Flight controllers of NASA's 2001 Mars Odyssey mission report that the aerobraking phase is proceeding right on schedule and should be completed in early January. During the aerobraking phase of the mission, the spacecraft is controlled so it skims the upper reaches of the martian atmosphere on each orbit, to reduce the vehicle's speed.

An artist's concept of Odyssey aerobraking in the Martian atmosphere. Image: NASA/JPL

As of Thursday, Odyssey's orbital period was three hours and 15 minutes, compared with the initial 18-and-a-half hours when the spacecraft first entered orbit in October. The orbital period is the time required to complete one revolution around the planet.

"We plan to perform a maneuver to raise the spacecraft up out of the atmosphere in early January. After that it will take about a month for us to circularize the orbit using our onboard thrusters and then prepare to start the science mission," said David A. Spencer, Odyssey's mission manager at NASA's Jet Propulsion Laboratory, Pasadena, Calif.

The primary two-and-a-half year science mission is scheduled to begin in February.

The high energy neutron detector provided by Russia's Space Institute has operated throughout much of the aerobraking phase and has completed its calibration in preparation for the science mission. The instrument is part of the gamma ray spectrometer payload suite, designed to map the elemental composition of the martian surface. Among its many science objectives, Odyssey will attempt to determine the amount and location of any near-surface water on Mars, if it exists.

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. 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.