Opportunity Updates: 2005

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sol 675-681, Dec 22, 2005: Evaluating Arm Positions

This week the Opportunity Instrument Arm Anomaly Team continued investigating the safety of different arm positions. The intent is to determine the safest position to leave the arm while the vehicle drives to new locations. The original position for the arm while driving was to tuck it underneath the rover, hooked on a small pin. This leaves the partially failed shoulder azimuth joint at 90 degrees to the direction of travel. If the arm stuck in this position we would be unable to use the arm.

The current plan is to investigate different versions of driving with the instrument arm's "elbow" sticking out towards the front of the vehicle, with the arm's instrument cluster above the solar panels. From that position the instrument arm could still be used without using the suspect azimuth joint. The variations include leaving the instrument cluster in mid air, or resting one or another instrument on different portions of the rover for stability.

These different positions are being evaluated on the test rover at the Jet Propulsion Laboratory in Pasadena, Calif. Meanwhile, on Mars, Opportunity is continuing to use the arm and its instruments to investigate rocks within its reach. The rover has also been acquiring images for a 360-degree, multi-filter panorama of "Erebus Crater."

Sol-by-sol summaries:

Sol 675 (Dec. 17, 2005): Opportunity completed a 17-hour reading with the alpha particle X-ray spectrometer and made observations with the panoramic camera.

Sol 676: The rover used the Mössbauer spectrometer for five hours and observed the atmosphere and a target called "Bellemont" with the miniature thermal emission spectrometer.

Sol 677: Opportunity completed a microscopic-imager mosaic of a target called "Williams," used the Mössbauer spectrometer for 11 hours, and observed targets with the panoramic camera.

Sol 678: The Mössbauer collected data about Williams' composition for 22 hours and the panoramic camera made observations.

Sol 679: Opportunity moved its robotic arm to a target called "Ted," which it began inspecting with the microscopic imager and the alpha proton X-ray spectrometer. The navigation camera took pictures of the rover's front deck.

Sol 680: Planned activities include using the rock abrasion tool to brush Ted for about 11 minutes, then placing the alpha particle X-ray spectrometer onto the target again for about 20 hours of data collection.

Sol 681 (Dec. 23, 2005): Plans for this and the following few sols are further inspection of Ted, plus targeted observations with the panoramic camera. Opportunity's total odometry remains at 6,502 meters (4.04 miles).

sol 668-674, Dec 16, 2005: Robotic Arm Deployed

Opportunity successfully deployed its robotic arm on sol 671 (Dec. 13, 2005) and used it to position the microscopic imager. The cause of a shoulder-joint motor stall during an attempt to deploy the arm on sol 654 appears to be a broken wire in the motor windings. The motor can still be operated by changing one of the parameters so that more current is delivered. However, the behavior is still being characterized, and stalls of the motor can still occur while the motor parameters are being adjusted. Analysis also continues for determining the best strategy for keeping the arm unstowed even when it is not in use, so that the arm could still position instruments on targets even if the motor with the broken wire becomes unusable.

While parked at "Erebus Crater," Opportunity has completed a campaign of atmospheric science, with sky surveys, photometry observations at several times of day, and atmospheric observations with the miniature thermal emission spectrometer. The rover also observed ground targets with the panoramic camera and the miniature thermal emission spectrometer.

Sol-by-sol summaries:

Sol 668 (Dec. 10, 2005): The team had planned some targeted remote sensing and atmospheric observations, but the plan did not get uplinked due to issues with ground servers.

Sol 669: The uplink succeeded, and Opportunity performed targeted remote sensing and atmospheric observations.

Sol 670: Early in the morning, the rover performed an atmospheric observation. Later in the day, some stares with the miniature thermal emission spectrometer were completed.

Sol 671: Results of diagnostic tests of the robotic arm were consistent with the performance of a motor with a broken wire in one of the windings. The motor can be operated in this configuration by modifying motor parameters. By making the necessary changes, the arm was successfully moved out of its stowed position. The team planned a two-image-by-two-image mosaic with the microscopic imager and a reading with the Mössbauer spectrometer. The first half of the mosaic completed as planned, but the arm sequence was halted after that due to a stall of the shoulder-joint motor.

Sol 672: Opportunity made atmospheric and photometric observations.

Sol 673: The plan was to complete the microscopic-imager mosaic that was started on sol 671 and place the Mössbauer spectrometer on a target called "Williams." However, the shoulder-joint motor stalled once again. Targeted observations with the panoramic camera were completed as planned.

Sol 674 (Dec. 16, 2005): After analysis of the sol 673 stall, the team redelivered a command sequence to close the microscopic imager's dust cover and to position the alpha particle X-ray spectrometer for an overnight integration on Williams. Opportunity's total odometry remains at 6,502 meters (4.04 miles).

sol 661-667, Dec 09, 2005: Encouraging Results from Shoulder-Motor Testing

Opportunity is currently parked at "Erebus Crater," where it has continued remote-sensing science while the team made progress in diagnosing why a motor in the robotic arm stalled on sol 654. The motor turned successfully when supplied with more current on sol 666 (Dec. 8, 2005), an encouraging result. The arm was still in a stowed position after that testing. Further tests and analysis are planned for determining the best strategy for future use of the arm. The arm, which deploys four tools for examining rocks and soils, has already operated more than seven times as long as originally planned.

This motor at the shoulder of the arm is necessary for getting the arm out of its stowed position. Earlier tests made some alternative explanations -- such as a physical obstruction or degraded lubrication -- appear unlikely. The sol 666 test established confidence in a hypothesis that a broken wire in the winding of the motor caused the sol 654 stall. The test rotated the motor four revolutions at each of three different applied voltages. Tests to characterize the motor's behavior will continue in the coming week.

In the target-rich environment of outcrop exposed in and near Erebus, Opportunity has acquired a color panorama of the surroundings, a color mosaic of itself, and high-resolution images of several outcrop targets. The miniature thermal emission spectrometer successfully collected data on some high-priority science targets during sol 664 (Dec. 6, 2005). Informal names for targets examined in this vicinity by the panoramic camera include "Drake," "Chino Valley," "Bellemont," "Camp Verde," "Young," "Cherry," and "Paulden."

Opportunity did not drive this week. The rover's odometry total as of sol 666 remained 6,502 meters (4.04 miles).

sol 649-660, Dec 01, 2005: Stalled Motor, Stowed Arm

Opportunity drove 43 meters on sol 649 (Nov. 20, 2005) and then bumped 10 meters to an outcrop for work with its robotic arm (instrument deployment device) over the Thanksgiving holidays. Opportunity's commands for sol 654 (Nov. 25, 2005) included unstowing the arm to begin using the tools on it for examining the layered outcrop that the rover had driven to three sols earlier. The arm is always stowed during drives. This time, a shoulder-joint motor that is needed for unstowing the arm stalled, and the arm stayed stowed. In subsequent sols, engineers worked to narrow the range of possibilities for the cause of the stall. Among the remaining possibilities is that, after working more than seven times longer than originally planned, the lubrication is degrading. One possible fix would be to increase the duration of the allowed motor start-up, to overcome the increased initial friction. The first diagnostic activity for the arm was performed sol 659, where a very small motion was recorded. Future diagnostic activities and continuing analysis will be performed to further characterize the shoulder-joint motor in upcoming sols.

As of sol 659 (Nov. 30, 2005), Opportunity has driven 6,502 meters (4.04 miles).

sol 641-648, Nov 18, 2005: Opportunity Gains Energy and Hits Four-Mile Mark

Opportunity is healthy. The solar array was apparently cleaned again on sol 638. Average solar array energy is around 720 watt-hours after the cleaning event!

Opportunity finished a campaign using the robotic arm on a cobble called "Antistasi." The Mössbauer spectrometer and alpha particle X-ray spectrometer data show that the cobble is very basaltic. On Sol 645 Opportunity drove 22 meters (about 72 feet) south on an outcrop path around "Erebus Crater." This drive pushed Opportunity's total driving distance past the four-mile mark.

Sol-by-sol summaries:

Sol 641 (Nov. 12, 2005): Opportunity unstowed the robotic arm, changed tools to the Mössbauer spectrometer and did a Mössbauer integration on a cobble called Antistasi.

Sol 642: The rover continued the Mössbauer integration on Antistasi up to the afternoon Mars Odyssey pass. It changed tools to the alpha particle X-ray spectrometer and started an overnight integration on Antistasi.

Sol 643: Opportunity changed tools to the Mössbauer spectrometer and started an integration. The rover then monitored dust with the panoramic camera and imaged surrounding cobbles.

Sol 644: The Mössbauer integration on Antistasi continued and panoramic-camera imaging of the surrounding outcrops was conducted.

Sol 645: Opportunity drove about 20 meters (about 66 feet) on an outcrop path so the rover would be able to analyze the outcrops more with the panoramic camera. Also, the panoramic camera was used for studying terrain for future drives.

Sol 646: The rover did untargeted remote sensing.

Sol 647: The plan for this sol is for Opportunity to check its composition and calibration target with the Mössbauer spectrometer, microscopic imager and alpha particle X-ray spectrometer. Also planned are observations of outcrop targets called "Show Low" and "Sedona" with the panoramic camera.

Sol 648 (Nov. 19, 2005): The plan is to conduct Mössbauer-spectrometer integration on the composition and calibration target, and to use the panoramic camera to observe an outcrop target called "Winslow" and a cobble target called "Snowflake."

Opportunity has driven a total of 6,446.45 meters (4.01 miles).

sol 633-640, Nov 11, 2005: Observing the Outcrops

Opportunity is healthy and is observing outcrops of "Erebus Crater." The rover used the tools on its robotic arm to examine an outcrop area named "Olympia."

Sol Summaries:

Sol 633 (Nov. 4, 2005): Opportunity took microscopic images of target "Kalavrita" before using the rock abrasion tool to grind the surface off of the target. After the grind, the rover took microscopic images of the exposed interior and began using the Mössbauer spectrometer on the target.

Sol 634: The rover examined Kalavrita with the Mössbauer spectrometer during the day and with the alpha particle X-ray spectrometer at night.

Sol 635: The Mössbauer spectrometer resumed an integration at Kalavrita.

Sol 636: Opportunity successfully used the miniature thermal emission spectrometer for the first time since sol 609. Extra precautions were taken by the operations team to allow quick recovery in the case of a reset.

Sol 637: Tasks were integration with the Mössbauer spectrometer and remote sensing with the panoramic camera.

Sol 638: Opportunity used the microscopic imager, the rock abrasion tool's brush, and the alpha particle X-ray spectrometer at a target dubbed "Ziakas."

Sol 639: Opportunity drove approximately 6 meters (about 20 feet) to a cluster of cobbles.

Sol 640 (Nov. 11, 2005): The rover conducted untargeted remote sensing.

Looking ahead: Sols 641 to 643 are planned as a robotic-arm campaign on a cobble target called "Agrafa."

As of sol 639 (Nov. 10, 2005), Opportunity had driven 6,424 meters (3.99 miles).

sol 631-634, Nov 04, 2005: Dusting Off and Getting Back to Work

Having weathered a recent dust storm, Opportunity is back to business. Energy levels are on the rise as the rover prepares for its next investigative campaign.

Sol-by-sol summaries:

Sol 631 (Nov. 2, 2005): With images of the rover's current location in hand, rover planners were able to plan a drive of just over 39 meters (128 feet), which brought Opportunity to the edge of a large stretch of outcrop.

Sol 632: Opportunity drove about 5 meters (16 feet) to a target called "Olympia."

Sols 633 and 634 (Nov. 4 and 5, 2005): The two-sol plan is to kick off the robotic arm campaign at Olympia. The plan includes grinding a target called "Kalavrita" with the rock abrasion tool, inspecting the target with the microscopic imager both before and after the grind, and using the panoramic camera to take images for a mosaic. Output from the solar panels on sol 633 was 528 watt hours.

Opportunity's total odometry, as of sol 633, is 6418.07 meters (3.99 miles).

sol 627-630, Nov 02, 2005: Dusty Weekend

The three-sol plan for Opportunity's sols 627 to 629 (Oct. 29 to 31, 2005) began well, with a drive of 51 meters (164 feet) on the first sol. To allow as much time as possible for driving on that sol, the rover's usual post-drive imaging from its new location had been planned for the following sol. Overnight, Opportunity went into the deep-sleep mode for saving energy. The morning after a deep sleep, the rover wakes up when solar panels start putting out a prescribed level of energy. However, a dust storm in the Meridiani region reduced sunshine enough on the morning of sol 628 that Opportunity did not wake from deep sleep early enough for the first scheduled activities of that sol. The rover's onboard software properly put Opportunity into self-protective automode for the day, so the rover did not take the post-drive images. Analysis continued on Sunday, and the team uplinked commands on Monday to resume activities. On sol 630, Opportunity successfully took pictures showing the terrain surrounding its new position. Dustiness of the atmosphere above Opportunity diminished a little on sol 630, as indicated by increased output from the solar panels.

Sol-by-sol summaries:

Sol 627 (Oct. 29, 2005): In the first sol of a three-sol plan, Opportunity drove 51 meters (164 feet). Wheel slippage averaged 3.7 percent, with a peak of 18 percent. Maximum tilt during the drive was 11.5 degrees. A dust storm in the Margaritifer region near Meridiani had been noticed before plans were set for sol 627, so researchers had told Opportunity to check the clarity of the atmosphere a few times during the sol. Those observations saw a maximum atmospheric opacity ("tau") of 1.6, on a scale where 0 is perfectly clear, 1.0 is about as obscured as a smoggy day in Los Angeles, and an earlier dust storm at Meridiani reached 2.0 on sol 489. Opportunity's solar panels generated 593 watt hours on sol 627. That is about 100 watt hours less than on recent days before the dust storm, but still more than typical daily output during winter. The rover used deep-sleep mode overnight.

