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Posted: October 10, 2008 NASA’s orbiting Mars Odyssey spacecraft has been given the go ahead for a third two-year extension of its mission to survey the red planet, making it the longest serving of six spacecraft currently studying Mars.
Mars Odyssey was launched in 2001 and now enters its third mission extension to survey the red planet. Image: NASA. On 30 September the spacecraft fired its thrusters for nearly six minutes to gradually ease it into a new orbit that will offer even better accuracy for its infrared mapping of Martian minerals. The orbit adjustment will also allow Odyssey's Thermal Emission Imaging System to look down at sites earlier in the day to measure infrared radiation emitted by the warmer rocks, which will provide clues to the rocks' identities. "This was our biggest maneuver since 2002, and it went well," says JPL's Gaylon McSmith, Odyssey mission manager. "The spacecraft is in good health. The propellant supply is adequate for operating through at least 2015." Up until now Odyssey's orbit has been synchronized with the Sun such that the local solar time has been about 5pm at whatever spot on Mars the spacecraft flew over as it passed between the north and south polar regions around a dozen times per day (and 5am under the track of the spacecraft during the south to north traverses). Last week’s thruster boost is gradually changing this synchronization so that the time of day on the ground when Odyssey is overhead is getting earlier by about 20 seconds per day. A follow-up maneuver, probably in late 2009 when the overpass time is between 2:30 and 3:00pm, will end the progression toward earlier times.
Odyssey has measured the change in nighttime ground surface temperature between summer and fall using the Thermal Emission Imaging System camera. Blue colours represent the locations with least change while red indicates areas with most change. The range in temperature changes corresponds to a depth to ice below the surface of less than 1cm to over 19.5cm. Image: NASA/JPL/ASU. Although the Thermal Emission Imaging System will perform well in the new conditions, the Gamma Ray Spectrometer suite’s gamma ray detector may overheat from the increased solar radiation. The suite's neutron spectrometer and high-energy neutron detector are expected to keep operating. The Gamma Ray Spectrometer has already provided dramatic discoveries of water-ice near the surface throughout much of high-latitude Mars, the impetus for NASA's Phoenix Mars Lander mission, which continues to dig the north polar soil despite the rapid decline in solar power as winter sets in. The gamma ray detector has also mapped the global distribution of many elements, such as iron, silicon and potassium, a high science priority for the first and second extensions of the Odyssey mission. One of the goals of the next mission extension is to increase the sensitivity for identifying surface minerals and to occasionally aim the imaging camera away from the straight-down pointing that has been used throughout the mission in order to create some stereo, three-dimensional images of the Martian landscape. Odyssey will continue to provide crucial support for all Mars surface missions and 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. It has also played a key role in observing sites that could be targets for future robotic, and perhaps one day human, missions to Mars. |
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