June 22, 2009

Mars Odyssey spacecraft changes orbit

The U.S. space agency has nudged the Mars Odyssey spacecraft's orbit, allowing it to look at the day side of Mars in mid-afternoon instead of late afternoon.

NASA said the change, which took eight months to complete, increases the sensitivity for infrared mapping of Martian minerals. Orbit design for Odyssey's first seven years of observing Mars used a compromise between what worked best for the infrared mapping and for another onboard instrument, officials said.

The orbiter is now overhead at about 3:45 in the afternoon instead of 5 p.m., so the ground is warmer and there is more thermal energy for the camera's infrared sensors to detect, said Jeffrey Plaut, project scientist for Mars Odyssey at NASA's Jet Propulsion Laboratory.

NASA said the change involves a trade-off. The orbital shift forced a halt to the use of one of three instruments in Odyssey's Gamma Ray Spectrometer suite. The new orientation would cause overheating in a critical component of the gamma ray detector. The suite's neutron spectrometer and high-energy neutron detector are expected to continue operating.

In another change motivated by science benefits, NASA said Odyssey has started making observations other than straight downward-looking. Scientists said the more-flexible targeting allows imaging of some latitudes near the poles that are never directly underneath the orbiter.

The spacecraft was launched in 2001.