Sols 628 and 629: Output from the solar panels did not climb high enough to wake Opportunity from deep sleep until 7:38:50 in the morning, local solar time. This was nearly five minutes too late for its first scheduled activity of the day, turning on heaters to warm the miniature thermal emission spectrometer. The rover realized it had woken up too late, so it properly put itself into protective automode. It remained in automode for sol 629. Solar panels' output was 479 watt hours on sol 628 and 470 watt hours on sol 629, indicating a diminished amount of sunlight getting through the dust.

Sol 630: The team sent commands for activities originally planned for sol 628. Opportunity returned to normal operations and took images of the surroundings at the location it had reached on sol 627. Solar panels produced 496 watt hours, which was enough to support an overnight UHF communications pass in addition to the imaging activities.

As of sol 630 (Nov. 1, 2005), Opportunity had driven a total of 6373.6 meters (3.96 miles).

sol 619-626, Oct 31, 2005: Riding Ripples and Working Issues

Opportunity is healthy and traversing around the northwest side of "Erebus Crater." The rover has driven on every sol possible, acquiring during and after each drive, and surveying the sky and horizon in the mornings with the panoramic camera.

Sol-by-sol summaries:

Sol 619 (Oct. 20, 2005): Opportunity drove 24 meters (79 feet) in a zigzag pattern to safely cross ripples.

Sol 620: The rover's observations used its panoramic camera to observe a feature informally named "Mogollon Rim" (for an area in Arizona) and onboard magnets. It also checked for dust devils.

Sol 621: Opportunity drove 30 meters (98 feet), mostly on sand. The average slip was only 2.5 percent.

Sol 622: Untargeted observations included a panorama to examine the amount of light reflected from the surface and a ground survey. A software glitch resulted in losing the afternoon communication relay session with Mars Odyssey. The problem was a repeat of one experienced previously on Spirit's sols 131 and 209 and on Opportunity's sol 596. It occurs when a "write" command reaches an area of memory during a vulnerability period of a few microseconds when that memory location cannot accept a new write command. The rover team is investigating the problem.

Sol 623: This was a recovery sol. Opportunity returned data directly to Earth during an X-band communication window after calibration of the high-gain antenna. It also performed a calibration of the panoramic camera mast assembly (the rover's "head") to regain use of it and to stow the camera. One of the rover's two batteries would not recharge, which at first puzzled the team. A switch that allows battery 1 to recharge was not enabled, so the battery was temporarily unable to recharge. On the following morning (sol 624), the switch was enabled and the battery subsequently operated normally. Engineers' analysis indicates that recharging was not enabled on sol 623 because the rover did not use enough electricity from the battery during the previous sol (622) to draw the battery's charge below a level pre-set as a threshold for allowing a recharge.

Sol 624: The rover drove and used the panoramic camera to look at its tracks. It covered 27.3 meters (nearly 90 feet).

Sol 625: At the end of sol 624, Opportunity found itself in an area with relatively small ripples. In this benign terrain, it was given commands for a drive that included a segment of autonomous navigation after an approximately 30-meter (98-foot) segment of blind driving. Preliminary analysis shows a total distance of 45.7 meters (150 feet) was traversed.

Sol 626: For this sol the team planned another drive, with about 30 meters (98 feet) expected.

Opportunity's total odometry as of sol 625 (Oct. 27, 2005) is 6,265 meters (3.89 miles). This week (sols 619 to 625), the rover drove 127 meters (417 feet).

sol 613-618, Oct 21, 2005: Maneuvering Around Ripples

Opportunity is healthy and has been making excellent progress around "Erebus Crater." At the beginning of the week, the rover was in automode as it was still recovering from a partial uplink, but on sol 614 the team sent a real-time activate command and the rover performed remote sensing. The team is no longer operating under restricted sols, and Opportunity traveled 101.65 meters (333 feet) in four sols. The rover is generally heading westward around the crater, but traveled northward on sol 618 to avoid some larger ripples to the west.

Sol-by-sol summaries:

Sol 613 (Oct. 14, 2005): The team planned untargeted remote sensing. However, the master sequence did not run because Opportunity was in automode.

Sol 614: The team sent a real-time command to activate the sol 614 master sequence. The plan included remote sensing.

Sol 615: Opportunity completed an 18.5-meter (61-foot) drive heading westward around Erebus Crater.

Sol 616: Opportunity drove 24 meters (79 feet), with an average slip of 2.3 percent.

Sol 617: The rover completed a 43.65-meter (143-foot) drive, zigzagging around low points in the ripples.

Sol 618: Opportunity completed a 15.5-meter (51-foot) drive on outcrop, heading northward to find some lower ripples to cross.

As of sol 618 (Oct. 19, 2005) Opportunity has driven 6,138.07 meters (3.81 miles).

sol 606-612, Oct 17, 2005: Around 'Erebus'

Opportunity is continuing to travel westward around "Erebus Crater."

The rover completed a 26.18-meter (about 86-foot) drive on sol 608 (Oct. 9, 2005) with very little slip. On sol 610, the team planned another drive, but the spacecraft experienced a software reset at about 9:20 a.m., local solar time. That deactivated all sequences and left the spacecraft in automode before the sol 610 master sequence was active. On sol 611, the team sent a recovery sequence to reestablish a master sequence and reinitialize the panoramic camera mast assembly state (the position of the rover's "head"). The team received confirmation of success. The sol 612 plan included another attempt to do the drive originally planned for sol 610. However, the master sequence for 612 was not received properly by the spacecraft because of bad pointing or weather. So, the run-out plan from sol 611 was executed.

Sol-by-sol summaries:

Sol 606 (Oct. 7, 2005): Untargeted remote sensing.

Sol 607: Targeted remote sensing during sol one of a three-sol plan.

Sol 608: Second sol of a three-sol plan. Opportunity drove 26.18 meters (about 86 feet) westward around Erebus Crater, with an average slip of 1.7 percent.

Sol 609: Untargeted remote sensing during the third sol of a three-sol plan.

Sol 610: The team planned a drive of about 21 meters (69 feet), but a software reset Opportunity into automode so the drive was not carried out. The reset was very similar to one on Opportunity's sol 563. Since the miniature thermal emission spectrometer was the instrument in use during the reset, use of that instrument has been precluded, pending further analysis.

Sol 611: Recovery sol. The master sequence was activated in real time and the panoramic camera mast assembly (the "head" of the rover) position was reinitialized. Data management sequences were run.

Sol 612 (Oct. 13, 2005): Commands included a drive, the one originally planned for sol 610. However, the master sequence for 612 was not received properly by the spacecraft, because of bad pointing or weather, so Opportunity instead executed the run-out sequence from sol 611.

Opportunity's total odometry, as of completion of the drive on sol 608 (Oct. 9, 2005) is 6,036.06 meters (3.75 miles)

sol 599-605, Oct 11, 2005: Opportunity Backs Out of Potentially Sticky Situation

Opportunity is healthy and traveling westward around 'Erebus Crater.' The rover is running in restricted sols, so the team is able to drive it only every other sol and has been doing so. On sol 601, Opportunity drove 34 meters (112 feet). On sol 603, the team planned a 45-meter (148-foot) drive. However, after the first 5-meter (16-foot) segment, the onboard slip check reported 44.5 percent slip. Because slip limits had been set to 40 percent, the drive was successfully stopped. On sol 605, the rover drove 5.3 meters (17 feet) back to outcrop material.

Note: The onboard slip check uses visual odometry to compare nearby features and determine the actual distance traveled. Software computes the amount of slip based on the difference between the actual distance traveled versus commanded wheel rotations. The team has defined a maximum allowable percentage of slip, and if the computed slippage exceeds the maximum allowable, further driving is precluded.

Sol-by-sol summaries:

Sols 599 and 600 (Sept. 30 and Oct. 1, 2005): The team planned two sols of remote sensing, including coordinated observations by the panoramic camera and miniature thermal emission spectrometer and use of the navigation camera to complete a 360-degree panorama.

Sols 601 and 602: Opportunity drove 34 meters (112 feet) on sol 601, heading northwest, to have a better view of the westward path. The drive was successful, and the maximum slip was reported at 2.5 percent. For sol 602, the team planned remote sensing.

Sols 603 and 604: On sol 603, the team scheduled a 45-meter (148-foot) drive. The first portion of the drive was blind for 35 meters (115 feet) with slip checks every 5 meters (16 feet), followed by 10 meters (33 feet) of autonomous navigation. However, after the first 5-meter (16-foot) segment, the onboard slip check detected slippage higher than the limit that had been set as a precaution, and the rover properly stopped. Wheel sinkage was approximately 5 centimeters (about 2 inches) for the left front wheel and 4 centimeters (1.6 inches) for the right front wheel. On Sol 604 the rover performed untargeted remote sensing.

Sol 605 (Oct. 6, 2005): The team analyzed the rover's position and the terrain and decided to back up Opportunity about 5 meters (16 feet) onto outcrop, the starting point of sol 603's drive. The sol 605 drive included slip checks and hazard-avoidance-camera movies of the wheels. Pre-drive, mid-drive, and post-drive imaging was acquired. The 5.3-meter (17-foot) drive was successful, and Opportunity reached the outcrop. Slippage during the drive ranged from 3 to 12 percent.

Opportunity's total odometry as of sol 605 was 6,009.88 meters (3.73 miles).

sol 592-598, Oct 03, 2005: Slight Hiccup Before Getting to 'Erebus Crater'

Opportunity suffered a warm reboot last week. After the flight computer rebooted, the spacecraft went into 'safe mode'. This error caused the team to miss two Odyssey passes. The evening pass was missed because the reboot occurred during the Odyssey pass. The morning pass was missed because safe mode enforces the deep sleep behavior.

Real-time commands were sent on sol 597 in order to access the state of the vehicle. Opportunity was healthy and the team regained control of the vehicle. A 'lite' master sequence was loaded and sol 597 became a stand down day. On sol 598, the initial system recovery steps were taken and subsystems were tested. All subsystems look good.

This is the first time this fault has been seen on Opportunity. It was seen twice before on Spirit, in May and August of 2004. The decision at that time was to not fix the software bug that causes this problem, and accept the rare interruptions in operations. The bug allows a 51 microsecond window where two different requests to write to a memory area can collide. When the writes collide, the software protects itself and the vehicle by terminating activities.

This week Opportunity will continue with nominal operations. The rover will continue to move west around Erebus Crater.

Sol-by-sol summaries:

Sol 592: Drover 1.75meter (69 inches) and approached target 'Deception' on the feature 'South Shetland'

Sol 593: Unstowed the robotic arm, used rock abrasion tool brush, took a stereo microscopic image and then placed the alpha particle X-ray spectrometer.

Sol 594: Continued the robotic arm campaign. Placed the alpha particle X-ray spectrometer, then changed tool to the Mössbauer spectrometer.

Sol 595: Continued the robotic arm campaign. Placed alpha particle X-ray spectrometer on new target then change tool to the Mössbauer spectrometer on the next sol.

Sol 596: Anomaly - warm reboot day

Sol 597: Stand Down Day

Sol 598: Recovery day, subsystem testing

sol 586-591, Sept 22, 2005: Approaching 'Erebus'

Opportunity is healthy and continuing its drive toward "Erebus Crater." Images taken this week show the interior of the crater. Plans for the next few sols are to get closer to the crater's edge and do extensive imaging. The team is also planning to use the tools on the robotic arm to examine a dark area of outcrop located on the way to the edge of the crater.

Sol-by-sol summaries:

Sol 586 (Sept. 16, 2005): Opportunity conducted remote sensing.

Sol 587: More remote sensing.

Sol 588: Drove about 20 meters (66 feet) at 208 degrees.

Sol 589: Drove about 22 meters (72 feet).

Sol 590: Drove 35 meters (115 feet).

Sol 591 (Sept. 22, 2005): Drove about 17.5 meters (57 feet), turned for weekend work with robotic arm. As of sol 591, Opportunity has traveled 5,933.69 meters (3.69 miles).

sol 580-585, Sept 19, 2005: Erebus Bound

Opportunity has resumed normal operations this week. The rover is healthy and making progress towards "Erebus Crater." The rover team has been commanding Opportunity to drive every chance it gets. The last two sols this week have been remote sensing only, due to a lack of critical data.

Sol-by sol summaries:

Sols 580 and 581 (Sept. 10 and 11, 2005): The weekend included a 26.3-meter (86-foot) drive with observations before and after the drive.

Sol 582: A 30-meter (98-foot) drive this sol brought the rover to the "Erebus Highway‚" an outcrop-rich area that extends south toward the crater.

Sol 583: The previous sol's drive appears to have completed successfully, however no data was received due to an issue at the Deep Space Network station where the data is received from space and transmitted to JPL.

Sol 584: Remote sensing was performed, which included as systematic foreground survey using the panoramic camera and miniature thermal emission spectrometer. The plan included commands for the rover to re-transmit the critical post-drive data to Earth, but these were not received due to a sequencing error.

Sol 585 (Sept. 15, 2005): This sol's plan included commands for remote sensing and for re-transmission of the post-drive imaging.

