NASA record-breaking mission to Mars. The space probe launched on 7 April 2001, arriving at the planet on 24 October 2001 for a four-year mission. On 11 Jauary 2004, Mars Odyssey achieved its first milestone of being in orbit around Mars for a full Martian year of 687 Earth days. In 2010, however, it broke a record for being the longest-serving piece of machinery to work at Mars, and its mission has been extended ever since (the spacecraft entered a safe standby mode on 26 December 2016, but it resumed full service after reverting on 3 January 2017).

The spacecraft’s main instruments are a thermal-emission imaging system (THEMIS) to determine the distribution of minerals and rock types; a gamma-ray spectrometer (GRS) to search for 20 chemical elements, especially hydrogen in the form of water ice in the shallow subsurface; and the Mars radiation environment experiment (MARIE) to study the radiation environment. The spacecraft has contributed numerous science results. Its images in December 2003, for instance, indicated that Mars may be coming out of an ice age. It has mapped the amount and distribution of chemical elements and minerals that make up the Martian surface and has found a source for Martian meteorites on Earth. It has also mapped the planet’s hydrogen distribution, leading scientists to discover vast amounts of water ice in the polar regions buried just beneath the surface.

Mars Odyssey also selected the rover Opportunity’s landing site, as well as that for the Phoenix spacecraft.