Article Posted on : - Oct 10, 2008

Artist concept of Odyssey. Image credit NASA

WASHINGTON (BNS): The longest-serving of six spacecraft now studying Mars is up to new tricks for a third two-year extension of its mission to examine the most Earthlike of known foreign planets.

According to NASA, the Mars Odyssey is altering its orbit to gain even better sensitivity for its infrared mapping of Martian minerals. During the mission extension through September 2010, it will also point its camera with more flexibility than it has ever used before. Odyssey reached Mars in 2001.

Odyssey mission manager and JPL's Gaylon McSmith said that this was their biggest manoeuver since 2002, and it went well. “The spacecraft is in good health. The propellant supply is adequate for operating through at least 2015,” McSmith said.

NASA said the orbit adjustment will allow Odyssey's Thermal Emission Imaging System (TEIS) to look down at sites when it's mid-afternoon, rather than late afternoon. The multi-purpose camera will take advantage of the infrared radiation emitted by the warmer rocks to provide clues to the rocks' identities.

Odyssey project scientist Jeffrey Plaut of NASA's Jet Propulsion Laboratory, Pasadena, California, said that the mission extension will allow them to do much more sensitive detection and mapping of minerals.

Increased sensitivity for identifying surface minerals is a key science goal for the mission extension beginning this month. Also, the Odyssey team plans to begin occasionally aiming the camera away from the straight-down pointing that has been used throughout the mission. This will allow the team to fill in some gaps in earlier mapping and also create some stereo, three-dimensional imaging.

The mission's orbit design before this used a compromise between what works best for the TEIS and the Gamma Ray Spectrometer.

On commands from its operations team at JPL and at Denver-based Lockheed Martin Space Systems, Odyssey fired thrusters for nearly 6 minutes on September 30, the final day of the mission's second two-year extension.

The Odyssey's orbit is synchronised with the Sun. The local solar time has been about 5 pm at whatever spot Mars Odyssey flew over as it made its dozen daily passes from between the North Pole region to the South Pole region for the past five years. The local time has been about 5 am under the track of the spacecraft during the South-to-North leg of each orbit.

The push imparted by the September 30 manoeuver will gradually change that synchronisation over the next year or so. Its effect is that the time of day on the ground when Odyssey is overhead is now getting earlier by about 20 seconds per day. A follow-up manoeuver, probably in late 2009 when the overpass time is between 2.30 and 3 pm, will end the progression toward earlier times.

According to the team while aiding performance of the TEIS, the shift to mid-afternoon is expected to stop the use of one of the three instruments in Odyssey's Gamma Ray Spectrometer suite. “The suite's gamma ray detector needs a later-hour orbit to avoid overheating of a critical component. The suite's neutron spectrometer and high-energy neutron detector are expected to keep operating,” they said.

The Odyssey will continue providing crucial support for Mars surface missions as well as conducting its own investigations. It has relayed to Earth nearly all data returned from NASA rovers Spirit and Opportunity. It shares with NASA's Mars Reconnaissance Orbiter the relay role for Phoenix.