[meteorite-list] NASA's Opportunity Rover Flexes Robotic Arm

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Wed Dec 14 15:53:06 2005
Message-ID: <200512142051.jBEKpW415944_at_zagami.jpl.nasa.gov>


NASA's Opportunity Rover Flexes Robotic Arm
By Tariq Malik
14 December 2005

NASA's Mars rover Opportunity has sucessfully reached out toward a
Martian rock with its robotic arm, overcoming a motor glitch that
prevented deployment last month.

Opportunity unstowed its instrument-laden robotic arm Tuesday, aiming
the multi-jointed appendage straight ahead towards a rock outcrop
jutting from a crater at its Meridiani Planum landing site, the
mission's project manager said.

"It went fine - we successfully put an instrument on the rock," Jim
Erickson, project manager for the Mars Exploration Rover mission
at NASA's Jet Propulsion Laboratory (JPL), told SPACE.com. "The team
did a great job but we've got more work to do."

Stalled science

Opportunity's robotic arm - which carries four instruments designed to
photograph, brush, grind and determine the composition of Martian rocks -
stalled in its stowed position on Nov. 25, preventing active study of the
nearby outcrop at its Erebus Crater location. A problematic shoulder joint
motor, which swings the arm out from its stowed position tucked under the
rover, appeared to be the cause.

"We were fearful for a time that the motor may have failed permanently,"
said Steve Squyres, principal investigator for the rover mission at
Cornell University, during a Dec. 12 discussion at the American Museum
of Natural History in New York City. "If that were the case, we'd never
be able to use the arm again."

But on Dec. 8, rover engineers managed to move the arm
slightly. The motor glitch appears to be the result of a broken wire in
one of nine windings - or coils - inside the shoulder joint, Erickson
said. By applying a higher voltage than normal to the windings, the
joint moved, he added.

"We're developing a mode for keeping the arm out in front," Erickson
said, adding that engineers are now studying various positions in which
to stow the arm and ensure its continued use as a science tool. "We'll
essentially stow it now by putting the instrument pack up over the
rover's deck."

Erickson said more analysis and arm motor tests are planned in order to
determine the best configuration for the arm during drives.

Martian year milestone

Like its robotic twin Spirit, which is currently descending Husband Hill
in Mars' Gusev Crater and heading toward a target dubbed "Home Plate,"
Opportunity has spent more than one entire Martian year - about 687 Earth
days, or 670 Martian sols - exploring the red planet. Opportunity's red
planet anniversary occurred on Dec. 12 and set a new milestone for the
Mars rover expedition, which had a primary mission that originally spanned
just 90 Martian days.

"I used to think that dust on our solar arrays was going to be the limit
for these rovers, I don't think that anymore," Squyres said. "I think,
instead, that something is going to break. We have a lot of moving parts
and electrical parts on these rovers."

Squyres added that the success of Spirit and Opportunity has changed the
way he looks at Mars.

"[Before launch] it just seemed impossibly far away, it seemed
unreachable," Squyres said of the red planet. "Tonight, I go out knowing
our rovers have been there a whole Martian year - it's a much more
familiar planet. We know the place."
Received on Wed 14 Dec 2005 03:51:31 PM PST

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