NASA’s Mars rovers are delighting scientists with their
extra credit assignments. Both rovers successfully completed
their primary three-month missions in April.
The Spirit rover is exploring a range of martian hills that
took two months to reach. It is finding curiously eroded
rocks that may be new pieces to the puzzle of the region’s
past. Spirit’s twin, Opportunity, is also negotiating sloped
ground. It is examining exposed rock layers inside a crater
informally named Endurance.
“Both rovers have begun exploring brand new places,” said
Dr. Mark Adler, mission manager at NASA’s Jet Propulsion
Laboratory, Pasadena, Calif. “Opportunity has entered
Endurance Crater. Spirit has arrived at the Columbia Hills.
Both rovers are getting their second wind in bonus time, and
we are very excited about the scientific potential we see at
their new homes. Of course, the terrain at both locations is
challenging, one up and one down. We are making certain that
we proceed safely to keep these wonderful machines as
healthy as we can for as long as we can,” he said.
Spirit began climbing into Columbia Hills late last week,
and right away sent pictures of tantalizing rocks. “Some of
the rocks appear to be disintegrating. They have an odd kind
of rotting appearance, with soft interiors and resistant
rinds or hulls,” said Dr. Larry Soderblom, a rover science-
team member from the U.S. Geological Survey, Flagstaff,
Ariz. “The strangest things we’ve encountered are what we’re
calling hooded cobras, which are evidently the resistant
remnants of some of those rocky rinds. They stand above the
surface like small canopies,” he said.
Another rock, dubbed Pot of Gold, appears to have nodules
and resistant planes in a softer matrix. Scientists have
chosen it as a target for Spirit to examine with the
instruments on the rover’s robotic arm. Afterwards,
controllers plan to send Spirit to an outcrop farther
uphill.
“Although it’s too early to even speculate as to the
processes these rocks have recorded, we are tremendously
excited over the new prospects,” Soderblom said.
The Columbia Hills rise approximately 90 meters (about 300
feet) above a plain Spirit crossed to reach them. Scientists
anticipate a complex blend of rocks in the hills, perhaps
holding evidence about a broader range of environmental
conditions than has been seen in the volcanic rubble
surfacing the plain. The entire area Spirit is exploring is
within Gusev Crater. Orbital images suggest water may have
once flowed into this Connecticut-sized basin.
“Halfway around Mars, Opportunity has driven about five
meters (16 feet) into stadium-sized Endurance Crater. “As we
look back up toward the rim, we can see the progress we’ve
made,” said Scott McLennan, science-team member from the
State University of New York, Stony Brook, N.Y.
Opportunity’s first target inside the crater is a flat-lying
stone about 36 centimeters by 15 centimeters (14 inches by 6
inches) dubbed Tennessee for its shape. Opportunity will
inspect it for analysis with the spectrometers and
microscopic imager on the rover’s robotic arm. It is in a
layer geologists believe corresponds to sulfate-rich rocks.
The rocks are similar to those, in which Opportunity
previously found evidence for a body of water covering the
ground long ago.
“The next step will be to move farther down from this layer
to our first close-up look at a different sedimentary
sequence,” McLennan said. “Color differences suggest at
least three lower, older layers are exposed below
Opportunity’s location,” he said.
“The interpretation of those lower units is in a state of
flux,” he said. “At first, we thought we would encounter
poorly consolidated, sandy material. But as we get closer,
we’re seeing more-consolidated, harder rock deeper into the
crater. If we can get to the lower units, this will be the
first detailed stratigraphic section ever done on another
planet. We’re doing exactly what a field geologist would be
doing,” he said.
Spirit is showing what may be the first sign of age and
wear. “The right front wheel is drawing about two to three
times as much current as the other wheels, and that may be a
symptom of degradation,” Adler said. “There may be steps we
can take to improve it. We’ll be studying that possibility
during the next few weeks,” he said.
JPL, a division of the California Institute of Technology in
Pasadena, Calif., manages the Mars Exploration Rover project
for NASA’s Office of Space Science, Washington. For images
and information about the project on the Internet, visit:
