.

Sol 1617: In the morning, Opportunity completed a survey of rock clasts with the panoramic camera. Before sending data to Odyssey, the rover acquired images with the rear hazard-avoidance cameras.

Sol 1618: Opportunity acquired a 2-by-2 mosaic of images with the panoramic camera before driving another 3.17 meters (10.4 feet). Just before and after ending the drive, Opportunity took images with the hazard-avoidance and navigation cameras.

Sol 1619: Opportunity took spot images of the sky for calibration purposes with the panoramic camera. After completing the daily assessment of atmospheric dust, Opportunity drove 1.04 meters (3.41 feet). Just before and after ending the drive, the rover took images with the hazard-avoidance cameras of the ground near its wheels. After the drive, Opportunity acquired a 2-by-1 and a 5-by-1 image mosaic of its new location with the navigation camera. The rover communicated with Odyssey before going to sleep.

Sol 1620 (Aug. 14, 2008): In the morning, Opportunity acquired six, time-lapse, movie frames in search of clouds with the navigation camera as well as spot images of the sky with the panoramic camera. Later in the day, Opportunity took thumbnail images of the sky and completed a sky survey at high Sun with the panoramic camera. Plans for the following morning called for Opportunity to acquire panoramic-camera images of a rock target known as "du Toit."

Odometry:

As of sol 1619 (Aug. 13, 2008), Opportunity's total odometry was 11,735.83 meters (7.29 miles).


sol 1607-1613, July 31-August 7, 2008: Heading for the Highway!

As stated in last week's report, rover operators have decided it's time for Opportunity to begin exiting "Victoria Crater." Their decision was motivated by concerns about a spike in electrical current drawn by the rover's left front wheel on Martian day, or sol, 1600 (July 24, 2008). Since then, the wheel has returned to normal operation, but engineers and scientists remain concerned that the wheel might come close to failing. If that happens, they would like to have the rover out of the crater.

Originally, Opportunity was to start driving out of the crater over the weekend, on sols 1608-1610 (Aug. 1-Aug. 4, 2008). In the morning of sol 1608, however, a flight software reset prompted Opportunity to reboot its computer and remain in a state called automode. In automode, the rover halts all activity and waits for new instructions from Earth.

On sols 1611-1612 (Aug. 5-6, 2008), engineers recovered the vehicle and again transmitted instructions for continued driving out of the crater. The drive began with some sharp turns to change Opportunity's heading, but was stymied somewhat by the right front wheel when it became slightly mired in loose material on the surface. The following Martian day, sol 1613 (Aug. 7, 2008), rover drivers took a slightly different tack, directing Opportunity to drive backward to extract the wheel from the small hole it had dug. Early analysis indicated that the strategy worked and Opportunity was on track to resume driving out of the crater.

Opportunity remains healthy, with all subsystems performing as expected as of sol 1613.

Sol-by-sol summary

In addition to measuring dust-related changes in atmospheric clarity each day with the panoramic camera and relaying data to NASA's Odyssey orbiter for transmission to Earth, Opportunity completed the following activities:

Sol 1607 (July 31, 2008): While following instructions for the day's drive, Opportunity documented progress by taking images with the hazard-avoidance and navigation cameras. After communicating with Odyssey, Opportunity went into a deep sleep.

Sol 1608: In the morning, Opportunity surveyed the Martian sky at high Sun with the panoramic camera. Following a flight software reset, Opportunity went into automode, ceasing all activity to await new instructions from Earth.

Sol 1609: Opportunity remained in automode.

Sol 1610: Opportunity remained in automode.

Sol 1611: Upon receiving new instructions from Earth, Opportunity recovered from automode and returned to normal operations. Opportunity acquired a 27-frame, panoramic image mosaic of the cliff known as "Cape Verde" at dusk with the right lens of the panoramic camera. After communicating with Odyssey, Opportunity acquired the other half of the 3-D panorama, a 27-frame image mosaic of the same scene as viewed through the left-hand lens of the panoramic camera.

Sol 1612: In the morning, Opportunity took spot images of the sky for calibration purposes with the panoramic camera, as well as a four-frame movie of potential clouds with the navigation camera. Afterward, Opportunity began to change its heading by making sharp, circular turns with its wheels. The rover completed a "get fine attitude" to pinpoint its position relative to the Sun. To document progress, Opportunity acquired images with the hazard-avoidance cameras and a 2-by-1 tier of images with the navigation camera. The rover acquired a 3-by-1 image mosaic of the terrain ahead with the navigation camera.

Sol 1613 (Aug. 7, 2008): In the morning, Opportunity acquired a 5-by-1 image mosaic with the navigation camera. Opportunity then drove backward to extract its right front wheel from a small hole it had dug into the Martian surface. To document progress, the rover took images with the hazard-avoidance and navigation cameras. Opportunity also acquired a panoramic mosaic of the drive ahead with the navigation camera. Plans for the following morning called for the rover to acquire a six-frame, time-lapse movie in search of clouds with the navigation camera.

Odometry

As of sol 1612 (Aug. 6, 2008), Opportunity's total odometry remained at 11,726.21 meters (7.29 miles).


sol 1600-1613, July 25-30, 2008: Opportunity to Exit "Victoria Crater"

Like a backpacker hiking up a steep grade, Opportunity has been trying to gain elevation using a "switchback" approach inside "Victoria Crater." The rover's goal was to zigzag back and forth across a steep slope toward an outcrop nicknamed "Nevada," where scientists had hoped to do scientific analysis and collect high-resolution, panoramic images of the cliff face known as "Cape Verde."

It was not to be. On Opportunity's 1,600th Martian day (July 24, 2008) of exploration, the motor on the left front wheel suddenly drew an unexpectedly high level of current that exceeded the maximum limit. The incident was unusual, and the rover immediately halted the drive. A similar event had occurred just prior to the failure of the right front wheel on Spirit, Opportunity's twin on the opposite side of Mars.

On Martian day, or sol, 1602 (July 26, 2008), rover engineers conducted tests of electrical resistance to determine if the motor on Opportunity's left front wheel had a short or an open circuit. They also steered the wheel and looked for unseen, natural obstructions near the wheel. Results from both tests indicated no problems. Engineers next performed a more aggressive set of tests on sol 1604 (July 28, 2008) by commanding Opportunity to rotate the wheel using the motor that generated the anomaly. Again, test results showed no issues.

Engineers have not yet determined what caused the anomaly. Though the wheel appears to have gone back to functioning normally, the condition of its drive motor is uncertain. Because of concerns that the rover might not be able to get out of the crater using only five wheels should the left front wheel fail, team members have decided not to continue toward Nevada. Instead, they plan to finish collecting images of Cape Verde from the rover's current position, then leave the crater as quickly as possible.

During the past week, Opportunity also took several panoramic-camera images of targets along the face of Cape Verde and completed two measurements of argon in the Martian atmosphere using the alpha-particle X-ray spectrometer. Scientists use the measurements of changing argon levels to map seasonal air flows.

Otherwise, Opportunity is healthy and all subsystems are performing as expected. The latest available power readings from sol 1605 (July 29, 2008) showed power at 377 watt-hours (400 watt-hours would be enough energy to light a 100-watt bulb for four hours).

Sol-by-sol summary

In addition to making daily measurements of dust-related changes in visibility with the panoramic camera, Opportunity completed the following activities:

Sol 1600 (July 25, 2008): While driving toward Nevada, Opportunity's left front wheel drew unexpectedly high electrical current. Opportunity acquired images during and after the drive with the hazard-avoidance and navigation cameras. The rover relayed data to NASA's Odyssey orbiter for transmission to Earth.

Sol 1601: Opportunity acquired full-color images, using all 13 filters of the panoramic camera, of rock exposures dubbed "Playfair," "Eugene Smith," and "King."

Sol 1602: First thing in the morning, Opportunity acquired four, time-lapse, movie frames in search of clouds with the navigation camera. Opportunity conducted diagnostic tests of the left-front-wheel motor in search of electrical shorts or open circuits. The rover also steered the wheel and then acquired images in search of terrain obstructions with the hazard-avoidance and panoramic cameras. After sending data to Odyssey, the rover integrated measurements of atmospheric argon using the alpha-particle X-ray spectrometer.

Sol 1603: Opportunity took images with the rear hazard-avoidance cameras and a 5-by-1 tier of images with the navigation camera.

Sol 1604: Upon awakening, Opportunity took thumbnail images of the sky for calibration purposes with the panoramic camera. Opportunity performed more diagnostic tests, rotating the left front wheel and taking images with the hazard-avoidance cameras. After sending data to Odyssey, the rover measured atmospheric argon with the alpha-particle X-ray spectrometer.

Sol 1605: In the morning, Opportunity acquired panoramic-camera images of a rock exposure called "Bretz," acquired images with the rear hazard-avoidance cameras, and acquired a 3-by-1 tier and a 5-by-1 tier of images with the navigation camera. The rover acquired new, full-color, panoramic-camera images of Eugene Smith.

Sol 1606 (July 30, 2008): Opportunity took thumbnail images of the sky with the panoramic camera and monitored dust on the rover's mast. With the panoramic camera, the rover completed a sky survey and acquired overlapping, super-resolution images of a rock exposure known as "Siever" (the overlapping images compensate for dust on the camera lens). Opportunity took panoramic-camera images of an outcrop known as "McKee." Plans for the following morning called for the rover to survey the horizon and take spot images of the sky for calibration purposes with the panoramic camera.

Odometry

As of sol 1606 (July 30, 2008), Opportunity's total odometry was 11,726.21 meters (7.29 miles).


sol 1593-1599, July 17-23, 2008: Opportunity Fights Uphill Battle

"Victoria Crater" continues to challenge Mars rover drivers as they try to find a location where Opportunity can do scientific studies of rocks near the "Cape Verde" cliff face. They have been trying to drive the rover to a location nicknamed "Nevada" after a rock shaped somewhat like the state of Nevada. Getting there, however, has been challenging.

After attempting unsuccessfully to drive the rover on steep slopes that caused the wheels to slip, they are aiming for a new location. They have identified a large flagstone to the left of Nevada that offers solid footing and a low amount of tilt. They hope to drive the rover there, re-evaluate the terrain, and re-assess whether it is possible to reach Nevada.

They are also working on a campaign to have Opportunity document different styles of weathering on local rocks. The rover, meanwhile, continues to measure argon gas in the Martian atmosphere and make other atmospheric observations.

Opportunity remains healthy, with all subsystems performing as expected as of the rover's 1,599th Martian day, or sol (July 23, 2008), of exploration. Solar energy on the vehicle has been averaging just under 360 watt-hours (100 watt-hours is the amount of energy needed to light a 100-watt bulb for one hour).

Sol-by-sol summary

In addition to making daily assessments of atmospheric dust based on the darkness of the sky as viewed by the panoramic camera and relaying data to NASA's Odyssey orbiter for transmission to Earth, Opportunity completed the following activities:

Sol 1593 (July 17, 2008): Opportunity drove and took post-drive images of the surrounding terrain with the hazard-avoidance and navigation cameras. After communicating with Odyssey, the rover went into a deep sleep.

Sol 1594: Opportunity spent 4 hours and 15 minutes integrating measurements of atmospheric argon with the alpha-particle X-ray spectrometer. The rover went into a mini-deep sleep.

Sol 1595: Opportunity took full-color images, using all 13 filters of the panoramic camera, of rock exposures dubbed "Mawson," "Murchison," "Mackay," and "King." After sending data to to Odyssey, the rover went into a deep sleep.

Sol 1596: Opportunity monitored dust on the rover mast, drove, and took post-drive images with the hazard-avoidance and navigation cameras. After the day's activities, the rover went into a deep sleep.

Sol 1597: Opportunity took full-color images, using all 13 color filters of the panoramic camera, of rock exposures nicknamed "Playfair" and "Eugene_Smith." After relaying data to Earth, Opportunity went into a deep sleep.

Sol 1598: In the morning, Opportunity took four freeze-frame images with the navigation camera for a movie to document potential clouds. Following a short drive, Opportunity took images with the hazard-avoidance and navigation cameras. After sending data to Odyssey, the rover measured atmospheric argon with the alpha-particle X-ray spectrometer.

Sol 1599 (July 23, 2008): Opportunity took more full-color, panoramic-camera images of Mackay and Mawson. Plans for the following morning called for Opportunity to take full-color images of Murchison.

Odometry

As of sol 1598 (July 22, 2008), Opportunity's total odometry was 11,725.96 meters (7.29 miles).


sol 1586-1592, July 10-16, 2008: Wheels Turn, Rover Slides

Opportunity lost about 30 watt-hours of energy after a short drive on sol 1584 (July 8, 2008) left the solar panels tilted in a slightly less favorable position relative to the Sun. The amount of energy lost is enough to light a 30-watt bulb for one hour.

Another scheduled drive on sol 1586 (July 10, 2008) was postponed to sol 1588 (July 12, 2008), then postponed again to sol 1591 (July 15, 2008) to give rover drivers more time to assess the terrain. Opportunity took camera images in support of the evaluation and measured argon gas in the Martian atmosphere using the alpha-particle X-ray spectrometer.

Also on sol 1591, Opportunity attempted to climb directly up the slope to the left of a flat rock nicknamed "Nevada" because it is shaped somewhat like the state. To gain extra traction, rover planners hoped to use rocks at or near the rover's wheels. Their goal was to have Opportunity advance in three short "steps" of 40 centimeters (16 inches) without changing direction.

The result was disappointing: Opportunity halted the drive after the second step because of excessive wheel slippage of 97.5 percent (meaning the wheels moved only 1 centimeter, or less than half an inch). Instead of advancing, Opportunity slid to the right about 5 centimeters (2 inches), resulting in a change of heading of about 2.5 degrees clockwise. Images showed small mounds of soil churned up by the rover's wheels.

Plans for next week call for Opportunity to continue driving as scientists decide whether to try again to reach Nevada from a different direction or begin driving out of "Victoria Crater."

Opportunity is healthy and all subsystems are performing as expected as of sol (Martian day) 1592 (July 16, 2008).

Energy has been averaging around 357 watt-hours (100 watt-hours is the amount of energy needed to light a 100-watt bulb for one hour). Tau, a measure of atmospheric darkness caused by dust, is at 0.24. The dust factor, representing the proportion of sunlight penetrating dust on the solar arrays, has been averaging 0.796 as of sol 1585 (July 9, 2008).

Since last week, both Tau and the dust factor have improved.

Sol-by-sol summary

In addition to measuring atmospheric dust each day based on the darkness of the sky as viewed by the panoramic camera and relaying data to NASA's Odyssey orbiter for transmission to Earth, Opportunity completed the following activities:

Sol 1586 (July 10, 2008): Opportunity acquired backward-looking images with the rear hazard-avoidance cameras and an 8-by-1 panel of images of nearby terrain with the navigation camera. After sending data to Odyssey, the rover spent 4.66 hours measuring atmospheric argon and went into a mini-deep sleep.

Sol 1587: After measuring atmospheric dust and relaying data to Odyssey, Opportunity went into a deep sleep.

Sol 1588: In the morning, Opportunity acquired a mosaic of images in search of atmospheric dust with the panoramic camera. After sending data to Odyssey, Opportunity spent 4.5 hours measuring atmospheric argon with the alpha-particle X-ray spectrometer. The rover then went into a mini-deep sleep.

Sol 1589: Opportunity acquired a 360-degree panorama of images with the navigation camera as well as full-color images, using all 13 filters of the panoramic camera, of a target nicknamed "Muller." The rover spent 2.66 hours measuring argon in the atmosphere with the alpha-particle X-ray spectrometer and went into a mini-deep sleep.

Sol 1590: Opportunity took thumbnail images of the sky with the panoramic camera. After relaying data to Odyssey, Opportunity went into a deep sleep.

Sol 1591: In the morning, Opportunity took spot images of the sky for calibration purposes using the panoramic camera. Before beginning the day's drive, Opportunity took images of Nevada with the panoramic camera. After the drive, Opportunity took images of the surface near the rover's wheels with the hazard-avoidance cameras and a 2-by-1 mosaic of images of the terrain ahead with the navigation camera. After sending data to Odyssey, the rover went into a deep sleep.

Sol 1592 (July 16, 2008): Early in the morning, Opportunity acquired four, time-lapse, movie frames in search of clouds with the navigation camera. After sending data to Odyssey, Opportunity went into a deep sleep. The following morning, the rover was to conduct a horizon survey with the panoramic camera.

Odometry

As of sol 1591 (July 15, 2008), Opportunity's total odometry was 11,725.21 meters (7.29 miles).


sol 1581-1585, July 05-09, 2008: Two Steps Forward, One Step Back

Opportunity's drive toward the cliff known as "Cape Verde" inside "Victoria Crater" was stopped on Martian day, or sol, 1582 (July 6, 2008) because of excessive slip in the rover's wheels. The command to the rover was to drive backward 0.33 meter (about a foot), but the actual distance traveled was 0.45 meters (approximately 1.5 feet). The drive was to begin with a backup arc followed by a forward arc (rather than a turn in place) to avoid a rock near the left rear wheel, then continue a short distance uphill and turn toward the cliff. Given the steep slopes and dusty terrain, slips in excess of 60 percent are not unexpected.

