NASA’s Spirit rover reached out with its versatile robotic arm early
today 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 MĖ†ssbauer 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.

Today, Spirit completes its 13th 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.

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. Pictures and additional information about
the project are available from JPL at

http://marsrovers.jpl.nasa.gov

and from Cornell University, Ithaca, N.Y., at

http://athena.cornell.edu/ .