LAKE BUENA
VISTA, Fl. - NASA's Mars rover Opportunity has successfully moved its robotic arm for the first time
in almost two weeks, prompting a series of discussions on the future use of the
automaton's appendage, the mission's manager said Thursday.
Jim
Erickson, project manager NASA's Mars
Exploration Rover (MER) mission, said engineers are going over the
different risks associated with a finicky shoulder motor used to deploy
Opportunity's instrument-laden robotic arm.
The motor
stalled on Nov. 25, fixing the arm in its stowed configuration - tucked close
to Opportunity's undercarriage for drives - and preventing study of a nearby
rock outcrop at the rover's Meridiani Planum landing site.
But rover
handlers managed to move the arm slightly in a Thursday test, Erickson told SPACE.com
after a presentation here at NASA's Risk Management 2005 conference.
The glitch,
a sign of Opportunity's age as it completes its first Martian year (about 687
Earth days) of exploration on Dec. 12, has prompted some talks over the risk of
driving the rover with its arm partially deployed - elbow
out - to ensure continued science operations, though more study is required
before a decision is made, rover managers said.
"Would we
get effective science at this position, what is the risk of doing it, what is
the risk of not doing it," Erickson said of the questions he hopes to discuss.
One
potential trade-off could affect Opportunity's ability to take stereo images of
science targets with its arm-mounted Microscopic Imager camera, rover managers
said. Since there is only one imager on the rover arm, Opportunity builds
stereo views of targets by shifting the camera slightly to the side. With the
shoulder joint locked in a partially deployed position, rover handlers would
have to shift Opportunity itself to generate the images, Erickson said.
Prior to
the January 2003 launch of Opportunity
and its robotic twin Spirit,
engineers did perform some test drives with the rover arm in a partially
deployed position, Erickson said. But before any decision is made for
Opportunity, rover planners will revisit the results of those tests, and likely
conduct new maneuvers, he added.
In order to
move Opportunity's stalled arm, engineers fed a higher voltage through the
coils of wire inside the shoulder motor to move it back and forth, said John
Callas, deputy manager of the rover mission, in a telephone interview.
"The motion
was very small, but it was perceptible," Callas said, adding that more tests
were set for Thursday evening.
A break in
one of the wire coils inside the affected shoulder joint motor appears to be
the source of the glitch, engineers said. Nine coils, or windings, sit inside
the motor, Callas added.
Meanwhile,
Spirit continues to function well at its Gusev Crater landing site, Callas
said.
Spirit,
which launched earlier than Opportunity in 2003, celebrated its first Martian birthday last month.
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