New pictures from NASA’s Mars Exploration Rover Opportunity reveal
thin layers in rocks just a stone’s throw from the lander platform
where the rover temporarily sits.

Geologists said that the layers — some no thicker than a finger —
indicate the rocks likely originated either from sediments carried by
water or wind, or from falling volcanic ash. "We should be able to
distinguish between those two hypotheses," said Dr. Andrew Knoll of
Harvard University, Cambridge, a member of the science team for
Opportunity and its twin, Spirit. If the rocks are sedimentary, water
is a more likely source than wind, he said.

The prime goal for both rovers is to explore their landing areas for
clues in the rocks and soil about whether those areas ever had watery
environments that could possibly have sustained life.

Controllers at NASA’s Jet Propulsion Laboratory, Pasadena, Calif.,
plan to tell Opportunity tonight to start standing up from the
crouched and folded posture in which it traveled to Mars.

"We’re going to lift the entire rover, then the front wheels will be
turned out," said Mission Manager Jim Erickson of JPL. Several more
days of activities are still ahead before the rover will be ready to
drive off the lander.

"We’re about to embark on what could be the coolest geological field
trip in history," said Dr. Steve Sqyures of Cornell University,
Ithaca, N.Y., principal investigator for the rovers’ science payload.

The layered rocks are in a bedrock outcrop about 30 to 45 centimeters
(12 to 18 inches) tall, and only about eight meters (26 feet) away
from where Opportunity came to rest after bouncing to a landing three
days ago. Examination of their texture and composition with the
cameras and spectrometers on the rover may soon reveal whether they
are sedimentary, Knoll predicted.

Scientists also hope to determine the relationship between those
light-colored rocks and the dark soil that covers most of the
surrounding terrain. The soil may contain the mineral hematite, which
was identified from orbit and motivated the choice of Opportunity’s
landing area, Squyres said.

Opportunity successfully used its high-gain antenna for the first time
yesterday. The rover is losing some if its battery charge each night,
apparently due to an electric heater at the shoulder joint of the
rover’s robotic arm. A thermostat turns on the heater whenever the
air temperature falls to levels that Opportunity is experiencing every
night. The heater is not really needed when the arm is not in use, but
ground control has not been able to activate a switch designed to
override the thermostat, Erickson said. Mission engineers are working
to confirm the diagnosis, determine the ramifications of the power
drain, and propose workarounds or fixes.

Meanwhile, engineers working on Spirit have determined that the
high-gain antenna on that rover is likely in working order despite
earlier indications of a possible problem. They are continuing to
take information out of Spirit’s flash memory. Results from a testbed
simulator of the rover’s electronics supported the diagnosis of a
problem with management of the flash memory, reported JPL’s Jennifer
Trosper, mission manager.

JPL, a division of the California Institute of Technology in Pasadena,
manages the Mars Exploration Rover project for NASA’s Office of Space
Science, Washington, D.C. Images and additional information about the
project are available from JPL at

and from Cornell University at .