Mars Global Surveyor has been circling Mars since 1997, snapping hundreds of thousands of high-resolution pictures. The two spacecrafts are designed to complement one another. Surveyor's camera can spot details as small as 3 meters, focusing better than the camera onboard Odyssey. By spotting possible hot spots, Odyssey could help determine whether and when Mars experienced volcanic activity. The orbiter also features a gamma ray spectrometer, which can peer into the shallow subsurface of Mars to measure elements, including hydrogen.
Scientists speculate hydrogen is probably present in the form of water ice.
The spectrometer is expected to measure permanent ground ice and how it changes with the seasons, NASA said. If liquid or ice water, or even hydrogen itself, is present, scientists say it might be possible for humans to inhabit the red planet. Not only might astronauts be able to find water, just as importantly they would be able to create fuel for the long flight back to Earth. But all these scientific possibilities hinge on a successful mission, something NASA hasn't taken for granted given the fatal problems with its last two Mars missions. Three months later, its sibling spacecraft, the Mars Polar Lander, crashed into the red planet.