Earth from Mars Odyssey

Alan M. MacRobert, Sky and Telescope

The 2001 Mars Odyssey spacecraft tested its cameras by snapping a view of the Earth. Courtesy NASA/JPL/Arizona State University.

Looking backward 12 days after its April 7th launch, NASA's 2001 Mars Odyssey spacecraft took this pair of images of its home planet from a distance of more than 3 million kilometers. The infrared view, by Odyssey's Thermal Emission Imaging System (THEMIS), shows the night side of Earth glowing with surface temperatures ranging from –50° Celsius in Antarctica to +9° C in northeastern Australia, agreeing well with temperature readings made on the ground.

Odyssey will arrive at Mars on October 24th, spend several months aerobraking into a low orbit, and begin its 29-month science mission in January 2002. If all goes well it will make high-resolution maps of Martian mineralogy, including any signs of shallow subsurface water, study the Martian atmosphere and climate, and investigate the radiation environment that might someday affect human explorers.