[meteorite-list] Durable Mars Rovers Sent Into Third Overtime Period

[Ron Baalke]

Dolores Beasley                                
Headquarters, Washington                  April 5, 2005
(Phone: 202/358-1753)

Guy Webster
Jet Propulsion Laboratory, Pasadena, Calif.
(Phone: 818/354-6278)

RELEASE: 05-091

DURABLE MARS ROVERS SENT INTO THIRD OVERTIME PERIOD

NASA has approved up to 18 more months of operations for Spirit and 
Opportunity, the twin Mars rovers that have already surprised engineers and 
scientists by continuing active exploration for more than 14 months.

"The rovers have proven their value with major discoveries about ancient watery 
environments on Mars that might have harbored life," said Dr. Ghassem Asrar, 
deputy associate administrator for NASA's Science Mission Directorate. "We are 
extending their mission through September 2006 to take advantage of having such 
capable resources still healthy and in excellent position to continue their 
adventures."

The rovers have already completed 11 months of extensions on top of their 
successful three-month prime missions. "We now have to make long-term plans for 
the vehicles because they may be around for quite a while," said Jim Erickson, 
rover project manager at NASA's Jet Propulsion Laboratory, Pasadena, Calif. 

Erickson cautioned though, "Either mission could end tomorrow with a random part 
failure. With the rovers already performing well beyond their original design 
lifetimes, having a part wear out and disable a rover is a distinct possibility 
at any time. But right now, both rovers are in amazingly good shape. We're going 
to work them hard to get as much benefit from them as we can, for as long as they 
are capable of producing worthwhile science results."

"Spirit and Opportunity are approaching targets that a year ago seemed well out 
of reach," said Doug McCuistion, director of NASA's Mars Exploration Program. 
"Their successes strengthen NASA's commitment to a vision with the ambitious 
targets of returning samples from Mars and sending human explorers to Mars."

Opportunity is within a few football fields' length of a region called "Etched 
Terrain," where scientists hope to find rocks exposed by gentle wind erosion 
rather than by disruptive cratering impacts, and rocks from a different time in 
Mars' history than any examined so far.

"This is a journey into the unknown, to something completely new," said Dr. Steve 
Squyres of Cornell University, Ithaca, N.Y., principal investigator for the 
rover's science instruments.

To reach the Etched Terrain, rover planners have been pushing the rover fast. 
Opportunity has overtaken Spirit in total distance driven. It has rolled more 
than three miles -- eight times the original goal. On March 20, Opportunity also 
set a new martian record of 722 feet in a single day's drive. Drive-distance 
estimates can vary by a few percent. The long drives take advantage of crossing a 
plain so smooth it's "like an East Coast beach," said JPL's Jeff Favretto, 
mission manager on the Opportunity shift in recent weeks. Also, Opportunity's 
solar panels, though now dustier than Spirit's, still generate enough power to 
allow driving for more than three hours on some days.

Spirit is in much rougher terrain than Opportunity, climbing a rocky slope toward 
the top of "Husband Hill." However, with a boost in power from wind cleaning its 
solar panels on March 9 and with its formerly balky right-front wheel now working 
normally, Spirit made some longer one-day drives last week than it had for 
months. "We've doubled our power," said JPL's Emily Eelkema, mission manager. "It 
has given us extra hours of operations every day, so we can drive longer and 
we've used more time for observations." 

The jump in power output has taken some urgency out of Spirit's southward climb. 
With Mars now beginning southern-hemisphere spring, the sun is farther south in 
the sky each day. If not for panel-cleaning, Spirit might be facing the prospect 
of becoming critically short of power if still on the north-facing slope by early 
June. 

"We still want to get to the summit of Husband Hill and then head down into the 
'Inner Basin' on the other side," Squyres said. "But now we have more flexibility 
in how we carry out the plan. Before, it was climb or die." Cresting the hill is 
now not as crucial for solar energy, but it still offers allures of potential 
exposures of rock layers not yet examined, plus a vista of surrounding terrain. 
In orbital images, the Inner Basin farther south appears to have terracing that 
hints of layered rock.

Both rovers do have some signs of wear and exposure. Spirit's rock abrasion tool 
shows indications that its grinding teeth might be worn away after exposing the 
interiors of five times more rock targets than its design goal of three rocks. 
Researchers probably won't know the extent of wear until Spirit's next rock-
grinding attempt, which may be weeks away. Also, troubleshooting continues for 
determining whether Opportunity's miniature thermal emission spectrometer is 
still usable despite tests indicating a problem last month. All other instruments 
on both rovers are still working normally.

For more information about the rovers and their discoveries on the Internet, 
visit:

http://www.nasa.gov/vision/universe/solarsystem/mer_main.html

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