[meteorite-list] Mars Odyssey Out of Precautionary 'Safe Mode'

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Tue, 19 Jun 2012 16:27:38 -0700 (PDT)
Message-ID: <201206192327.q5JNRcq4023556_at_zagami.jpl.nasa.gov>

http://www.jpl.nasa.gov/news/news.cfm?release=2012-181
  
Orbiter Out of Precautionary 'Safe Mode'
Jet Propulsion Laboratory
June 19, 2012

*Mars Odyssey Mission Status Report*

PASADENA, Calif. -- NASA's Mars Odyssey orbiter has been taken out of a
protective status called safe mode. Remaining steps toward resuming all
normal spacecraft activities will probably be completed by next week.

Odyssey resumed pointing downward toward Mars on Saturday, June 16,
leaving the Earth-pointed "safe mode" status that was triggered when one
of its three primary reaction wheels stuck for a few minutes on June 8,
Universal Time (June 7, Pacific Time). Mission controllers put the
orbiter's spare reaction wheel into use in control of Odyssey's
orientation while pointed downward, or nadir.

"Attitude control in nadir pointing is being maintained with the use of
the replacement wheel, and the suspect wheel has been taken out of use,"
said Odyssey Project Manager Gaylon McSmith of NASA's Jet Propulsion
Laboratory, Pasadena, Calif.

Controllers will continue characterizing the performance of the
replacement wheel in coming days while assessing which other activities
of the spacecraft, besides nadir pointing, can be performed reliably
with reaction-wheel control of attitude. The spacecraft can also use
thrusters for attitude control, though that method draws on the limited
supply of propellant rather than on electricity from the spacecraft's
solar array.

In returning to full service, Odyssey will first resume its
communication relay function for NASA's Mars Exploration Rover
Opportunity, and then will resume the orbiter's own scientific
observations of Mars. As a priority, activities will resume for
preparing Odyssey to serve as a communications relay for NASA Mars
Science Laboratory mission.

Like many other spacecraft, Odyssey uses a set of three reaction wheels
to control its attitude, or which way it is facing relative to the sun,
Earth or Mars. Increasing the rotation rate of a reaction wheel inside
the spacecraft causes the spacecraft itself to rotate in the opposite
direction. The configuration in use from launch in 2001 until three days
ago combined the effects of three wheels at right angles to each other
to provide control in all directions. The replacement wheel is skewed at
angles to all three others so that it could be used as a substitute for
any one of them.

Odyssey has worked at Mars for more than 10 years, which is longer than
any other Mars mission in history. Besides conducting its own scientific
observations, it serves as a communication relay for robots on the
Martian surface. NASA plans to use Odyssey and the newer Mars
Reconnaissance Orbiter as communication relays for the Mars Science
Laboratory mission during the landing and Mars-surface operations of
that mission's Curiosity rover.

Odyssey is managed by NASA's Jet Propulsion Laboratory, Pasadena, for
NASA's Science Mission Directorate in Washington. Lockheed Martin Space
Systems in Denver built the spacecraft. JPL and Lockheed Martin
collaborate on operating the spacecraft. For more about the Mars Odyssey
mission, visit: http://mars.jpl.nasa.gov/odyssey .

Guy Webster 818-354-6278
Jet Propulsion Laboratory, Pasadena, Calif.
guy.webster at jpl.nasa.gov

2012-181
Received on Tue 19 Jun 2012 07:27:38 PM PDT