Another drive on sol 1584 (July 8, 2008) was also stopped because of excessive slip. As Opportunity slipped to the right, the rover's left front wheel started to scoop up a potato-sized rock. At the same time, the right rear wheel moved closer to a rock that rover drivers had been trying to avoid. Images taken by the rover's rear hazard-avoidance cameras showed the rear wheels starting to dig into the soil.

After the drive, Opportunity successfully calibrated the Z-axis movement of the rock abrasion tool after the device had not fully retracted during a cold-temperature, Z-axis characterization test on sol 1578 (July 2, 2008). (The mechanical parts functioned properly but the sequence of commands controlling them stopped too soon).

Opportunity re-acquired two super-resolution images of rock exposures of interest on the cliff known as "Cape Verde," replacing overexposed images taken the previous week of targets dubbed "Charles" and "Delta." Opportunity also made atmospheric observations.

Opportunity is healthy and all subsystems are performing as predicted, based on data received from the Odyssey orbiter on sol 1585 (July 9, 2008). Energy levels are averaging about 385 watt-hours (almost enough to light a 100-watt bulb for four hours). The Tau measurement of atmospheric darkness caused by suspended dust is 0.3. The dust factor measurement of the amount of sunlight penetrating dust on the solar arrays is averaging about 0.77.

Sol-by-sol summary

During the week, Opportunity completed the following activities:

Sol 1581 (July 5, 2008): Opportunity measured atmospheric darkness due to dust with the panoramic camera and re-acquired "dusty," super-resolution images of Charlie and Delta. To acquire "dusty" images, the rover compensates for dust accumulation on the right side of each panoramic-camera lens by taking images with a subset of available pixels. Opportunity completed a survey at low Sun before relaying data to Odyssey for transmission to Earth. After sending data to Odyssey, the rover went into a deep sleep.

Sol 1582: Opportunity greeted the day by assessing atmospheric dust, surveying the horizon, and taking spot images of the sky for calibration purposes with the panoramic camera. The rover measured atmospheric dust with the navigation camera, then drove 0.45 meters (1.5 feet). Just before and after completing the drive, the rover took images with the hazard-avoidance cameras of the Martian surface next to its wheels, and took post-drive images of the terrain ahead with the navigation camera. Opportunity relayed data to Odyssey.

Sol 1583: Opportunity monitored atmospheric dust with the panoramic camera and acquired a time-lapse, six-frame movie to record the movement of any clouds that might be overhead. The rover relayed data to Odyssey.

Sol 1584: Upon awakening, Opportunity assessed atmospheric dust with the panoramic and navigation cameras and took offset, thumbnail images of the sky for calibration purposes with the panoramic camera. The rover calibrated the rock abrasion tool and drove a short distance, taking images just before and after the drive with the hazard-avoidance cameras. Opportunity acquired a post-drive tier of images with the navigation camera, sent data to Odyssey, and went into a deep sleep.

Sol 1585 (July 9, 2008): First thing in the morning, Opportunity monitored dust accumulation on the panoramic-camera mast assembly and assessed atmospheric dust with the panoramic camera. Opportunity then took six, time-lapse movie frames in search of Martian clouds with the navigation camera. Before going into a deep sleep, the rover relayed data to Odyssey. Plans for the following morning called for Opportunity to measure atmospheric dust with the panoramic camera.

Odometry

As of sol 1583 (July 7, 2008), Opportunity's total odometry was 11,724.39 meters (7.29 miles).


sol 1574-1580, June 28-July 04, 2008: Rover Takes Photos of Scenic View

Opportunity has completed work on the stand-off portion of the full-color panorama of the layered cliff known as "Cape Verde." It may take a couple of weeks for the entire panorama to arrive on Earth, depending on the volume of data the rover is able to transmit during communications links.

Next, Opportunity will move closer to Cape Verde to take a high-resolution image of a smaller area in front of the rover.

During the past week, engineers characterized the performance of the rover's rock abrasion tool along the z-axis by comparing voltage and the speed of the actuator at different temperatures. In the event that the z-axis encoder lines break, as have the encoder lines for the rotate and revolve axes, this characterization will be essential in developing a functional strategy for operating the rock abrasion tool with full, open-loop control. The z-axis encoder is responsible for moving the cutting head outward into the rock.

Next week's plans call for Opportunity to bump forward to a point only a few meters away from the cliff face to take high-resolution images. If possible, Opportunity will also conduct scientific studies of an outcrop target called "Nevada" (so named because of a rock next to it which has a shape reminiscent of the outline of the state of Nevada) using instruments on the robotic arm.

Opportunity is healthy and all subsystems are performing as expected. Energy is around 376 watt-hours (100 watt-hours is the amount of energy required to light a 100-watt bulb for one hour). As of Sol 1578 (July 2, 2008), Tau (a measure of darkness due to atmospheric dust) was at 0.413 and the dust factor (a measure of the proportion of sunlight penetrating dust on the solar arrays) was at 0.771.

Sol-by-sol summary

In addition to receiving morning, direct-from-Earth instructions via the rover's high-gain antenna, sending evening UHF data to NASA's Odyssey orbiter for transmission to Earth, measuring atmospheric dust with the panoramic camera, surveying the sky for clouds with the navigation camera, and monitoring dust accumulation on the rover mast, Opportunity completed the following activities:

Sol 1574 (June 28, 2008): Opportunity began acquiring "dusty," super-resolution images of targeted portions of the outcrops exposed in the Cape Verde cliff dubbed "Alpha," "Bravo," "Charlie," "Delta," and "Echo." To do this, the rover compensated for dust accumulation on the right side of each lens by taking images using only a subset of available pixels. On this particular sol, Opportunity acquired dusty, super-resolution images of "Alpha" and "Echo."

Sol 1575: Opportunity acquired dusty, super-resolution images of Bravo, Charlie, Delta, and Echo using the panoramic camera. The rover also acquired six, time-lapse movie frames in search of clouds using the navigation camera.

Sol 1576: Opportunity acquired more dusty, super-resolution images of Echo with the panoramic camera and took images of Cape Verde in shadow at 2:30 p.m. local Mars time and at 3 p.m. local Mars time.

Sol 1577: Opportunity acquired dusty, super-resolution images of a target dubbed "Foxtrot" with the panoramic camera and characterized the performance of the rock-abrasion tool along the z-axis at warm temperatures. The rover reacquired five dusty, super-resolution images of Cape Verde and Bravo.

Sol 1578: Opportunity characterized the ability of the z-axis encoder to move the cutting head of the rock abrasion tool outward at cold temperatures and reacquired dusty, super-resolution images of Alpha.

Sol 1579: In the morning, Opportunity surveyed the horizon with the panoramic camera. The rover measured argon gas in the Martian atmosphere using the alpha-particle X-ray spectrometer. Opportunity also acquired a 27-by-1 panel of images of Cape Verde at dusk with the left-hand lens of the panoramic camera.

Sol 1580 (July 4, 2008): Opportunity acquired a 27-by-1 panel of images of Cape Verde at dusk with the right-hand lens of the panoramic camera.

Odometry

As of sol 1580 (July 4, 2008), Opportunity's total odometry was 11,723.94 meters (7.28 miles).


sol 1566-1573, June 19-26, 2008: Happy Winter Solstice!

Opportunity has begun work on the much anticipated panorama of the layered promontory known as "Cape Verde" inside "Victoria Crater." The panorama will take several Martian days, or sols, to complete and will be made up of a mosaic of panoramic-camera images. The Cape Verde panorama is expected to be spectacular, "one for the textbooks."

With each move closer to Cape Verde, power to Opportunity's solar arrays has decreased as more of the promontory obscures the sky. Currently, Opportunity is about 7 meters (20 feet) from the Cape Verde cliff face. The rover's next short advance toward the cliff will tilt its solar panels away from the Sun, limiting the amount of solar energy even more. Rover drivers will take great care to ensure that Opportunity stays out of the shadow cast by Cape Verde, which currently extends approximately 3 meters (about 10 feet) from the cliff face. Even with all these constraints, the team is confident Opportunity will have enough power to finish the Cape Verde panorama.

The winter solstice occurred during sols 1570-1571 (June 24-25, 2008). This is the point at which the arc that the Sun traces across the sky reaches its most northerly point. Because Opportunity is south of the equator, the arc that the Sun traces now will move gradually to the south and higher in the sky. In coming months, this will result in more solar power for Opportunity.

Next week, Opportunity is expected to complete the Cape Verde panorama, then roll slightly forward to a point only a few meters away from the cliff face to take additional high-resolution images of the nearest portion of the cliff face.

Opportunity is healthy and all subsystems are performing as expected. Solar energy is around 367 watt-hours (100 watt-hours is the amount of energy needed to light a 100-watt bulb for one hour). As of sol 1572 (June 26, 2008), tau, a measurement of sun-blocking dust suspended in the atmosphere, was 0.409. The dust factor, the proportion of sunlight penetrating the coating of dust on the solar arrays, was 0.771.

Sol-by-sol summary

In addition to receiving morning, direct-from-Earth instructions via the rover's high-gain antenna, sending evening UHF data to NASA's Odyssey orbiter for transmission to Earth, measuring atmospheric dust with the panoramic camera, surveying the sky for clouds with the navigation camera, and monitoring dust accumulation on the rover mast, Opportunity completed the following activities:

Sol 1566 (June 19, 2008): Opportunity drove 3.52 meters (11.6 feet) closer to Cape Verde and acquired post-drive images of the surrounding terrain with the navigation and panoramic cameras.

Sol 1567: Opportunity approached Cape Verde another 1.54 meters (5.05 feet), to a position roughly 7 meters (20 feet) away from the cliff face. After the drive, the rover took images of its new locale with the navigation and panoramic cameras.

Sol 1568: Opportunity recharged the battery. Before sending data to Odyssey, Opportunity surveyed the sky at low Sun with the panoramic camera. The rover took images of Cape Verde's shadow with the navigation camera.

Sol 1569: Opportunity recharged the battery and surveyed the sky at high Sun with the panoramic camera.

Sol 1570: Opportunity recharged the battery and completed 10 pointings of the panoramic camera at Cape Verde. The rover acquired a mosaic of panoramic-camera images of the atmosphere in search of dust.

Sol 1571: In the morning, Opportunity surveyed the horizon with the panoramic camera and completed 20 pointings of the panoramic camera at Cape Verde.

Sol 1572: Opportunity completed 14 pointings of the panoramic camera at Cape Verde.

Sol 1573 (June 26, 2008): In the morning, Opportunity took thumbnail images of the sky with the panoramic camera. The rover completed 14 pointings of the panoramic camera at Cape Verde.

Odometry

As of sol 1565 (June 18, 2008), Opportunity's total odometry was 11,723.94 meters (7.28 miles).


sol 1558-1565, June 11-18, 2008: On the Move

Opportunity has resumed driving through challenging terrain in "Victoria Crater," making significant progress toward a promontory of layered rocks known as "Cape Verde." On Martian day, or sol, 1565 (June 18, 2008), the rover made it to within 2 meters (6.5 feet) of a staging area dubbed "Safe Haven," where Opportunity will acquire images of the cliff face.

During the drive, Opportunity observed no motion of the robotic arm in its new unstowed position in front of the rover. Additionally, Opportunity experimented with a post-drive "salute," in which the rover swung the robotic arm at the elbow joint out of the field of view of the front hazard-avoidance cameras, took an image, and then returned the arm to its starting position.

Opportunity collected a variety of remote sensing observations, including images of shadows cast by the Cape Verde promontory and images of holes the rover's wheels dug into the terrain. Opportunity also took images of and measured argon gas in the atmosphere.

Opportunity is healthy and all subsystems are performing as expected. Solar-array energy has averaged about 447 watt-hours (100 watt-hours is the amount of energy needed to light a 100-watt bulb for one hour).

Sol-by-sol summary

In addition to measuring atmospheric dust one to three times a day with the panoramic camera, Opportunity completed the following activities:

Sol 1558 (June 11, 2008): Opportunity acquired images of a cobble informally named "Wilson" using all 13 color filters of the panoramic camera.

Sol 1559: Opportunity acquired a 2-by-1 mosaic of images with the navigation camera and a 3-by-3 mosaic of images of wheel holes with the panoramic camera. The rover acquired hazard-avoidance camera images of terrain near its wheels just before and after ending the day's drive. Opportunity completed a "Get Quick Fine Attitude" calibration to determine the rover's precise location relative to the Sun and acquired a 3-by-1, post-drive mosaic of images with the navigation camera. The rover also acquired a navigation-camera image mosaic of Cape Verde. After relaying data destined for Earth to NASA's Odyssey orbiter, Opportunity measured atmospheric argon using the alpha-particle X-ray spectrometer.

Sol 1560: Opportunity acquired six, time-lapsed movie frames in search of clouds with the navigation camera.

Sol 1561: Opportunity took spot images of the sky for calibration purposes with the panoramic camera.

Sol 1562: Opportunity surveyed the horizon and acquired a 4-by-1 mosaic of images of shadows cast by Cape Verde with the panoramic camera. Opportunity drove to a location where the rover was to make scuff marks with its wheels and acquired hazard-avoidance camera images just before and after the end of the drive. Using the navigation camera, Opportunity took a 3-by-1, post-drive mosaic of images with the panoramic camera; post-drive images of old scuff marks made by the rover's wheels; and images of shadows cast by Cape Verde. After relaying data to Odyssey, Opportunity measured argon gas in the atmosphere with the alpha-particle X-ray spectrometer and acquired navigation-camera images of shadows cast by Cape Verde.

Sol 1563: In the morning, Opportunity took offset, thumbnail images of the sky with the panoramic camera. The rover performed a toe-dip, moving its front wheels forward and then backing up again, and did a salute with the robotic arm, moving it in and out of the field of view of the hazard-avoidance cameras. Opportunity acquired hazard-avoidance camera images of the surface near its wheels just before and after ending the drive; a 3-by-1, post-drive mosaic of images with the navigation camera; and a 2-by-1, post-drive mosaic of images of the wheel scuffs with the navigation camera. The rover took post-drive images of Cape Verde's shadow using the navigation camera.

Sol 1564: In the morning, Opportunity took more images of Cape Verde's shadow with the navigation camera. The rover drove a little closer to the promontory, took images with the hazard-avoidance cameras just before and after ending the drive, and acquired post-drive image mosaics with the navigation camera.

Sol 1565 (June 18, 2008): Upon waking, Opportunity took images of Cape Verde's shadow with the navigation camera. The rover drove a little closer, acquired images just before and after ending the drive with the hazard-avoidance cameras, and acquired a 5-by-1 tier of images with the navigation camera. The following morning, Opportunity was to acquire four, time-lapsed movie frames in search of clouds with the navigation camera and take spot images of the sky with the panoramic camera.

Odometry

As of sol 1565 (June 18, 2008), Opportunity's total odometry was 11,718.88 meters (7.28 miles).


sol 1551-1557, June 03-10, 2008: Bustin' Loose!

Opportunity finally escaped the Martian sand and backed up onto solid rock inside "Victoria Crater." Driving backward on Martian day, or sol, 1557 (June 10, 2008), the rover successfully moved the last of its six wheels up over a rocky ledge. The successful maneuver freed Opportunity to follow another route that will bring the rover closer to the cliff known as "Cape Verde." From there, the rover will collect high-resolution, panoramic images of rock layers in the promontory.

Also this week, the rover engineering team had the honor of hosting Houston-area Congressman and Mars exploration enthusiast John Culberson. The congressman participated in the planning of sols 1557 and 1558 (June 10-11, 2008). Culberson even helped design a science observation of the cobble informally named "Barnes" in honor of Virgil E. Barnes, former emeritus professor of geological sciences at The University of Texas at Austin.

Sol-by-sol summary:

In addition to receiving morning instructions directly from Earth via the rover's high-gain antenna and measuring atmospheric dust with the panoramic camera, Opportunity completed the following activities:

Sol 1551 (June 4, 2008): Opportunity acquired a 5-by-1 mosaic of images for a shadow test to determine how well imaging of Cape Verde can proceed in shadowed conditions.

Sol 1552: In the morning, Opportunity took spot images of the sky for calibration purposes and surveyed the horizon with the panoramic camera. After driving backward, the rover took images of cleat marks made with its wheels using the hazard-avoidance cameras. Opportunity took post-drive images of the rover mast and a 3-by-1 mosaic of images with the navigation camera. After relaying data to the Odyssey orbiter for transmission to Earth, Opportunity measured argon gas in the Martian atmosphere with the alpha-particle X-ray spectrometer.

Sol 1553: Opportunity completed a morning survey of the horizon and took spot images of the sky with the panoramic camera. The rover acquired a 5-by-1 mosaic of images for the shadow test and surveyed the sky at high Sun with the panoramic camera.

Sol 1554: In the morning, Opportunity acquired a six-frame, time-lapse movie of potential clouds passing overhead with the navigation camera. The rover acquired another 5-by-1 mosaic of shadow-test images with the panoramic camera. Opportunity then acquired full-color images, using all 13 filters of the panoramic camera, of a cobble dubbed "Agassiz." The rover completed a sky survey at high Sun with the panoramic camera and, after sending data to Odyssey, measured atmospheric argon with the alpha-particle X-ray spectrometer.

Sol 1555: Opportunity surveyed the horizon and took spot images of the sky with the panoramic camera. The rover acquired a six-frame, time-lapse movie in search of clouds with the navigation camera. After communicating with Odyssey, Opportunity measured atmospheric argon with the alpha-particle X-ray spectrometer.

