Press Release

Opportunity Digs; Spirit Advances

By SpaceRef Editor
February 17, 2004
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Opportunity Digs; Spirit Advances

NASA’s Mars Exploration Rover Opportunity has scooped a
trench with one of its wheels to reveal what is below the
surface of a selected patch of soil.

“Yesterday we dug a nice big hole on Mars,” said Jeffrey
Biesiadecki, a rover planner at NASA’s Jet Propulsion
Laboratory, Pasadena, Calif.

The rover alternately pushed soil forward and backward out of
the trench with its right front wheel while other wheels held
the rover in place. The rover turned slightly between bouts
of digging to widen the hole. “We took a patient, gentle
approach to digging,” Biesiadecki said. The process lasted 22

The resulting trench — the first dug by either Mars
Exploration Rover — is about 50 centimeters (20 inches) long
and 10 centimeters (4 inches) deep. “It came out deeper than
I expected,” said Dr. Rob Sullivan of Cornell University,
Ithaca, N.Y., a science-team member who worked closely with
engineers to plan the digging.

Two features that caught scientists’ attention were the
clotty texture of soil in the upper wall of the trench and
the brightness of soil on the trench floor, Sullivan said.
Researchers look forward to getting more information from
observations of the trench planned during the next two or
three days using the rover’s full set of science instruments.

Opportunity’s twin rover, Spirit, drove 21.6 meters closer to
its target destination of a crater nicknamed “Bonneville”
overnight Monday to Tuesday. It has now rolled a total of
108 meters (354 feet) since leaving its lander 34 days ago,
surpassing the total distance driven by the Mars Pathfinder
mission’s Sojourner rover in 1997.

Spirit has also begun using a transmission rate of 256
kilobits per second, double its previous best, said JPL’s
Richard Cook. Cook became project manager for the Mars
Exploration Rover Project today when the former manager,
Peter Theisinger, switched to manage NASA’s Mars Science
Laboratory Project, in development for a 2009 launch.

Spirit’s drive toward “Bonneville” is based on expectations
that the impact that created the crater “would have
overturned the stratigraphy and exposed it for our viewing
pleasure,” said Dr. Ray Arvidson of Washington University in
St. Louis, deputy principal investigator for the rovers’
science instruments. That stratigraphy, or arrangement of
rock layers, could hold clues to the mission’s overriding
question — whether the past environment in the region of
Mars where Spirit landed was ever persistently wet and
possibly suitable for sustaining life.

Both rovers have returned striking new pictures in recent
days. Microscope images of soil along Spirit’s path reveal
smoothly rounded pebbles. Views from both rovers’ navigation
cameras looking back toward their now-empty landers show the
wheel tracks of the roversí travels since leaving the

Each martian day, or “sol” lasts about 40 minutes longer than
an Earth day. Opportunity begins its 25th sol on Mars at
10:59 p.m. Tuesday, PST. Spirit begins its 46th sol on Mars
at 11:17 a.m. Wednesday, Pacific Standard Time. The two
rovers are halfway around Mars from each other.

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 and from Cornell
University at

SpaceRef staff editor.