January 28, 2004 - 4:15 AM

Second Mars rover having problems

By Steve Gorman

LOS ANGELES (Reuters) - As NASA scientists pored over striking new photos from Mars revealing
finely layered formations of ancient bedrock, engineers laboured to diagnose problems with two robotic
rovers on opposite sides of the Red Planet.

Besides a serious malfunction that has idled the first rover, Spirit, since last Wednesday, mission
controllers at NASA's Jet Propulsion Laboratory said they are now contending with a power drain on
Spirit's newly arrived twin, Opportunity.

Mission manager Jim Erickson told reporters on Tuesday the power loss appeared to be from one of
the craft's heating units that keeps turning itself on and running overnight without receiving commands
from NASA to do so.

While engineers do not believe the faulty thermostat will overheat the vehicle, the long-term
consequences of the glitch and whether it can be fixed are not yet known, Erickson said.

"I'd like to have a little more information on what we're seeing from the vehicle before we make any
judgements there," he said.

Otherwise, the rover was "in pretty good shape" as a new martian day, its fourth, dawned over
Opportunity's landing site on a wide, flat plain known as the Meridiani Planum.

The area is of interest to scientists because it is believed to contain large deposits of an iron-bearing
crystalline mineral called hematite, which on Earth usually forms in the presence of liquid water.

Both Opportunity and Spirit are equipped with a mobile laboratory of geologic tools designed to
search for evidence that the barren martian surface was once wetter, and possibly more hospitable to
life, than it is now.

ROCK LAYERS

The first three-dimensional, panoramic images beamed back from Opportunity showed an intriguing
outcrop of exposed bedrock "in exquisite detail," said principal science investigator Steve Squyres of
Cornell University.

The nearby bedrock formation, the first ever found on Mars, consists of fine layers, some no thicker
than a finger, that are believed to be billions of years old, Squyres said. Also visible is a feature believed
to be cross-bedding, in which the mineral layers lie at angles to the horizontal stack, which can form
from cyclical patterns of sediments that build up, then partially erode away, then rebuild again.

"It's going to be fascinating beyond words to get up close" to the bedrock, he said. "We're going to
drive up to this rock outcropping and beat on it with everything we've got."

Andrew Knoll, a science team leader from Harvard University, said the rock layers either originated
from ash spewed by volcanic activity early in Mars' history, or from sediments deposited there by wind
or water. Closer examination should answer those questions, he said.

Opportunity's "high-gain" antenna, the one used for high-speed communications directly with Earth,
has been moved into position, and engineers plan to lift the folded rover off its belly during the day and
stretch out its front wheels, Erickson said.

He added that Opportunity was probably still a week away from being ready to roll off its landing
platform and onto the floor of the small, shallow crater where the spacecraft is resting. Spirit rolled onto
the martian surface 12 days after it landed January 3 in a giant, Connecticut-sized basin known as
Gusev Crater, half a planet away.

SPIRIT STILL IDLE

JPL controllers say they are proceeding cautiously with Opportunity in hopes of avoiding a repeat of
the difficulties that have left Spirit crippled since last week.

Mission manager Jennifer Trosper said engineers are exploring several scenarios for what may have
caused problems with Spirit's onboard computer memory, including an overload from the buildup of data
files during the spacecraft's eight-month voyage to Mars.

Another possibility is a burst of charged particles from a solar flare that could have bombarded the
rover at a vulnerable point during its communications with Earth.