Opportunity Updates

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M I S S I O N     M A N A G E R S
	Dan Gaines		Matt Keuneke		Bill Nelson		Colette Lohr

P R E V I O U S    M I S S I O N    M A N A G E R S
	Cindy Oda		Richard Morris		Al Herrera		Byron Jones		Mark Adler

	Leo Bister		Beth Dewell		Emily Eelkema		Jeff Favretto		Saina Ghandchi

	Andy Mishkin		Art Thompson		Rick Welch

sol 1655-1660, September 12-18, 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.

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 condu