Opportunity's balancing act; Winter solstice two weeks away for Spirit

Opportunity drove twice in the last week. The rover took time in between drives to recharge her batteries and performed a soil campaign with the instrument deployment device (IDD).

The drives took place on Sols 2220 (April 22, 2010), and 2226 (April 28, 2010). The drive on Sol 2220 (April 22, 2010) halted after about 10 meters (33 feet) when a slip check failed while traversing the soft side of a sand dune.

Post drive analysis determined that this slip-check failure was of the type that is expected occasionally from driving in this terrain and did not indicate a fundamental change in hazard level. Therefore, following the completion of the IDD soil campaign, a drive was planned for Sol 2226 (April 28, 2010), which executed nominally and added approximately 33 meters (108 feet) of progress.

A complicating factor for Opportunity during this winter period is that she has to balance her recharge efforts against the need to stay warm. That is, if she doesn't expend a minimum amount of energy into the electronics during a given sol, she risks thermostatic heaters coming on that will consume even greater amounts of energy. At this point, this balancing act is primarily an impact on driving as Opportunity can at anytime park herself on a sunny northerly slope to satisfy survival requirements.

As of Sol 2226 (April 28, 2010), the solar array energy production was 245 watt-hours with an atmospheric opacity (tau) of 0.355 and a dust factor of 0.4695.

Total odometry is 20,596.37 meters (20.60 kilometers, or 12.80 miles).

Winter solstice two weeks away for Spirit

Spirit remains silent at her location called "Troy" on the west side of Home Plate. No communication has been received from the rover since Sol 2210 (March 22, 2010).

It is likely that Spirit has experienced a low-power fault and has turned off all sub-systems, including communication. The rover will use the available solar array energy to recharge her batteries. When the batteries recover to a sufficient state of charge, Spirit will wake up and begin to communicate. When that does happen, Spirit will also trip an up-loss timer fault. This fault response will allow the rover to communicate over Ultra-High Frequency (UHF), as well as X-band.

It is not known when the rover will wake up, so the project has been listening for any X-band signal from Spirit through the Deep Space Network every day. The Mars Odyssey orbiter is also listening over any scheduled UHF relay passes. The winter solstice is about two weeks away.

Total odometry is unchanged at 7,730.50 meters (4.80 miles).

 

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