[meteorite-list] MRO Swapping Motion-Sensing Units

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Mon, 12 Aug 2013 09:48:52 -0700 (PDT)
Message-ID: <201308121648.r7CGmqD5002822_at_zagami.jpl.nasa.gov>

http://www.jpl.nasa.gov/news/news.php?release=2013-245

Swapping Motion-Sensing Units
Jet Propulsion Laboratory
August 12, 2013

Mars Reconnaissance Orbiter Mission Status Report

PASADENA, Calif. -- NASA's Mars Reconnaissance Orbiter is switching from
one motion-sensing device to a duplicate unit onboard.

The veteran orbiter relies on this inertial measurement unit (IMU) for
information about changes in orientation. This information is important
for maintaining spacecraft attitude and for pointing the orbiter's large
antenna and science-observation instruments.

The spacecraft has two identical copies of this motion-sensing device,
called IMU-1 and IMU-2. Either of them can be used with either of the
spacecraft's redundant main computers. Each contains three gyroscopes
and three accelerometers.

"The reason we're doing this is that one of the gyroscopes on IMU-1 is
approaching its end of life, so we want to swap to our redundant unit
early enough that we still have some useful life preserved in the first
unit," said Mars Reconnaissance Orbiter Mission Manager Reid Thomas of
NASA's Jet Propulsion Laboratory, Pasadena, Calif.

The orbiter began investigating Mars in 2006. Since completing its
primary science phase in 2008, it has continued to work as an extended
mission.

The swap has been planned for this week, with procedures expected to
take less than two days before the orbiter resumes its normal functions
of science observations from orbit and communication relay for Mars rovers.

"To make sure we have a smooth transition, regaining attitude knowledge
as quickly as possible, we will power off all instruments, do the IMU
swap, maneuver to sun point, do the IMU swap, and then put the
spacecraft into safe mode," Thomas said. "The safe-mode process
re-initializes the spacecraft's knowledge of its attitude."

IMU-2 has been used previously, but IMU-1 has been used much more. After
the swap, IMU-1 will remain available if needed for short periods.

The Mars Reconnaissance Orbiter has provided more data about Mars than
all other earlier and current missions combined. It also relays to Earth
information from both of NASA's active Mars rovers, Opportunity and
Curiosity, sharing that function with the NASA Mars Odyssey orbiter.

JPL, a division of the California Institute of Technology in Pasadena,
manages the Mars Reconnaissance Orbiter for NASA's Science Mission
Directorate, Washington. Lockheed Martin Space Systems, Denver, built
the orbiter and partners in its daily operation.

More information about the Mars Reconnaissance Orbiter is available
online at http://mars.jpl.nasa.gov/mro/ .

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

2013-245
Received on Mon 12 Aug 2013 12:48:52 PM PDT