Another Takes A New, More 'Spirit'-ed Route
On a plain that stretches for miles
in every direction, the panoramic camera on NASA's Mars rover
Opportunity has caught a first glimpse on the horizon of the
uplifted rim of the big crater that has been Opportunity's
long-term destination for six months.
Opportunity's twin, Spirit, also has a challenging destination,
and last week switched to a different route for making
progress.
Endeavour Crater, 22 kilometers (14 miles) in diameter, is still
12 kilometers (7 miles) away from Opportunity as the crow flies,
and at least 30 percent farther away on routes mapped for evading
hazards on the plain. Opportunity has already driven about 3.2
kilometers (2 miles) since it climbed out of Victoria Crater last
August after two years of studying Victoria, which is less than
one-twentieth the size of Endeavour.
"It's exciting to see our destination, even if we can't be
certain whether we'll ever get all the way there," said John Callas
of NASA's Jet Propulsion Laboratory, Pasadena, CA project manager
for the twin Mars rovers, Opportunity and Spirit. "At the pace
we've made since leaving Victoria, the rest of the trek will take
more than a Martian year." A Martian year lasts about 23
months.
Steve Squyres of Cornell University, Ithaca, NY principal
investigator for the rovers' science instruments, said, "We can now
see our landfall on the horizon. It's far away, but we can
anticipate seeing it gradually look larger and larger as we get
closer to Endeavour. We had a similar experience during the early
months of the mission watching the Columbia Hills get bigger in the
images from Spirit as Spirit drove toward them."
Both rovers landed on Mars in January 2004 to begin missions
designed to last for three months. Both are still active after more
than five years.
For the next several days, the rover team plans to have
Opportunity use the tools on its robotic arm to examine soil and
rock at an outcrop along the route the rover is taking toward
Endeavour.
"We're stopping to taste the terrain at intervals along our
route so that we can watch for trends in the composition of the
soil and bedrock," Squyres said. "It's part of systematic
exploration."
The pause for using the tools on the
arm also provides two other benefits. Opportunity's right-front
wheel has been drawing more electric current than usual, an
indication of friction within the wheel. Resting the wheel for a
few days is one strategy that has in the past helped reduce the
amount of current drawn by the motor. Also, on March 7, the rover
did not complete the backwards-driving portion of its commanded
drive due to unanticipated interaction between the day's driving
commands and onboard testing of capabilities for a future drive.
The team is analyzing that interaction before it will resume use of
Opportunity's autonomous-driving capabilities.
Meanwhile, on March 10, the rover team decided to end efforts to
drive Spirit around the northeastern corner of a low plateau called
"Home Plate" in the inner basin of the Columbia Hills, on the other
side of Mars from Opportunity. Spirit has had the use of only five
wheels since its right-front wheel stopped working in 2006.
Consequently, it usually drives backwards, dragging that wheel, so
it can no longer climb steep slopes.
Callas said, "After several attempts to drive up-slope in loose
material to get around the northeast corner of Home Plate, the team
judged that route to be impassable."
The new route to get toward science targets south of Home Plate
is to go around the west side of the plateau.
Squyres said, "The western route is by no means a slam dunk. It
is unexplored territory. There are no rover tracks on that side of
Home Plate like there are on the eastern side. But that also makes
it an appealing place to explore. Every time we've gone someplace
new with Spirit since we got into the hills, we've found
surprises."