Total odometry as of sol 584 (Sept. 14, 2005): 5,874.32 meters or 3.65 miles.

sol 574-579, Sept 19, 2005: Heading for the Highway

A healthy Opportunity spent the week making progress east towards the "Erebus Highway." Since the sol 563 anomaly, the rover has been performing nominally. The team has now re-certified the use of driving with and without visual odometry. The team is still operating with additional post-anomaly restrictions, including shutting down after the morning uplink window to save the high-gain antenna position, napping before use of the miniature thermal emission, and a "keepout" time after wakeup to allow the flight software to boot without other activities in parallel. The sol 563 anomaly is still under investigation.

Sol-by sol summaries:

Sols 574 and 575 (Sept. 4 and 5, 2005): These were the first two sols of a three-sol plan. The rover performed targeted observations with the panoramic camera and navigation camera.

Sol 576: Opportunity completed the three-sol plan. Since the team is running in restricted mode, this plan did not execute until Tuesday (Sept. 13, 2005). The drive sequence was bundled separately, so if another anomaly were to occur the drive could be pulled from the plan. After a nominal weekend, the drive sequence was uplinked. It resulted in a successful visual odometry drive of about 12 meters (39 feet). This was the first use of visual odometry since the sol 563 anomaly.

Sol 577: Still in restricted mode, the rover performed untargeted remote sensing using the panoramic camera, navigation camera, and miniature thermal emission spectrometer. All sequences executed successfully.

Sols 578 and 579 (Sept. 8 and 9, 2005): This two-sol plan included commands for a visual odometry drive of about 15 meters (49 feet) on sol 578 and untargeted remote sensing on sol 579.

As of sol 577 (Sept. 7, 2005), Opportunity's total odometry was 5,767.11 meters (3.58 miles).

sol 566-573, Sept 02, 2005: Cautious Recovery

Recovery from the sol 563 power-off event is well underway. Each sol, the team has planned one new activity. By sol 570 (Aug. 31, 2005), the rover had successfully performed observations with the panoramic camera, navigation camera, and miniature thermal emission spectrometer and had completed a short alpha particle X-ray spectrometer integration (with the robotic arm stowed) and a 6.5-meter (21-foot) blind drive.

Additional precautions are being taken with each sol's plan, including shutting down after the morning uplink (to save the high-gain antenna position, thus preventing an X-band fault in case of another anomaly) and waiting 15 minutes after wakeup to start any science activities.

Sol-by sol summaries:

Sols 566 through 568 (Aug. 27 through Aug. 29, 2005) were devoted to engineering activities. Science activities were put on hold over the weekend while engineers investigated the sol 563 reset.

Sol 569: Opportunity completed step two in the post-anomaly recovery plan: a short blind drive. (Step one, remote sensing with the panoramic camera and navigation camera, was performed on sol 565). The 6.5-meter (21-foot) drive executed perfectly, and all motor currents were nominal.

Sol 570: This sol marked the first use of the miniature thermal emission spectrometer since the sol 563 reset, which was step three in recovery from the anomaly. After waking from a nap and waiting 15 minutes, the rover performed a short alpha particle X-ray spectrometer integration with the robotic arm stowed. This was simply to test the payload service board, which controls the spectrometers. Five minutes after the end of the alpha particle X-ray spectrometer test, a low-elevation raster was taken successfully with the miniature thermal emission spectrometer. The resulting data product has been received on Earth.

Sol 571: Opportunity completed a blind drive of 11.8 meters (38.7 feet) designed to take it across some outcrop then over a small ripple.

Sols 572 and 573 (Sept. 2 and Sept. 3, 2005): Commands sent for these sols are for observations with the panoramic camera and navigation camera.

Opportunity's total distance driven on Mars, as of Sept. 2, 2005, is 5,755 meters (3.58 miles).

sol 560-565, Aug 30, 2005: Recovering from a Reset

On sol 560 (Aug. 21, 2005), Opportunity retracted the Mössbauer spectrometer from a rock target called "Lemon Rind" that had been brushed earlier with the rock abrasion tool. The rover then used the grinding bit of the abrasion tool to reveal a patch of Lemon Rind's interior and used the microscopic imager to inspect the abraded area. On sol 561, Opportunity stowed its robotic arm and backed up 85 centimeters (2.8 feet) for a view of the target. The rover drove about 7 meters (23 feet) on sol 562.

Early in the morning of sol 563 (Aug. 21, 2005), Opportunity experienced a software reset. The rover shut down after the reset and woke up in what is called automode. While in automode, Opportunity responded as expected to planned communication sessions. The sol plan for sol 563 was not executed. The plan for sol 564 was executed, returning diagnostic data for further analysis into the cause of the reset and returning Opportunity to master sequence control. The plan for sol 565 included observations with the navigation camera and panoramic camera, but not with the miniature thermal emission spectrometer. The observations were completed successfully. Engineers believe Opportunity is in good health, although the team will refrain from using the miniature thermal emission spectrometer pending further analysis of the software reset.

Opportunity's total odometry as of sol 565 (Aug. 26, 2005) is 5,737 meters (3.56 miles).

sol 552-559, Aug 19, 2005: Opportunity Biting into 'Strawberry'

Opportunity completed a study of the cobble area by taking a close look at the cobble "Arkansas" and a nearby soil target named "Reiner Gamma" with the instruments on the robotic arm. A 3-meter (10-foot) bump took the rover to an outcrop dubbed "Fruit Basket" for an intensive investigation of targets there. So far Opportunity has studied "Lemon Rind" with its complete suite of robotic arm instruments, and begun an inspection of "Strawberry." The plan is to drive east to the "Erebus Highway" after finishing work at Fruit Basket.

Sol-by-sol summaries:

Sol 552 (Aug. 12, 2005): Opportunity took pictures with the microscopic imager of soil target Reiner Gamma and took alpha particle X-ray spectrometer readings on cobble Arkansas.

Sol 553 and 554: Opportunity took more Mössbauer spectrometer readings on Arkansas and took alpha particle X-ray spectrometer readings on Reiner Gamma.

Sol 555: Opportunity finished work with the robotic arm on the cobble area and drove to a new outcrop, Fruit Basket.

Sol 556 and 557: Opportunity performed robotic arm work on Lemon Rind, a target on Fruit Basket. The microscopic imager took pictures before and after the rock abrasion tool brushed the area. The rover also used the alpha particle X-ray spectrometer and Mössbauer spectrometer.

Sol 558: Opportunity performed robotic arm work on another target, Strawberry, taking pictures with the microscopic imager before and after a light grinding with the rock abrasion tool. Spirit also used the alpha particle X-ray spectrometer.

Sol 559 (Aug.19, 2005): The plan is to use the Mössbauer spectrometer on Lemon Rind.

As of the end of its 558th sol on Mars, Opportunity has driven 5,729 meters (about 3.56 miles).

sol 544-551, Aug 18, 2005: Opportunity Entering Cobble Field

Opportunity had a busy week! The rover has been using the rock abrasion tool and all of its spectrometers and imaging instruments. It has been healthy but slightly constrained in the flash memory. Last week, the rover mission had to share its Odyssey memory allocation with a project named the Mars Bi-Static UHF Radar Experiment, which had the effect of reducing the buffer space available to the rovers. This caused a backlog of data onboard Opportunity. This week the team started to offload some of that data by taking advantage of overnight Odyssey passes. The rover buffer space is back to normal. The planning team is also making sure that experiments do not create too much new data this week. The planning team wants to ensure that Opportunity has enough flash memory for next week's operations since the plan calls for a continuation of the drive toward "Erebus." The general consensus is that the rover will take the easterly route to the Erebus highway. This route is longer by about 100 meters (328 feet), but should result in much more access to outcrop during the drive. The outcrop is attractive both for rover footing and for science targeting.

During the first weekend in August, there was a sequencing error that failed to run the alpha particle X-ray spectrometer. The team had added a miniature thermal emission spectrometer observation before starting the alpha particle X-ray spectrometer, and the added sequence ran long. The alpha particle X-ray spectrometer start sequence did not complete and the instrument did not collect any data. After discovering what happened on Monday, the team reacquired the observation on sol 548 (Aug. 9, 2005).

On sol 549 (Aug. 10, 2005), there was a mobility fault. Under the "rules of the road," the team is required to stop the vehicle if any of the driving actuators draws more than 0.4 amperes of current for more than half a second. This protects the rover from digging into a "Purgatory Dune" situation. On sol 549, while the rover was turning into a position more favorable for communication, the front right driving actuator went above 0.4 amperes for more than half a second and stopped the drive. This is expected behavior. The turn for better communication was an optional move done at the very end of the drive. The front right drive actuator will sometimes (especially when performing a turn-in-place) pull more current than the other drive actuators. This is because the front right steering actuator is not working, and its drive motor is not turning in the same direction as the other five motors.

On sols 550 and 551 (Aug. 10 and Aug. 11, 2005), Opportunity moved about 2 meters (nearly 7 feet) forward into a cobble field. The team has wanted to use Opportunity's alpha particle X-ray spectrometer and Mössbauer spectrometer on some cobbles, and there has never been a better chance than this location. Rover drivers were able to approach the targets in one sol and get multiple cobbles into the robotic arm's work volume. On sol 551, the rover planners successfully planted the Mössbauer on a cobble that is roughly 2.5 centimeters to 3 centimeters (1 inch to 1.2 inches) in size. This precision pointing was intended to allow the spectrometer to integrate for most of the weekend and tell the science team something new about cobbles.

Sol-by-sol summaries:

Sols 545 to 547 (Aug. 6 to Aug. 8, 2005):Sol 545 was used to grind a rock-abrasion-tool hole. On sol 546, Opportunity took a post-grind microscopic imager mosaic and planted the Mössbauer spectrometer in the expected rock-abrasion-tool hole.

Sol 548: The rover retracted the Mössbauer spectrometer from the target called "OneScoop," and then performed a sequence of observations of the rock abrasion tool's grinding bit. Opportunity then placed the alpha particle X-ray spectrometer back down on the rock abrasion tool hole at OneScoop to re-acquire that spectral observation.

Sol 549: The rover retracted the alpha particle X-ray spectrometer and then retook the microscopic image of the rock-abrasion-tool hole. On the previous attempt, Opportunity had not made contact with the surface of the rock, so this sol it was commanded to overdrive 2 centimeters (0.8 inches) in order to ensure contact with the bottom of the 6-millimeter hole. After acquiring the microscopic image, the rover stowed its arm and bumped back 0.85 meters (2.8 feet) to image the rock-abrasion-tool hole. Opportunity then proceeded about 26 meters (85 feet) south towards a group of cobbles, taking a 360-degree panoramic image with the navigation camera at the halfway point. The team commanded the rover to turn to 215 degrees azimuth for communication at the end of the drive.

Sol 550: Opportunity bumped about 1.8 meters (6 feet) over to the cobble field. The team planned to get two of the cobbles in the robotic arm work volume.

Sol 551 (Aug. 11, 2005):On this sol, Opportunity un-stowed its arm and then took a microscopic imager mosaic of cobble target "Arkansas." The rover then used its microscopic imager to inspect a soil target, followed by a placement of the Mössbauer spectrometer on cobble target "Arkansas."

As of the end of its 551st sol on Mars, Opportunity has driven 5,725 meters (3.56 miles).

sol 538-543, Aug 09, 2005: On an Ice-Cream-Cone Outcrop

Opportunity continues to make progress south toward "Erebus" crater. The rover planners are doing an excellent job keeping Opportunity safely within the confines of the ripple troughs and determining where the rover can cross from one ripple trough into another. The rover team tries to keep Opportunity inside the ripple troughs, and plans to follow the troughs south until Opportunity can safely move into a "better" trough.

This week (July 29 to August 3), Opportunity has driven an additional 80 meters (262 feet). Opportunity's odometer now reads 5,696 meters (3.54 miles). As Opportunity continues a southward trek, team members are seeing more and more outcrop. Opportunity is still about about 50 meters (164 feet) north of the "Erebus highway" -- an area the team suspects to be highly populated with outcrop and perhaps easier to navigate. Opportunity is roughly 185 to 200 meters (607 to 656 feet) north of Erebus crater, the next large crater Opportunity will encounter.

The team has been watching Opportunity's power very carefully. It seems that Opportunity is losing some of the power boost it received during the last cleaning event. The solar array wake up time has been getting later each day and is currently 9:48 Mars Local Solar Time. The team has been planning accordingly, taking steps to preserve power where appropriate.

Sol-by-sol summaries:

Sol 538 (July 29, 2005) to Sol 540 (July 31, 2005):Opportunity took pictures of the solar arrays and magnets with the microscopic imager, then did an overnight integration with the alpha particle X-ray spectrometer. On sol 539, Opportunity drove. On sol 540, it performed remote sensing.

Sol 541:The rover drove 25 meters (82 feet).

Sol 542:The rover drove 23 meters (75 feet).

Sol 543 (August 3, 2005): Opportunity executed a very impressive 8-meter (26-foot) approach drive. Scott Maxwell and Jeng Yen were given the task to drive about 8 meters (26 feet) and place the rover on top of an ice-cream-cone-shaped plot of outcrop. Normally this would be a two-sol endeavor: an approach sol and a final bump to the robotic-arm target. But this single-sol drive worked perfectly. They managed to send Opportunity across a ripple and place the rover in exactly the location specified by the science team! To paraphrase Scott Maxwell while describing the drive: "We will cross over 'fudge ripple,' move along the 'Rocky Road,' and park right at the scoop." This is exactly what happened.

sol 531-537, Aug 02, 2005: Opportunity Exploring Southward

Opportunity continued its trek south toward "Erebus Crater," making 61 meters (200 feet) of progress over two sols of driving. The rover is approaching greater quantities of outcrop as it heads south, and the team is excited at the possibility of using the robotic arm before reaching Erebus.