Sol 1556: In the morning, Opportunity took thumbnail images of the sky with the panoramic camera. After communicating with Odyssey, the rover measured atmospheric argon with the alpha-particle X-ray spectrometer.

Sol 1557 (June 10, 2008): In the morning, Opportunity acquired a six-frame, time-lapse movie in search of clouds with the navigation camera and surveyed surrounding rock clasts with the panoramic camera. The rover acquired full-color images, using all 13 filters of the panoramic camera, of Barnes. Opportunity then drove backward and acquired post-drive images of surrounding terrain and of the rover mast with the navigation camera as well as images of cleat imprints made by the rover's wheels with the hazard-avoidance cameras. After sending data to Odyssey, Opportunity measured atmospheric argon. Plans for the following morning called for the rover to monitor dust on the rover mast and take another six-frame movie of potential clouds passing overhead.

Odometry:

As of sol 1557 (June 10, 2008), Opportunity's total odometry was 11,691.84 meters (7.26 miles).


sol 1545-1550, May 29 - Jun 03, 2008: On the Road Again!

After passing a series of tests to earn a new driver's certificate, Opportunity resumed driving while keeping its robotic arm in a new, "stowed" position that is essentially mostly unstowed. Engineers studied the vehicle's response in a variety of scenarios and determined that the new, unstowed position minimizes joint stresses, provides a clear field of view for driving, provides sufficient clearance between the turret holding the scientific instruments and the surface, and allows the largest possible work volume for in-situ science.

In fact, tests of a surrogate rover on Earth were in some ways an "overtest," because gravitational forces on Earth are greater than on Mars.

Opportunity completed two drives, advancing about 0.5 meters (1.6 feet) on Sol 1547 (May 31, 2008) and 0.22 meters (0.72 feet) on Sol 1550 (June 3, 2008). The robotic arm behaved as expected during both drives.

Prior to the recent electrical anomaly that caused the robotic arm to stall, Opportunity performed a "toe dip," during which the rover drove forward a short distance and then backward to characterize the sandy terrain en route to a promonotory dubbed "Cape Verde." During the procedure, Opportunity experienced significant wheel slippage of more than 90 percent in addition to high tilt while moving backward. After a series of adjustments, rover operators discovered that the rover's front wheels had begun to dig into the terrain. They decided to stop driving forward and focus on driving backward to extract the rover's front wheels from the sand.

During this week's two drives, Opportunity continued to make slow and steady progress toward backing out of the sand. Once the rover's wheels are free, Opportunity will head for a staging area to make more observations of the Cape Verde promontory. The staging area is about 15 meters (49 feet) away, or about the length of two passenger buses lined up end to end.

Opportunity continued to acquire images for the full-color "Garrels panorama" as well as images of the soil target informally named "Williams." The rover remains healthy and all subsystems are performing as expected. Solar-array energy has averaged about 475 watt-hours (100 watt-hours is the amount of energy needed to light a 100-watt bulb for one hour).

Sol-by-sol summary:

In addition to receiving morning instructions directly from Earth via the rover's high-gain antenna and measuring atmospheric dust with the panoramic camera, Opportunity completed the following activities:

Sol 1545 (May 29, 2008): Opportunity acquired Part 12 of the Garrels panorama.

Sol 1546: Opportunity took images of Williams, surveyed the sky at high Sun, took thumbnail images of the sky for calibration purposes and surveyed the horizon with the panoramic camera.

Sol 1547: Opportunity drove 0.5 meters (1.6 feet). Before and after the drive, the rover took images of the robotic arm with the navigation camera. The rover took post-drive images of the surface near the wheels with the hazard-avoidance cameras and images of the surrounding terrain with the navigation camera.

Sol 1548: In the morning, Opportunity took spot images of the sky for calibration purposes with the panoramic camera and six time-lapse movie frames in search of clouds with the navigation camera. The rover measured argon gas in the Martian atmosphere with the alpha-particle X-ray spectrometer.

Sol 1549: After relaying data to NASA's Odyssey orbiter, Opportunity continued to measure atmospheric argon with the alpha-particle X-ray spectrometer.

Sol 1550 (June 3, 2008): In the morning, Opportunity produced a six-frame, time-lapse movie in search of Martian clouds with the navigation camera. The rover drove 0.22 meters (0.72 feet) toward Cape Verde and acquired post-drive images with the hazard-avoidance and navigation cameras. After sending data to Odyssey, Opportunity measured atmospheric argon. Plans for the next morning called for Opportunity to acquire panoramic-camera images of the rover's external magnets and survey as well as acquire thumbnail images of the sky with the panoramic camera for calibation purposes.

Odometry:

As of sol 1550 (June 3, 2008), Opportunity's total odometry was 11,690.27 meters (7.26 miles).


sol 1539-1546, May 23-30, 2008: Getting Ready to Roll

During the past week, Opportunity continued work on a detailed analysis of factors that will affect the driving of the six-wheeled rover and operation of its robotic arm in the future. Among other things, rover operators analyzed the dynamic strength of the robotic arm and its actuators while the rover is driving.

Test results back on Earth, together with observations of robotic arm performance on board the vehicle on Mars, led to the establishment of a new position for stowing the robotic arm that will enable Opportunity to continue driving. Engineers selected the stow position to minimize stress on arm joints, provide a clear field of view while driving, supply adequate clearance between scientific instruments on the arm and the Martian surface, and provide access to the largest possible work volume for scientific observations.

Opportunity acquired additional images for the full-color "Garrels panorama" and studied two piles of loose material known informally as "Harland" and "Williams" next to the rover's wheels. The rover measured argon gas in the Martian atmosphere, quantified atmospheric dust and searched for potential clouds.

Opportunity is healthy and all subsystems are performing as expected. Energy is currently around 467 watt-hours (100 watt-hours is the amount of energy needed to light a 100-watt bulb for one hour). The earliest drive opportunity will be Friday.

Sol-by-sol summary:

In addition to receiving morning instructions directly from Earth via the rover's high-gain antenna and measuring atmospheric dust with the panoramic camera, Opportunity completed the following activities:

Sol 1539 (May 23, 2008): Opportunity acquired Part 9 of the mosaic of images that will make up the Garrels panorama, using all 13 color filters of the panoramic camera. After relaying data to NASA's Odyssey orbiter for transmission to Earth, Opportunity used the alpha-particle X-ray spectrometer to measure argon gas in the Martian atmosphere.

Sol 1540: Following early-morning measurements of atmospheric dust, Opportunity acquired panoramic-camera images of Harland and Williams.

Sol 1541: In the morning, Opportunity acquired six time-lapse movie frames in search of Martian clouds with the navigation camera and made several measurements of atmospheric dust at different times of day.

Sol 1542: Opportunity tested electrical resistance while stowing the robotic arm in its new position in front of the rover and acquired six time-lapse movie frames in search of clouds. After relaying data to Odyssey, Opportunity spent 3.5 hours collecting data on atmospheric argon with the alpha-particle X-ray spectrometer.

Sol 1543: In the morning, Opportunity acquired six time-lapse movie frames in search of clouds with the navigation camera. The rover completed work on Part 10 of the Garrels panorama.

Sol 1544: Opportunity shot another six-frame movie in search of clouds and tested movement of the robotic arm while taking images of the arm.

Sol 1545: In-between acquiring Part 11 and Part 12 of the Garrels panorama, Opportunity took navigation-camera and panoramic-camera images of the rover's arm in its new stowed position.

Sol 1546 (May 30, 2008): Opportunity acquired images of Williams in the morning, surveyed the sky at high Sun, took thumbnail images of the sky for calibration purposes and surveyed the horizon, all with the panoramic camera.

Odometry:

As of sol 1546 (May 30, 2008), Opportunity's total odometry remained at 11,689.53 meters (7.26 miles).


sol 1533-1538, May 19-22, 2008: Opportunity Waves for the Camera

Like a candidate waving to the crowd, Opportunity has been waving at its spacecraft cameras to document the movement of joints in the rover's robotic arm. The images record the arm's position and can be used to recalibrate the arm if it ever moves unexpectedly during a drive.

On sol 1536 (May 19, 2008), engineers conducted three tests of electrical resistance in joint 1 in the early Martian afternoon, when temperatures were warmest. Joint 1 is the shoulder joint that moves the arm from side to side (also known as the shoulder azimuth joint, because it determines the compass direction in which the arm is pointed). Using Ohm's law, they calculated electrical resistance based on measurements of the amount of electrical current drawn by the motor as they applied different electrical forces (voltages) to it. Out of three tests, resistance values were normal in all but the first. The measured resistances were, in order, 96.9, 68.06, and 65.50 ohms.

Normal resistance in an optimally functioning joint motor would be 32.2 ohms. Ever since the Joint 1 motor lost one of its electrical windings, the motor has had three possible resistance values that are considered normal, depending on the position of the rotor. Those values are 32.2, 56.3, or 75.1 ohms. Some measurements from these tests have registered resistance values above 200 ohms. At that level, the motor cannot move the joint.

On Sol 1538 (May 22, 2008), rover operators repeated an earlier attempt to place science instruments on the arm into position to take measurements. Joint 1 stalled when Opportunity tried to suspend ("hover") the Mö:ssbauer spectrometer above the surface. This precluded remaining planned attempts to hover the science instruments that sol (Martian day). Opportunity had not attempted to move the science instruments since sol 1503 (April 16, 2008). At that time, the electrical anomaly attributed to further degradation of the joint 1 motor interrupted the unstowing of the arm.

Engineers will complete several additional tasks before permitting Opportunity to continue its trek toward the cliff of layered rocks known as "Cape Verde" inside "Victoria Crater." One is a review of all data from the accelerometers of both Mars rovers since they landed on Mars in January 2004. The data will provide a highly detailed record of the "real-world" experience of the rovers while driving, which engineers will use to understand and predict conditions in the future.

Opportunity's operators also have been conducting safety tests of the robotic arm using an engineering model of the rover on Earth. To do this, they drive the vehicle on and off of steps of varying heights and instrument the arm with accelerometers to be able to measure forces imparted to the arm during driving. In some of the tests, engineers allowed a wheel to drop suddenly from a step onto either gravel or bricks to simulate the kind of forces Opportunity might experience while driving with the arm unstowed on Mars. Though the vehicle's movement caused the robotic arm to jiggle fairly dramatically, the arm joints did not shift position. Engineers will incorporate the test results into computer models of the behavior of Opportunity's unstowed robotic arm on Mars.

Meanwhile, Opportunity remains healthy, with all subsystems performing as expected. Energy is currently around 442 watt-hours (100 watt-hours is the amount of energy needed to light a 100-watt bulb for one hour). Sun-blocking dust levels have been favorable; wind-related events have even cleared small amounts of dust from the solar arrays. As of Sol 1539 (May 23, 2008), Tau, a measure of atmospheric opacity caused by dust, was 0.581, and the dust factor, a measure of how much sunlight penetrated dust on the solar arrays, was 0.80.

Team members hope to determine next week when to have Opportunity continue the drive to the Cape Verde promontory.

Sol-by-sol summary

In addition to receiving morning instructions directly from Earth via the rover's high-gain antenna, relaying data back to Earth via the UHF antenna on the Mars Odyssey orbiter, measuring atmospheric dust with the panoramic camera and monitoring dust accumulation on the panoramic-camera mast, Opportunity completed the following activities:

Sol 1533 (May 16, 2008): Activity plans for the day did not make it on board the rover. The plans were to have Opportunity acquire images of robotic arm joints 2 and 3 (the shoulder joint that moves the arm up and down and the elbow joint, respectively), monitor atmospheric dust levels with the navigation camera, and conduct a sky survey with the panoramic camera.

Sol 1534: Opportunity acquired part 7 of the full-color "Garrels panorama" using all 13 filters of the panoramic camera. The rover measured argon gas in the atmosphere with the alpha-particle X-ray spectrometer, monitored atmospheric dust with the navigation camera, scanned the sky for clouds with the navigation camera, and took thumbnail images of the sky for calibration purposes with the panoramic camera.

Sol 1535: Opportunity completed a sky survey at high Sun with the panoramic camera, assessed atmospheric dust with the navigation camera, and scanned the sky for clouds with the navigation camera.

Sol 1536: Opportunity completed the second attempt to take images of joints 2 and 3 (shoulder elevation and wrist joints) for calibration purposes. The rover measured atmospheric dust opacity with the navigation camera, scanned the sky for clouds and acquired time-lapse movie frames in search of clouds with the navigation camera. After instructions were sent to the rover, a fault occurred in the high-frequency, X-band transmission link.

Sol 1537: The X-band communications link with Opportunity was restored.

Sol 1538 (May 22, 2008): Opportunity continued to characterize the operation of the rover's robotic arm but terminated the work early following another stall in the shoulder azimuth joint (joint 1). The rover acquired part 8 of the Garrels panorama.

Odometry

As of sol 1538 (May 22, 2008), Opportunity's total odometry remained at 11,689.53 meters (7.26 miles).


sol 1525-1532, May 08-15, 2008: Injured Shoulder Joint Back in the Game

Like an athlete with a shoulder injury whose arm is folded in a sling, NASA's Mars rover Opportunity has been unable to move its robotic shoulder joint for weeks. Early Wednesday (May 14, 2008), after a regimen of electrical stimulation and heat, the rover finally moved its shoulder joint and swung its robotic arm back to the front. Opportunity accomplished this after surviving four Earth years, two Martian winters, a major dust storm, and more than 1,500 day-to-night temperature cycles on the red planet.

The story of Opportunity's shoulder begins way back on Sol 2 (Jan. 25, 2004), the rover's second day on Mars. That's when engineers discovered that the heater on the shoulder azimuth joint, which controls side-to-side motion of the robotic arm, was stuck in the "on" position. Closer investigation revealed that the on-off switch had probably failed during assembly, test, and launch operations on Earth. Fortunately for Opportunity, the rover was equipped with a built-in safety mechanism called a "T-stat box" (thermostatic switch) that provided protection against overheating. When the shoulder azimuth joint, also known as Joint 1, got too hot, the T-stat switch automatically opened and temporarily disabled the heater. When the joint got cold again, the T-stat closed. As a result, the heater stayed on all night but not all day.

The safety mechanism worked until Opportunity approached the first winter on Mars. As the Sun began to retreat lower in the sky and solar power levels dropped, it became clear that Opportunity would not be able to keep the batteries charged with a heater draining power all night long. On Sol 122 (May 28, 2004), rover operators began using a procedure known as "deep sleep," during which Opportunity disconnected the batteries at night. Deep sleep prevented the stuck heater (and everything else on the rover except the clock and the battery heaters) from drawing power. When the Sun came up the next morning and sunlight began hitting the solar arrays, the batteries automatically reconnected, the robotic arm became operational, the shoulder joint warmed up, and the thermostatic switch opened, disabling the heater. As a result, the shoulder joint was extremely hot during the day and extremely cold at night. Such huge temperature swings, which tend to make electric motors wear out faster, were taking place every sol.

This strategy worked for Opportunity until Sol 654 (Nov. 25, 2005), when the Joint-1 azimuth motor stalled because of increased electrical resistance. Rover operators responded by delivering higher-than-normal current to the motor. This approach also worked, though Joint 1 continued to stall periodically. Typically, the rover's handlers simply tried again the next sol and the joint worked. They determined that the Joint-1 motor stalls were most likely due to damage caused by the extreme temperature cycles the joint experienced during deep sleep. As a precaution, they started keeping the robotic arm out in front of the rover overnight, rather than stowing it underneath the rover deck, where it would be virtually unusable in the event of a Joint-1 motor failure. They stowed the arm only while driving and unstowed it immediately at the end of each drive.

This strategy worked for Opportunity until Sol 1502 (April 15, 2008), when the motor stalled at the beginning of an unstowing operation at the end of a drive, when the arm was still tucked underneath the rover. The motor continued to stall on all subsequent attempts, sol after sol. Engineers performed tests at various times of day to measure electrical resistance. They found that the resistance was lowest (essentially normal) when the joint was at its warmest -- in the morning, following deep sleep, after the heater had been on for several hours, and just before the T-stat opened. They decided to try to unstow the arm one more time under these conditions.

At 08:30 Mars time on Sol 1531 (May 14, 2008), they allowed Opportunity to direct as much current as possible to the warm, joint-1 azimuth motor in order to get the robotic arm into a usable position, in front of the rover. It worked.

Because Opportunity will likely never again stow the robotic arm, engineers are working on a strategy for driving the rover safely with the arm deployed in front. In this way, Opportunity will continue to explore Mars, having weathered yet another challenge!

Sol-by-sol summary:

In addition to receiving morning instructions directly from Earth via the rover's high-gain antenna, relaying data back to Earth via the UHF antenna on the Mars Odyssey orbiter, and measuring atmospheric dust with the panoramic camera, Opportunity completed the following activities:

Sol 1525 (May 8, 2008): Opportunity used the alpha-particle X-ray spectrometer to measure argon gas in the Martian atmosphere and used the navigation camera to acquire time-lapse movie frames in search of clouds.

Sol 1526: Opportunity continued to study the Martian atmosphere.

Sol 1527: Opportunity made atmospheric measurements.

Sol 1528: Opportunity contined to make atmospheric measurements.

