Opportunity drives by twin craters; Spirit in hibernation

Opportunity has been driving, making good progress toward Endeavour crater. The rover has had to pause between drives to recharge her batteries because of the diminishing sunlight during the advance into winter.

On Sol 2193 (March 26, 2010), Opportunity drove about 68 meters (223 feet) towards a pair of highly eroded craters. On the next sol, the rover performed a drive-by imaging of the twin craters, covering about 55 meters (180 feet).

Further driving next to the twin craters was performed on Sol 2197 (March 30, 2010), getting a good look inside, with the rover covering about 30 meters (98 feet) of distance. On Sol 2199 (April 1, 2010), Opportunity left the area of the twin craters with a 50-meter (164-foot) drive and resumed her push toward Endeavour, still many kilometers away. Opportunity will rest from driving on Sol 2200 (April 2, 2010) to recharge her batteries. As of Sol 2199 (April 1, 2010), the solar array energy production was 238 watt-hours with an atmospheric opacity (tau) of 0.371 and a dust factor of 0.501. Total odometry is 20,245.20 meters (20.25 kilometers, or 12.58 miles).

The scheduled downlink from Spirit on Sol 2218 (March 30, 2010), via Ultra-High Frequency (UHF) relay through the Odyssey orbiter was not received.

Odyssey reported nominal operations for their orbiter, but there was no received Spirit telemetry and no evidence of a UHF signal from the surface of Mars at Gusev crater. The team was anticipating Spirit to experience a low-power fault about this time. So, the most likely explanation for the missing downlink is that Spirit did go into that low-power fault taking her batteries off-line, sometime between the last downlink on Sol 2210 (March 22, 2010), and Sol 2218 (March 30, 2010).

With a low-power fault, Spirit is in a deep sleep with all loads turned off (no communication) and only the master clock being powered. The clock will stir Spirit on regular intervals to see if the batteries have recharged enough to wake up. If not, Spirit will remain deeply sleeping with the solar arrays trying to charge the rover batteries. The project had already begun listening for the possible X-band fault [communication] windows associated with the low-power fault. No X-band fault window has been detected, yet. The Deep Space Network radio science receiver (RSR) is being used to search for any X-band signal from Spirit. The rover will also experience an Uploss timer fault, since the rover would not be awake for us to reset that timer with a ground command. When the Uploss timer does expire, Spirit will also be responsive to UHF relay passes. However, Spirit will only respond with an X-band fault window or a UHF relay pass, if her batteries have recharged sufficiently. The team does not expect a response from Spirit for some time, but will listen every day. Total odometry is unchanged at 7,730.50 meters (4.80 miles).

 

Source: Jet Propulsion Laboratory
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