Status Report

NASA Mars Rover Status 4 August 2004

By SpaceRef Editor
August 3, 2004
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NASA’s Spirit rover has climbed higher into rocky hills on Mars, and
its twin, Opportunity, has descended deeper into a crater, but both
rovers, for the time being, are operating with some restrictions while
team members diagnose unexpected behavior.

Both rovers have successfully operated for more than double the span
of their three-month primary missions. They have been conducting bonus
science in extended missions since April.

While Spirit was executing commands on Aug. 1, a semiconductor
component failed to power on as intended. The component, a
programmable gate array, directly affects usability of the rover’s
three spectrometer instruments. Subsequent commands for using the
miniature thermal emission spectrometer in that day’s sequence
resulted in repeated error messages.

Engineers on the Mars Exploration Rover team at NASA’s Jet Propulsion
Laboratory, Pasadena, Calif., have determined the most likely cause is
a timing issue of one instruction reaching the gate array microseconds
before another that was intended to precede it. If that diagnosis is
confirmed, a repeat could be avoided by inserting a delay between
commands that might reproduce the problem, engineers expect. Until
then, the rover science team’s daily choices for how to use Spirit do
not include using the miniature thermal emission spectrometer, the
Moessbauer spectrometer or the alpha particle X-ray spectrometer.

“While we’re being very cautious in how we operate today and tomorrow,
we expect to verify the problem and resolve this issue with a
relatively easy workaround,” said JPL’s Jim Erickson, project manager
for the twin rovers.

Spirit has driven to a bedrock exposure near the top of a spur of the
“Columbia Hills.” The location sits about nine meters (30 feet) above
a plain that the rover crossed for months to get from its landing site
to the hills. Planners intend for Spirit to spend more than a week at
this site, inspecting the rock exposure, dubbed “Clovis,” and
recording the panoramic scene from this viewpoint.

Halfway around Mars, Opportunity has driven about 20 meters (66 feet)
into “Endurance Crater,” examining increasingly older layers of
bedrock as it advances. If assessments of traversability continue
giving positive indications, the rover team plans next to send
Opportunity counterclockwise across the inner slope of the crater to
study possible targets of dune tendrils, boulders and the base of a

Four times in the past two weeks, Opportunity has sent error messages
while successfully taking pictures with its microscopic imager. One
theory for the cause is degradation of flexible cabling that runs down
the rover’s robotic arm to the instrument. As a precaution while
undertaking further analysis, the rover team is treating use of the
arm as a consumable resource, with cable wear each time the arm is
moved decreasing the possible number of future microscopic images.

“We are being very conservative about this because we certainly don’t
want to do anything to jeopardize the instruments,” said Dr. Ken
Herkenhoff of the U.S. Geological Survey Astrogeology Team, Flagstaff,
Ariz., lead scientist for both rovers’ microscopic imagers. “We are
running more diagnostics that we hope will identify the problem. There
are potential explanations that would mean we do not have to treat arm
use as a consumable.”

Erickson said, “We will no doubt have more issues with them in the
future. We’ll do everything we can to milk the most value out of them
while they are usable, but they won’t last forever.”
JPL, a division of the California Institute of Technology in Pasadena,
manages the Mars Exploration Rover project for NASA’s Science Mission
Directorate, Washington. Additional information about the project is
available from JPL at and from Cornell
University, Ithaca, N.Y., at .

SpaceRef staff editor.