Sol 1529: Opportunity conducted tests of electrical resistance in the robotic arm and acquired full-color images, with all 13 filters of the panoramic camera, of soil. The rover began acquiring parts 3 and 4 of the so-called "Garrels" panorama, a sweeping view of Cape Verde and the slope where the rover will exit Victoria Crater.

Sol 1530: In the morning, Opportunity completed work on parts 3 and 4 of the Garrels panorama. The rover took spot images of the sky for calibration purposes with the panoramic camera and acquired six time-lapse movie frames in search of overhead clouds.

Sol 1531: Opportunity moved Joint 1 to an unstowed position and acquired part 5 of the Garrels panorama. The rover measured argon gas in the atmosphere with the alpha-particle X-ray spectrometer and surveyed the sky at high Sun with the panoramic camera.

Sol 1532 (May 15, 2008): Opportunity moved robotic arm joints 2 through 5 to an unstowed position and acquired part 6 of the Garrels panorama. The rover monitored atmospheric dust with the navigation camera and monitored dust on the rover mast. Opportunity acquired a movie in search of clouds with the navigation camera and took spot images of the sky for calibration purposes with the panoramic camera.

Odometry:

As of sol 1532 (May 15, 2008), Opportunity's total odometry remained at 11,689.53 meters (about 7.25 miles).


sol 1518-1524, May 01-07, 2008: Opportunity Gearing Up for Attempt to Move Robotic Arm

After completing a battery of diagnostic tests, engineers planned to attempt to move Opportunity's shoulder azimuth joint, also known as Joint 1, during the coming week.

Tests during the past week included electrical resistance tests at the warmest and coldest times of day to determine if a persistent stall in the joint was dependent on temperature. Test results indicated that electrical resistance in the shoulder motor at the warmest time of day approached normal levels.

A series of mild dust-cleaning events gave power levels a slight boost. The dust factor -- a measure of the amount of sunlight actually penetrating dust on the solar panels -- was about 73 percent. As recently as Martian day, or sol, 1486 (March 29, 2008), the dust factor was only 69 percent. Average solar-array energy during the past week was nearly 385 watt-hours, almost enough energy to light a 100-watt bulb for four hours.

Opportunity conducted a variety of remote-sensing activities, including photometric observations at varying times of day, soil observations, horizon surveys, imaging of a cobble known as "Jin" and wheel trenches informally named "Harland" and "Williams," atmospheric observations, and measurements of argon gas in the Martian atmosphere.

Opportunity is healthy and all subsystems are operating as expected, with the exception of the robotic arm.

Sol-by-sol summary:

In addition to receiving morning instructions directly from Earth via the rover's high-gain antenna, relaying data back to Earth via the UHF antenna on the Mars Odyssey orbiter, and measuring atmospheric dust with the panoramic camera, Opportunity completed the following activities:

Sol 1518 (May 1, 2008): Opportunity acquired a six-frame movie of navigation-camera images in search of clouds. After sending data to Odyssey, the rover went into a deep sleep.

Sol 1519: Opportunity acquired color images, using all 13 filters of the panoramic camera, of Jin, a cobble upslope near one edge of the "Lyell" outcrop. The rover went into a mini-deep sleep.

Sol 1520: The rover scanned the sky for clouds by acquiring six, time-lapse movie frames with the navigation camera. Later, Opportunity acquired another six-frame, time-lapse movie of potential clouds passing overhead. After communicating with Odyssey, Opportunity measured atmospheric dust at sunset with the panoramic camera and measured atmospheric argon with the alpha-particle X-ray spectrometer.

Sol 1521: Opportunity acquired a mosaic of images with the panoramic camera, took six movie frames in search of clouds with the navigation camera, surveyed the early-morning sky with the panoramic camera, and monitored dust accumulation on the rover mast. Opportunity took color images, using all 13 filters of the panoramic camera, of Harland, followed by a mosaic of images.

Sol 1522: In addition to assessing atmospheric dust at different times of day, Opportunity produced a six-frame movie in search of clouds with the navigation camera.

Sol 1523: In the morning, Opportunity took color images, using all 13 filters of the panoramic camera, of Williams and the surrounding soil. Opportunity ran tests of the shoulder joint at cold and warm temperatures. Using the navigation camera, the rover created a time-lapse movie in search of clouds and took images of the sky, known as "sky flats," for calibration purposes.

Sol 1524 (May 7, 2008): Opportunity surveyed the sky at low sun. The rover measured atmospheric argon with the alpha-particle X-ray spectrometer and took thumbnail images of the sky for calibration purposes with the panoramic camera. Opportunity created a movie in search of clouds with the navigation camera.

Odometry:

As of sol 1524 (May 7, 2008), Opportunity's total odometry remained at 11,689.53 meters (about 7 and one-quarter miles).


sol 1511-1517, Apr 24-30, 2008: Opportunity Continues to Investigate Robotic-Arm Anomaly

Opportunity is healthy and all subsystems are performing normally except the robotic arm, also known as the Instrument Deployment Device (IDD). Power has been favorable during the past week, primarily due to a better state of charge in the rover's batteries. During the investigation of the anomaly in the robotic arm, which has worked far beyond its expected lifetime, other activities have been put on hold, resulting in less use of battery power. For the past week, energy has averaged just over 380 watt-hours (almost enough energy to light a 100-watt bulb for 4 hours). Opportunity has also seen a slight decrease in Tau measurements of atmospheric opacity caused by dust, which was measured at 0.59 on Martian day, or sol, 1517 (April 30, 2008).

As previously reported, on Sol 1502 (April 15, 2008), Opportunity experienced a Joint-1 stall during a routine operation of moving the robotic arm from its stowed position. Every attempt to move Joint 1 since the initial stall has failed, producing at most a single motor revolution. Opportunity's Earthbound handlers have been running tests to determine the cause of the stall.

On Sol 1511 (April 24, 2008) engineers conducted a test intended to rule out the motor controller as a cause of the Joint-1 stall. The results were not consistent with a motor controller issue. The motor controller delivered the programmed voltage to the Joint 1 motor. Engineers also tested the right front wheel, because the controller that operates the Joint-1 motor also controls the right-front drive motor. The drive motor operated normally and showed electrical characteristics consistent with those of a healthy controller.

On Sol 1513 (April 26, 2008), team members tested two other arm joints. Up to this point, they had concentrated only on Joint 1. While it was unlikely, other joints could have had problems as well. To rule out that hypothesis, engineers performed electrical resistance tests on joints 2 and 3 without moving the arm. They applied very low voltages, enough to produce a measurable current but insufficient to generate enough torque to turn the motor. Both joints showed normal resistance.

On Sol 1516 (April 29, 2008), the engineering team performed a motion test, moving joints 2 and 3 slightly, 1 degree away from the rover body. The moves were successful. In both this and the previous sol's resistance tests, rover handlers chose not to move joints 4 and 5 because of potential hazards associated with moving those joints and also because the test could be meaningful without moving them.

The next planned step in the investigation is to conduct another round of low-voltage resistance tests on Joint 1, this time at opposite extremes of temperature. Those tests were planned for sol 1519 (May 2, 2008), at night and in the early morning, at predicted local Mars temperatures of around -70 degrees C (-94 degrees F.) and 40 degrees C (104 degrees F.), respectively. All previous motor diagnostics occurred at around -20 degrees C (-4 degrees F.).

In the event the temperature tests shed no more light on the issue, rover handlers will likely try to move Joint 1 out as much as possible using maximum voltage, which is about 50 percent higher than that used in previous attempts to move the arm. Team members are in agreement that if the arm can move at all, its remaining movability may be limited. The good news is that the rover can still use all four of the science instruments at the end of its arm. Engineers are exploring potential risks to the robotic arm while driving with the arm unstowed.

At this point, the best explanation for the anomalous behavior of the shoulder joint is a fractured or broken motor brush. Measurements of the joint angles on the robotic arm -- both from Mars and from a surrogate rover on Earth -- confirm that the arm's elbow is off its storage hook and the arm is free to move.

Opportunity's handlers have determined that the best course of action is to complete the investigation of the Joint-1 problem before driving approximately 15 meters (50 feet) to a new planned staging area for observations of the "Cape Verde" promontory.

Beyond investigating the robotic-arm anomaly, Opportunity continued to acquire images of future drive paths, photometry (measurements based on images), and calibration images. The rover also measured argon gas in the Martian atmosphere using the alpha-particle X-ray spectrometer.

Sol-by-sol summary:

In addition to receiving morning instructions directly from Earth via the rover's high-gain antenna, relaying data back to Earth via the UHF antenna on the Mars Odyssey orbiter, and measuring atmospheric dust with the panoramic camera, Opportunity completed the following activities:

Sol 1511 (April 24, 2008): Opportunity completed diagnostic tests of the Joint-1 drive controller and acquired panoramic-camera image mosaics of potential exit paths out of "Victoria Crater." After communicating with Odyssey, the rover went into a deep sleep.

Sol 1512: Opportunity monitored dust on the panoramic-camera mast asssembly and surveyed the horizon with the panoramic camera. The rover performed photometry using the panoramic camera. After relaying data to Odyssey, Opportunity went into a deep sleep.

Sol 1513: Opportunity took thumbnail images of the sky for calibration purposes with the panoramic camera and completed diagnostic tests of electrical resistance on robotic-arm joints 1, 2, and 3. The rover acquired images in darkness as well as lossless-compression (highly detailed) images of the sky, called "sky flats," for calibration purposes with the panoramic camera. After sending data to Odyssey, Opportunity went into a deep sleep.

Sol 1514: Opportunity rested for collection of temperature data, then surveyed the horizon and acquired image mosaics with the panoramic camera. After communicating with Odyssey, Opportunity measured argon gas in the atmosphere with the alpha-particle X-ray spectrometer. The rover went into a mini-deep sleep.

Sol 1515: Opportunity took thumbnail images of the sky looking starboard (to the right) with the panoramic camera. The rover relayed data to Odyssey and went into a deep sleep.

Sol 1516: Opportunity tested the motion of robotic-arm joints 2 and 3, took spot images of the sky for calibration purposes with the panoramic camera, communicated with Odyssey, and went into a deep sleep.

Sol 1517 (April 30, 2008): Opportunity acquired full-color images, using all 13 filters of the panoramic camera, of soil. The rover relayed data to Odyssey. Plans for the following morning called for Opportunity to take spot images of the sky with the panoramic camera.

Odometry:

As of sol 1517 (April 30, 2008), Opportunity's total odometry was 11,689.53 meters (about 7 and one-quarter miles).


sol 1505-1510, Apr. 18-23, 2008: Opportunity Investigates Arthritic Joint

Opportunity is healthy and all subsystems are performing as expected, with the exception of the Instrument Deployment Device (the robotic arm). Power has improved slightly during the last week, primarily as the result of a better state of charge in the batteries. Given the recent difficulties with the robotic arm, the rover hasn't been using the batteries as much as usual. Energy has averaged about 380 watt-hours (almost enough energy to light four 100-watt bulbs for one hour).

Tau, a measure of direct sunlight (and thus of dust in the atmosphere) has been fairly steady at 0.62, meaning that about half the sunlight streaming through the atmosphere of Mars reaches the ground. The rest is either absorbed or scattered. Like direct sunlight, scattered light generates power. Absorbed sunlight does not.

Opportunity's dust factor has been fairly steady at 0.7, meaning that about 70 percent of the sunlight hitting the solar arrays penetrates the dust layer to make electricity.

In mid-may (May 12, 2008), Mars will reach aphelion, its farthest point from the Sun. At that time it will be 249 million kilometers (155 million miles) from the Sun, about 1.6 times farther from the Sun than Earth ever gets.

On June 25, 2008, Opportunity will enter the winter solstice. This is the date when the Sun is lowest in the sky that marks the official start of the six-Earth-month Martian winter.

Ever since sol 654 (Nov. 25, 2005), Opportunity has experienced occasional motor stalls in the shoulder joint of the robotic arm known as Joint 1. Joint 1 is the shoulder azimuth joint, the one that swings the arm out from the rover, and left or right in front of the rover. The motor has worked long past its expected lifetime.

Apparently random in occurrence, the stalls have been accompanied by step increases in electrical resistance, which is consistent with a broken winding within the motor. (The rover's motors have bifilar coils, consisting of two parallel windings. If one wire breaks, a second coiled wire provides some torque to turn the motor. Torque is a force that causes rotation about an axis. With one wire broken, there is less torque during part of each rotation.)

Each motor has magnetic detents -- permanent magnets that pull the rotor into a fixed position to prevent it from rotating when necessary. The detents can also prevent the motor from turning when engineers want it to turn. At that point, it takes a bit more torque to start the motor turning. If a broken coil happens to align with a detent, the remaining, unbroken coil has a hard time starting to rotate. This can result in a stall.

Opportunity's handlers have been living with this for nearly 900 Martian days and until now, they have overcome every stall simply by trying the motion again.

To minimize the chance of getting "stuck" in an unfavorable position where Joint 1 is permanently stalled, the rover's handlers keep the robotic arm deployed (that is, unfolded and suspended in front of the rover) except when driving. This approach is known as the "Stow/Go/Unstow" strategy. When rover drivers want to drive, they stow the arm (that is, fold it up with the elbow in horizontal position and the fist against the chest). After the drive, they promptly unstow the arm (move the elbow down and the turret, or fist, up).

On Sol 1502 (April 15, 2008), during a routine post-drive unstow, Opportunity experienced a Joint 1 stall that was quantitatively different from prior stalls. Tests since then have continued to result in stalls with significantly higher electrical resistance five to 10 times greater than previously measured values. Motor currents have been very low, consistent with higher electrical resistance.

Engineers are conducting diagnostic tests of Joint 1 and other components. So far, every attempt to move Joint 1 has failed, producing at most a single motor revolution. The joint seems to stall in the same spot each time. The rover's handlers are pursuing a slow and steady approach of fully understanding the problem and possibly devising strategies for living with or working around the issue. They already know that even if the joint is permanently stalled, Opportunity can still do some science observations with instruments on the robotic arm.

Sol-by-sol summary:

In addition to receiving morning instructions directly from Earth via the rover's high-gain antenna, relaying data back to Earth via the UHF antenna on the Mars Odyssey orbiter, and measuring atmospheric dust with the panoramic camera, Opportunity completed the following activities:

Sol 1505 (April 18, 2008): Opportunity ran diagnostic tests of the robotic arm.

Sol 1506: Opportunity acquired six time-lapse movie frames in search of morning clouds with the navigation camera and surveyed the horizon with the panoramic camera. Later, the rover acquired a 3-by-1 panel of images with the navigation camera.

Sol 1507: Opportunity took morning spot images of the sky for calibration purposes with the panoramic camera. The rover ran more diagnostic tests of the robotic arm.

Sol 1508: Opportunity began work on a 360-degree, two-tier panorama of lossless-compression (highly detailed and precise) images with the navigation camera.

Sol 1509: Opportunity spent most of the day characterizing dust in the atmosphere.

Sol 1510 (April 23, 2008): Opportunity acquired full-color images, using all 13 filters of the panoramic camera, of one of the two trenches made by the rover's wheels, dubbed "Williams." At 11:05 a.m. local Mars time, Opportunity acquired the left-hand view of a mosaic of panoramic-camera images. The rover acquired part 2 of the lossless-compression, 360-degree panorama with the navigation camera and surveyed the sky at high Sun with the panoramic camera. The following morning, Opportunity was to acquire full-color images, using all 13 filters of the panoramic camera, of the other wheel trench, dubbed "Harland."

Odometry:

As of sol 1510 (April 10, 2008), Opportunity's total odometry was 11,689.53 meters (7.26 miles).


sol 1498-1504, Apr. 10-17, 2008: Opportunity Reverses Path

During the past week, Opportunity celebrated another major milestone by reaching 1,500 sols (Martian days) of continuous exploration of the red planet!

Meanwhile, Opportunity continued to execute a "toe dip" stategy of driving forward a short distance and backing up again to characterize the sandy terrain beneath the rover's wheels. While driving toward the promontory known as "Cape Verde" in the rim of "Victoria Crater," Opportunity experienced wheel slippage of more than 90 percent. The rover also experienced high tilt during the backward part of the drive. Following a series of adjustments to both slippage and tilt limits, Opportunity's front wheels had begun to dig into the terrain. At that point, the rover's handlers decided to concentrate on driving backward to extract the rover's front wheels and prevent them from digging further into the sand. Making slow and steady progress, as of sol 1502 (April 15, 2008), Opportunity had driven backward 24 centimeters (9.5 inches) with no errors, giving rover drivers hope that the rover would soon be out of the sand.

Opportunity's handlers implemented a "Stow/Go/Unstow" strategy of unstowing the robotic arm after each day's drive to avoid having the arm in the stow position during thermal cycling (overnight temperature changes). This freed the arm for full use of its scientific tools in the event of a cold-induced motor failure. On sol 1502 (April 15, 2008), while attempting to unstow the arm, Opportunity experienced a stall in the joint that controls shoulder position. The nature of the stall appeared to be different from previous stalls in the same joint (known as Joint 1). On sol 1504 (April 17, 2008), the rover's handlers directed Opportunity to run a diagnostic test of movement in the robotic arm. While moving the joint, Opportunity experienced another stall. Investigation of this anomaly is expected to continue for the remainder of this week.

