[meteorite-list] Mars Exploration Rovers Update - July 11, 2005

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Tue Jul 12 11:33:28 2005
Message-ID: <200507121532.j6CFWd826327_at_zagami.jpl.nasa.gov>

http://marsrovers.jpl.nasa.gov/mission/status.html

SPIRIT UPDATE: Spirit Scuffs - sol 532-537, July 11, 2005

Over the Fourth of July weekend, Spirit completed a robotic-arm campaign
which had some surprising results. It turned out that targets at
"Independence Rock" seem to have less iron than expected. This result
prompted the science team to take a closer look. On sol 536 (July 6),
because the grinding teeth on the rock abrasion tool are worn, the rover
team decided to remove some of the surface area by scuffing it with the
front left wheel.

The scuff worked as follows:

   1. Spirit moved into position with a turn in place.
   2. Rotated only the front left wheel -- reverse 1 radian.
   3. Rotated only the front left wheel -- forward 2 radians.
   4. Rover used onboard visual odometry.
   5. Repeated steps 2 through 4, two more times.
   6. Turned in place back to the starting position in order to present
      the "scuff" to the robotic-arm workspace.

Since the rover gets better alpha particle X-ray spectrometer and
Moessbauer spectrometer spectral readings when we let them run long (more
than 10 hours for the alpha particle X-ray spectrometer and more than 20
hours for the Moessbauer spectrometer). The rest of the weekend (sols 538
to 541) will be dedicated to work using the instruments on the robotic arm.

Sol-by-sol summaries:

Sol 532 to 535 (July 2 to July 5, 2005): Over this period, Spirit took
data with the alpha particle X-ray spectrometer and the Moessbauer
spectrometer and made observations with the microscopic imager and
remote-sensing instruments. The results motivated a decision to do more
work with the robotic arm.

Sol 536: The scuff today worked nicely, except that it did not seem to
remove a whole lot of material from the place Spirit scuffed. Overall,
the rover only scuffed 9 radians on the rock surface, which is less than
1.5 wheel revolutions. Engineers received no errors during the drive,
and it looked like all drive-related telemetry was within acceptable
parameters.

After the scuff and before Spirit moved back to its original position,
the rover took a picture with the hazard avoidance camera in order to
see the effect the scuff had on the wheel treads.

The rover team favored the forward wheel rotation because this creates a
torque that needs to work against gravity in order to rotate the rover body.

Sol 537 (July 7, 2005): Spirit started an "Independence" 360-degree
color panorama. This mosaic will be run all weekend.

------------------------------------------------------------------------

OPPORTUNITY UPDATE: Pushing Away from Purgatory - sol 510-517,
July 11, 2005:

This week Opportunity finished examining "Purgatory Dune" and started
driving again. The first few drives were to the north so that possible
paths to the south could be imaged and evaluated. The next few steps
took the rover east, then southward down a wide trough. A new set of
"rules of the road" have been developed and implemented to prevent the
rover from getting bogged down again.

The miniature thermal emission spectrometer has also been cleared for
regular use, and has returned some useful science products during the
last week.

Sol-by-sol summaries:

Sol 510 (June 30, 2005): Opportunity finished characterizing Purgatory
ripple with microscopic imager pictures of soil (tracks and
undisturbed), and took a first step back. The rover collected several
images to document the 2.1-meter (6.9-foot) drive. Visual odometry
confirmed that slip was less than 10 percent during the short traverse.
After the drive, the rover took pictures of the surroundings to evaluate
possible safe pathways to the south.

Sol 511: Opportunity backed up 8.5 meters (28 feet), and again imaged
the terrain to the south. The drive used visual odometry and slip checks
to stop the rover if it failed to make progress.

Sol 512: The long-term goal for Opportunity is to drive south and
slightly east. Before continuing on this path the rover must either go
east or west to sidestep Purgatory Dune. Extensive remote sensing with
the panoramic camera and navigation camera was done this sol to assist
in the decision.

Sol 513: With all imaging needed for driving already acquired,
Opportunity spent the sol doing atmospheric observations, dust
monitoring, and also imaging of the magnets with the panoramic camera.

Sol 514: The engineering and science team took an Independence Day break
today, and the rover executed its planned runout science sequence, which
included atmospheric observations with the panoramic camera.

Sol 515: Imaging acquired over the weekend showed that the path to the
east contained very small ripples (less than 6 centimeters or 2.4
inches), and led to a wide trough to the south. This sol, rover planners
sequenced a 5.5-meter (18-foot) backwards drive over old tracks, then
turned in short segments (less than 20 degrees), and drove east 2.5
meters (8.2 feet) over one small ripple. Tilt limits, visual odometry
failure limits, and cycle limits were employed to prevent the rover from
bogging down. The drive succeeded as planned.

Sol 516: An 11-meter (36-foot) drive to the east crossed two small
ripples and positioned the rover to enter the trough leading south.
Limits and slip checks were used to ensure that Opportunity would not
get stuck.

Sol 517 (July 8, 2005): A new safety check was added to this drive: The
drive current limits were lowered from 1 ampere to 0.4 amperes. The
standard safety checks were also used on this drive, designed to take
Opportunity 4 meters (13 feet) east to the north end of the trough, then
11 meters (36 feet) south through the trough.

Opportunity's total odometry after sol 517 is 5,406.6 meters (3.36 miles).

Looking ahead:
Opportunity will continue the drive south, more slowly than before to
ensure a safe path.
Received on Tue 12 Jul 2005 11:32:39 AM PDT