Mars Odyssey Mission Status 17 Jan 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.