Opportunity is healthy and all subsystems are performing as expected, with the exception of the investigation of the robotic arm. Immediate plans call for continued focus on getting out of the sand and resolving the robotic-arm anomaly.

Sol-by-sol summary:

In addition to receiving morning instructions directly from Earth via the rover's high-gain antenna, sending data back to Earth via the UHF antenna on the Mars Odyssey orbiter, and measuring atmospheric dust with the panoramic camera, Opportunity completed the following activities:

Sol 1498 (April 10, 2008): Opportunity surveyed the horizon and the sky and measured atmospheric dust at sunset with the panoramic camera. After transmitting data to Odyssey, the rover measured atmospheric argon with the alpha-particle X-ray spectrometer.

Sol 1499: In the early part of the sol, Opportunity took thumbnail images of the sky with the panoramic camera and shot a 4-frame movie of potential clouds with the navigation camera. The rover stowed the robotic arm, drove toward Cape Verde, acquired post-drive images with the hazard-avoidance cameras, and unstowed the robotic arm.

Sol 1500: Opportunity acquired a full-color, 2-by-1 panel of images of Cape Verde using all 13 filters of the panoramic camera.

Sol 1501: Opportunity recharged the battery.

Sol 1502: Opportunity started the day by monitoring dust on the panoramic-camera mast assembly and measuring atmospheric dust. The rover stowed the robotic arm, drove toward Cape Verde, acquired images of the wheel cleats in the rover's tracks to assess traction and other post-drive images with the hazard-avoidance cameras. Opportunity unstowed the robotic arm before sending data to Odyssey and going to sleep.

Sol 1503: In the morning, Opportunity surveyed the horizon with the panoramic camera. The rover acquired microscopic images of the robotic arm to document changes during the diagnostic test of the arm's ability to move.

Sol 1504 (April 17, 2008): In the morning, Opportunity acquired full-color images, using all 13 filters of the panoramic camera, of trenches created by the rover's wheels that have been informally named "Williams" and "Harland." The rover took spot images of the sky for calibration purposes with the panoramic camera and ran more diagnostic tests of the robotic arm. Opportunity took thumbnail images of the sky with the panoramic camera. After relaying data to Odyssey, the rover used the alpha-particle X-ray spectrometer to measure argon gas in the atmosphere. Plans for the next morning called for the rover to take more thumbnail images of the sky with the panoramic camera.

Odometry:

As of sol 1502 (April 15, 2008), Opportunity's total odometry was 11,691.49 meters (7.26 miles).


sol 1491-1497, Apr. 03-09, 2008: Driving on Mars Is Hard

This week Opportunity demonstrated the challenges of operating a vehicle on the surface of another planet. The rover is en route to Cape Verde to acquire high-resolution images of the layering in the rocks. To get there, Opportunity must cross some sandy stretches. Before entering the sandy areas, Opportunity will need to stop and take a "toe dip'' -- that is, drive forward a short distance and back out again -- to characterize the terrain.

On Sol 1491 (April 3, 2008), Opportunity performed a 4-wheel toe dip, driving forward until the front four wheels were on the sand and backing up again.

As part of ensuring vehicle safety, rover drivers set conservative limits on what the rover may do. For example, if Opportunity exceeds the maximum amount of wheel slippage or the maximum amount of tilt allowed, the rover must abort the drive. This gives the rover's handlers a chance to further evaluate the situation and make changes to the drive plan on subsequent sols (Martian days). The toe dips provide valuable insight into the nature of the terrain Opportunity is likely to encounter on the way to Cape Verde.

Opportunity is healthy and all subsystems are performing as expected.

Sol-by-sol summary:

In addition to receiving morning instructions directly from Earth via the rover's high-gain antenna, sending data back to Earth via the UHF antenna on the Mars Odyssey orbiter, and measuring atmospheric dust with the panoramic camera, Opportunity completed the following activities:

Sol 1491 (April 3, 2008): Before the day's drive, Opportunity took panoramic-camera and navigation-camera images of a previously made wheel scuff. The rover stowed the robotic arm and drove toward Cape Verde, taking hazard avoidance-camera images before and after ending the drive. Opportunity unstowed the robotic arm and acquired post-drive images with the navigation and panoramic cameras.

Sol 1492: In the early part of the sol, Opportunity took spot images of the sky for calibration purposes and surveyed the horizon with the panoramic camera.

Sol 1493: Opportunity monitored dust on the panoramic-camera mast assembly, stowed the robotic arm, and continued driving toward Cape Verde. Just before and after ending the drive, Opportunity took images of the area close to the rover with the hazard-avoidance cameras. The rover unstowed the robotic arm, took post-drive images with the navigation camera, and after communicating with Odyssey, obtained measurements of argon gas in the Martian atmosphere using the alpha-particle X-ray spectrometer.

Sol 1494: Opportunity took thumbnail images of the sky with the panoramic camera and six movie frames in search of clouds with the navigation camera.

Sol 1495: Opportunity took spot images of the sky for calibration purposes with the panoramic camera, stowed the robotic arm, and drove toward Cape Verde. Before and after ending the drive, the rover took images with the hazard-avoidance cameras. Opportunity unstowed the robotic arm (known to engineers as the instrument deployment device) and acquired post-drive images with the navigation camera.

Sol 1496: In the morning, Opportunity took spot images of the sky for calibration purposes with the panoramic camera and shot a 4-frame movie in search of clouds with the navigation camera. Opportunity stowed the robotic arm and drove backward onto bedrock to extract its wheels from the sand before proceeding toward Cape Verde. Before and after ending the day's drive, the rover took images with the hazard-avoidance cameras. The rover then unstowed the robotic arm.

Sol 1497 (April 9, 2008): In the morning, Opportunity took thumbnail images of the sky with the panoramic camera and shot another 4-frame movie in search of clouds with the navigation camera. The rover acquired diagnostic images with the hazard-avoidance cameras and a mosaic of images of the work volume reachable by the robotic arm with the panoramic camera. When the evening Sun was low, Opportunity surveyed the sky with the panoramic camera. Plans transmitted to the rover for the following morning called for another 6-frame movie of potential clouds in the Martian sky.

Odometry:

As of sol 1497 (April 9, 2008), Opportunity's total odometry was 11,689.21 meters (7.26 miles).


sol 1484-1490, Mar 27, 2008 - Apr. 02, 2008: Opportunity Goes Sightseeing

Opportunity has begun the drive toward a spectacular cliff in the wall of "Victoria Crater" known as "Cape Verde," about 30 meters (98 feet) away. The rover is expected to complete the drive in 6 to 7 segments, each covering an average distance of 5 meters (16 feet).

Along the way are several sandy patches. Before entering these sandy areas, Opportunity will stop for a "toe dip" -- a scuff with the front wheels to assess the depth of the sand. Rover planners hope the sandy spots will turn out to be bedrock with only a sandy veneer.

Opportunity executed the first of the toe dips upon arriving at a sandy patch on Sol 1489 (April 1, 2008). The scuff was successful. Electrical currents indicated that despite relatively deep sand on both sides, the wheels had good purchase. The sand was 4 centimeters (1.5 inches) deep on the left and 6 to 8 centimeters (2 to 3 inches) deep on the right. The tilt of the rover indicated that the left wheel encountered rock quickly, experiencing large vibrations after a short, smooth period. The right wheel got into deep sand after only brief contact with rock. Wheel slip and bogie (wheel suspension) angles indicated the rover moved backward about 3 centimeters (1 inch) during the scuffing. Rover planners concluded that the terrain was drivable but required caution.

Opportunity remains healthy and all subsystems are performing as expected. Energy is around 360 watt-hours (100 watt-hours is the amount of energy needed to light a 100-watt bulb for one hour). As of sol 1490 (April 2, 2008), Tau measurements of atmospheric opacity caused by dust stood at 0.65. The dust factor, a measure of the proportion of sunlight penetrating dust on the solar arrays, stood at 0.69.

Power may fluctuate slightly as Opportunity continues the drive toward the Cape Verde promontory, depending on the slopes of the local terrain and the rover's attitude relative to the Sun.

Sol-by-sol summary:

In addition to receiving morning instructions directly from Earth via the rover's high-gain antenna, sending data back to Earth via the UHF antenna on the Mars Odyssey orbiter, measuring atmospheric dust with the panoramic camera, monitoring dust accumulation on the rover mast, and surveying the sky for clouds with the navigation camera, Opportunity completed the following activities:

Sol 1484 (March 27, 2008): Opportunity began the drive to Cape Verde, advancing 5.55 meters (18.2 feet) and pausing midway through the drive to take full-color images, using all 13 filters of the panoramic camera, of the hole in the Gilbert rock layer created with the rover's rock abrasion tool. After the drive, Opportunity acquired a 3-by-1 mosaic of images with the navigation camera and a 3-by-2 mosaic of images with the panoramic camera. The rover went into a deep sleep.

Sol 1485: After relaying data to Odyssey, Opportunity spent six hours using the alpha-particle X-ray spectrometer to measure argon gas in the Martian atmosphere and went into a mini-deep sleep.

Sol 1486: Opportunity advanced another 5.02 meters (16.5 feet) toward Cape Verde, acquired a post-drive, 3-by-1 tier of navigation-camera images, and went into a deep sleep.

Sol 1487: Opportunity acquired six movie frames in search of clouds with the navigation camera and a 6-by-3 mosaic of the base of the Cape Verde cliff. After relaying data to Odyssey, Opportunity spent six hours measuring atmospheric argon and went into a mini-deep sleep.

Sol 1488: Opportunity acquired six movie frames in search of clouds with the navigation camera, recharged the battery, and went into a deep sleep.

Sol 1489: Opportunity drove another 4.97 meters (16.3 feet) toward Cape Verde and acquired a 3-by-1 tier of post-drive, navigation-camera images. The rover also acquired post-drive shadow images of Cape Verde and went into a deep sleep.

Sol 1490 (April 2, 2008): Opportunity acquired a 5-by-1 tier of shadow images of Cape Verde, recharged the battery, and went into a deep sleep. Plans for the following morning called for the rover to take thumbnail images of the sky for calibration purposes with the panoramic camera.

Odometry:

As of sol 1489 (April 1, 2008), Opportunity's total odometry was 11,686.77 meters (7.26 miles).


sol 1478-1483, Mar. 21-26, 2008: Opportunity Completes Dental Checkup

Opportunity is wrapping up its scientific investigation of the outcrop exposure known as "Gilbert_A" at the bottom of the alcove known as "Duck Bay," the lowest traversable portion of the crater's interior. Duck Bay is a recess in the walls of "Victoria Crater."

Opportunity performed a dental self-examination of teeth in the rover's rock abrasion tool on Sol 1482 (March 25, 2008). Images of the grinding bit, taken with the hazard avoidance cameras, showed no appreciable wear since the last measurement on sol 1443 (Feb. 14, 2008). In fact, the rover's handlers saw a slight increase rather than decrease in bit height, highlighting the uncertainty inherent in the bit measurement technique. Indeed, the calculated 32 percent of grinding material left is subject to a 39-percent relative error, resulting in an absolute error of 12 percent (based on a statistical calculation, 0.32 * 0.39 = 12). Unfortunately, there is no clear way to reduce the error in bit measurement.

Opportunity is healthy and all subsystems are operating as expected. Energy is currently around 360 watt-hours (100 watts is the amount of energy needed to light a 100-watt bulb for 1 hour). Tau measurement of opacity caused by atmospheric dust is 0.68 (a Tau of zero would correspond to a perfectly clear sky). The dust factor is 0.679, meaning that about 68 percent of sunlight reaching the solar arrays penetrates the coating of dust to generate electricity.

Next week, Opportunity is scheduled to drive toward the promontory known as "Cape Verde" for a better look at the rocks exposed in the crater walls.

Sol-by-sol summary:

In addition to receiving morning instructions directly from Earth via the rover's high-gain antenna, relaying data to Earth each evening via the UHF antenna on the Mars Odyssey orbiter, and completing atmospheric observations that included measuring atmospheric dust with the panoramic camera, monitoring dust accumulation on the rover mast, and scanning the sky for clouds with the navigation camera, Opportunity completed the following activities:

Sol 1478 (March 21, 2008): Opportunity spent 12 hours acquiring data from Gilbert with the Mössbauer spectrometer. The rover completed a survey at high Sun with the panoramic camera and went into a mini-deep sleep.

Sol 1479: Opportunity spent 12 hours acquiring data from Gilbert with the Mössbauer spectrometer. The rover took thumbnail images of the sky for calibration purposes with the panoramic camera and went into a mini-deep sleep.

Sol 1480: Opportunity spent 5 hours acquiring data from Gilbert with the Mössbauer spectrometer and took full-color images, using all 13 filters of the panoramic camera, of the backslope to the left of the Gilbert area. The rover acquired images of the rock target dubbed "Lyell Oxford" and surveyed the horizon with the panoramic camera. The rover went into a deep sleep.

Sol 1481: Opportunity spent 7 hours acquiring data from Gilbert with the alpha-particle X-ray spectrometer and took images of Lyell Oxford with the panoramic camera. The rover took six movie frames spaced at regular intervals in search of clouds with the navigation camera and went into a mini-deep sleep.

Sol 1482: Opportunity took a microscopic image of the hole ground into Gilbert with the rock abrasion tool and completed a survey of the grinding bit on the tool. Opportunity spent 8 hours integrating data from Gilbert with the Mössbauer spectrometer and went into a mini-deep sleep.

Sol 1483 (March 26, 2008): Opportunity spent 7 hours integrating data from Gilbert with the Mössbauer spectrometer and went into a deep sleep.

Odometry:

As of sol 1483 (March 26, 2008), Opportunity's total odometry was 11,671.23 meters (7.25 miles).


sol 1471-1477, Mar. 14-20, 2008: Opportunity Continues Reading the Story in the Rocks

Opportunity has finished grinding into the surface and acquiring microscopic images of a rock target informally named "Gilbert," at the bottom of the alcove inside "Victoria Crater" known as "Duck Bay." The rover is in the middle of a campaign to study the composition of the exposed interior of the rock using both the Möessbauer and alpha-particle X-ray spectrometers.

Some time next week, Opportunity is expected to begin driving toward the spectacular promontory in the crater rim known as "Cape Verde" for some close-up imaging.

Because of Opportunity's tilt inside the crater relative to the path of the Mars Odyssey orbiter as it travels across the Martian sky, Opportunity has had difficulty relaying data via UHF links to Odyssey. In the afternoon of Martian day, or sol, 1473 (March 16, 2008), sending data at a rate of 128 kilobits per second, Opportunity returned only 9.5 megabytes of data. On sol 1475 (March 18, 2008), transmitting data at a rate of 32 kilobits per second, Opportunity returned only 3.4 megabytes of data. The rover made up for lost time, however, transmitting 129 megabytes and 91 megabytes on sols 1474 (March 17, 2008) and 1476 (March 19, 2008), respectively.

Power levels continue to drop as expected for the winter season.

Sol-by-sol summary:

In addition to receiving instructions directly from Earth via the rover's high-gain antenna, relaying data to Earth via the UHF antenna on the Mars Odyssey orbiter, and measuring atmospheric dust with the panoramic camera, Opportunity completed the following activities:

Sol 1471 (March 14, 2008): Opportunity acquired data about iron-bearing minerals in a rock target known as "Dorsal New" using the Möessbauer spectrometer. The rover acquired part 10 of the super-resolution panorama of the rim of Victoria Crater, known as the rimshot, using the panoramic camera.

Sol 1472: Opportunity retracted the robotic arm, acquired full-color images of "Dorsal" using all 13 filters of the panoramic camera, and moved the robotic arm back into position to place the rock abrasion tool above Dorsal New. The rover then completed a grind-scan maneuver with the rock abrasion tool to locate the surface of the rock target. Opportunity also surveyed the sky and the horizon with the panoramic camera, acquired parts 11 and 12 of the super-resolution rimshot of Victoria Crater with the panoramic camera, scanned the sky for clouds with the navigation camera, and took spot images of the sky for calibration purposes with the panoramic camera.

Sol 1473: Opportunity acquired parts 13 and 14 of the super-resolution rimshot of Victoria Crater with the panoramic camera, measured argon gas in the Martian atmosphere with the alpha-particle X-ray spectrometer, and took images of the sky (known as "sky flats") for calibration purposes with the navigation camera.

Sol 1474: Opportunity monitored dust on the panoramic-camera mast assembly and surved the horizon with the panoramic camera.

Sol 1475: Opportunity ground into the surface of Dorsal New with the rock abrasion tool, swung the robotic arm out of the way, and took panoramic-camera images of the freshly ground surface.

Sol 1476: Opportunity acquired movie frames in search of clouds with the navigation camera and took spot images of the sky with the panoramic camera.

Sol 1477 (March 20, 2008): Opportunity acquired a 2-by-2-by-5 stack of microscopic images, along with eight extra microscopic images, of the freshly abraded rock surface, and placed the Möessbauer spectrometer on the target for further study.

Odometry:

As of sol 1476 (March 19, 2008), Opportunity's total odometry was 11,671.23 meters (7.25 miles).


sol 1463-1470, Mar. 5-13, 2008: Opportunity Finds More Evidence of Ancient Water

Opportunity has completed scientific studies of the undisturbed surface of a rock target informally named "Dorsal" in the "Gilbert" rock layer inside "Victoria Crater." Dorsal is a protruding fin of rock created by minerals deposited in cracks that remained in place long after the original rock eroded away because they were more resistant to weathering.

