Spirit investigates Ancient Rocks, as Opportunity Rolls On

SPIRIT UPDATE: Spirit investigating ancient rocks – sol 272-278, October 20, 2004

Spirit had a productive week investigating the rock “Tetl.” On sol 277, Spirit attempted a drive to the next rock target, “Uchben,” which means “ancient” in the old Mayan language. Halfway into that drive, Spirit experienced a repeat problem in the steering motor control system that engineers first saw on sol 265. Engineers repeated diagnostic tests for the problem on sol 278. Those tests showed that the electronics relay in question is still functional, but appears to operate intermittently. Spirit is otherwise healthy and is in a safe location.

On sol 272, Spirit took images with the microscopic imager to create a mosaic of Tetl’s layered rock face.

On sol 273, Spirit captured more microscopic images of Tetl’s layered face, then put the alpha particle X-ray spectrometer in place for an early morning observation.

On sol 274, Spirit woke up at 4:00 a.m. to start the alpha particle X-ray spectrometer observation. The alpha particle X-ray spectrometer stayed on until the start of normal morning atmospheric science observations. Spirit also used its miniature thermal emission spectrometer to observe nearby rocks named “Zackuk” and “Palenque,” which are possible future targets for in-depth observations. Later, Spirit changed tools on its robotic arm, placing the Mössbauer instrument on Tetl for an observation the next morning.

On sol 275, Spirit completed a 6-hour Mössbauer integration and performed daily atmospheric observations. This was the final sol of Spirit’s weekend plan and was purposely simple to enable the sequencing team to complete a 3-day plan on Friday.

On sol 276, Spirit restarted the Mössbauer instrument at 4:00 a.m. for another 10 hours of integration time on the same spot. Spirit also took a few final microscopic images of Tetl, then stowed the robotic arm in preparation for the next sol’s drive.

On sols 277 and 278, Spirit attempted a drive to Uchben, another layered rock roughly 6 meters (20 feet) northeast of Tetl. About 2.5 meters (8 feet) into the drive, the mobility software attempted to move a steering motor by first commanding open a relay (electronic switch) that releases a dynamic brake. The feedback from that command indicated that the relay was still closed, so the motor control software declared an error. Due to the error, the rover ignored that steering command and all subsequent driving commands. The root cause of the failed relay command is under investigation. A diagnostic test last run on sol 270 was repeated on sol 278, which ended on Oct. 14. That test showed that the steering motor’s dynamic brake relay can still be opened and closed, but does occasionally (5 out of 10 times) indicate that it is still closed after being commanded open.

More diagnostics tests are needed before the source of the problem can be positively identified. Until then, engineers will continue to drive, but will steer the rover in a tank-like fashion, not using the steering actuator in question.

Future plans are to clear the drive error and attempt another drive to Uchben on sol 281. Engineers are also planning to run more diagnostic tests starting on sol 282.

OPPORTUNITY UPDATE: Working towards ‘Wopmay’ – sol 245-250, October 13, 2004

Opportunity is in excellent health. The current pattern is to use the deep-sleep mode every second night, and to support an early morning Odyssey communications pass on the non-deep-sleep nights. Opportunity is experiencing good solar exposure, averaging more than 660 watt-hours per sol from the solar arrays. The rover is poised for final approach to “Wopmay,” a fascinating creviced rock with a brain-like appearance.

Sol details:

Sol 245 was a restricted sol. Opportunity could perform only remote sensing. The rover took images in all directions with its navigation camera. It used its miniature thermal emission spectrometer for sky and ground observations. Then it went into deep sleep for the night of sol 245 into the morning of sol 246.

Sols 246 through 248 were planned in a single planning cycle as part of our 5-day-a-week schedule. The uplink team accomplished a Herculean task, successfully completing and uplinking three science-intensive sol plans despite some issues encountered during the day.

Opportunity began sol 246 by placing the Mössbauer spectrometer and starting a long reading with it on a target called “Void.” While collecting the Mössbauer data, Opportunity also performed two hours of observations with its panoramic camera and its miniature thermal emission spectrometer. The Mössbauer integration was paused just before the afternoon communication session with Mars Odyssey. Deep sleep was disabled so that Opportunity could support an early morning communications session on sol 247 and restart the Mössbauer integration.

Sol 247 was day two of the long Mössbauer integration; the integration ran throughout the sol until early evening, at which time Opportunity again paused and entered deep sleep overnight. During the day, Opportunity also completed a series photometric observations with its panoramic camera.

On sol 248 Opportunity exited deep sleep and restarted the Mössbauer integration. During pre-uplink science activities in the early morning, the rover completed a sky observation pattern that planners call an itty-bitty cloud movie. In the martian afternoon, Opportunity ended the long Mössbauer integration and turned the tool turret on its arm to place the alpha particle X-ray spectrometer on Void. The X-ray instrument did not start taking data until early the next morning. Opportunity did not go into deep sleep overnight. Instead, it used an early morning Odyssey communications session and immediately afterwards started the alpha particle X-ray spectrometer integration.

Opportunity completed the alpha particle X-ray spectrometer integration on the morning of sol 249. The rover then performed a series of microscopic imaging activities, stowed the instrument deployment device and began driving toward its next target, Wopmay. The 19.98-meter (about 66-foot) drive went well, but with more slippage than expected. At the end of the drive, the nearest visible face of Wopmay was only 2 meters (about 7 feet) from the center of the rover; far enough not to have been a hazard during the drive, but closer than was predicted. Slip estimates indicate radial slippage as high as 64 percent. Opportunity used deep sleep overnight on sol 249.

On sol 250, which ended on Oct. 7, Opportunity performed the first part of a planned two-sol approach to Wopmay. This nearly 7-meter (23-foot) drive went well. The end of the drive incorporated conditional arcs to be executed only if the rover was in the appropriate position. The drive put the rover in very good position for the final approach on sol 251.

Total odometry after sol 250 puts Opportunity just over the one-mile mark: 1,611.99 meters (1.0016 mile)!