Opportunity vicino a "Victoria Bowl"

Sept. 6, 2006

Dwayne Brown/Erica Hupp
Headquarters, Washington

Guy Webster
Jet Propulsion Laboratory, Pasadena, Calif.

RELEASE: 06-307


NASA’s Mars rover Opportunity is closing in on what may be the
grandest overlook and richest science trove of its long mission.

During the next two weeks, the robotic geologist is likely to reach
the rim of a hole in the Martian surface wider and deeper than any it
has visited. The crater, known as “Victoria,” is approximately
one-half mile wide and 230 feet deep.

Images from NASA’s Mars Global Surveyor orbiter show the crater walls
expose a stack of rock layers approximately 100 to 130 feet thick.
Opportunity will send back its initial view into the crater as soon
as it gets to the rim. Scientists and engineers will use
Opportunity’s observations from points around the rim to plot the
best route for entering the crater.

“Victoria has been our destination for more than half the mission,”
said Ray Arvidson of Washington University, St. Louis. Arvidson is
deputy principal investigator for Opportunity and its twin rover,
Spirit. “Examination of the rocks exposed in the walls of the crater
will greatly increase our understanding of past conditions on Mars
and the role of water. In particular, we are very interested in
whether the rocks continue to show evidence for having been formed in
shallow lakes.”

The NASA rovers have been exploring landscapes on opposite sides of
Mars since January 2003. Their prime missions lasted three months.
Both are still investigating Mars’ rocks, soils and atmosphere after
more than 30 months. Opportunity works in a region where rock layers
hundreds of yards in thickness cover older, heavily cratered terrain.

“We have a fully functional vehicle with all the instruments working.
We’re ready to hit Victoria with everything we’ve got,” said Byron
Jones, a rover mission manager at NASA’s Jet Propulsion Laboratory,
Pasadena, Calif.

Though it’s still winter in Mars’ southern hemisphere, days have begun
getting longer again, and Opportunity’s power supply from its solar
panels is increasing daily. During its first two months on Mars,
Opportunity examined a one-foot stack of rock layers at its landing
site inside “Eagle Crater” and found geological evidence that water
had flowed across the surface long ago.

The rover spent the next nine months driving to and exploring a larger
crater, “Endurance.” There it examined a stack of exposed layers 23
feet thick. Over the drive from Endurance to Victoria, the rocks tell
a history of shallow lakes, drier periods of shifting dunes and
groundwater levels that rose and fell. Minerals indicate the ancient
water was very acidic.

The much thicker stack of revealed rock layers at Victoria beckons.
Arvidson said, “We want to examine the thick section of rocks exposed
on the walls in Victoria crater to understand whether the environment
that produced these materials was similar to the environment recorded
in the rocks that we have seen so far. Is there a record of a
different type of deposition? Was there a wet environment that was
less acidic, perhaps even more habitable? Where do the layers from
Endurance fit in this thicker sequence?”

NASA’s Mars Reconnaissance Orbiter reached Mars in March 2006. It will
begin its primary science phase in November, offering higher
resolution images and mineral mapping than have been possible with
previous orbiters.

Victoria will be one target for the orbiter. “By combining the data
from Opportunity and Mars Reconnaissance Orbiter, we’ll be able to do
some fantastic coordinated analysis,” Arvidson said. Such analysis
will enhance the science return of both missions and aid in
interpreting orbiter data taken of potential landing sites for future
missions elsewhere on Mars.

“It’s an amazing accomplishment that Spirit and Opportunity have
completed the equivalent of 10 prime missions,” said John Callas,
rover project manager at JPL. “Each of them shows some signs of
aging, though. We can’t say how long the rovers will last, but we
will push to get the best possible science out of these national
treasures as long as they keep operating. Victoria could very well be
the most productive and exciting science of the entire mission.”

JPL manages the rovers and the Mars Reconnaissance Orbiter for NASA’s
Science Mission Directorate. For rover images and information, visit: