Microscope Used on Martian Soil
NASA's Spirit rover
reached out with its versatile robotic arm early Friday and
examined a patch of fine- grained martian soil with a microscope at
the end of the arm. "We made our first use of the arm and took the
first microscopic image of the surface of another planet," said Dr.
Mark Adler, Spirit mission manager at NASA's Jet Propulsion
Laboratory, Pasadena, Calif.
The rover's microscopic imager, one of four tools on a turret at
the end of the arm, serves as the functional equivalent of a field
geologist's hand lens for examining structural details of rocks and
soils.
"I'm elated and relieved at how well things are going. We got
some great images in our first day of using the microscopic imager
on Mars," said Dr. Ken Herkenhoff of the U.S. Geological Survey
Astrogeology Team, Flagstaff, Ariz. Herkenhoff is the lead
scientist for the microscopic imagers on Spirit and on Spirit's
twin Mars Exploration Rover, Opportunity.
The microscope can show features as small as the width of a
human hair. While analysis of today's images from the instrument
has barely begun, Herkenhoff said his first impression is that some
of the tiny particles appear to be stuck together. Before driving
to a selected rock early next week, Spirit will rotate the turret
of tools to use two spectrometer instruments this weekend on the
same patch of soil examined by the microsope, said Jessica
Collisson, mission flight director. The Mossbauer Spectrometer
identifies types of iron-bearing minerals. The Alpha Particle X-ray
Spectrometer identifies the elements in rocks and soils.
The rover's arm is about the same size as a human arm, with
comparable shoulder, elbow and wrist joints. It is "one of the most
dextrous and capable robotic devices ever flown in space," said
JPL's Dr. Eric Baumgartner, lead engineer for the robotic arm,
which also goes by the name "instrument deployment device."
"Best of all," Baumgartner said, "this robotic arm sits on a
rover, and a rover is meant to rove. Spirit will take this arm and
the tremendous science package along with it, and reach out to
investigate the surface."
The wheels Spirit travels on provide other ways to examine Mars'
soil. Details visible in images of the wheel tracks from the
rover's first drive onto the soil give information about the soil's
physical properties.
"Rover tracks are great," said Dr. Rob Sullivan of Cornell
University, Ithaca, N.Y., a member of the science team for Spirit
and Opportunity. "For one thing, they mean we're on the surface of
Mars! We look at them for engineering reasons and for science
reasons." The first tracks show that the wheels did not sink too
deep for driving and that the soil has very small particles that
provide a finely detailed imprint of the wheels, he said.
Opportunity, equipped identically to Spirit, will arrive at Mars
Jan. 25 (Universal Time and EST; 9:05 p.m. Jan. 24, PST). The
amount of dust in the atmosphere over Opportunity's planned landing
site has been declining in recent days, said JPL's Dr. Joy Crisp,
project scientist for the Mars Exploration Rover Project.
On Sunday, Spirit completes its 15th martian day, or "sol", at
its landing site in Gusev Crater. Each sol lasts 39 minutes and 35
seconds longer than an Earth day. The rover project's goal is for
Spirit and Opportunity to explore the areas around their landing
sites for clues in the rocks and the soil about whether the past
environments there were ever watery and possibly suitable for
sustaining life.