Opportunity Updates

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M I S S I O N     M A N A G E R S
	Colette Lohr		Cindy Oda		Richard Morris		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
	Byron Jones		Mark Adler		Leo Bister		Beth Dewell		Emily Eelkema

	Jeff Favretto		Saina Ghandchi		Andy Mishkin		Art Thompson		Rick Welch

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 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, 2