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ZL2VAL > ROVERS 06.10.04 10:53l 74 Lines 3313 Bytes #999 (0) @ WW
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Subj: Press release, 5th October
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Sent: 041006/0908Z @:ZL2AB.#46.NZL.OC #:49166 [New Plymouth] FBB7.00g
From: ZL2VAL@ZL2AB.#46.NZL.OC
To : ROVERS@WW
JPL Press Release
October 05, 2004
Team Checks Rover's Steering
Engineers on NASA's Mars Exploration Rover team are investigating
possible causes and remedies for a problem affecting the steering on
Spirit.
The relay for steering actuators on Spirit's right-front and left-rear
wheels did not operate as commanded on Oct. 1. Each of the front and
rear wheels on the rover has a steering actuator, or motor, that adjusts
the direction in which the wheels are headed independently from the
motor that makes the wheels roll. When the actuators are not in use,
electric relays are closed and the motor acts as a brake to prevent
unintended changes in direction.
Engineers received results from Spirit today from a first set of
diagnostic tests on the relay. "We are interpreting the data and
planning additional tests," said Rick Welch, rover mission manager at
NASA's Jet Propulsion Laboratory, Pasadena, Calif. "We hope to determine
the best work-around if the problem does persist."
Spirit and its twin, Opportunity, successfully completed their
three-month primary missions in April and five-month mission extensions
in September. They began second extensions of their missions on Oct. 1.
Spirit has driven more than 3.6 kilometers (2.2 miles), six times the
distance set as a goal for mission success. It is climbing into uplands
called the "Columbia Hills."
JPL's Jim Erickson, rover project manager, said, "If we do not identify
other remedies, the brakes could be released by a command to blow the
fuse controlling the relay, though that would make those two brakes
unavailable for the rest of the mission." Without the steering-actuator
brakes, small bumps or dips that a wheel hits during a drive might twist
the wheel away from the intended drive direction.
"If we do need to disable the brakes, errors in drive direction could
increase. However, the errors might be minimized by continuing to use
the brakes on the left-front and right-rear wheels, by driving in
smaller segments, and by adding a software patch to reset the direction
periodically during a drive," Erickson said. Engineers believe the
steering-brake issue is not related to excessive friction detected
during the summer in the drive motor for Spirit's right-front wheel,
because the steering actuator is a different motor.
Meanwhile, the team continues to use Spirit's robotic arm and camera
mast to study rocks and soils around the rover, without moving the
vehicle until the cause of the anomaly is understood and corrective
measures can be implemented.
JPL, a division of the California Institute of Technology in Pasadena,
manages the Mars Exploration Rover project for NASA's Science Mission
Directorate, Washington. Additional information about the project is
available from JPL at http://marsrovers.jpl.nasa.gov and from Cornell
University, Ithaca, N.Y., at http://athena.cornell.edu
73, Alan, ZL2VAL @ ZL2AB.#46.NZL.OC (Sysop)
IP: zl2val@qsl.net
APRS: 3906.34s/17406.45e]
Message timed: 21:55 on 06-Oct-2004
Message sent using WinPack-AGW V6.80, by Roger Barker G4IDE, SK 9/9/04.
Zen Wisdom
----------
Do not walk behind me, for I may not lead. Do not walk ahead of me, for I
may not follow. Do not walk beside me, either. Just pretty much leave me
alone.
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