NASA Mars Exploration Rover Mission Status 11 November 2004

Operators of NASA’s Mars Exploration Rover Opportunity have determined
that a proposed route eastward out of "Endurance Crater" is not
passable, so the rover will backtrack to leave the crater by a southward
route, perhaps by retracing its entry path.

"We’ve done a careful analysis of the ground in front of Opportunity and
decided to turn around," said Jim Erickson, rover project manager at
NASA’s Jet Propulsion Laboratory, Pasadena, Calif. "To the right, the
slope is too steep — more than 30 degrees. To the left, there are sandy
areas we can’t be sure we could get across."

Before turning around, Opportunity will spend a few days examining the
rock layers in scarp about 10 meters (33 feet) high, dubbed "Burns
Cliff." From its location at the western foot of the cliff, the rover
will use its panoramic camera and miniature thermal emission
spectrometer to collect information from which scientists hope to
determine whether some of the layers were deposited by wind, rather than
by water. The rover will not reach an area about 15 meters (50 feet)
farther east where two layers at different angles meet at the base of
the cliff.

"We have pushed the vehicle right to the edge of its capabilities, and
we’ve finally reached a spot where we may be able to answer questions
we’ve been asking about this site for months," said Dr. Steve Squyres,
rover principal investigator at Cornell University, Ithaca, N.Y. "But
after we’re done here, it’ll be time to turn around. Going any farther
could cut off our line of retreat from the crater, and that’s not
something anybody on the team wants to do."

Opportunity entered the stadium-size crater on June 8 at a site called
"Karatepe" along the crater’s southern rim. Inside the crater, it has
found and examined multiple layers of rocks that show evidence of a wet
environment in the area’s distant past.

Opportunity and its twin, Spirit, successfully completed their primary
three-month missions on Mars in April. NASA has extended their missions
twice, most recently on Oct. 1, because the rovers have remained in good
condition to continue exploring Mars longer than anticipated.

Engineers have finished troubleshooting an indication of a problem with
steering brakes on Spirit. The brakes are designed to keep the rover
wheels from being bumped off course while driving. Spirit has
intermittently sent information in recent weeks that the brakes on two
wheels were not releasing properly when the rover received commands to
set a new course. Testing and analysis indicate that the mechanism for
detecting whether the brakes are released is probably sending a false
indication. The rover team will disregard that signal and presume the
brakes have actually released properly when commanded to do so. This
anomaly has not been observed on the Opportunity rover.

"We’re going back to using the full steering capabilities of Spirit,"
Erickson said.

JPL, a division of the California Institute of Technology in Pasadena,
manages the Mars Exploration Rover project for NASA’s Science Mission
Directorate, Washington, D.C. Additional information about the project
is available from JPL at http://marsrovers.jpl.nasa.gov/ and from
Cornell University, Ithaca, N.Y., at http://athena.cornell.edu.