Spirit well behaved, less dusty, in difficult terrain

Changes were made to rover wake-sleep cycle to be more resilient against any future "amnesia" occurrences. Also, changes were made to record internal data for a longer period of time if the rover again misses any wakeups.

Four drive sols were successfully executed this week. However, the terrain, once again, is very difficult, and the rover achieved very limited progress. The rover drove on sols 1886, 1889, 1891 and 1892 (April 23, 26, 28 and 29, 2009), covering a total of about 3 meters (10 feet).

Spirit experienced another small solar array dust cleaning event. On Sol 1891, energy production improved by more than 10 percent, supplementing a similar improvement the previous week.

As of Sol 1892 (April 29, 2009), Spirit's solar array energy production is about 372 watt-hours, compared with 223 watt-hours at the end of March (Sol 1864). Atmospheric opacity (tau) is around 0.855. The dust factor has improved to around 0.418, meaning that about 41.8 percent of sunlight hitting the solar array penetrates the layer of accumulated dust on the array. The rover's behavior has been good and responsive, and solar energy production is well improved. Spirit's total odometry is 7,729.73 meters (4.80 miles).

Spirit slipped in soft ground during short backward drives on the 1,886th and 1,889th Martian days, or sols, of the rover's mission on Mars (April 23 and 26, 2009). Spirit used its front hazard-avoidance camera after driving on Sol 1889 to get this wide-angle view, which shows the soil disturbed by the drives. Spirit drove 1.11 meters (3.6 feet) on Sol 1889 and 1.68 meters (5.5 feet) on Sol 1886. The rover drags its right front wheel, which no longer rotates. For scale, the distance between the wheel tracks is about 1 meter (40 inches). This view is looking northward, with Husband Hill on the horizon. Credit: NASA/JPL-Caltech

Backing off of a ripple, then a rise in wheel current

Opportunity's drive on Sol 1865 (April 23, 2009) ended with the front wheels starting to dig into a large ripple. The first order of business this week then was to back off of the ripple and proceed down a different path. A backup drive on Sol 1866 (April 24, 2009) had only limited success as the rover moved only about 28 centimeters (11 inches) before limits stopped the drive. The drive on the next sol completed the backup, accomplishing 3.7 meters (12 feet) of movement.

Drives performed on sols 1870 and 1871 (April 28 and 29, 2009) totaled more than 64 meters (210 feet). The Sol 1871 drive showed a return of the increase in the amount of current drawn by drive actuator in the right-front wheel. The project is considering mitigation practices of resting the actuator and/or driving backwards for a while.

As of Sol 1871 (April 29, 2009), Opportunity's solar array energy production is 504 watt-hours, with atmospheric opacity (tau) at 0.763 and solar array's dust factor at 0.605. Total odometry is 15,805.06 meters (9.82 miles).

Source: Jet Propulsion Laboratory
	More on • Spirit • Opportunity • Mars Exploration Rovers • Mars