June 28, 2007

Dwayne Brown/Tabatha Thompson
Headquarters, Washington
202-358-1726/3895

Guy Webster
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-6278 

RELEASE: 07-146

NASA MARS ROVER READY FOR DESCENT INTO CRATER

WASHINGTON - NASA's Mars rover Opportunity is scheduled to begin a 
descent down a rock-paved slope into the Red Planet's massive 
Victoria Crater. This latest trek carries real risk for the 
long-lived robotic explorer, but NASA and the Mars Rover science team 
expect it to provide valuable science.

Opportunity already has been exploring layered rocks in cliffs around 
Victoria Crater. The team has planned the descent carefully to enable 
an eventual exit, but Opportunity could become trapped inside the 
crater or lose some capabilities. The rover has operated more than 12 
times longer than its originally intended 90 days.

The scientific allure is the chance to examine and investigate the 
compositions and textures of exposed materials in the crater's depths 
for clues about ancient, wet environments. As the rover travels 
farther down the slope, it will be able to examine increasingly older 
rocks in the exposed walls of the crater.

"While we take seriously the uncertainty about whether Opportunity 
will climb back out, the potential value of investigations that 
appear possible inside the crater convinced me to authorize the team 
to move forward into Victoria Crater," said Alan Stern, NASA 
associate administrator, Science Mission Directorate, NASA 
Headquarters, Washington. "It is a calculated risk worth taking, 
particularly because this mission has far exceeded its original 
goals."

The robotic geologist will enter Victoria Crater through an alcove 
named Duck Bay. The eroding crater has a scalloped rim of cliff-like 
promontories, or capes, alternating with more gently sloped alcoves, 
or bays.

A meteor impact millions of years ago excavated Victoria, which lies 
approximately 4 miles south of where Opportunity landed in January 
2004. The impact-created bowl is half a mile across and about five 
times as wide as Endurance Crater, where Opportunity spent more than 
six months exploring in 2004.

The rover began the journey to Victoria from Endurance 30 months ago. 
It reached the rim at Duck Bay nine months ago. Opportunity then 
drove approximately a quarter of the way clockwise around the rim, 
examining rock layers visible in the promontories and possible entry 
routes in the alcoves. Now, the rover has returned to the most 
favorable entry point.

"Duck Bay looks like the best candidate for entry," said John Callas, 
rover project manager, NASA's Jet Propulsion Laboratory, Pasadena, 
Calif. "It has slopes of 15 to 20 degrees and exposed bedrock for 
safe driving."

If all of its six wheels continue working, engineers expect 
Opportunity to be able to climb back out of the crater. However, 
Opportunity's twin rover Spirit lost the use of one wheel more than a 
year ago, diminishing its climbing ability.

"These rovers are well past their design lifetimes, and another wheel 
could fail on either rover at any time," Callas said. "If Opportunity 
were to lose the use of a wheel inside Victoria Crater, it would make 
it very difficult, perhaps impossible, to climb back out."

"We don't want this to be a one-way trip," said Steve Squyres, 
principal investigator for the rovers' science instruments, Cornell 
University, Ithaca, N.Y. "We still have some excellent science 
targets out on the plains that we would like to visit after Victoria. 
But if Opportunity becomes trapped there, it will be worth the 
knowledge gained."

The Jet Propulsion Laboratory manages the Mars Exploration Rover 
project for NASA's Science Mission Directorate.

For more information on the Mars Rovers, visit:

http://www.nasa.gov/rovers 

Visuals describing this decision and the anticipated science can be 
viewed at:

http://www.nasa.gov/mission_pages/mer/070628

	
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