NASA’s Spirit has returned to full health and resumed doing things
never attempted on Mars before.

“Our patient is healed, and we’re very excited about that,” said
Jennifer Trosper of NASA’s Jet Propulsion Laboratory, Pasadena,
Calif., mission manager for Spirit.

Spirit temporarily stopped communicating Jan. 22; the problem was
later diagnosed as a memory-management issue. Engineers regained
partial control of the spacecraft within days and reformatted Spirit’s
flash memory Wednesday to prevent recurrence of the problem.

JPL’s Glenn Reeves, flight software architect for the Mars Exploration
Rovers, said Friday,
“We’re confident we know what the problem is, and we have a procedure
in place we believe can work around this problem indefinitely.”

Spirit’s first day of science operations after the memory reformatting
featured the first brushing of a rock on a foreign planet to remove
dust and allow inspection of the rock’s cleaned surface. Steel
bristles on the rover’s rock abrasion tool cleaned a circular patch on
the rock unofficially named Adirondack. The tool’s main function is to
grind off the weathered surface of rocks with diamond teeth, but the
brush for removing the grinder’s cuttings can also be used to sweep
dust off the intact surface.

The brushing on Thursday was the first use of a rock abrasion tool by
either Spirit or its twin rover, Opportunity. The brush swirled for
five minutes, said Stephen Gorevan of Honeybee Robotics, New York,
lead scientist for the rock abrasion tools on both rovers.

“I didn’t expect much of a difference. This is a big surprise,”
Gorevan said about a picture showing the brushed area is much darker
than the rest of the rock’s surface. “Ladies and gentlemen, I present
you the greatest interplanetary brushing of all time.”

One reason scientists first selected Adirondack for close inspection
is because it appeared relatively dust free compared to some other
rocks nearby. “To our surprise, there was quite a bit of dust on the
surface,” said Dr. Ken Herkenhoff of the U.S. Geological Survey’s
Astrogeology Team, Flagstaff, Ariz., lead scientist for the rovers’
microscopic imagers.

Spirit was instructed Friday afternoon to grind the surface of
Adirondack with the rock abrasion tool. After the grinding, the turret
of tools at the end of the rover’s robotic arm will be rotated to
inspect the freshly exposed interior of the rock. Controllers plan to
tell Spirit tomorrow to begin driving again.

Meanwhile, halfway around Mars, NASA’s Opportunity drove early Friday
for the second day in a row. It arrived within about a half a meter
(20 inches) of the northeastern end of a rock outcrop scientists are
eager for the rover to examine. “We expect to complete that approach
tomorrow,” said JPL’s Matt Wallace, mission manager for Opportunity.

During Friday’s drive, Opportunity did not travel as far as planned.
The rover is climbing a slope of about 13 degrees, and the shortage in
distance traveled is probably due to slippage in the soil, Wallace

The main task for both rovers is to explore the areas around their
landing sites for evidence in rocks and soils about whether those
areas ever had environments that were watery and possibly suitable for
sustaining life.

Each martian day, or “sol,” lasts about 40 minutes longer than an
Earth day. Spirit begins its 35th sol on Mars at 4:02 a.m. Saturday,
Pacific Standard Time. Opportunity begins its 15th sol on Mars at
4:23 p.m. Saturday, PST.