[meteorite-list] Diagnostic Tests Planned for Instrument on Mars Rover

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Mon Mar 21 13:24:57 2005
Message-ID: <200503160114.j2G1EKo15365_at_zagami.jpl.nasa.gov>

MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIFORNIA 91109. TELEPHONE (818) 354-5011
http://www.jpl.nasa.gov

Guy Webster (818) 354-6278
Jet Propulsion Laboratory, Pasadena, Calif.

Dolores Beasley (202) 358-1753
NASA Headquarters, Washington

News Release: 2005-045 March 15, 2005

Diagnostic Tests Planned for Instrument on Mars Rover

NASA has suspended use of one of the mineral-identifying
tools on the Opportunity Mars rover while experts
troubleshoot a problem with getting data from the
instrument, the robot's miniature thermal emission
spectrometer.

"As always, our first priority is to protect the instrument,
so we have turned it off while we plan diagnostic tests,"
said Jim Erickson of NASA's Jet Propulsion Laboratory,
Pasadena, Calif., project manager for the Mars Exploration
Rover Project. "Opportunity's other instruments are healthy
and providing excellent science, and Spirit's entire
instrument suite is working well and being kept busy by the
science team."

Both Opportunity and Spirit, its twin, have been examining
Mars since January 2004, more than four times as long as
their successful three-month primary missions. While
researchers work to diagnose the spectrometer-data problem
and seek the best way to mend it or work around it,
Opportunity is continuing its journey and observing a crater
called "Vostok." On the other side of the planet,
meanwhile, martian winds have revealed themselves as dust
devils in new images from Spirit and caused mixed effects on
the rover itself, depositing dust on a camera and removing
dust from solar panels.

On March 3 and 4, Opportunity transmitted data sets for 17
successful readings by its miniature thermal emission
spectrometer but also reported that eight other attempted
readings yielded incomplete data sets. This spectrometer,
from high on the rover's mast, observes rocks and other
targets from afar. It measures the infrared radiation they
emit in 167 different wavelengths, providing information
about the targets' composition. Two other types of
spectrometers, mounted on the rover's robotic arm, provide
additional information about composition when the rover is
close enough to touch the target.

Researchers are considering several possible root causes for
the spectrometer-data problem. One possibility is
malfunctioning of an optical switch that tells a mirror in
the instrument when to begin moving. Another is that the
mirror is not properly moving at a constant velocity. "If it
is the optical switch, we could use a redundant one built
into the instrument," said Dr. Phil Christensen of Arizona
State University, Tempe, lead scientist for the miniature
thermal emission spectrometers on both rovers. He added
that, if the root cause cannot be remedied, scientists could
still get useful data from the instrument in its currently
impaired condition.

Even a total loss of the miniature thermal emission
spectrometer would not end the rover's usefulness. In fact,
NASA took a calculated risk by disabling this instrument on
Opportunity 10 months ago, though the current problem
appears unrelated to potential damage anticipated then. At
that time, rover operators began using a "deep sleep"
technique to conserve energy on Opportunity during reduced-
sunshine months of Mars' winter. Turning off power to
overnight heaters let the instrument get cold enough to
possibly damage its beam-splitter. However, the spectrometer
kept working through the coldest months. Christensen said,
"What we're seeing now does not appear to be any problem
with the beam-splitter."

The rover team is not restricting use of Spirit's miniature
thermal emission spectrometer while troubleshooting the
problem on Opportunity.

Spirit's work capabilities grew with a sudden jump in output
from solar panels on March 9, which caused the daily power
supply to double. In a possibly related development three
days earlier, some dust appeared to have blown onto lenses
of Spirit's front hazard-avoidance camera, enough for slight
mottling in images from both the left and right eyes of the
stereo camera, but not enough to affect the usefulness of
the camera. Mottling in left-eye images cleared markedly the
same day the power increased. Team members speculated that
Spirit's power boost, like similar ones on Opportunity in
October, resulted from wind removing some accumulated dust
from solar panels. Spirit captured pictures of dust-lofting
whirlwinds on March 10, adding evidence for windy local
conditions. Images the next day showed solar panels cleaned
of most of their dust buildup.

Opportunity's rear hazard-avoidance camera picked up some
dust contamination three months ago. The dust on it has not
affected operations and has neither decreased nor increased
perceptibly since first noticed. No dust has contaminated
lenses of the navigation cameras or panoramic cameras on
either rover. From all cameras combined, the rovers have
returned more than 72,000 images. Images and other
geological data from Spirit and Opportunity are successfully
providing unprecedented evidence about wet environmental
conditions in Mars' past.

JPL, a division of the California Institute of Technology in
Pasadena, has managed NASA's Mars Exploration Rover project
since it began in 2000. Images and additional information
about the rovers and their discoveries are available on the
Internet at
http://www.nasa.gov/vision/universe/solarsystem/mer_main.html
and http://marsrovers.jpl.nasa.gov .
                              
                            -end-
Received on Tue 15 Mar 2005 08:14:19 PM PST