Data collected with the Mössbauer and alpha-particle X-ray spectrometers show that the fins in Gilbert contain large quantities of the mineral hematite. This iron-bearing mineral is also abundant in the frequently occurring, round concretions known as "blueberries" that are believed to have formed in water. Scientists have been looking for such pristine fins ever since Opportunity first noticed them back in "Eagle Crater," where the rover landed more than four years ago.

Next, Opportunity will grind into the rock surface at a point informally named "Gilbert_A" to measure the chemical composition of the rock's interior using the alpha-particle X-ray spectrometer. Along the way, the rover has been getting close-up views of the fin with the microscopic imager.

Sol-by-sol summary:

In addition to receiving instructions directly from Earth via the rover's high-gain antenna, relaying data to Earth via the UHF antenna on the Mars Odyssey orbiter, and measuring atmospheric dust with the panoramic camera, Opportunity completed the following activities:

Sol 1463 (March 5, 2008): Opportunity ran diagnostic tests of the robotic arm and acquired a 1-by-1-by-5 stack of microscopic images, with some extras thrown in for good measure, of Dorsal. The rover placed the Mössbauer spectrometer on a specific target informally named "Dorsal Tail" and spent about 10 hours collecting data with the instrument. Opportunity began work on a super-resolution mosaic of images of the rim of Victoria Crater known as the "rimshot panorama," acquiring part 1 of the mosaic using the panoramic camera. The rover acquired full-color images, using all 13 filters of the panoramic camera, of a cobble nicknamed "Jin" on the slope above the rover.

Sol 1464: Opportunity restarted the Mössbauer spectrometer and continued its investigation of Dorsal Tail. The rover acquired images with the navigation camera as well as part 2 of the super-resolution rimshot panorama, which will encompass the crater rim from "Cape Verde" to "Cabo Frio." Opportunity participated in a UHF relay of data with the Mars Reconnaissance Orbiter as part of a panoramic-camera data compression test. The rover monitored dust on the panoramic-camera mast assembly and took super-resolution images of a rock target informally named "Lyell Oxford."

Sol 1465: Opportunity restarted the Mössbauer spectrometer for continued investigation of Dorsal Tail and acquired part 3 of the rimshot pan. Opportunity participated in another UHF relay with the Mars Reconnaissance Orbiter to test compression of panoramic camera data. The rover measured argon gas in the Martian atmosphere with the alpha-particle X-ray spectrometer and used the panoramic camera to survey the horizon and take spot images of the sky for calibration purposes.

Sol 1466: Opportunity restarted the Mössbauer spectrometer and continued work on Dorsal Tail. The rover acquired full-color frames, using all 13 filters of the panoramic camera, of a disturbed slope.

Sol 1467: Opportunity restarted the Mössbauer spectrometer and continued its investigation of Dorsal Tail. The rover completed work on part 4 of the super-resolution rimshot pan.

Sol 1468: Opportunity acquired a 1-by-1-by-3 stack of microscopic images of Dorsal Tail and a 1-by-1-by-3 stack of microscopic images of a rock exposure nicknamed "Dorsal New." The rover placed the Mössbauer spectrometer on Dorsal New, took calibration images known as "sky flats" with the navigation camera, and acquired part 5 of the super-resolution rimshot panorama. Opportunity acquired data with the Mössbauer spectrometer and acquired part 6 of the super-resolution rimshot panorama.

Sol 1469: Opportunity restarted the Mössbauer spectrometer and began to investigate Dorsal Tail with the instrument. The rover acquired parts 7 and 8 of the rimshot panorama.

Sol 1470 (March 13, 2008): Opportunity restarted the Mössbauer spectrometer and resumed studies of Dorsal Tail with the instrument. The rover acquired part 9 of the rimshot panorama and also used the panoramic camera to take spot images and thumbnail images of the sky.

Odometry:

As of sol 1469 (March 12, 2008), Opportunity's total odometry was 11,671.23 meters (7.25 miles).


sol 1457-1462, Feb. 28 - Mar. 04, 2008: Opportunity Adjusts to Fluctuating Power Levels

Opportunity is healthy and all subsystems are performing as expected. Solar array energy rose slightly (approximately 12 watt-hours) during the past week despite a slight increase in Tau, the measure of dust in the atmosphere. Then, on Sol 1462 (March 4, 2008), energy plunged about 19 watt-hours despite a drop in Tau. The dust factor, a measure of the amount of sunlight penetrating dust on the arrays, remained virtually unchanged at 0.72 (meaning 72 percent of sunlight made it through the layer of dust to generate electricity).

During the same time period, power went up to 432 watt-hours, then dropped to 419 watt-hours. The week before, it had declined from about 440 watt-hours to 415 watt-hours (100 watt-hours is the amount of energy needed to light a 100-watt bulb for one hour). Nothing in the environment explains this. Mars is in late fall at the Opportunity site and moving toward winter, with the Sun sinking slightly lower each sol (Martian day). The rover hasn't moved or changed orientation. Tau and dust factor have been relatively steady. So why did power increase, then decrease?

During the previous week, Opportunity used its batteries. A lot. As the batteries discharged, their voltage dropped. Because power is just the product of the voltage and the solar array current, for a given amount of sunlight, the power is lower when recharging a discharged battery than a more fully charged battery. Opportunity's batteries were only about half-charged at the start of the week, bringing energy down a bit. The rover then recharged the batteries and energy went up. Opportunity then dipped into the battery again and energy went back down.

One reason for the increase in energy during the week was that Opportunity didn't complete all of the tasks rover handlers had planned because of a transmitter failure in NASA's Deep Space Network. This network is a collection of big dish antennas that talk and listen to spacecraft, including the Mars Exploration Rovers. Engineers send new plans, called sequences, to the rovers using the Deep Space Network. On sol 1458 (Feb. 29, 2008), they attempted to send plans to Opportunity for sols 1458-1460 (Feb. 29-March 2, 2008), giving instructions for work to be done over the weekend. When the transmitter failed and could not be immediately repaired, the rover repeated a section of the plan for sol 1457 (Feb. 28, 2008) called the "runout."

Each plan controls the rover for a single sol. At the end of the plan, the on-board computer tries to "handover" to the next day's plan. If the next day's plan isn't there, the existing plan continues running with a limited and standardized set of generic observations. In this case, the sol 1457 plan executed its runout for sols 1458, 1459 and 1460 (Feb. 29, March 1, and March 2, 2008).

Of course, there isn't room for an infinite runout, so at the end of the third sol, the rover usually executes a sequence known as "drop into automode." Automode means the plan has ended and is no longer controlling the rover. At that point, the rover is on its own and follows instructions programmed into its flight software for staying healthy and listening for further commands. If there's enough sunlight to power its systems, the rover wakes up, honors any preprogrammed communication windows, and shuts down if either the "up-too-long" limit is reached or the solar arrays aren't generating enough power, whichever comes first.

Because the runout didn't require as much power as the originally planned activities, Opportunity's batteries charged a bit more than expected, causing energy levels to rise.

Opportunity successfully tested communications with the European Space Agency's Mars Express Orbiter, which relays data to Earth much like NASA's Mars Odyssey orbiter, on sol 1461 (March 3, 2008). This and similar demonstrations are aimed at helping NASA's Phoenix mission, now en route to Mars, during entry, descent and landing in late May, 2008.

Opportunity also performed a "quick fine attitude" calibration. This is a procedure to hone the performance of a device called the inertial measurement unit that measures changes in orientation (yaw, pitch and roll). Like all gyroscopes, the unit drifts slightly with time and must be recalibrated every so often. During this procedure, a set of commands tells the panoramic camera to look for the Sun, identify where it is, compute the difference between its predicted and actual position, and update the inertial measurement unit accordingly. The correction from this particular recalibration was about 2.25 degrees, slightly larger than usual but not hugely so.

Sol-by-sol summary:

In addition to receiving instructions directly from Earth via the rover's high-gain antenna, relaying data to Earth via the UHF antenna on the Mars Odyssey orbiter, and measuring atmospheric dust with the panoramic camera, Opportunity completed the following activities:

Sol 1457 (Feb. 28, 2008): Opportunity placed the microscopic imager over a rock target known as "Dorsal" and acquired a 2-by-1-by-20 stack of stereo (3-D) microscopic images. The rover placed the alpha-particle X-ray spectrometer on Dorsal and spent about 6 hours acquiring data with the instrument, then went into a mini-deep sleep.

Sol 1458: Opportunity was unable to complete the day's activites after a Deep Space Network transmitter outage. Items not completed included spot images of the sky, navigation camera measurements of atmospheric dust, movie frames in search of clouds, a "quick get fine attitude," acquisition of data with the Mössbauer spectrometer, and transmission of data to Odyssey.

Sol 1459: Following the previous sol's transmitter outage, Opportunity was unable to execute plans to acquire a 2-by-1 mosaic of panoramic camera images of an alcove in the rim of "Victoria Crater" known as"Cabo Frio," a 5-by-1 mosaic of rearward-looking navigation camera images, and Mössbauer spectrometer data. Opportunity was also not yet able to test communications with Mars Express or transmit data to Odyssey.

Sol 1460: Following the transmitter outage on Sol 1458, Opportunity was not able to execute plans to acquire full-color images using all 13 filters of the panoramic camera of a target dubbed "Jin," survey the horizon with the panoramic camera, acquire data with the Mössbauer spectrometer, take full-color images of the hole created with the rock abrasion tool in the rock layer known as "Lyell," or acquire six movie frames in search of clouds.

Sol 1461: With Deep Space Network transmissions restored, Opportunity suspended the Mössbauer spectrometer over Dorsal to set its position before moving the robotic arm out of the field of view of the hazard avoidance cameras, executed a "quick fine attitude," and acquired images for mapping and modeling the terrain with the front hazard avoidance cameras. The rover placed the Mössbauer spectrometer on Dorsal and spent approximately 9 hours collecting data with the instrument. Opportunity successfully tested communications with Mars Express.

Sol 1462 (March 4, 2008): Opportunity acquired the previously planned 2-by-1 mosaic of images of Cabo Frio with the panoramic camera and 8-by-1 mosaic of rearward-looking images with the navigation camera. The rover switched tools from the Mössbauer spectrometer to the alpha-particle X-ray spectrometer and, after communicating with Odyssey, collected roughly 7 hours worth of compositional data with the instrument. The rover went into a mini-deep sleep. The following morning, Opportunity was scheduled to take the previously planned, full-color, panoramic-camera images of the hole ground into Lyell.

Odometry:

As of sol 1461 (March 3, 2008), Opportunity's total odometry was 11,671.23 meters (7.25 miles).


sol 1451-1456, Feb. 22-27, 2008: Opportunity Studies Martian Dust and "Victoria Crater" Rocks

Opportunity continues to be healthy with all subsystems performing as expected. Energy has been declining slowly, from 440 watt-hours at the start of the period to 415 watt-hours at the end. Some of that decline is due to the advancing winter season but much of it is due to heavy battery usage. By dipping into the battery, the rover lowers its bus voltage (the bus is the main power distribution cable. All systems get their power through their connection to the bus.) As power is the product of voltage and array current, for a given amount of sunlight, power will be lower when the batteries are discharged compared to when they are more fully charged. This lower power is by design -- the rover uses the batteries to execute the science plan and then recharges the batteries to increase energy.

Tau, a measure of the amount of dust in the atmosphere blocking incoming sunlight, has averaged about 0.74. (A Tau of zero would correspond to a perfectly clear atmosphere.) A Tau of 0.74 means only about 45 percent of the direct sunlight reaches the solar array. (Note that atmospheric dust both absorbs and scatters sunlight. The absorbed light is lost as it turns to heat and warms the atmosphere. Scattered sunlight is not lost. It makes the whole sky "glow" and gives it a pinkish color. It also reaches the solar panels and generates a significant fraction of the rover's total power.)

For example, during the worst of the Martian dust storms some 200 sols ago, Tau hit 5.6, which meant only about 40 percent of the direct sunlight reached Opportunity's solar arrays. Scattered light generated virtually all the rover's power, about 130-160 watt-hours per sol. Currently, scattered light generates as much as half the rover's power depending on the time of day.

The rover measures Tau at various times of day, sometimes using two different cameras. The reason for this is that dust accumulates on the camera lenses, affecting the measurement. By taking Taus at different times, the rover sees the Sun through different depths of the atmosphere. If Tau is constant (and to a first approximation, it is), engineers can estimate how much sunlight is blocked by atmospheric dust and how much by camera dust. Comparing measurements from both the navigation and panoramic cameras, each with different amounts of dust, provides another means of determining how much sunlight is being blocked by the atmosphere or the camera. And as every photographer knows, different lighting conditions require different exposure times. The rover does the same thing by changing the exposure at different times of the Sol. Typically, the rover uses the panoramic camera to measure Tau, taking regular Tau measurements between mid-morning and early afternoon, "new Tau" measurements in mid-afternoon, and a sunset Tau near sunset.

Opportunity's dust factor, which is different from Tau, has been steady at 0.73, meaning that 73 percent of the sunlight reaching the solar arrays penetrates the dust layer to generate electricity.

While studying the various layers of rock in "Victoria Crater," Opportunity has discovered that the "Steno" layer is coarse-grained with well-defined, fine layering called laminae. The "Smith" rock layer is lighter in color and has still finer laminae. "Lyell" is darker again and has slightly coarser layers. "Gilbert," the lowest layer examined so far, appears similar to Lyell but without apparent layering. Scientists are comparing the layers in Victoria Crater to other craters Opportunity has visited to determine whether the processes that produced them were local or regional.

One of the interesting features at Gilbert is a line of "fins." These look like thin, little burrs of rock along one edge of the rock slab. A few have broken off and are lying flat on the surface of Gilbert. One of these, named "Dorsal," will be studied over the next week.

Sol-by-sol summary:

In addition to receiving instructions directly from Earth via the rover's high-gain antenna and relaying data back to Earth via the UHF antenna on the Mars Odyssey orbiter, Opportunity completed the following activities:

Sol 1451 (Feb. 22, 2008): Opportunity acquired 6 movie frames in search of clouds with the navigation camera in addition to regular Tau, new Tau, and sunset Tau measurements with the panoramic camera. The rover spent about 6.3 hours measuring argon gas in the Martian atmosphere with the alpha-particle X-ray spectrometer and went into a mini-deep sleep.

Sol 1452: Upon awakening, Opportunity measured Tau with the navigation camera. The rover took spot images of the sky with the panoramic camera and acquired 6 movie frames in search of clouds with the navigation camera. Opportunity took a regular Tau measurement, followed by a 2-by-2-by-3 stack of microscopic images of dust on the capture magnet and a 2-by-2-by-3 stack of microscopic images of dust on the filter magnet. Before sending data to Odyssey, the rover took a sunset Tau measurement. After communicating with Odyssey, Opportunity studied the elemental composition of dust on the filter magnet by integrating data from the alpha-particle X-ray spectrometer for 5.5 hours. The rover went into a mini-deep sleep.

Sol 1453: Upon solar array wakeup, Opportunity took Tau measurements with the navigation camera and thumbnail images of the sky with the panoramic camera. The rover acquired 6 movie frames in search of clouds with the navigation camera. Opportunity took a regular and a new Tau measurement. After sending data to Odyssey, Opportunity spent about 6.3 hours studying the elemental chemistry of dust on the filter magnet with the alpha-particle X-ray spectrometer. The rover went into a mini-deep sleep.

Sol 1454: Shortly after sunrise, Opportunity measured Tau and acquired 6 movie frames in search of clouds with the navigation camera. Opportunity monitored the physical characteristics of dust on the rover mast assembly, surveyed the horizon with the panoramic camera, and created 6 more movie frames in search of clouds with the navigation camera. The rover made standard Tau measurements and, after the overpass of Odyssey, a new Tau measurement. Opportunity spent about 7.25 hours collecting data from the filter magnets with the alpha-particle X-ray spectrometer before going into a mini-deep sleep.

Sol 1455: Upon solar array wakeup, Opportunity measured Tau with the navigation camera, created two six-frame movies in search of clouds with the navigation camera, and took spot images of the sky for calibration purposes with the panoramic camera. The rover acquired a 4-by-1 panel of panoramic camera images of a target called "Shrock." Opportunity made a regular Tau measurement and took full-color images, using all 13 filters of the panoramic camera, of a rock exposure dubbed "Gilbert_A." The rover placed the microscopic imager on Gilbert_A and acquired a 2-by-2-by-14 stack of stereo (3-D) microscopic images, then switched tools and placed the alpha-particle X-ray spectrometer on the target. The rover took a new Tau measurement and, after sending data to Odyssey, spent about 6.25 hours acquiring compositional data from Gilbert_A.

Sol 1456 (Feb. 27, 2008): First thing in the morning, Opportunity took full-color images, using all 13 filters of the panoramic camera, of both magnets. The rover made regular Tau measurements with the panoramic camera as well as a Tau measurement with the navigation camera and created a 6-frame movie in search of clouds with the navigation camera. Opportunity took full-color images of Gilbert_A as well as panoramic-camera images of the brush on the rock abrasion tool. The rover ran diagnostic tests related to a stall in Joint 1 (controlling shoulder position), placed the microscopic imager over Gilbert_A, and acquired a 2-by-2-by-12 stack of stereo images of the target. Opportunity then placed the alpha-particle X-ray spectrometer on Gilbert_A. After communicating with Odyssey, Opportunity collected compositional data from Gilbert_A for about 4 hours. The following morning, the rover was to acquire regular Tau measurements, navigation-camera Tau measurements, and a 3-by-1 panel of panoramic-camera images of the promontory known as "Cape Verde."

