[meteorite-list] Mars Exploration Rovers Update: March 31 - April 7, 2010

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Mon, 12 Apr 2010 15:41:57 -0700 (PDT)
Message-ID: <201004122241.o3CMfvpf015332_at_zagami.jpl.nasa.gov>


SPIRIT UPDATE: Spirit Remains Silent - sols 2219-2226,
March 31 - April 07, 2010:

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
all 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. It is not known when that will happen, so the
project has been listening for any X-band signal from Spirit through the
Deep Space Network (DSN) every day. The Mars Odyssey orbiter is also
listening over selected Ultra-High Frequency (UHF) relay passes for any
signal from Spirit. It may be weeks to months before Spirit communicates.

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


OPPORTUNITY UPDATE: Sharp Turns Make Driving Difficult -
sols 2200-2204, April 2-6, 2010:

Opportunity had a couple of difficult moves this week.

After taking some time to recharge her batteries, the rover attempted a
drive on Sol 2202 (April 4, 2010). That drive stopped after the initial
arc turn due to elevated current draw in the motors on the right side of
the rover. The rover is between two ripples with the space in between
forming a bowl. The rover had to push harder on the right to make the
sharp turn. Conservatively-set current limits stopped the drive, as a
way for controllers on the ground to assess the driving conditions
before proceeding.

With everything looking okay, another drive on Sol 2204 (April 6, 2010),
was commanded. It too began with a short, sharp arc. This time the drive
stopped after a short distance because of wheel slip exceeding the limit
of 40 percent. Again ground controllers assessed the conditions and
found no problems. With these sharp turns, the rover's wheels must
impart more thrust. When the wheel thrust exceeds the shear strength of
the terrain, slip occurs.

Opportunity will drive again on Sol 2206 (April 8, 2010). This time the
rover is already aligned with the drive direction, so no sharp turns are
needed. Extra slip checks will be performed to make sure there are no
terrain issues. As of Sol 2204 (April 6, 2010), the solar array energy
production was 235 watt-hours with an atmospheric opacity (tau) of 0.371
(from Sol 2199) and a dust factor of 0.500.

Total odometry is 20,247.56 meters (20.25 kilometers, or 12.58 miles).
Received on Mon 12 Apr 2010 06:41:57 PM PDT

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