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
an excellent position to continue their adventures."
Image above: Opportunity's view near "Vostok Crater," taken on March 8. The larger image is a 360-degree view. Image credit: NASA/JPL
+ 360 view
+ Opportunity's map of southward trek
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
"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
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 rovers' 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 4.9 kilometers (3
miles) -- eight times the original goal. On March 20,
Opportunity also set a new martian record of 220 meters (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
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.
JPL, a division of the California Institute of Technology in
Pasadena, has managed NASA's Mars Exploration Rover project
since it began in 2000. Images and additional information about
the rovers and their discoveries are available on the Internet
Guy Webster (818) 354-6278
NASA's Jet Propulsion Laboratory
Dolores Beasley (202) 358-1753
NASA Headquarters, Washington