Mars Odyssey Mission Status
January 17, 2002
NASA's Mars Odyssey spacecraft completed two maneuvers this
week, fine-tuning its orbit in preparation for the science mapping
mission that will begin in late February.
At 2 p.m. Pacific Time, January 17, Odyssey reduced the
farthest point in its orbit, called the apoapsis, from an altitude of
520 kilometers (323 miles) to an altitude of 450 kilometers
(280 miles). The spacecraft fired its thrusters for 195 seconds, and
decreased the velocity of the spacecraft by 27 meters per second
(60 miles per hour). This maneuver also moved the closest point of
the orbit, called the periapsis, under the south pole of the planet.
Earlier this week, on January 15, Odyssey fired its thrusters
for 398 seconds, increasing its speed by 56 meters per second
(125 miles per hour) and raising the closest point in its orbit from
186 kilometers (116 miles) to 419 kilometers (260 miles). Flight
controllers also changed the inclination of the orbit, the angle
between the orbit plane and the Mars equator, to 93.1 degrees.
"Aside from the orbit insertion burn in October, these are
the largest maneuvers that we have executed and they help us
circularize the orbit. They were also the most complex to design
and implement," said Bob Mase, Odyssey's lead navigator at
NASA's Jet Propulsion Laboratory, Pasadena, Calif. "These
burns had to be executed at specific times to achieve the desired
results, so the flight team had a lot of work to do in a very short
amount of time. The maneuver performance was excellent."
During the next few weeks, flight controllers will continue to
refine the orbit to achieve a final mapping orbit with a periapsis
altitude of 387 kilometers (240 miles) and apoapsis altitude of
450 kilometers (280 miles).
Also this week, engineers turned on the neutron spectrometer,
the high-energy neutron detector and a portion of the gamma ray
spectrometer subsystem. These science instruments are working as
expected. The formal mapping mission will begin next month.
JPL manages the 2001 Mars Odyssey mission for NASA's Office
of Space Science, Washington, D.C. Principal investigators at
Arizona State University in Tempe, the University of Arizona in
Tucson, and NASA's Johnson Space Center, Houston, Texas, operate
the science instruments. Additional science investigators are
located at the Russian Space Research Institute and Los Alamos
National Laboratories, N.M. Lockheed Martin Astronautics,
Denver, Colo., is the prime contractor for the project, and
developed and built the orbiter. Mission operations are conducted
jointly from Lockheed Martin and from JPL, a division of the
California Institute of Technology in Pasadena. NASA's Langley
Research Center in Hampton, Va., is providing aerobraking support
to JPL's navigation team during mission operations.
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