This week, restricted sols allowed the team to drive only every other sol. Next week, however, there will be a shift back to an early planning cycle that will allow driving every sol if desired.

Sol-by-sol summaries:

Sol 531 (July 22, 2005): Opportunity pointed its navigation camera rearward to shoot images for a seven-frame by one-frame mosaic. The miniature thermal emission spectrometer systematically observed the foreground. The panoramic camera took thumbnail images of the sky.

Sol 532: This sol's remote-sensing work included a pre-sunset observation.

Sol 533: The rover completed a successful drive of 34 meters (112 feet), including an attitude update.

Sol 534: Opportunity looked rearward with its navigation camera from the new location and made observations with its miniature thermal emission spectrometer.

Sol 535: The rover used the miniature thermal emission spectrometer for a large set of observations, jokingly referred to at the "Uberraster" because of its size.

Sol 536: Opportunity drove 27 meters (89 feet), with approximately 10 percent slip. The drive duration was two hours, with a final heading of 155 degrees.

Sol 537 (July 28, 2005): Planned work for this sol included another large raster by the miniature thermal emission spectrometer.

Opportunity's total odometry after the sol 536 drive is 5,617 meters (3.49 miles).

sol 524-530, July 25, 2005: Rocks and Cobbles on the Way to 'Erebus'

The Opportunity team's current strategy for driving alternates segments of using visual odometry to check for slippage with segments of blind driving for less than 5 meters (16 feet). The strategy and hard work designing and commanding drives through troughs between ripples contributed to the rover making 89 meters (292 feet) of progress over three drive plans.

Rocks and cobbles have begun appearing in images of Opportunity's new surroundings, for the first time in many weeks of traversing through rippled terrain.

The rover's power team reported a dust-cleaning event on Opportunity between sols 524 and 526. Daily power output from solar panels increased from about 500 watt hours to about 650 watt hours.

Sol-by-sol summaries:

Sol 524 (July 15, 2005): The uplink team planned and executed a successful 27-meter (89-foot) drive. This signified the first use of a combination of short segments of blind driving followed by small slip-check drive segments. One small rock was seen in imaging.

Sol 525: Opportunity performed remote sensing and repeated a right-front steering actuator diagnostic test from sol 435. The actuator moved slightly more than in the last test, but there was no significant change.

Sol 526: Rover planners used the drive technique established on sol 524 to complete a successful 32-meter (105-foot) drive. Small cobbles were seen in imaging.

Sol 527: Opportunity used the sol for remote sensing and battery recharging.

Sol 528: The uplink team planned a drive of 30 meters (98 feet), continuing in the troughs and crossing one ripple crest. The crest was estimated at 8.5 percent slope. However, the drive did not succeed because of a timeout on the first turn command. The duration was set to 15 seconds for a 15-degree turn. The rover made 14.9 degrees of progress before using up the allotted time.

Sol 529: On this second sol of a two-sol plan, the rover performed remote sensing.

Sol 530 (July 21, 2005): The uplink team repeated the planned drive from sol 528, with changes to the timeout durations of turn and waypoint commands. The drive succeeded in covering 30 meters (98 feet). It brought Opportunity's total odometry to 5,555 meters (3.45 miles).

sol 518-524, July 15, 2005: Edging Toward 'Erebus'

Opportunity made impressive progress toward "Erebus Crater" during the week. Four sols of driving totaled 57 meters (187 feet), while slipping less than 10 percent on each drive. A longer drive was plotted for the fifth day.

The rover has continued to drive down ripple troughs. We have a series of checks in place to prevent excessive bogging down, including, tilt, roll, pitch limit checks, current checks and slip checks (set at 40 percent slip).

We look forward to more progress south over the coming week.

Sol-by-sol summaries:

Sol 518 and 519 (July 9 and July 10, 2005): In light of extensive driving and data collection the previous week, these sols were designed to conduct light remote sensing, recharge batteries, and downlink data to free up memory space on the rover.

Sol 520:The uplink team designed a 16-meter (52-foot) drive. Opportunity completed 10.34 meters (33.92 feet) of the drive before tripping a mobility-goal error. There was a bad position estimate given to the onboard slip-checking software, so it incorrectly thought the rover was 0.5 to 1 meters (1.6 to 3.3 feet) back from its actual position, thus making insufficient progress because it thought it was slipping excessively. However, analysis by the mobility team on the ground determined the true slip, and we were "go" to drive the following sol.

Sol 521:Opportunity completed a successful drive of 15.2 meters (about 50 feet) without any faults.

Sol 522:The rover completed another successful drive of 15 meters (49 feet), with only 6.4 percent reported slip.

Sol 523:We drove 16.2 meters (53 feet) of a planned 20-meter (66-foot) drive. The drive stopped short because onboard slip-checking software was having difficulty tracking the rover's rear wheel tracks, which are used as a reference point to monitor the slip. Opportunity does not want to keep trying to drive if it is unsure of how much it is slipping, so the team sets a limit to this failure count. This prevents bogging down in the terrain.

Sol 524 (July 15):The uplink team planned a drive of 27 meters (89 feet). The drive plan is the first in Opportunity's current terrain using a combination of short segments of blind driving followed by shorter segments (40 centimeters, or 16 inches) of slip-check driving. This drive strategy is designed to allow us to drive farther by using a less time-consuming drive option while still verifying every 5 meters that we are not bogging down.

Odometry total after sol 523 drive: 5464.09 meters (3.39 miles).

sol 510-517, July 11, 2005: Pushing Away from Purgatory

This week Opportunity finished examining "Purgatory Dune" and started driving again. The first few drives were to the north so that possible paths to the south could be imaged and evaluated. The next few steps took the rover east, then southward down a wide trough. A new set of "rules of the road" have been developed and implemented to prevent the rover from getting bogged down again.

The miniature thermal emission spectrometer has also been cleared for regular use, and has returned some useful science products during the last week.

Sol-by-sol summaries:

Sol 510 (June 30, 2005): Opportunity finished characterizing Purgatory ripple with microscopic imager pictures of soil (tracks and undisturbed), and took a first step back. The rover collected several images to document the 2.1-meter (6.9-foot) drive. Visual odometry confirmed that slip was less than 10 percent during the short traverse. After the drive, the rover took pictures of the surroundings to evaluate possible safe pathways to the south.

Sol 511: Opportunity backed up 8.5 meters (28 feet), and again imaged the terrain to the south. The drive used visual odometry and slip checks to stop the rover if it failed to make progress.

Sol 512: The long-term goal for Opportunity is to drive south and slightly east. Before continuing on this path the rover must either go east or west to sidestep Purgatory Dune. Extensive remote sensing with the panoramic camera and navigation camera was done this sol to assist in the decision.

Sol 513: With all imaging needed for driving already acquired, Opportunity spent the sol doing atmospheric observations, dust monitoring, and also imaging of the magnets with the panoramic camera.

Sol 514: The engineering and science team took an Independence Day break today, and the rover executed its planned runout science sequence, which included atmospheric observations with the panoramic camera.

Sol 515: Imaging acquired over the weekend showed that the path to the east contained very small ripples (less than 6 centimeters or 2.4 inches), and led to a wide trough to the south. This sol, rover planners sequenced a 5.5-meter (18-foot) backwards drive over old tracks, then turned in short segments (less than 20 degrees), and drove east 2.5 meters (8.2 feet) over one small ripple. Tilt limits, visual odometry failure limits, and cycle limits were employed to prevent the rover from bogging down. The drive succeeded as planned.

Sol 516: An 11-meter (36-foot) drive to the east crossed two small ripples and positioned the rover to enter the trough leading south. Limits and slip checks were used to ensure that Opportunity would not get stuck.

Sol 517 (July 8, 2005): A new safety check was added to this drive: The drive current limits were lowered from 1 ampere to 0.4 amperes. The standard safety checks were also used on this drive, designed to take Opportunity 4 meters (13 feet) east to the north end of the trough, then 11 meters (36 feet) south through the trough.

Opportunity's total odometry after sol 517 is 5,406.6 meters (3.36 miles).

Looking ahead:
Opportunity will continue the drive south, more slowly than before to ensure a safe path.

sol 503-509, July 11, 2005: Done with this Dune

Opportunity spent the week positioning itself for robotic-arm work and studying the area at the base of "Purgatory Ripple." The rover has examined its tracks (which contain material carried out of Purgatory Dune by the wheels) and undisturbed dune material.

Sol-by-sol summaries:

Sols 503 and 504 (June 23 and 24, 2005): Opportunity drove partway to the position for robotic-arm work on Purgatory Dune. Remote sensing over these two sols included a panoramic camera image of the robotic-arm work volume, a navigation camera panorama, and a miniature thermal emission spectrometer raster.

Sol 505 and 506: Opportunity acquired two microscopic imager mosaics and an alpha particle X-ray spectrometer integration on soil before a short drive to the position for examining the tracks.

Sol 507: This was the first of three days using the robotic arm at Purgatory Dune. The rover completed two microscopic imager mosaics and an alpha particle X-ray spectrometer integration. Opportunity also fired up the miniature thermal emission spectrometer for an afternoon raster.

Sol 508: The rover completed a 24-hour Mössbauer integration and collected more data with the miniature thermal emission spectrometer.

Sol 509 (June 29, 2005): Opportunity collected data with the alpha particle X-ray spectrometer and made a late-night observation of the dune with the miniature thermal emission spectrometer.

sol 497-502, July 05, 2005: Back to 'Purgatory'

Opportunity made its way back toward "Purgatory Dune" for a chance to explore its own tracks. During the drive the rover stopped along the way to study the soil at "North Dune."

Sol Details:

Sol 497 (June 16)
This was the second sol of a two-sol plan. Today was dedicated to remote sensing, including panoramic camera usage with 13 filters and stares with the miniature thermal emission spectrometer.

Sol 498
On sol 498, Opportunity deployed its robotic arm to get a "taste" of the North Dune. The rover did this using both the microscopic imager and the alpha particle X-ray spectrometer. The next sol, the rover moved slightly back (about 40 centimeters or 1.3 feet) and then slightly forward (the same distance) in a move designed to place it on an optimal approach, ready to drive to its destination on Purgatory Dune. The last sol of this three-sol plan was again spent as a remote-sensing sol.

Sols 501 and 502
Opportunity had been trying to line itself up with the science target by performing arcs. Due to nature of this terrain, it had not been yawing as much as expected so its approach was slightly off. The team decided to have the rover try a turn in place. Engineers had been staying away from turning in place because Opportunity has a bad steering actuator on one wheel, and this makes turning in place more cumbersome. This turn in place, however, had some advantages because it was in the right direction and it was a small turn. The rover performed it perfectly.

The turn in place churned up soil in front of Opportunity. This made the immediate area in front of the rover more prone to slippage. Opportunity detected excessive slippage (more than 30 percent) when it attempted to perform the first of two 25-centimeter (9.8-inch) arcs. The visual odometery system detected that the first arc went only 17.1 centimeters (6.7 inches). This constituted a 32 percent slip. The engineers had limited the acceptable amount of slippage to 30 percent, so the rover was not commanded to perform the second arc. The next sol was a remote-sensing day.

Sols 503 and 504 (June 22 and 23)
The team planned another drive consisting of three 25-centimeter (9.8-inch) arcs. This drive was calculated to bring the rover to its destination at Purgatory Dune.

sol 490-496, June 17, 2005: Examining 'Purgatory'

Opportunity is happy to be moving again and it's heading back to "Purgatory Dune." The rover's wheels dug wonderful trenches during its egress, and the science team is eager to get the robotic arm out and have a look at the soil inside and outside of the tracks. As you can imagine, Opportunity has been driving very carefully, backing away from the dune, turning around and then re-approaching it.

Sol Details:

490: (June 9, 2005) Drive away from Purgatory Dune.

491-493: Over the weekend the rover team had a problem with the uplink. On sol 491 they were loading all files for sols 491, 492 and 493. Due to an error at the Deep Space Network antenna, the sol 492 master file was not loaded. A drive scheduled for 492 did not occur. The 491 master file performed the run out science submaster and then self-recovered on sol 493. The vehicle was never in any danger and autonomously continued its science objectives.

494: First half of turning around. The team must turn the rover around, using a "k-turn" maneuver (a three-point turn that mimics the sideways "v" formation of the letter "k") to approach the Purgatory Dune with the robotic arm.

496: Second half of the "k-turn."

sol 484-489, June 10, 2005: Opportunity is out!

Success! Opportunity made forward progress to free itself from the Purgatory Dune! Another exciting achievement for the week was the healthy return of data from the Mini-TES instrument, which the mission team turned back on for the first time in 47 sols. The rover also returned pancam and navcam images, and the team is now planning the rover's next drive on sol 490.

Sol Details:

Sol 484: 20 meters (65.62 feet) commanded; 14 meters (45.93 feet) executed, 98.4 centimeters (38.74 inches) progress. Opportunity is out of Purgatory Dune!

Sol 485: This was the second sol of a 2-sol plan. The team planned to drive, but didn't send the drive sequences to the rover because the rover was already out of the dune.

Sol 486: This was the third sol of a 3-sol plan. Again, the team planned to drive, but didn't send the drive sequences because Opportunity were already out of the dune. The team took post-drive imaging, including a navcam of the trench.

