Spirit: Surprise from right-front wheel; Opportunity: Preparing to grind

Spirit remains embedded in the location called "Troy" on the west side of Home Plate. Because of continuing problems with the right-rear wheel, a test of the right-front wheel was done on Sol 2113 (Dec. 12, 2009) to gain insight into the signature for a failed wheel.

The right-front wheel had become inoperable back on Sol 779 (March 13, 2006). Surprisingly, the right-front wheel indicated normal motor continuity.

The project also discovered a change in what is known as the single-point ground. A negative voltage is present where no voltage should be. This suggests some sort of electrical short to the rover chassis. The behavior of this single-point ground correlates with the onset of problems with the right-rear wheel and with usage of any of the mobility actuators. This suggests that the rover's motor controller board is suspect.

The right wheels were tested again and driven as part of an extrication maneuver on Sol 2117 (Dec. 16, 2009). The right-front wheel functioned normally for the first three steps of the drive and stopped working during the last step, completing about 10 wheel revolutions. The right-rear wheel did not move at all. The rover only moved slightly during this drive. The project is continuing the investigation of these electric and wheel problems and continuing to explore the functionality of the right-front wheel.

As of Sol 2117 (Dec. 16, 2009), Spirit's solar-array energy production is down ro 277 watt-hours, with an atmospheric opacity (tau) of 0.503 and a dust factor of 0.557. Total odometry is 7,730.01 meters (4.80 miles).

 

Opportunity has been investigating the rock known as "Marquette Island," which has been of great interest. Assessments of its composition suggest that it might be ejecta from deep within Mars.

The plan is to position the rover to be able to perform a rock abrasion tool (RAT) grind on an accessible surface target on Marquette. On Sol 2093 (Dec. 13, 2009), Opportunity drove about 10 meters (33 feet) around the rock to position an accessible rock surface within reach of the robotic arm (instrument deployment device, or IDD). On Sol 2095 (Dec. 15, 2009), the rover performed a 5-centimeter (2-inch) bump to set up for RAT grinding.

The elevation mirror shroud of the miniature thermal emission spectrometer (Mini-TES) is being opened when appropriate with the expectation of eventual dust cleaning. No dust cleaning of the Mini-TES mirror has been noted yet.

As of Sol 2096 (Dec. 16, 2009), Opportunity's solar-array energy production is 354 watt-hours, with an atmospheric opacity (tau) of 0.462 and a dust factor of 0.528. Total odometry is 18,927.56 meters (11.76 miles).

 

Source: Jet Propulsion Laboratory
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