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 2001 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 Mini-TES (analysis is still in progress), Opportunity is in excellent health.
Sol 422: On this restricted sol, only remote sensing was conducted. A panoramic camera mosaic of Viking Crater was acquired. Sol 422 Images: panorama
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 424 Images: navigation
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).
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 (100 feet) 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.
Sols 430-432 (April 9-11 April, 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. Images: panorama navigation front hazcam showing wheel
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. Images: panorama navigation front hazcam
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 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.
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 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.
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 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.
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.
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.