Sol 487: The team took a pancam of the tracks and then turned on the Mini-TES for the first time after the sol 440 anomaly. Mini-TES rasters were taken of of Purgatory Dune and Ante-Purgatory Dune. The team was excited to receive healthy data products from this activity!

Sol 488: On this remote-sensing sol, the rover took a 360-degree navcam panorama and a pancam image of the magnets, and then deep slept for the night.

Sol 489: On this remote-sensing sol, the rover took a 13-filter pancam image of Purgatory tracks and deep slept for the night.

As of sol 489, distance traveled is 5347.89 meters (3.32 miles).

sol 476-483, June 03, 2005: Opportunity Working Its Way Out of Dune

Opportunity continues to make progress out of the dune. Recent sols have seen a slight decrease in slip and a decrease of the bogie angles, which might indicate that the rover has crested a dune. The bogie supports the rear and middle wheels, allowing the wheels to move up and down in response to the terrain. The bogie angle is the angle that the support beam makes to the horizontal.
Since the rover began making its way out of the sand trap last month, it has driven enough to have moved 177.2 meters (581 feet) if there were no slippage, and has made actual forward progress of 93 centimeters (3 feet).
Weather report: Atmospheric opacity (measured as "tau") has increased over the past few sols, decreasing the amount of solar energy received by Opportunity. The rover has still been able to drive every sol, but has had to use the deep-sleep mode on most nights to save energy.

Sol-by-sol summaries:

Sol 476 (beginning on May 26, 2005): 12 meters (39 feet) commanded, 5.5 centimeters (2.2 inches) progress.

Sol 477: 12 meters (39 feet) commanded, 11.2 meters (37 feet) executed, 4.9 centimeters (2 inches) progress. (Visual odometry indicated that the rover had gone farther than it had, and flight software stopped the drive early.)

Sol 478: 12 meters (39 feet) commanded, 5.2 meters (17 feet) executed (due to the same issue with visual odometry), 2.2 centimeters (0.9 inch) progress.

Sol 479: 12 meters (39 feet) commanded and executed, 5.9 centimeters (2.3 inches) progress.

Sol 480: 12 meters (39 feet) commanded and executed, 6.3 centimeters (2.5 inches) progress.

Sol 481: 20 meters (66 feet) commanded and executed, 12.9 centimeters (5.1 inches) progress.

Sol 482: 20 meters (66 feet) commanded and executed, 10.7 centimeters (4.2 inches) progress.

Sol 483 (ending on June 3, 2005): 20 meters (66 feet) commanded and executed, about 13 centimeters (5.1 inches) progress.

sol 469-475, May 27, 2005: Still Progressing Through Dune

Opportunity continues to make slow progress through the sand dune, at a slip rate of roughly 99.5 percent. From the time Opportunity resumed driving after digging into the dune until May 26, drives totaling 64.8 meters (about 213 feet) of wheel rotations have been commanded and executed, producing 34.8 centimeters (1.1 feet) of forward progress.

Opportunity has also been performing atmospheric observations. Each sol the rover takes two measurements of how clear the sky is, checks for clouds, and does a Sun survey. A few sols ago a daily horizon survey was added, and Opportunity also imaged its magnets with the panoramic camera.

Sol-by-sol summaries:

Sol 469 (ending on May 20):
Two meters (6.6 feet) of commanded motion, resulting in 1.1 centimeters (0.4 inch) of progress.

Sol 470:
Twelve meters (39 feet) of commanded motion; about 6 centimeters (2.4 inches) of progress.

Sol 471:
Twelve meters (39 feet) of commanded motion; about 6 centimeters (2.4 inches) of progress.

Sol 472:
Twelve meters (39 feet) of motions was commanded. Only the first 2 meters were executed. After that step, the rover stopped the drive by itself due to uncertainty about its own position. One centimeter (0.4 inch) of progress was made.

Sol 473:
Planning was suspended today due to issues with the ground data system. The rover executed a pre-loaded science sequence.

Sol 474:
Eight-meter (26-foot) drive planned, yielding 3.7 centimeter (1.5 inches) of progress.

Sol 475 (ending on May 26, 2005):
Ten-meter (33-foot) drive planned; 8.8 meters (29 feet) executed; 3.5 centimeters (1.4 inches) of progress

Looking ahead:
Thursday, May 26, the team planned two sols (476 and 477), and Friday, May 27, the team is planning three sols to cover the holiday weekend. Sol 476 will command 12 meters (39 feet), and every other sol will require a "go/no-go" decision that will allow for 0 meters, 2 meters (7 feet), or 12 meters (39 feet) of commanded motion per sol.

sol 467-470, May 20, 2005: Moving Slowly in the Dune

Opportunity continues to make inch-by-inch progress toward getting out of the dune where it has been dug-in since sol 446 (April 26).

Sol-by-sol summaries:

Sol 467 (May 17):
Opportunity was commanded to rotate its wheels enough to have rolled 4 meters (13 feet) if there were no slippage. It advanced 2.1 centimeters (0.8 inch) through the loose material of the dune.

Sol 468:
A commanded motion of 8 meters (26 feet) was executed this sol. Forward progress was about 4 centimeters (1.6 inches).

Sol 469:
A 2-meter (7-foot) drive was commanded, and Opportunity advanced about 1 centimeter (0.4 inch).

Sol 470 (May 20):
The rover was sent commands for a 12-meter (39-foot) drive. This drive incorporates larger step sizes, lower current limits for the drive motors, and a lower bogie angle limit.

sol 465-466, May 17, 2005: Progress Inch-by-Inch for Opportunity

On Opportunity's first three drives to get out of the sand trap, the rover has advanced a total of 7.4 centimeters (2.9 inches) in getting off the dune. Each of the first two drives -- one on sol 463 and one on sol 465 -- turned the wheels about two and a half rotations, enough to drive two meters (7 feet) if there were no slippage. Images from the hazard-avoidance cameras taken during the drives show that some of caked powder adhering to wheels between cleats had come off. The team was encouraged by the results, and decided go ahead with a 4-meter (13-foot) commanded drive for sol 466.

Sol-by- sol summaries:

Sol 465 (May 15, 2005):
Opportunity rotated its wheels in a series of 10 steps, each step enough to roll 20 centimeters (7.9 inches) if there were no slippage. The wheels are slipping a great deal in the sand of the dune, but the rover advanced better than anticipated from simulated tests, covering 1.9 centimeters (0.7 inch). The rover used its panoramic camera for observations of the sky and dunes.

Sol 466 (May 16, 2005):
Results from the sol 465 drive were good (some wheel cleats are clean and the rover is making forward progress), so the team commanded a drive that, if there were no slippage, would roll 4 meters (13 feet), consisting of ten 40-centimeter (16 inch) steps. Opportunity gained an additional 2.7 centimeters (1.1 inch). The panoramic camera made more observations of the atmosphere and dunes.

sol 464, May 14, 2005: Opportunity Begins Careful Rollout

Opportunity rotated its wheels on sol 463 for the first time since the rover dug itself into a sand dune more than two weeks earlier. The wheels made about two and a half rotations, as commanded, and the results were a good match for what was expected from tests on Earth. In the loose footing, the rover advanced 2.8 centimeters (1.1 inch) forward, 4.8 millimeters (0.19 inch) sideways and 4.6 millimeters (0.18 inch) downward. After further analysis of the results, the rover team will decide whether to repeat the same careful movement again on sol 465. Meanwhile Opportunity's main tasks for sol 464 were remote-sensing observations.

sol 456-463, May 13, 2005: Opportunity Mission Manager Report

Opportunity has started moving its wheels again after a couple weeks of holding still while taking some amazing images. While waiting for the rover team to finish tests for planning the best strategy for driving out of a sand trap, Opportunity has been busy taking a comprehensive color panorama of the area. On sol 461 (May 11), Opportunity straightened its wheels. After checking data and images confirming the success of that move, the team planned commands for beginning to rotate the wheels on sol 463 (May 13). The rover is healthy and ready to go.

Sol-by-sol details:

Sol 456 - 460:
The rover's situation, dug into a sand dune, limited in the amount and type of science possible. While sitting here, Opportunity has taken the opportunity to take a 360 panorama of the area called "Rub al Khali," a name meaning the "empty quarter," from a region of the Arabian Peninsula with that name. During sol 456, power engineer Eric Wood happily recognized a cleaning event. Winds removed some dust from solar panels and Opportunity's daily energy supply increased to about 650 watt-hours, from a recent range of about 620 to 630 watt-hours.

Sol 461:
Today Opportunity was allowed to position its wheels to their egress direction. The plan is for the rover to leave the sand trap with an arc, moving forward and slightly to the left. The wheels were placed in that position. Before this sol's steering move, the wheels were in position from a turn in place that was Opportunity's last attempted move on sol 446.

Sol 462:
Opportunity is still in restricted sols, and is precluded from driving today, so the rover spent the day taking some additional panoramic camera frames of Rub al Khali.

Sol 463 (May 13):
After confirming the new position of the wheels, the team proceeded with plans for Opportunity to rotate its wheels about two and a half times on sol 463. Results from that move will be evaluated before rotating them some more.

sol 449-455, May 06, 2005: Testing on Earth Before Moving on Mars

Opportunity is imaging the plains and performing atmospheric science observations while waiting for engineers on Earth to give it the go-ahead to move. The team is diligently working to determine why Opportunity dug itself into a small dune, the best way to exit the dune, and what added precautions to use during future driving.

Sol summary:

Sols 449 to 455 (April 29 to May 5, 2005):

In JPL's In-situ Instrument Laboratory sandbox, engineers, scientists and even the project manager have been mixing sandy and powdery materials, digging holes and building dunes. A mixture was concocted to simulate properties of the soil underneath Opportunity, using sand, clay and diatomaceous earth (silica-rich powder composed mainly of microscopic plant shells, used in these tests for its texture, not its fossil origin). The team wants to have a full understanding of how Opportunity will respond before commanding it to back out of its current position.

sol 447-448, May 03, 2005: Continuing Exit Plan

The Opportunity team continues working with an engineering test rover on Earth to determine the safest way to attempt to drive the rover out of the dune where it's currently parked on Mars. In the meantime, Opportunity is collecting science data with its instruments and cameras.

Sol-by-sol summaries:

Sol 447 (April 27, 2005):
Opportunity performed detailed remote sensing to support drive analysis, including images of the left and right tracks taken with the front hazard-avoidance camera, the rear hazard-avoidance camera and the panoramic camera. Opportunity also took panoramic camera images of the rippled dunes.

Sol 448:
Opportunity performed additional remote sensing. Opportunity used the panoramic camera to acquire images of the rover's far tracks, where Opportunity had performed a successful "K-turn" at the start of the drive on sol 446. A "K-turn" is the technique engineers have figured out for safely turning the rover 180 degrees while the right front wheel is stuck in a position of 7 degrees left of straight ahead. To turn 180 degrees, the rover makes smaller arcing movements without cranking the wheels as much as a normal during a 180-degree turn. These movements create a "K" shape in the soil. In addition, Opportunity acquired another panoramic camera image of the right track and a navigation camera image covering 360 degrees of the near deck of the rover.

As of sol 448 (ending on April 28, 2005), Opportunity's odometry total is 5,346 meters (3.32 miles).

sol 443-446, April 29, 2005: Testing Options to Exit Dune

Opportunity used the spectrometers on its arm to examine the soil where the rover stayed for six sols, then resumed driving on sol 446. However, the drive ended after 40 meters when Opportunity was crossing a dune and dug into it. Engineers are using a test rover to evaluate options for getting off the dune.

Sol-by-sol summaries:

Sol 443 (ending on April 23, 2005):
IDD campaign! We started off by unstowing the instrument deployment device -- the robotic arm -- and performing a joint stare of the sky using the microscopic imager and panoramic camera. We then changed tools to the alpha particle X-ray spectrometer and collected data for 5 hours and 41 minutes about the composition of the soil in front of the rover.

Sol 444:
Opportunity deep-slept overnight, and woke up to perform a sky survey while the Sun was high in the sky. We then changed tools to the Mössbauer spectrometer and started a 31-hour integration on the soil.

Sol 445:
In order to keep the Mössbauer integration running, the rover did not use the deep-sleep mode overnight. Today was devoted to continued Mössbauer integration on the soil. At last, we stopped the Mössbauer integration at 11:12 p.m. local time and Opportunity deep-slept for the rest of the night.

Sol 446:
We planned a drive of about 90 meters (295 feet). After driving about 40 meters (131 feet), Opportunity dug into soft dune material, impeding further progress. Imaging indicates all four corner wheels have dug in by more than a wheel radius as the rover attempted to climb over a dune about 30 centimeters (12 inches) tall. Opportunity is healthy and in a stable configuration but further analysis is needed to understand this event and plan future driving. Over next several sols, Opportunity will focus on remote sensing while on Earth a series of testbed runs are in progress to simulate terrain interaction and evaluate different egress options.

As of sol 446 (ending on April 26, 2005), Opportunity's odometry total is 5,346 meters (3.32 miles).

sol 438-442, April 26, 2005: Continuing Southward

Opportunity keeps driving southward and studying new locations despite a disabled right-front steering motor. Opportunity has driven about 110 meters (361 feet) without use of that motor. The miniature thermal emission spectrometer began returning good data again. That instrument was in use when the rover stopped operating for a software reset on sol 440. The rover continues making scientific observations while engineers diagnose the cause of the reset.

