Healthy Spirit Cleans a Mars Rock; Opportunity Rolls
February 6, 2004
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 said.
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.
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
http://marsrovers.jpl.nasa.gov and from Cornell
University at http://athena.cornell.edu.
