Current Missions - 2001 Mars Odyssey Spacecraft Launch: April 7, 2001 Arrival: October 24, 2001 Mass: 758 kilograms (1,671 pounds), fueled Science instruments: Thermal emission imaging system, gamma ray spectrometer, Mars radiation environment experiment Overview 2001 Mars Odyssey is an orbiting spacecraft designed to determine the composition of the planet's surface, to detect water and shallow buried ice, and to study the radiation environment. The surface of Mars has long been thought to consist of a mixture of rock, soil and icy material. However, the exact composition of these materials is largely unknown. Odyssey will collect images that will be used to identify the minerals present in the soils and rocks on the surface and to study small-scale geologic processes and landing site characteristics. By measuring the amount of hydrogen in the upper meter of soil across the whole planet, the spacecraft will help us understand how much water may be available for future exploration, as well as give us clues about the planet's climate history. The orbiter will also collect data on the radiation environment to help assess potential risks to any future human explorers, and can act as a communications relay for future Mars landers. For more information, see the 2001 Mars Odyssey home page.