Sol-by-sol summaries:

Sol 438 (April 17, 2005):
Opportunity made remote-sensing observations.

Sol 439:
Opportunity performed a 13-filter panoramic camera observation to study soil in a trench that was scooped by a wheel when the rover turned to a good communications orientation after its sol 437 drive. Opportunity followed the camera observations with an 80-meter (262-foot) drive south.

Sol 440:
The team's plan was for Opportunity to make remote-sensing observations and then drive farther south. Panoramic camera imaging and some miniature thermal emission spectrometer observations were successfully completed. A miniature thermal emission spectrometer observation was underway when a software reset occurred at approximately 12:45 Mars local solar time.

Sol 441:
The team prepared a recovery plan responding to the software reset the sol before. The plan included transmission of data acquired prior to and during the sol 440 event. Some of this data was returned during a downlink through the Odyssey orbiter on sol 441. Additional data were requested for transmission on sol 442 in hopes of pinpointing the cause of the software reset. Opportunity is otherwise healthy.

Sol 442: The team told Opportunity to perform remote science and study the surface at its present location while the engineering evaluation continued.

As of sol 442 (April 22, 2005) Opportunity's odometry total is 5,306 meters (3.30 miles).

sol 430-437, April 18, 2005: Steering Tests After a Long Drive

The terrain that Opportunity is crossing has been steadily getting more wavy. After a long drive southward from "Voyager" crater, Opportunity's right-front steering motor stalled out on sol 433 during an end-of-drive turn. While performing tests to help the team diagnose the condition of that motor, the rover also continued to make remote-sensing observations. Testing in sol 435 did show motion in the steering motor, but analysis is still underway. The rover resumed normal science and driving operations on sol 436, but with restrictions on use of the right-front steering motor. It drove 30 meters on sol 437. Opportunity and Spirit are capable of driving with one or more steering motors disabled, though turns would be less precise. The latest revision in flight software on both rovers, uploaded in February, gives them improved capabilities for dealing with exactly this type of condition. It gives them upgraded ability to repeatedly evaluate how well they are following the intended course during a drive, and to adjust the steering autonomously if appropriate.

Sol-by-sol summaries:

Sols 430-432 (April 9-11, 2005):
The weekend plan scheduled Opportunity to do some remote-sensing science on sol 430, a drive on sol 431 and more remote sensing on sol 432. However, the drive did not happen, due to a sequencing error that left the rover suspension limit active when it should not have been.

Sol 433:
Opportunity drove 151 meters (495 feet) on its continued trek southward. During a turn at the end of the drive, the steering motor (not the drive motor) faulted out.

Sol 434:
The rover completed some remote-sensing observations. Then it backed up 85 centimeters (33 inches) to see if the right-front wheel had bumped up against anything to cause the steering-motor stall. No rock or other obstacle was there. During the first attempt to straighten the wheels after backing up, the right-front steering motor stalled again. The wheel remained pointed about 8 degrees left of straight ahead.

Sol 435:
The sol's plan included more remote sensing, plus diagnostic tests using attempts to change the steering direction of the right-front wheel very slightly at different times of day and at different voltage levels. The testing did show motion in the steering motor. While analysis continues, the rover is resuming normal science and driving activities with restrictions on the use of the right-front steering motor.

Sol 436:
Opportunity used the panoramic camera for some ground and sky observations, and continued testing of the miniature thermal emission spectrometer.

Sol 437:
The team planned a southward drive of about 45 meters, but Opportunity curved left, sensed it was off course, and ended the drive after 30 meters. The same driving commands produced the same results in a software testbed at JPL, indicating that the curving resulted from how software parameters were set, rather than a hardware problem. Observations with the panoramic camera were completed as planned.

Odometry total as of sol 437 (April 16, 2005): 5,225 meters (3.25 miles).

sol 421-429, April 12, 2005: Opportunity visits 'Viking' and 'Voyager' craters

Opportunity drove to "Viking Crater," then continued to "Voyager Crater." The rover took panoramas of each crater. While this was happening on the surface, the Mars Odyssey orbiter had gone into safe mode. Relay operations were suspended. With no post-drive imaging from the weekend, and very little data volume available in flash, Opportunity executed a few sols of low-volume remote sensing. Driving resumed on sol 428 with data downlinked via the direct-to-Earth link. With the exception of the miniature thermal emission spectrometer (analysis is still in progress), Opportunity is in excellent health.

Sol-by-sol summaries:

Sol 421 (March 31, 2005):
Opportunity stowed its robotic arm (instrument deployment device) and drove 71.2 meters (234 feet) to Viking Crater.

Sol 422:
On this restricted sol, only remote sensing was conducted. A panoramic camera mosaic of Viking Crater was acquired.

Sol 423:
Opportunity drove 109.2 meters (358 feet) to Voyager Crater.

Sol 424:
The rover used autonomous navigation to drive south 2.6 meters (about 9 feet). The drive ended early because the tilt limit of 12 degrees was reached, with Opportunity perched on the rim of Voyager Crater.

Sol 425:
Before this remote-sensing-only plan kicked off, the rover team learned that its main communication link, Mars Odyssey, had gone into safe mode and the latest data available was from the afternoon of sol 422. On April 2, Odyssey entered "safe mode," which is a protective state a spacecraft automatically enters when onboard fault protection software instructs the spacecraft to disregard its onboard sequence of commands and wait for instructions from the ground. As a result, relay communication with the rovers was suspended. The rover team was able to add a direct-to-Earth session to the plan, which confirmed that Opportunity was healthy.

Sol 426:
After a 90-minute direct-to-Earth pass, Opportunity performed a small amount of remote sensing. Operations were restricted because post-drive imaging had not yet been transmitted to Earth, and the team wanted to save the small amount of volume in flash memory for an eventual drive.

Sol 427:
Still operating in restricted mode, Opportunity again collected a small amount of remote-sensing data. It used the panoramic camera to assess the clarity of the atmosphere, tested the miniature thermal emission spectrometer and took a reading of air with the alpha particle X-ray spectrometer. A 90-minute direct-to-Earth pass during the day returned data for future planning. The Odyssey team brought the orbiter back on-line, and the Opportunity team received 50 megabits of data. The Odyssey team is investigating the cause behind the fault protection software sending the orbiter into safe mode.

Sol 428:
The sol 427 direct-to-Earth pass returned enough data to plan a long drive. Opportunity drove 48.4 meters (159 feet), which put it over the 5-kilometer mark. The odometry total after this drive is 5,044 meters (3.13 miles).

Sol 429 (April 8, 2005):
Restricted sol; remote science only.

sol 415-420, March 31, 2005: Soil Survey

Sometimes Opportunity needs to stop and smell the roses … uh, or the soil as the case may be. This week, the science team chose to examine the mineral content of the rippled ground before continuing the southward trek. The team is interested in comparing the chemical makeup of the ripples' troughs to that of the ripples' crests. Opportunity stopped at a nice trough, extended its robotic arm and investigated the soil. It then drove up onto one of the ripples to examine the crest.

Sol-by-sol summaries:

Sols 415 to 417 (March 25-27, 2005):
Zeroing in on a soil target called "Mobarak" in honor of Persian New Year, Opportunity has had its head down in a trough for three sols trying to figure out what the trough soil is made of. During an observation like this, it uses all of its in-situ instruments taking microscopic images, alpha particle X-ray spectrometer readings and Mössbauer spectrometer readings.

Sol 418:
After Opportunity had looked at the soil in the trough, it was time to examine the soil at the top of the ripple. The rover planners perfectly executed a 7-meter (23-foot) drive that placed the rover right at the top of the ripple. Opportunity deployed its arm once again and inspected the soil.

Sols 419 and 420:
Here, Opportunity has the chance to look at two targets, "Norooz" and "Mayberooz," again studying the soil properties.

Sols 421 and 422 (March 31 and April 1, 2005):
Actually, this is kind of neat. As this report is being written, Opportunity is on Mars driving away from this soil survey spot and heading toward the "Viking" crater. When it gets there, it will stop and image the crater for two days.

sol 408-414, March 31, 2005: Opportunity Continues to Set Martian Records

This is the martian rover that keeps going and going and going. This week Opportunity continued to move on, performing panoramic camera soil surveys and imaging the lay of the land as it progressed southward toward craters called "Viking" and "Voyager." On sol 408, Opportunity again broke the martian one-day driving record, traveling an impressive 190 meters (623 feet) in a single sol. However, this record did not stand very long. The rover surpassed it on sol 410 (March 20, 2005) and set the new record of 220 meters (722 feet). The rover is healthy and ready to take on yet another week of exploration.

Sol-by-sol summaries:

Sol 408:
Continuing south, Opportunity broke a Mars driving-distance record. This time the rover made its way 190 meters (623 feet) toward "Viking" and "Voyager" craters. On this sol, the rover was able to image a small crater called "James Caird." The crater was informally named for the financier of Sir Ernest Shackleton's Endurance expedition. The rover imaged features on the ground, and then the team compared them to features taken by orbiting spacecraft. This technique allows us to pinpoint the location of the rover on Mars.

Sol 409:
Today Opportunity needed a rest. The rover has been driving long and hard since sol 405. In fact it has driven roughly 630 meters (2,067 feet - well over a quarter of a mile) in just 4 sols, and it's time to sit out a day, make some observations, recharge the batteries and clear out some of the memory by sending data back to Earth.

Sol 410:
Yestersol's rest day was just what the doctor ordered. The rover woke up ready to go, and boy did it go! Today the rover set a new (and likely long-standing) driving record of 220 meters (722 feet). This incredible vehicle navigated more than half of that drive by itself!

Sol 411:
After yestersol's marathon race, Opportunity took the day off to rest.

Sols 412-414:
Opportunity is all about the driving these days: on sol 412, 183 meters (600 feet); on sol 413, 175 meters (574 feet); on sol 414, 183 meters (600 feet). From sol 405 to sol 414 (just ten sols) Opportunity has traveled 1.394 kilometers (4,573 feet, approaching a mile). This is almost 30 percent of all the driving that Opportunity has done in its 414-sol career!

The odometer total as of sol 414 (March 24, 2005) is 4.806 kilometers (just shy of three miles).

sol 403-407, March 31, 2005: Opportunity's Cruisin'!

This week Opportunity's engineering and science teams got some good news and some bad news. Unfavorable results were obtained when the engineering team ran some diagnostic observations on the miniature thermal emission spectrometer. Very few of the readings obtained during these test were of nominal length; most were short. The team has decided to suspend the use of this spectrometer until further analysis can be performed. On the good side, the rover continues to make progress southward toward its next goal, a pair of craters referred to as "Viking" and "Voyager." Also, Opportunity has set a martian single sol drive-distance record of 183 meters (just over 600 feet)!

Sol-by-sol summaries:

Sol 403 (March 12, 2005):
This sol, the rover used its microscopic imager to take pictures of a rock called "Gagarin," changed tools to the Mössbauer spectrometer, and placed it on rock-interior material exposed by the rock abrasion tool. The rover did not use the deep-sleep mode this night.

Sol 404:
Opportunity woke and resumed collecting Mössbauer data until a little before midnight. During the day, it was able to perform some remote sensing. Around midnight the rover went into a mini deep sleep.

Sol 405:
The spacecraft woke up this morning and continued to acquire data on Gagarin using the Mössbauer spectrometer. This sol the team tested the miniature thermal emission spectrometer to look at short readings the instrument has been making. Opportunity then bumped back from the crater and drove 100 meters (328 feet). After a long day, the rover used deep sleep overnight.

Sol 406:
Opportunity, guided by its rover planners, took an hour to drive 100 meters (328 feet). The rover then took control and used autonomous navigation to drive the next 83 meters (272 feet), setting a new one-sol driving record of 183 meters (600 feet)!

Sol 407:
This sol was another drive day. The rover drove 100 meters (328 feet) guided by rover planners and then 60 meters (197 feet) autonomously. Odometry total as of sol 407 (March 16, 2005) is 3,856 meters (2.4 miles).

sol 396-402, March 17, 2005: Opportunity Arrives at 'Vostok'

After a long, sustained series of traverses (with a few stops along the way to see the sights) Opportunity has reached "Vostok Crater." The rover began a set of in-situ measurements on the soil and rock of Vostok. The miniature thermal emission spectrometer instrument seems to be showing some symptoms of its age, resulting in some failed images; diagnostic observations using the instrument will be performed shortly. Opportunity otherwise continues to be in excellent health.

Sol-by-sol summaries:

Sols 396 and 397 (March 5 and 6) were designed as a two-sol plan, with two sols of driving toward Vostok. The intent was to cover about 130 meters (427 feet) through combined directed-drive segments and autonomous-navigation segments on sol 396, followed by another 60-meter (197-foot) autonomous-navigation drive on sol 397. However, due to a partially misdefined waypoint (correct coordinates, but with too small a radius) on the first sol, Opportunity drove farther in its directed drive than intended. A safety timeout was triggered, and no driving took place on sol 397. The issue was quickly analyzed and fully understood by the mobility team and the rover planners, so nominal traverse planning resumed on sol 398.

In the meantime, the miniature thermal emission spectrometer failed some command executions, and a command was uplinked on sol 396 to prevent further use of this instrument until diagnostic testing is completed.

Sol 398 was primarily a drive sol, with Opportunity covering 95 meters (312 feet) via a combination of directed drives and autonomous navigation.

At the end of a 35-meter (115-foot) traverse, Opportunity finally reached Vostok during sol 399. The crater is almost completely buried in sand.

