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View Full Version : Durable Mars Rovers Sent Into Third Overtime Period


April 5th 05, 10:57 PM
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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