Mars Odyssey Mission Status 17 Sep 2001

NASA’s 2001 Mars Odyssey spacecraft performed its third
trajectory correction maneuver last night to fine-tune its
flight path for arrival at Mars next month.

At 4:06 a.m. Universal time on Monday, Sept. 17 (9:06
p.m. Pacific time, Sunday, Sept. 16), Odyssey fired its small
thrusters for 12 seconds, which changed the speed and
direction of the spacecraft by .45 meters per second (1 mile
per hour). Odyssey will arrive at Mars at 0230 Universal time
Oct. 24 (7:30 p.m. Pacific time Oct. 23).

“This was the first maneuver to target our final aim
point for Mars orbit insertion. Early indications are that
the maneuver was right on the money,” said David A. Spencer,
Odyssey’s mission manager at NASA’s Jet Propulsion Laboratory,
Pasadena, Calif.

During the past several weeks, the flight team has been
troubleshooting occasional problems with its star camera.
Flight controllers use the star camera to determine Odyssey’s
orientation in space. During most of cruise, the star camera
has been shaded from the sun by the high gain antenna. When
the spacecraft has been rotated so that the star camera is no
longer shaded, the images from the star camera have been
saturated by sunlight. An internal shade within the star
camera is supposed to prevent image saturation. Engineers
determined that part of the problem was reflected light from
the open door of the gamma ray spectrometer instrument. The
door was closed on August 31. A subsequent checkout of the
planned spacecraft orientations for the rest of the mission
showed that the star camera should provide valid images during
these critical periods.

Also on August 31, the flight team transitioned the
spacecraft to a new orientation for the remainder of its
cruise. The new orientation is designed to limit the number
of times Odyssey needs to fire its small thrusters to de-spin
the reaction wheels as they build up momentum.

On September 6, the flight team performed a checkout of
the spacecraft telecommunications subsystem for Mars orbit
insertion. During the checkout, the spacecraft was turned to
the planned orientation for the large burn, and the radio
signal from the spacecraft was monitored. All systems
performed as expected.

Today, Odyssey is 10.8 million kilometers (6.7 million
miles) from Mars, traveling at a speed of 24 kilometers per
second (52,700 miles per hour) relative to the Sun.

The 2001 Mars Odyssey mission is managed by JPL for
NASA’s Office of Space Science, Washington, D.C. JPL is a
division of the California Institute of Technology in
Pasadena. The Odyssey spacecraft was built by Lockheed Martin
Astronautics, Denver. The thermal emission imaging system is
managed by Arizona State University, Tempe, and the gamma ray
spectrometer is managed by the University of Arizona, Tucson.
NASA’s Johnson Space Center, Houston, built and manages the
Martian radiation environment experiment. The thermal emission
imaging system is managed by Arizona State University, Tempe,
and the gamma ray spectrometer is managed by the University of
Arizona, Tucson