On sol 400, thanks to fortuitous positioning of the rover, in-situ targets were already in the work volume of the robotic arm, eliminating the need for an approach sol. Opportunity proceeded to examine a soil target, "Laika," and a rock, "Gagarin," with its microscopic imager, then positioned the alpha particle X-ray spectrometer for later measurements on Gagarin. After taking a panoramic image of Vostok, the rover took a long nap, waking up for its afternoon downlink and to begin taking data with the alpha particle X-ray spectrometer. Opportunity awoke again before midnight to stop the integration, and then went into the deep-sleep mode until morning.

Since the plan called for Opportunity to continue in-situ measurements, the team chose to combine sols 401 and 402 as a two-sol plan. For sol 401, the plan is to use the brush of the rock abrasion tool brush on Gagarin and capture a microscopic imager mosaic afterwards. This will be followed by an evening alpha particle X-ray spectrometer measurement of the brushed surface, and then by a mini-deep sleep. On sol 402, ending on March 11, the rover will grind Gagarin for two hours with the rock abrasion tool, then perform an early morning alpha particle X-ray spectrometer integration on the resulting hole.

sol 389-395, March 15, 2005: Examining a Little Crater Before Moving on Toward 'Vostok'

The rover took some time away from driving and explored a little crater it approached last week. Once Opportunity is done with the crater, plans call for continuing toward a larger crater, "Vostok." With its front legs just on the lip of the small crater, Opportunity was able to extend its robotic arm to characterize some of the mineralogy found here.

Sol-by-sol summaries:

The last previous drive left Opportunity in a position where it could make its final approach to the lip of one of the craters in a cluster of three small craters. On sol 389 (Feb. 26, 2005) the rover took images of the site with its panoramic camera and its miniature thermal emission spectrometer. On sol 390, Opportunity took a panoramic camera mosaic of the crater, then bumped forward to the edge of the crater. Sol 391 was another day of remote-sensing science and rest.

For sol 392, the team decided to take an in situ look at a rock target called "Normandy." The Mössbauer spectrometer was placed on the rock and it conducted a three-hour long integration. Then the rover switched to the alpha particle X-ray spectrometer and performed a very short (10-minute) measurement. The science team needed a sample reading, and by using this technique, the engineering team was able to give the scientists some idea of what they had in time for a communication window with Mars Odyssey. The science team used this data to determine if sol 393 would be a grinding day (with the rock abrasion tool). After getting the alpha particle X-ray spectrometer reading, the rover went to sleep, woke up at about 4:00 a.m. local solar time and started collecting data again with the alpha particle X-ray spectrometer. The instrument ran for about 6 hours.

On sol 393, the rover switched back to the Mössbauer spectrometer and started a very long (about 12-hour) integration. The rover was able to use the mini-deep-sleep mode after the integration.

Plans for sols 394 and 395, uplinked on March 3, call for the rover to stow its robotic arm and back away from the crater on sol 394. At this point the rover will take some remote-sensing images. After confirmation that these important images have been acquired, Opportunity will turn and drive toward Vostok.

sol 380-388, March 07, 2005: Opportunity Continues South with New Mobility Software

After a busy week of driving with new mobility software, Opportunity continues to be in excellent health. The rover has traveled 450 meters (just over a quarter of a mile) in 6 sols. Opportunity took a couple of breaks from the trek south to use the tools on its robotic arm for investigating of a rock called "Russet" and to image a crater triplet. Atmospheric opacity has been stable, with tau hovering between 0.85 and 0.90.

Sol-by-sol summaries:

On sol 380, Opportunity placed its Mössbauer spectrometer on Russet for a five-hour integration, with remote sensing in parallel. The rover then switched to the alpha particle X-ray spectrometer for an eight-hour overnight integration.

On sol 381 Opportunity took one microscopic image of Russet, stowed the arm and bumped back for some remote sensing of the same target, then went for an approximately 60-meter (197-foot) drive to the crater "Jason."

Sol 382 was the second sol of a two-sol plan. Opportunity performed two hours of remote sensing.

The plan for sols 383 through 385 contained a first-time activity: to drive on all three sols over the weekend. On sol 383 there was a record-breaking 105-meter (344-foot) blind drive, in which the rover follows a route determined in advance by rover planners, followed by 72 meters (236 feet) of autonomous navigation, in which the rover chooses its own route around any obstacles it recognizes in images taken along the way. Sol 384 continued with 104 meters (341 feet) of autonomous navigation. Finally, Sol 385 completed the plan with an additional 109 meters (358 feet) of autonomously.

Autonomous navigation collects 15 megabytes to 25 megabytes of data per hour by imaging the passing terrain. (This would allow mobility engineers to reconstruct what happened if the drive faulted out.) As a result, flash memory was filled almost to the brim on sol 385, and sol 386 added only 6 megabytes of science data (all atmospheric science).

On sol 387, with a bit more free data volume to work with, and the team planned an approximately 80-meter (262-foot) drive to end up at a group of three small craters. The team also told Opportunity to use its navigation camera after the drive to take images for providing a 360-degree panorama of the craters.

The plan for sol 388, ending on Feb. 25, is to repeat the 6-megabyte atmospheric-science observations.

Current odometry total: 3014.77 meters (1.87 miles)

sol 374-379, February 22, 2005: Opportunity Gets New Flight Software

Opportunity received a software tuneup that should improve its mobility capabilities. With the new load on board, Opportunity booted into it and began an initial checkout. After a short test drive with promising results, there remains more checkout to do before blessing the load and having the rover's sister craft, Spirit, boot up the new software. Atmospheric opacity has been stable, with tau around 0.9. Solar power is still relatively plentiful and Opportunity continues to be in excellent health.

Sol-by-sol summaries:

Sols 374 through 376 were used to load the files for the new flight software, so Opportunity did not move during this operation. There were a few hours of remote-sensing observations on sols 374 and 375. Opportunity successfully booted into the new flight software on sol 376.

Starting out slowly, Opportunity performed three hours of remote-sensing activities on sol 377.

Sol 378 was the first driving sol using the improved flight software. The drive employed various methods, such as blind driving, auto-navigation, and visual-odometry driving to exercise the rover's new software. Opportunity traversed approximately 25 meters (82 feet) this sol.

After completing the drive on sol 378, Opportunity had a very nice rock target just outside its front right wheel. On sol 379, Opportunity performed two hours of remote sensing and then turned to 170 degrees, putting the rock target "Russet" perfectly in the rover's work volume. Sol 379 ended on Feb. 16, with Opportunity's total odometry at 2,559.88 meters (1.59 miles).

sol 367-373, February 11, 2005: Examining a Trench and Scuff

Opportunity is in good health after more than a year on the martian surface. The rover completed its investigation of a trench and soil materials on sol 373 and is ready for a software patch, which will be uploaded over next few sols. There have been no recent dust storm events, and tau -- a measurement of atmospheric opacity -- has remained close to 0.9 for the past two weeks.

Sol-by-sol summaries:

For sols 367 and 368, a two-sol plan focused on investigation of a trench that Spirit had dug with its wheels on sol 366. Opportunity awoke on sol 367 at about 7:30 a.m. local solar time after a night in the deep-sleep mode. It made some early-morning photometry measurements, then napped until the morning uplink window from 10:40 to 11:00 a.m. local solar time. After this, the rover acquired microscopic images of the trench wall, performed a short reading with the Mössbauer spectrometer, and then positioned the alpha particle X-ray spectrometer for data collection. After an afternoon communications relay session via Mars Odyssey, the rover slept until the sol 368 morning relay pass, at which time it started the alpha particle X-ray spectrometer integration. In the morning of sol 368, Opportunity acquired more photometry observations, gathered more microscopic images, performed another short Mössbauer integration, and then positioned the alpha particle X-ray spectrometer for an overnight integration.

On sol 369, Opportunity completed more trench investigations. It gathered additional microscopic images on new targets in the trench, completed another short data-collection session with the Mössbauer spectrometer, and placed the alpha particle X-ray spectrometer for another overnight integration.

On sol 370, the rover acquired more microscopic images, more Mössbauer data and a variety of remote-sensing observations before using the deep-sleep mode overnight.

On sol 371, after waking from deep sleep, Opportunity restarted the Mössbauer integration. The rover made remote-sensing observations during the middle of the day. Later, it gathered the last microscopic images on the trench, stowed its robotic arm and used its left front wheel to scuff the soil. Opportunity then bumped backwards to put the scuffed area into the arm's work volume.

On sol 372, Opportunity completed microscopic imaging of the scuffed area, collected Mössbauer data, and switched to the alpha particle X-ray spectrometer. The rover did not use the deep sleep mode overnight so that it could perform an overnight reading with the alpha particle X-ray spectrometer.

On sol 373, Opportunity completed the alpha particle X-ray spectrometer work and then changed tools back to the Mössbauer for more integration during the day. In the afternoon the rover acquired some final microscopic images of the scuff, used the hazard avoidance camera to inspect wear on the grinding teeth of the rock abrasion tool, and then stowed the arm. Opportunity then bumped back about 1.5 meters (about 5 feet) to position itself for observing the trench with the instruments on the mast. It turned to a heading of 250 degrees to be in good position for four hours of high-gain antenna tracking for receiving an upload of improved flight software. Sol 373 ended on Feb. 10.

sol 360-366, February 04, 2005: Poking Around on the Plains

Opportunity continues to be active and healthy, making good progress south across the Meridiani plains with a few hiccups along the way. Despite the early end of one autonomous traverse and a Deep Space Network problem that precluded sending commands on sol 364, the rover covered more than 300 meters (984 feet) in the past week, breaking its own one-sol distance records twice! Having scuffed and trenched in the sands of the plain, Opportunity is now examining the trench and nearby soil targets.

Sol-by-sol summaries:

Since the Opportunity team was operating in restricted-sol mode, the team chose to plan sols 360 and 361 together as a drive sol followed by a remote-sensing sol. On sol 360, Opportunity traversed a record 154.65 meters (507.4 feet), using a combination of blind drives and auto-navigation software. On the next sol, Opportunity carried out three hours of remote-sensing observations.

Sols 362 and 363 were planned together as another two-sol plan, again with the basic intent of driving as far as possible. After a directed drive of 90 meters (295 feet), the rover turned 180 degrees and continued in auto-navigation mode, resulting in an impressive 156.55-meter (513.6-foot) traverse. That is a new record for a single sol of driving on Mars. Alternating the rover's drive direction is part of the engineering strategy for maintaining the long-term health of our wheel drives. For the second sol of the plan, Opportunity was commanded to continue driving for up to 120 meters (394 feet), as long as no drive errors had occurred on the first sol. However, due to a previously unidentified navigation software vulnerability, the sol 363 drive errored out at its start.

The plan for sol 364 was to continue the series of long traverses south. Unfortunately, there was a problem with a coolant line at a Deep Space Network transmitter, most of the pass was lost, and the plan could not be uplinked in the couple of minutes remaining. So, for what may have been the first time during Opportunity's mission, a sol's worth of nominal activities was lost, and the science run-out sequence from earlier commands was executed instead. Run-out sequences give the rover some useful tasks to do in case it does not get a new set of commands.

On sol 365, Opportunity used its panoramic camera and miniature thermal emission spectrometer to observe a target dubbed "Strange Rock," then moved a few meters (several feet) to get in position for trenching through a dune ripple crest.

For sol 366, rover planners worked very closely with the science team to choreograph a rover trenching dance: Opportunity moved, scuffed (dragging its front wheels backwards multiple times), and finally trenched in the sand, all while placing the rover in a good orientation for later communications. The rover then went into deep sleep in preparation for an early morning photometric observation. Sol 366 ended on Feb. 3.

sol 353-359, January 28, 2005: Opportunity Continues on the Plains After Marking One Year on Mars

After spending 25 sols at the heat shield and nearby meteorite, Opportunity has completed its investigation of both and has started a long migration south. The rover is currently heading for a small crater called "Argo." Dust storms in the vicinity of Meridiani Planum appear to be settling down, and solar power has stabilized. On Jan. 24, 2005, the rover team celebrated Opportunity's first anniversary (one Earth year) on Mars. The rover continues to be in excellent health for its long drives out on the plains of Meridiani.

Sol-by-sol summaries:

Sol 353 was a restricted sol. (Results of 352 drive were not known by the planning team in time to calculate the final heat shield approach). Opportunity performed over two hours of observations using the panoramic camera and miniature thermal emission spectrometer.

On sol 354, Opportunity performed 10 minutes of pre-drive remote-sensing observations, then moved forward to get in final position for extending its instrument deployment device (robotic arm) to the heat shield. A drive of 0.7 meter (2.3 feet) was successful, placing the heat shield in reach of the arm. Opportunity performed more than an hour of post-drive imaging.

Sol 355 was a restricted sol. Opportunity performed over two hours of remote sensing.

Sols 356 and 357 were planned in a single planning cycle. On sol 356, Opportunity used the microscopic imager to examine the heat shield. Using the arm to position the microscopic imager, Opportunity spent 90 minutes collecting high-resolution images of the heat shield. On sol 357, the rover performed thermal inertia measurements throughout the sol. Using the miniature thermal emission spectrometer to image the same target at different times, Opportunity took measurements as late as 23:00 Mars local solar time.

On sol 358, Opportunity retook some microscopic images of the heat shield with the dust cover open. The rover then stowed its arm and began its drive south, away from the heat shield. Opportunity is now headed for a small crater called Argo, which is approximately 300 meters (about 984 feet) away. Opportunity successfully covered 86.3 meters (283 feet) on this sol.