Odometry:

As of sol 1455 (Feb. 26, 2008), Opportunity's total odometry was 11,671.23 meters (7.25 miles).


sol 1444-1450, Feb. 15-21, 2008: Multi-Tasking Rover Helps Pave the Way for Next Mars Mission

Opportunity completed the first leg of a two-part drive toward an area of scientific interest known as "Gilbert" that involved moving backward in order to continue the drive without running into some unexpectedly deep soil to the rover's right. En route, Opportunity spent two Martian days acquiring compositional data from a rock exposure dubbed "Lyell-Exeter," measured argon gas in the Martian atmosphere, and conducted remote-sensing activities.

In addition, Opportunity tested relay communications in support of NASA's Phoenix mission, due to land on Mars in late May. The first test, with the European Space Agency's Mars Express spacecraft, took place on sol 1444 (Feb. 15, 2008) and was primarily a trial of a new command strategy to permit the orbiter to acquire a larger amount of data from the surface of Mars. The second test was a possible relay through the NASA's Mars Reconnaissance Orbiter on sol 1446 (Feb. 17, 2008). This was an attempt to take advantage of an anomaly on the orbiter that turned off science instruments and placed the orbiter on standby to await instructions from Earth. The recovery timeline ended up not supporting this particular test. The third, with Mars Express on sol 1449 (Feb. 20, 2008), was part of a series of tests to determine differences in performance when the orbiter receives data from directly overhead and when the orbiter receives data when not directly overhead.

Opportunity remains healthy, with all subsystems performing as predicted. On sol 1449 (Feb. 20, 2008), the rover had 447 watt-hours of power (100 watt-hours is the amount of energy needed to light a 100-watt bulb for 1 hour).

Assuming Opportunity successfully completes a planned drive on sol 1450 (Feb. 21, 2008), the rover will be in position to begin a full complement of scientific investigations of Gilbert.

Sol-by-sol summary:

In addition to receiving instructions directly from Earth via the rover's high-gain antenna, relaying data to Earth via the UHF antenna on the Mars Odyssey orbiter, and measuring atmospheric dust with the panoramic camera, Opportunity completed the following activities:

Sol 1444 (Feb. 15, 2008): After sending overnight data to Odyssey as it passed overhead, Opportunity measured the composition of Lyell-Exeter with the alpha-particle X-ray spectrometer.

Sol 1445: Opportunity acquired early-morning, full-color images of a scuff made by the rover's left wheel using all 13 filters of the panoramic camera. The rover took spot images of the sky for calibration purposes with the panoramic camera and scanned the sky for clouds with the navigation camera. After communicating with Odyssey, Opportunity continued to acquire data from Lyell-Exeter with the alpha-particle X-ray spectrometer. The rover surveyed the sky at high Sun with the panoramic camera.

Sol 1446: Opportunity surveyed the horizon with the panoramic camera and scanned the morning sky for clouds in movie frames taken with the navigation camera. Opportunity stowed the robotic arm, drove toward Gilbert, acquired images just before completing the drive with the hazard avoidance cameras, and acquired a 4-by-1, post-drive mosaic of images with the navigation camera. The rover then unstowed the robotic arm.

Sol 1447: Opportunity surveyed and took spot images of the sky with the panoramic camera and documented potential clouds in movie frames taken with the navigation camera. After sending data to Odyssey, Opportunity measured argon gas in the Martian atmosphere using the alpha-particle X-ray spectrometer.

Sol 1448: Opportunity took thumbnail images of the sky with the panoramic camera and acquired movie frames in search of clouds with the navigation camera. The rover surveyed the horizon and surveyed the sky at high Sun with the panoramic camera.

Sol 1449: Upon awakening, Opportunity made a movie to document potential clouds with the navigation camera. The rover took spot images of the sky and surveyed the horizon with the panoramic camera. Opportunity surveyed the evening sky at low Sun prior to communicating with the Odyssey orbiter.

Sol 1450 (Feb. 21, 2008): Opportunity took early-morning thumbnail images of the sky with the panoramic camera. The rover also took spot images of the sky with the panoramic camera and acquired movie frames in search of clouds with the navigation camera. Opportunity stowed the robotic arm, drove toward Gilbert, acquired images just before completing the drive with the hazard avoidance cameras, unstowed the arm, and acquired a 360-degree mosaic of images with the navigation camera. The rover created 6 movie frames in search of clouds with the navigation camera. The following morning, Opportunity was to measure atmospheric dust with both the navigation and panoramic cameras, create another 6-frame movie in search of clouds with the navigation camera, and complete a survey of the horizon with the panoramic camera.

Odometry:

As of sol 1449 (Feb. 20, 2008), Opportunity's total odometry was 11,669.13 meters (7.25 miles).


sol 1437-1443, Feb. 8-14, 2008: Opportunity Proceeds with Caution on Sandy Slopes

After recovering from a stall in Joint 1, which controls the compass orientation of the shoulder on the rover's robotic arm, Opportunity is proceeding carefully to its next target, an exposure of layered rocks known as "Gilbert."

Opportunity ran the usual diagnostic tests for this sort of fault, which occurred while the rover was studying a rock target known as "Buckland," and successfully placed the Mössbauer spectrometer on the target on Sol 1437 (Feb. 8, 2008). On Sol 1438 (Feb. 9, 2008), the rover's handlers decided to relinquish further scientific studies of the target and proceed instead with a drive toward Gilbert. As this meant the rover would wander into new terrain, the team created a series of steps to allow Opportunity to characterize the surroundings along the way.

One of these steps involved placing the front two wheels on an area of soil to leave a scuff on the surface and backing up to take images of the exposed area. On Sol 1438, however, prior to reaching the intended soil area, Opportunity aborted the drive. The rover completed the second planned "scuffing" on Sol 1441 (Feb. 12, 2008). This time the scuff was successful, though it revealed an interesting surprise -- Opportunity's right front wheel dug in much more than the rover's handlers had expected, highlighting the need to proceed cautiously toward Gilbert.

Because Opportunity was unable to relay all of the diagnostic data to Earth at one time because the volume of data was more than could be accommodated, the rover's handlers decided that the prudent course of action was to wait one planning cycle before having Opportunity proceed with the drive. On Sol 1443 (Feb. 14, 2008), Opportunity completed a diagnostic examination of the grind bit on the rock abrasion tool and collected a mosaic of microscopic images of a rock target dubbed "Lyell Exeter," commemorating the college attended by geologist Sir Charles Lyell in the early 1800s, as well as compositional data using the alpha-particle X-ray spectrometer.

Opportunity is healthy and all subsystems are performing as expected. The latest available measurements on Sol 1443 showed a power level of 469 watt-hours (100 watt-hours is the amount of energy needed to light a 100-watt bulb for 1 hour). Plans for the coming weekend called for the rover to proceed with the first of a two-step drive toward Gilbert.

Sol-by-sol summary:

In addition to receiving instructions directly from Earth via the rover's high-gain antenna, relaying data to Earth via the UHF antenna on the Mars Odyssey orbiter, and assessing atmospheric dust levels with the panoramic camera, Opportunity completed the following activities:

Sol 1437 (Feb. 8, 2008): Opportunity recovered from last week's stall of Joint 1 on the robotic arm, succesfully placing the Mössbauer spectrometer on the surface of the rock target dubbed "Buckland" and spending 12 hours studying iron-bearing minerals with the instrument. The rover acquired a 2-by-1 mosaic of images of dunes with the panoramic camera.

Sol 1438: Opportunity surveyed and took spot images of the sky with the panoramic camera. The rover acquired movie frames in search of clouds with the navigation camera before rolling a short distance to get into position for a photo session, during which the rover took full-color images of Buckland, using all 13 filters of the panoramic camera. Opportunity then drove in the direction of Gilbert and acquired a mid-drive, 3-by-1 image mosaic of Gilbert using the panoramic camera. The rover collected a 2-by-2 mosaic of post-drive images with the navigation camera, took images with the hazard avoidance cameras, and unstowed the robotic arm. Opportunity was unable to complete a planned soil scuff followed by a backward drive.

Sol 1439: After awakening, Opportunity took spot images of the sky, surveyed the horizon, and surveyed the sky at high Sun with the panoramic camera. Opportunity then completed a systematic ground survey, using all 13 filters of the panoramic camera. After relaying data to NASA's Odyssey orbiter as it passed overhead, the rover studied argon gas in the Martian atmosphere with the alpha-particle X-ray spectrometer.

Sol 1440: Upon receiving enough solar energy to wake up autonomously, Opportunity took thumbnail images of the sky with the panoramic camera. The rover searched for morning clouds in movie frames taken with the navigation camera, took spot images of the sky with the panoramic camera, and monitored dust accumulation on the mast assembly. Opportunity made additional measurements of atmospheric argon with the alpha-particle X-ray spectrometer after transmitting data to Odyssey.

Sol 1441: Upon awakening, the rover surveyed the sky with the panoramic camera. Opportunity then acquired movie frames in search of morning clouds with the navigation camera. The rover stowed the robotic arm, scuffed the soil with its wheels while driving toward Gilbert, and acquired a 3-by-1 mosaic of post-drive images of Gilbert with the panoramic camera as well as a 2-by-2 mosaic of navigation camera images and hazard avoidance camera images. Opportunity unstowed the robotic arm.

Sol 1442: Upon awakening, Opportunity took spot images of the sky and surveyed the horizon with the panoramic camera. The rover also surveyed the sky at high Sun with the panoramic camera.

Sol 1443 (Feb. 14, 2008): Upon awakening, Opportunity took thumbnail images of the sky with the panoramic camera and acquired movie frames in search of clouds with the navigation camera. The rover surveyed the grinding bit on the rock abrasion tool and acquired a 2-by-2-by-14 stack of stereo microscopic images of Lyell Exeter. Opportunity placed the alpha-particle X-ray spectrometer on Lyell Exeter, acquired a 2-by-1 mosaic of images of Gilbert with the navigation camera, and, after sending data to Odyssey, collected compositional data with the spectrometer. The following morning, Opportunity was to acquire full-color images, using all 13 filters of the panoramic camera, of the area exposed by the rover's wheels and survey the sky at high Sun with the panoramic camera.

Odometry:

As of sol 1443 (Feb. 14, 2008), Opportunity's total odometry was 11,668.08 meters (7.25 miles).


sol 1430-1436, Feb. 1-7, 2008: Opportunity Searches for Martian Frost

During the past week, Opportunity took advantage of fresh rock tailings ground up by the rock abrasion tool to look for any frost accumulation on them on Sol 1435 (Feb. 6, 2008). The rover also used the WATCH sequence of computer commands to hunt for winter clouds above Victoria Crater on Sol 1431 (Feb. 2, 2008).

Meanwhile, Opportunity began wrapping up its campaign of scientific investigations of the outcrop target called "Buckland" at "site B" in the "Lyell" layer of rocks that rings the interior of "Victoria Crater." Plans call for Opportunity to drive deeper into Victoria Crater next week, to the next stratigraphic layer, dubbed "Gilbert."

In support of NASA's Phoenix mission, now en route to the red planet, Opportunity conducted a joint UHF communications test with NASA's Mars Reconnaissance Orbiter on Sol 1436 (Feb. 7, 2008).

Opportunity is healthy and all subsystems are nominal. Energy is currently around 483 watt-hours (100 watt-hours is the amount of energy needed to light a 100-watt bulb for 1 hour). On Sol 1437 (Feb. 8, 2008), Tau measurements of atmospheric dust were at 0.757 and dust factor measurements of sunlight penetration to the solar panels at 0.75.

Sol-by-sol summary:

In addition to receiving instructions directly from Earth via the rover's high-gain antenna, relaying data to Earth via the UHF antenna on the Mars Odyssey orbiter, and taking panoramic camera measurements of atmospheric opacity caused by dust, Opportunity completed the following activities:

Sol 1430 (Feb. 1, 2008): Opportunity swung the robotic arm out of the way and acquired full-color images using all 13 filters of the panoramic camera and a 2-by-2-by-14 stack of stereo (3-D) images of Buckland. The rover went into a deep sleep.

Sol 1431: Upon receiving enough solar energy to wake up autonomously, Opportunity watched for Martian clouds and acquired movie frames in search of clouds with the navigation camera. The rover placed the alpha-particle X-ray spectrometer on the surface of Buckland and, after relaying data to the Odyssey orbiter, used the spectrometer to gather data about the rock's elemental chemistry.

Sol 1432: Upon awakening, Opportunity surveyed the horizon with the panoramic camera, scanned the sky for clouds with the navigation camera, and acquired a 2-by-1 mosaic of images of an area of layered rock known as "Harland" with the panoramic camera. Opportunity placed the Mössbauer spectrometer on the surface of Buckland and spent 7 hours studying iron-bearing minerals in the rock with the instrument. The rover acquired a 2-by-1 mosaic of images of Harland with the panoramic camera before going into a deep sleep.

Sol 1433: Upon awakening, Opportunity acquired a 2-by-1 mosaic of images of Harland with the panoramic camera and scanned the sky for clouds with the navigation camera. The rover restarted the Mössbauer spectrometer and acquired 12 hours worth of data with the instrument. Opportunity acquired an afternoon, 2-by-1 mosaic of images of Harland. The rover went into a mini-deep sleep.

Sol 1434: Upon awakening, Opportunity took thumbnail images of the sky and completed a sky survey at high Sun with the panoramic camera. Opportunity restarted the Mössbauer spectrometer on Buckland and spent 9 hours studying iron-bearing minerals with the instrument. The rover went into a mini-deep sleep.

Sol 1435: Upon awakening, Opportunity surveyed the horizon with the panoramic camera and scanned the sky for clouds with the navigation camera. Opportunity exchanged tools to the microscopic imager and acquired a 1-by-1-by-1 stack of microscopic images of Buckland prior to acquiring another 1-by-1-by-1 stack for comparison prior to searching for frost. At 3:33 p.m. local Mars time, Opportunity acquired a 1-by-1-by-4 stack of microscopic images in search of frost on the rock tailings exposed at Buckland.

Sol 1436 (Feb. 7, 2008): Upon awakening, Opportunity acquired thumbnail images of the sky with the panoramic camera and scanned the sky for clouds with the navigation camera. Additional plans, which included a survey of the bit on the rock abrasion tool, a survey of the rock abrasion tool with the panoramic camera, placement of the Mössbauer spectrometer on Buckland, and continued analysis of iron-bearing minerals, did not take place because of a stall in Joint 1, which controls the orientation of the shoulder on the rover's robotic arm. Opportunity did, however, close the cover of the microscopic imager. The rover went into a deep sleep. Plans for the following morning included surveying the horizon with the panoramic camera, searching the sky for clouds with the navigation camera, and surveying the sky at high Sun with the panoramic camera.

Odometry:

As of sol 1436 (Feb. 7, 2008), Opportunity's total odometry remained at 11,664.00 meters (7.25 miles).


sol 1424-1429, Jan. 25-31, 2008: Opportunity Expands Geologic Studies in "Victoria Crater"

Opportunity has been investigating a rock outcrop nicknamed "Buckland" at "site B," at the deepest part of the ring of rocks known as the "Lyell" layer. For those keeping tabs on Opportunity's location, the rover is inside Victoria Crater, in an alcove known as "Duck Bay."

The planned roster of scientific investigations for the coming week includes taking microscopic images, analyzing elemental composition with the alpha-particle X-ray spectrometer, and studying iron-bearing minerals with the Mössbauer spectrometer.

The rover is healthy and all subsystems are performing as expected. Energy is currently around 505 watt-hours (a little more than the energy needed to light a 100-watt bulb for 5 hours). As of the end of January, Tau measurements of atmospheric dust stood at about 0.685 and dust factor measurements of sunlight penetrating dust on the solar panels stood at about 0.74.

Sol-by-sol summary:

In addition to receiving instructions directly from Earth via the rover's high-gain antenna, relaying data to Earth via the UHF antenna on the Mars Odyssey orbiter, and taking panoramic camera measurements of atmospheric opacity caused by dust, Opportunity completed the following activities:

Sol 1424 (Jan. 25, 2008): The day's plans did not make it on board Opportunity because of an outage in the Deep Space Network of antennas on Earth. Those plans included exchanging tools to the Mössbauer spectrometer and collecting data with the instrument, in addition to acquiring a 2-by-1 mosaic of images of an area of dust-covered, possibly layered rocks below the Lyell layer known as "Gilbert," taking spot images of the sky and surveying the horizon with the panoramic camera, and scanning the sky for clouds with the navigation camera.

Sol 1425: Instead of acquiring data about iron-bearing minerals with the Mössbauer spectrometer because of the previous day's communications lapse, Opportunity acquired data with the instrument pointed at the Martian atmosphere. Opportunity acquired a full-color, 2-by-1 mosaic of images of Gilbert using all 13 filters of the panoramic camera. The rover surveyed and acquired thumbnail images of the sky with the panoramic camera and scanned the sky for clouds with the navigation camera.

