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 to it.
Endeavour
Crater, 14 miles (22 kilometers) in diameter, is still 7 miles (12 kilometers)
away from Opportunity
as the crow flies, and at least 30 percent farther away on routes mapped for
evading hazards on the plain.
"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,"
said Steve Squyres of Cornell University, and the principal investigator for
the rovers' science instruments. "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."
Opportunity
has already driven about 2 miles (3.2 kilometers) 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 rover project manager John Callas of NASA's
Jet Propulsion Laboratory in Pasadena, Calif. "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 Earth months.
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
also gives Opportunity a chance to rest its right-front wheel, which has been
drawing more electric current than usual, an indication of friction within the
wheel. This strategy has worked in the past.
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.
"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," Callas said.
The new
route to get toward science targets south of Home Plate is to go around the
west side of the plateau, though even it could prove tricky.
"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," Squyres said. "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."
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