Sol 359, which ended on Jan. 27, was another restricted sol. The rover was sent commands for over 2.5 hours of remote sensing.

Total odometry as of sol 358 is 2,200.6 meters (1.37 miles).

sol 347-352, January 24, 2005: Opportunity Checks Out the First Meteorite Found on Another Planet!

Opportunity completed its work on "Heat Shield Rock" during sols 347 through 352, then got into position for more observations of the heat shield. This rock is now known to be an iron-rich meteorite, thanks to findings of the alpha particle X-ray spectrometer, Mössbauer spectrometer and the miniature thermal emission spectrometer. The rover remains in good health.

The team continues to closely monitor orbital images for signs of dust storms. Tau, a measure of the sky opacity, has hovered in the 0.8 to 0.9 range for the past week; tau was roughly 0.5 before recent dust disturbances in the region.

Since sol 331, a mottled pattern has been seen on sky portions of images from the rear hazard avoidance camera. The pattern was originally thought to be a sky pattern caused by the dust storm occurring at that time. After a closer look at the mottled pattern in subsequent images, it appears that there is actually a deposit of some sort on the rear hazard avoidance camera lenses. The deposit may be storm dust that blew in their direction. It might also be fine dust from the heat shield debris that blew onto them or was kicked up by Opportunity's wheels as it drove around the debris site. The team decided to go ahead with a final close-up imaging campaign of the heat shield despite the risk of further deposition on the camera lenses because of the rare opportunity to examine a spent heat shield on Mars. Rover drivers are taking extra precautions to drive around debris and to find safe orientations for the rover as it works. The team has decided to forgo observations at the heat shield divot due to the possibility of further contamination at that site.

Sol-by-sol summaries:

On sol 347, Opportunity unstowed its instrument deployment device (robotic arm) to take microscopic images of Heat Shield Rock, and then placed the Mössbauer spectrometer instrument on the rock for a 19-hour observation. Mössbauer integration times are longer now because the Mössbauer source has weakened as expected since landing.

On sol 348, the rover placed the alpha particle X-ray spectrometer instrument on Heat Shield Rock during the afternoon for an overnight observation. That instrument provides best results when it is cold.

On sol 349, the rover brushed an area on Heat Shield Rock using the rock abrasion tool, took microscopic images of the brushed spot, then placed the alpha particle X-ray spectrometer on the spot for another overnight observation.

350 - Opportunity changed tools on the arm to the Mössbauer instrument for another long observation on the brushed area.

351 - The rover changed tools on the arm back to the alpha particle X-ray spectrometer instrument again, putting it in place for another overnight observation of Heat Shield Rock.

352 - Opportunity took some final microscopic images of the rock then backed away for observations with the panoramic camera and miniature thermal emission spectrometer. The rover then drove to within about 1 meter (about 3.3 feet) of the largest piece of the heat shield in preparation for more observations of spent heat shield material with the microscopic imager.

sol 341-346, January 14, 2005: Hovering Near Heat Shield and a Holey Rock

Opportunity is healthy. It acquired microscopic images of the fractured edge of the heat-shield wreckage and began a detailed investigation of an intriguing, pitted rock a few meters to the north, called "Heat Shield Rock." The team continues to closely monitor orbital images for dust storms. The opacity of the atmosphere above Opportunity has averaged 0.75 with a slight downward (clearing) trend over the past week.

Sol-by-sol summaries

Sols 341 through 343 were combined in a three-sol plan for the Earth weekend. On sol 341, Opportunity used a morning Mars Odyssey pass for a communications relay at about 4 a.m. local solar time and then slept until solar-array wakeup at about 8:45 a.m. After another short nap, the rover did a bit of remote sensing and received its new commands for the sol. Opportunity deployed its robotic arm and acquired 96 microscopic images of the fractured edge of the heat shield. In the afternoon it used its Mössbauer spectrometer to analyze dust on the science filter magnet. It used the deep-sleep mode overnight. On sol 342, Opportunity woke from deep sleep at about 7 a.m. local solar time and restarted the Mössbauer integration on the magnet. It was a light day of activity with afternoon remote sensing, an evening Odyssey relay pass, and then deep-sleeping overnight. On sol 343, the rover restarted Mössbauer integration on the magnet and completed afternoon remote sensing before deep-sleeping.

On sol 344, Opportunity stowed its instrument deployment device (robotic arm) and backed up about 4 meters (13 feet) before acquiring a panorama of the heat shield and other remote sensing. The rover did not deep-sleep overnight in order utilize the morning Odyssey relay and return as much data as possible. The flash memory is relatively full.

On sol 345, Opportunity acquired additional navigation-camera images of the heat shield to support a future re-approach for additional microscopic imaging. It then turned and drove north toward "Heat Shield Rock," which has pits in its surface. The rover traversed about 10 meters (33 feet) and arrived at the desired 1-meter (about 3.3 feet) standoff distance to acquire remote sensing of the rock. Opportunity used the energy-conserving deep-sleep mode overnight.

Sol 346 - Opportunity acquired additional remote sensing and then bumped forward, putting the rock within the work volume of the tools on the instrument deployment device. The rover took advantage of an early-morning communications pass, so it did not deep-sleep overnight.

sol 333-340, January 14, 2005: More Heat Shield Observations

The week saw Earthlings celebrate a new year and Spirit's first birthday on Mars (one Earth year) while Opportunity continued its trek around its own heat shield. On Earth, the operations team experienced a few tool problems, but the support team was in position to fix most problems as soon as they were discovered.

A dust storm that affected Opportunity the previous week has slowly receded, allowing increasing solar exposure. To conserve energy, Opportunity has been going into the deep-sleep mode every night, but as power continues to improve, the team is planning to resume using some early-morning Mars Odyssey communication passes to reduce a backlog of unsent telemetry.

Opportunity continues to be in excellent health as the rover team looks forward to the Jan. 24 anniversary of Opportunity's landing.

Sol-by-sol summaries:

Sol 333 was the second sol of a two-sol plan. The day was spent monitoring the opacity of the atmosphere and performing almost three hours of remote sensing. Atmospheric opacity peaked on sol 321 at 1.25. On sol 333 it was down to 0.97 and decreasing, indicating that the sky was clearing. The amount of power generated by Opportunity's solar panels increased from 546 watt-hours on sol 321 to 630 watt-hours on sol 333.

Sols 334, 335 and 336 were planned in a single planning cycle.

On Sol 334 (New Year's Eve), Opportunity performed 90 minutes of remote-sensing observations, inspected debris from the heat shield's flank with the microscopic imager, and then placed the alpha particle X-ray spectrometer on the capture magnet on the rover's solar panel.

On New Year's Day, sol 335, Opportunity started taking data with the alpha particle X-ray spectrometer early in the morning, napped several hours, awoke and turned off that spectrometer, performed another hour of remote sensing, and then went to sleep for the night.

On sol 336, Opportunity collected another two hours of alpha particle X-ray spectrometer data on the capture magnet and made remote-sensing observations for an hour.

On the morning of sol 337, Opportunity examined the flank portion of the heat shield wreckage with the microscopic imager, imaged the capture magnet, then stowed the arm and began its drive for the day. Opportunity banked up 2 meters (about 6.6 feet), turned and drove 10 meters (33 feet) to "East Point." At East Point, Opportunity performed 30 minutes of imaging, capturing a stereo image of the heat shield and a 360-degree view with the navigation camera. The rover then drove another 12.5 meters (41 feet) to a standoff point facing the heat shield seal.

The team experienced a problem with onboard file deletion on sol 337. There was a bad parameter in one command, so Opportunity rejected the entire set of commands. The result of rejecting the command file was that Opportunity's flash memory filled up and the flight software began deleting lowest-priority data products. Approximately 150 megabits of stored data products were lost. Because many images were being acquired and processed at the same time auto-deleting was taking place, the rover's computer was running very slowly. When Opportunity attempted to perform a "Get Fine Attitude," (a command that updates the rover's knowledge of its tilt and orientation), it timed out. The rover monitors itself and cancels things that take longer than planned, the same way home computers cancel attempts to access the internet if the server doesn't respond within a certain time. Due to the time-out, Opportunity responded that it didn't know its exact attitude (setting the surface attitude pointing and positioning -- SAPP -- knowledge to "unknown"). As a result of this, subsequent commands for using the miniature thermal mission spectrometer images were rejected. Pointing the spectrometer at the Sun would severely damage it, so in order for the rover to point the instrument, it must know its attitude.

Sol 338 became a restricted-operations sol due to a long latency in receiving relayed data. Telemetry was delayed more than seven hours, so Opportunity spent the sol performing more than four hours of remote sensing. The operations team was able to react to the failed Get Fine Attitude on sol 337 by creating a real-time command to reset the surface attitude pointing and positioning knowledge. The command was sent as part of the sol 338 uplink and worked as planned. Opportunity also performed both a left-eye and right-eye Get Fine Attitude.

Sol 339 was another "image, drive, image, drive" sol. Opportunity performed 30 minutes of pre-drive imaging, drove about 10 meters (33 feet), performed 80 minutes of mid-drive imaging, drove another 13 meters (about 43 feet) toward the charred side of the heat shield, and performed 30 minutes of post-drive imaging. All operations worked as planned, leaving Opportunity in position to approach the heat shield to perform microscopic imaging over the weekend. Sol 339 ended on Jan. 6.

Total odometry after sol 339 is 2075.52 meters (nearly 1.29 miles).

Atmospheric opacity on sol 339 was 0.83; solar array energy was 836 watt-hours.

sol 325-332, January 05, 2005: Sizing Up the Heat Shield

Opportunity is healthy and has reached the site where its heat shield hit the ground. The rover will make detailed observations of the heat shield's remains, weather permitting. The rover experienced its first dust storm since landing, which has affected the amount of energy Opportunity gets each sol. When the rover landed nearly one Earth year ago, a dust storm was subsiding and the atmosphere had an opacity of 0.9 (the higher the number, the murkier the skies). Since then, the opacity had improved significantly and was roughly 0.5 on sol 327. On sol 328 the opacity jumped to 0.6 then to 0.8, 1.2, and 1.25 on sols 329-331. As of sol 332 it is at 1.2 and dropping. Images from Mars Global Surveyor orbiter have confirmed the presence of a few small dust storms in the region. The energy intake has decreased roughly 30 percent, leaving Opportunity with less energy for operations and communications but still enough, with comfortable margin, to continue with the plan to investigate the heat shield remains. The dust storms will be monitored carefully using the rover's own instruments and images from Mars Global Surveyor. The team will also be walking through low-energy contingencies should they become necessary.

Sol-by-sol summaries:

On sol 325, Opportunity drove 27 meters (about 89 feet) backward, to "West Point." It imaged the heat shield debris field from that vantage point. The engineers choose to occasionally drive the rover backward for convenience and to keep the wheel-motor lubrication more evenly distributed.

Sol 326 was the second sol of a two-sol plan. This sol was spent imaging the heat shield debris field.

On sols 327 to 329, the Mössbauer spectrometer was placed on the compositional calibration target for a series of observations over the Earth weekend. This is done periodically to calibrate the Mössbauer instrument. The rover continued routine atmospheric observations and remote sensing of the heat shield debris field.

On sol 330, Opportunity used its panoramic camera to take images of the heat shield debris field, then drove 15 meters (about 49 feet) to a location called "South Point" for another look at the debris field.

On sol 331, Opportunity drove roughly 10 meters (33 feet) to approach the flank portion of the heat shield remains. The heat shield broke into two main piece when it hit the ground. The flank is the smaller of those portions.

On sol 332, which ended on Dec. 30, the rover made its final approach to the flank portion of the heat shield wreckage in preparation for close-up inspection of the heat shield material over the New Year's holiday weekend. The drive brought Opportunity's odometer total to 2,051 meters (1.27 miles).

sol 320-324, January 05, 2005: Heading for the Heat Shield

As of sol 324 (Dec. 21), a healthy Opportunity has driven to within about 30 meters (about 98 feet) from the remains of the heat shield that hit the ground about 250 meters (820 feet) south of "Endurance Crater." Ending this year exploring part of the rover's entry system is a great reminder of the tremendous year Opportunity and Spirit have had thanks to the dedication and hard work of so many.

Sol-by-sol summaries:

On sol 320, Opportunity completed a variety of observations including imaging toward the heat shield. It then went into deep sleep overnight.

Sols 321, 322 and 323 were combined in a single activity plan for the Earth weekend. On the first sol of the three-sol plan, Opportunity looked at the front edge of its solar array with its microscopic imager to assess dust accumulation there. It then drove nearly 60 meters (about 197 feet) south toward the heat shield and acquired post-drive imagery to support planning of the next drive. Opportunity did not deep-sleep overnight so it could wake up to take advantage of a Mars Odyssey communications pass to return data during the night. On sol 322, Opportunity made some observations and then went into deep sleep overnight. On sol 323 it made more observations and did not deep-sleep overnight.

On sol 324, Opportunity drove nearly 90 meters (about 295 feet), bringing it within 30 meters (98 feet) of the heat shield. This was a record length for a drive that did not use the rover's auto-navigation software. It was enabled by the team's ability to identify a hazard-free route in images that the navigation camera and panoramic camera had taken of the flat terrain to be covered in the drive. The rover also made use of low-level hazard-detection software that reads rocker-bogie ("rover leg") position and rover tilt to halt a drive if the rover encounters a hazard. This drive brings the odometer 1,998 meters (1.24 miles).