Sol 1426: Instead of acquiring data about iron-bearing minerals with the Mössbauer spectrometer because of the communications lapse on Sol 1424, Opportunity acquired data with the instrument pointed at the Martian atmosphere. Opportunity studied iron-bearing minerals with the Mössbauer spectrometer. Using the panoramic camera, the rover acquired a 6-by-2 mosaic of images, took thumbnail images of the sky, and completed a survey at high Sun.

Sol 1427: Opportunity took images with the front hazard avoidance cameras, completed a grind-scan procedure with the rock abrasion tool to locate the surface of Buckland, and acquired a 2-by-1 mosaic of images of Gilbert with the panoramic camera. The rover measured atmospheric argon with the alpha-particle X-ray spectrometer.

Sol 1428: Upon generating enough solar energy to wake up automously, Opportunity acquired a 2-by-1 mosaic of images of Gilbert with the panoramic camera. The rover monitored dust on the panoramic-camera mast assembly.

Sol 1429: (Jan. 31, 2008): Opportunity awoke autonomously and acquired full-color images, using all 13 filters of the panoramic camera, of dust particles captured by the rover's external magnets. Opportunity scanned the sky for clouds with the navigation camera and ground into the surface of Buckland with the rock abrasion tool. The rover acquired a 2-by-1 mosaic of images of Gilbert with the panoramic camera. The following morning, Opportunity was to acquire movie frames in search of Martian clouds with the navigation camera.

Odometry:

As of sol 1429 (Jan. 31, 2008), Opportunity's total odometry remained at 11,664.00 meters (7.25 miles).


sol 1416-1423, Jan. 17-24, 2008: Opportunity Marks Fourth Anniversary on Mars

Like the Spirit rover three weeks earlier, Opportunity achieved a new milestone of four years of exploration on the surface of Mars.

Opportunity drove even deeper into "Victoria Crater" along the slopes of the alcove known as "Duck Bay" to a rock outcrop called "Buckland." On sol 1416 (Jan. 17, 2008) the rover attempted a 5-meter (16-foot) drive. In the middle of the drive, however, Opportunity stopped and drove back uphill to ensure the rover could drive back out again. During this drive the vehicle experienced a slippage rate of 46 percent, exceeding the limit of 40 percent set by rover planners, and stopped driving.

On sol 1418 (Jan. 19, 2008), rover planners decided to increase the limit to 60 percent. While backing up, the rover experienced only 23-percent slip, possibly as a result of making contact with bedrock and getting better traction after the rover's wheels had removed a thin layer of sand. Following the successful slip check, the rover continued downslope to Buckland. On sol 1421 (Jan. 22, 2008) Opportunity commenced a campaign of scientific investigations of the outcrop by amassing 60 microscopic images. Weekend plans call for Opportunity to spend approximately 46 hours studying iron-bearing minerals using the Mössbauer spectrometer.

Opportunity is healthy, with all systems performing as expected.

Sol-by-sol summary:

In addition to receiving instructions directly from Earth via the rover's high-gain antenna. returning data to Earth via the UHF antenna on the Mars Odyssey orbiter, and taking panoramic camera measurements of atmospheric opacity caused by dust, Opportunity completed the following activities:

Sol 1416 (Jan. 17, 2008): Opportunity stowed the robotic arm, which carries many of the rover's scientific instruments, and drove 5 meters downslope toward Buckland. The rover unstowed the robotic arm and acquired a 5-by-1 mosaic of images of surrounding terrain and a 1-by-1 mosaic of a target area known as "site C" with the navigation camera. Opportunity scanned the sky for clouds above Victoria Crater with the navigation camera.

Sol 1417: Opportunity measured argon gas in the Martian atmosphere with the alpha-particle X-ray spectrometer, surveyed the sky with the panoramic camera, monitored dust on the rover mast, and scanned the sky for clouds with the navigation camera.

Sol 1418: Opportunity stowed the robotic arm, drove to Buckland, unstowed the robotic arm, and acquired a post-drive, 5-by-1 mosaic of images of surrounding terrain as well as a rearward-looking, 5-by-1 mosaic of images with the navigation camera. The rover scanned the sky for clouds with the navigation camera and surveyed the horizon with the panoramic camera.

Sol 1419: Opportunity acquired a 3-by-5 mosaic of images with the panoramic camera, scanned the sky for clouds with the navigation camera, and took spot images and thumbnail images of the sky with the panoramic camera.

Sol 1420: Opportunity took spot images and thumbnail images of the sky with the panoramic camera and scanned the sky for clouds with the navigation camera.

Sol 1421: Opportunity acquired a 2-by-2-by-5 stack of microscopic images plus 36 extras and a full-color view of the work volume reachable by the robotic arm using all 13 filters of the panoramic camera. The rover placed the alpha-particle X-ray spectrometer on Buckland and collected compositional data with the instrument. Oppportunity took spot images of the sky and completed a sky survey at high Sun using the panoramic camera.

Sol 1422: Opportunity placed the alpha-particle X-ray spectrometer on Buckland and acquired more compositional data. The rover took spot images of the sky and surveyed the horizon with the panoramic camera. Opportunity searched for clouds using the navigation camera.

Sol 1423 (Jan. 24, 2008): Opportunity acquired a 2-by-5 mosaic of images. The rover completed a sky survey and took thumbnail images of the sky with the panoramic camera.

Odometry:

As of sol 1423 (Jan. 24, 2008), Opportunity's total odometry was 11,664.00 meters (7.25 miles).


sol 1411-1415, Jan. 12-16, 2008: Plans Call for Opportunity to Drive Deeper into "Victoria Crater"

Opportunity has experienced no further stalls in the shoulder joint that recently stalled two times in a row. Engineers have identified at least four variables that may have contributed to the stall, including very small movements, very slow movements, movements that exert torque (a twisting force) on the shoulder joint while the robotic arm is extended far away from the vehicle, and movements in an uphill direction that go against the force of Martian gravity.

The team is employing techniques to avoid moving the robotic arm under these conditions.

After completing investigation of the contact between the "Smith" and "Lyell" rock layers inside "Victoria Crater," Opportunity continues its exploration of "Duck Bay," an alcove in the crater's rim. Plans call for Opportunity to drive about 5 meters (16 feet) deeper into the crater on sol 1416 (Jan. 17, 2008) and take images of the terrain.

Sol-by-sol summary:

In addition to receiving instructions directly from Earth via the rover's high-gain antenna and taking panoramic camera measurements of atmospheric opacity caused by dust, Opportunity completed the following activities:

Sol 1411 (Jan. 12, 2008): Opportunity acquired a 4-by-1-by-5 mosaic of stereo microscopic images on the Lyell side of the Smith-Lyell contact, placed the alpha-particle X-ray spectrometer on target, and searched the Martian sky for clouds with the navigation camera.

Sol 1412: Opportunity searched the sky above Victoria Crater for clouds with the navigation camera and collected compositional data from the surface with the alpha-particle X-ray spectrometer.

Sol 1413: Opportunity continued to watch the Martian sky for clouds and acquire compositional data with the alpha-particle X-ray spectrometer.

Sol 1414: Opportunity acquired a 1-by-1-by-5 stack of images on the Lyell side of the Smith-Lyell contact with the microscopic imager. The rover placed the alpha-particle X-ray spectrometer on the Lyell layer and acquired compositional data about the rock. Opportunity relayed data to Odyssey during the orbiter's overnight pass.

Sol 1415 (Jan. 16, 2008): Opportunity completed measurements of the Lyell rock layer with the alpha-particle X-ray spectrometer.

Odometry:

As of sol 1415 (Jan. 16, 2008), Opportunity's total odometry was 11,653.18 meters (7.24 miles).


sol 1402-1410, Jan. 3-11, 2008: Opportunity Continues Exploration Despite Stall in Robotic Arm

On sol 1404 (Jan. 5, 2008), as Opportunity was in the process of moving the robotic arm out of the field of view of the hazard avoidance cameras, the rover experienced a stall in joint 1, which has stalled before and controls shoulder orientation. Rover handlers directed Opportunity to perform a set of diagnostic tests on sol 1407 (Jan. 8, 2008) to determine what happened. Opportunity successfully completed the first part of the diagnostic test but experienced another stall in the joint during the second part of the test, when the rover attempted to repeat the move it had been making during the first stall.

In the activity plan for sol 1409 (Jan. 10, 2008), rover drivers directed Opportunity to again execute the same motion. This time, Opportunity retracted the robotic arm, reducing the load on joint 1.

The rover science team will continue to closely monitor and evaluate use of the joint as Opportunity explores Victoria Crater. This week, Opportunity drove a short distance to get into position study the contact area between two rock layers inside "Victoria Crater" known as "Lyell" and "Smith."

Sol-by-sol summary:

In addition to morning uplinks directly from Earth via the rover's high-gain antenna and panoramic camera measurements of atmospheric opacity caused by dust, Opportunity completed the following activities:

Sol 1402 (Jan. 3, 2008): Opportunity stowed the robotic arm, drove to a new position, acquired images of the new location with the hazard avoidance cameras, unstowed the robotic arm, and acquired a 360-degree view of the surrounding terrain with the navigation camera.

Sol 1403: Upon receiving enough solar energy to wake up autonomously, Opportunity scanned the sky for clouds with the navigation camera and took spot images of the sky with the panoramic camera. The rover surveyed the sky at high Sun and acquired a 4-by-2 mosaic of images with the panoramic camera.

Sol 1404: After swinging the robotic arm out of the way, Opportunity acquired full-color images, using all 13 filters of the panoramic camera, of surfaces reachable by instruments on the robotic arm. In particular, Opportunity examined "Tijuana," a rock exposure in the contact zone between the rock layers known as "Smith" and "Lyell." Opportunity also took images of the target area with the rover's front hazard avoidance cameras and acquired a 5-by-1 tier of images with the navigation camera. After communicating with the Odysssey orbiter, Opportunity spent 5.5 hours measuring atmospheric argon with the alpha-particle X-ray spectrometer. The rover went into a mini-deep sleep.

Sol 1405: Upon awakening, Opportunity took thumbnail images of the sky with the panoramic camera. The rover acquired a mosaic of images with the panoramic camera in search of dust. After relaying data to Odyssey, Opportunity spent 6.5 hours measuring atmospheric argon with the alpha-particle X-ray spectrometer. The rover then went into a mini-deep sleep.

Sol 1406: After sending data to Odyssey, Opportunity continued to assess atmospheric argon, spending 7.5 hours integrating data with the alpha-particle X-ray spectrometer. The rover went into another mini-deep sleep.

Sol 1407: Opportunity conducted diagnostic tests in an effort to recover from a stall in joint 1 that occurred on sol 1404.

Sol 1408: Opportunity took thumbnail images of the sky with the panoramic camera.

Sol 1409: Opportunity scanned the sky for morning clouds using the navigation camera. Opportunity conducted additional diagnostic tests of the robotic arm, acquired a 4-by-1-by-5 mosaic of microscopic images of Smith, and placed the alpha-particle X-ray spectrometer on Smith to collect compositional data. After communicating with Odyssey, Opportunity collected data with the instrument until 11:30 p.m. Mars time.

Sol 1410 (Jan. 11, 2008): Opportunity acquired spot images of the sky for calibration purposes and surveyed the horizon with the panoramic camera. After transmitting data to Odyssey, Opportunity resumed collecting data with the alpha-particle X-ray spectrometer. Plans for the following morning called for the rover to assess dust accumulation on the rover mast.

Odometry:

As of sol 1409 (Jan. 10, 2008), Opportunity's total odometry remained at 11,653.18 meters (7.24 miles).


sol 1396-1401, Dec. 28, 2007 - Jan. 2, 2008: Opportunity Works the Night Shift Inside "Victoria Crater"

Opportunity has seen almost no change in atmospheric dust levels or dust accumulation on the solar panels. Even so, energy has varied as Opportunity's activity levels have varied. In particular, the timing of those activities changes the state of charge of the batteries as well as the bus voltage.

The bus is the main electrical conductor in the rover's power distribution system. It connects directly to the battery and distributes energy to all the rover's instruments. The rover monitors the bus voltage, which is usually within a few millivolts of the battery voltage. When the rover uses battery power -- that is, when energy is transferred from the battery to the bus to rover instruments -- the bus voltage goes down. When the battery recharges, the bus voltage goes up.

In a sense, the bus voltage is an indicator of energy efficiency -- solar arrays generate more energy for a given amount of sunlight when bus voltage is up than when bus voltage is down. This is because the total amount of electrical power available, measured in watts, depends not only on the amount of sunlight reaching the solar panels (which generates electrical current) but also the bus voltage. Voltage is analogous to water pressure; electrical current is analogous to water flow measured in gallons per minute. For a given water pressure, a large pipe transfers more gallons per minute than does a small pipe. For a given pipe size, high water pressure sends more water per minute gushing through the pipe than does low water pressure.

During the past week, Opportunity completed some evening and overnight activities that drew heavily on the batteries. As a result, bus voltage was relatively low when the rover began recharging the battery the following day, resulting in somewhat lower total energy.

Energy has hovered in the range of 575 to 590 watt-hours, averaging about 580 watt-hours (almost enough to light a 100-watt bulb for six hours) per Martian day. Tau measurements of atmospheric opacity caused by dust have been remarkably steady, averaging about 0.71. The dust factor has also been steady, averaging 0.787.

Opportunity continued to investigate the chemistry of the "Lyell" layer inside "Victoria Crater." Lyell is the third and lowest layer of a light-colored band of material that rings the crater. The rover conducted compositional analysis with the alpha-particle X-ray spectrometer. Afterward, Opportunity took measurements with the Mössbauer spectrometer to characterize iron-bearing minerals beneath the surface of Lyell, inside a hole the rover drilled last week.

These days, it takes longer to acquire data with the Mössbauer spectrometer than it did at the beginning of the mission. The Mössbauer spectrometer uses a radioactive source containing cobalt-57 to irradiate the rocks. Because the half-life of the source is about 271.8 days and more than 1,640 days have passed since the spacecraft left Earth, a little more than six half-lives have elapsed. The source now has only about 1.5 percent of its original strength. With the source so depleted, Opportunity must spend tens of hours (60 hours is more or less the minimum) collecting enough data to "see" fine details of the iron chemistry.

Comparisons between observations of two targets in the rock surface, known as "Lyell_3" and "Lyell_1," will enable scientists to assess variability within the rock layer. Comparisons with the two higher rock layers, "Smith" and "Steno," and with observations from other craters will help scientists determine the geologic histories along with local and regional similarities and differences.

Mid-week, Opportunity took images of the grind bit on the rock abrasion tool to assess wear and the condition of the wire brush -- wear is about the same and the brush remains bent but usable. Opportunity also took images of the Mössbauer spectrometer, where a small clod of dirt is clinging to the contact sensor. This has happened before and is not a concern.

Finally, Opportunity took images looking downslope in search of new drive destinations and science targets.

Opportunity is healthy and all subsystems are operating as expected.

Sol-by-sol summary:

In addition to morning uplinks directly from Earth via the rover's high-gain antenna, evening downlinks to Earth via the Odyssey orbiter at UHF frequencies, and panoramic camera measurements of atmospheric opacity caused by dust, Opportunity completed the following activities:

Sol 1396 (Dec. 28, 2007): Opportunity placed the alpha-particle X-ray spectrometer on Lyell_3, and after communicating with the Odyssey orbiter, went into a deep sleep.

Sol 1397: Upon collecting enough sunlight to wake up, Opportunity took a 2-by-1 mosaic of images of a spot known as "drive target 1" and acquired a full-color mosaic of images, using all 13 filters of the panoramic camera, of a target dubbed "Walcott," a rough exposure of the Steno rock layer. After communicating with Odyssey, Opportunity spent approximately 17 hours integrating data from Lyell_3 with the alpha-particle X-ray spectrometer.

Sol 1398: Opportunity acquired a 2-by-1 mosaic of images of a destination referred to as "drive target 2." After sending data to the Odyssey orbiter, the rover went into a deep sleep.

Sol 1399: Opportunity took spot images of the sky for calibration purposes and surveyed the horizon with the panoramic camera. The rover observed the ondition of the grind bit and brush on the rock abrasion tool using the hazard avoidance cameras. Similarly, the rover surveyed the overall condition of the rock abrasion tool with the panoramic camera. Opportunity surveyed the dirt clod clinging to the Mössbauer spectrometer, placed the Mössbauer spectrometer on the hole previously ground into Lyell_1, and spent about 11.25 hours acquiring data from the rock with the instrument. After communicating with Odyssey, the rover went into a mini-deep sleep.

Sol 1400: Opportunity spent approximately 12 hours acquiring data from Lyell_1 with the Mössbauer spectrometer and took full-color images from the rover's current position of a hole previously ground into the surface of Smith. The rover took full-color images, using all 13 filters of the panoramic camera, of a nearby rock target known as "Grabau." After transmitting data to Odyssey, Opportunity went into a mini-deep sleep.

Sol 1401 (Jan. 2, 2008): Opportunity characterized dust accumulation on the rover mast and spent approximately 12 hours collecting data from Lyell_1 with the Mössbauer spectrometer. Following the overhead pass of the Odyssey orbiter, Opportunity went into a mini-deep sleep.

Odometry:

As of sol 1401 (Jan. 2, 2008), Opportunity's total odometry remained at 11,591.21 meters (7.2 miles).

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