After
nearly a year rolling around inside an expansive crater on Mars, NASA's trusty
rover Opportunity is headed back out to explore the Martian plains.
"The rover
is back on flat ground," said Paolo Belluta, engineer and rover driver at NASA's
Jet Propulsion Laboratory in Pasadena, Calif.
The golf
cart-sized Opportunity climbed up and out of half-mile (800-meter) wide Victoria
Crater on Mars late Thursday with one last 22-foot (6.8-meter) push that sent it
charging over the top of the crater's rim and through a sand ripple on the
other side. The maneuver brought to an end Opportunity's studies of Victoria,
which began in September 2007 when the rover made its first foray into the
crater.
"We're
headed to the next adventure out on the plains of Meridiani," said John Callas,
NASA's rover project manager for Opportunity and its robotic twin Spirit on the
other side of Mars. "We safely got into the crater, we completed our exploration
there and we safely got out."
Opportunity
and Spirit have been exploring different parts of Mars since they landed in
January 2004. Since then, the rovers have found evidence that water once soaked
the Martian terrain in the ancient past among
their other discoveries.
But
Victoria Crater, a deep depression blasted into the Martian surface with
exposed bedrock that serves as a window into planet's geological history, has
dominated Opportunity's attention. The rover spent more than half of the four
years since it landed on Mars studying the giant crater.
Opportunity
first headed for Victoria in late 2004 after visiting a smaller, stadium-sized crater,
dubbed Endurance, earlier that year. The rover took 22 months to cross the few
miles between Endurance and Victoria, and managed to escape
a deep sand dune that held it fast for five weeks before engineers were
able to work it back out.
After
arriving at Victoria, Opportunity spent a year meticulously circling partway
around the crater's rim to find the best spot to drive into its interior. The rover
spent so long at Victoria that NASA's Mars Reconnaissance Orbiter circling the
red planet managed to catch its path around the massive crater.
Opportunity's
handlers decided last month to order the rover to leave Victoria Crater after
spotting a power spike in the automaton's left front wheel. The rover
steadfastly backtracked along its entry path to get back out, mission managers
said.
"We were
concerned that any wheel failure on our aging rover could have left us trapped
inside the crater," Callas said.
A similar
spike preceded the full-blown failure of wheel on the Spirit rover in 2006. Spirit
is currently building a full-color panorama photograph as it awaits better
sunlight conditions for is solar panels at its "Home Plate" location on Mars,
mission managers said.
A third
NASA spacecraft, the Phoenix Mars Lander, also hit a
milestone this week. The stationary probe surpassed its initial 90-day
mission earlier this week and began extended operations while digging for
buried Martian ice in the planet's arctic circle.
Since
landing, Opportunity has spent 1,635 days exploring Mars and traversed more
than 7 miles (11 km) of Martian terrain during its mission.
The rover
is now poised to begin hunting new targets: chunks of Mars rocks called cobbles
that lie strewn across the red planet's surface. Researchers believe the
cobbles, which are about the size of a human fist and larger, are chunks of
material ejected from impacts that caused craters that are too far away from
Opportunity to be fully explored.
"Our experience tells us there's lots of diversity
among the cobbles," said rover mission planner Scott McLennan of the State
University of New York, Stony Brook. "We want to get a better
characterization of them. A statistical sampling from examining more of them
will be important for understanding the geology of the area."
advertisement
