Opportunity's Arm in 'Hover-Stow' Position
In January 2006, NASA's Mars Exploration Rover team adopted a new strategy
for carrying Opportunity's robotic arm (the instrument deployment device
with its turret of four tools at the end) when the rover is driving.
On short drives over smooth terrain, Opportunity now holds the arm in a
"hover-stow" position as shown in this image taken by the navigation
camera during the rover's 706th Martian day, or sol (Jan. 18, 2006), with
elbow forward and the tool turret held above the rover deck. (In this
image, the Moessbauer spectrometer is facing upwards, the alpha particle
X-ray spectrometer faces to the right and the rock abrasion tool faces to
the left). On longer or rougher drives, Opportunity still holds the arm in
the original stow position used throughout the mission, tucked underneath
the deck.
During Opportunity's 654th sol (Nov. 25, 2005), symptoms began appearing
that have been diagnosed as a broken wire in the motor windings for the
azimuth actuator at the shoulder joint, a motor that moves the arm from
side to side. The motor still works when given extra current, but the
change in strategy for stowing the arm results from concern that, if the
motor were to completely fail with the arm in the original stow position,
the arm could no longer be unstowed for use. If that motor were to fail
while the arm is in the hover-stow position, the arm could still be
manipulated for full use of the tools on the turret. However, the
hover-stow position gives less protection to the arm during drives.
Concern about protecting the arm during drives led to the compromise
strategy of using hover-stow only during short, smooth drives.
Release Date: 2/2/06
Image Credit: NASA/JPL-Caltech
Reference URL: http://photojournal.jpl.nasa.gov/catalog/PIA02156
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