The 2001 Mars Odyssey Orbiter is scheduled for launch on April 7, 2001with a planned arrival at Mars on Oct. 20, 2001. After a propulsive maneuver into a 25-hour capture orbit, aerobraking will be used during 273 orbits taking 76 days to achieve the science orbit. The satellite will be placed in an orbit with an altitude of 400 kilometers (216 nmi) in a near-polar Sun-synchronous orbit, with a period of 2 hours. Its orbit will bring it over targets in late afternoon on the day side of the planet and shortly before dawn on the night side of the planet.

The spacecraft is designed to orbit Mars for three years, conducting a detailed analysis of the planet's surface from orbit and measuring the radiation environment. The orbiter will also act as a communications relay for future missions to Mars.

The spacecraft will study the kinds of minerals on the surface and measure the amount of hydrogen in the shallow subsurfaces of the planet, which will give scientists clues about the presence of water, either past or present. It will also provide information on the structure of the Martian surface and on the geological processes that may have caused it. The orbiter will also take measurements of the planet's radiation environment so potential health risks to future human explorers can be evaluated. To do this, the spacecraft carries three science instruments: The Thermal Emission Imaging System (THEMIS), the Gamma Ray Spectrometer (GRS), and the Mars Radiation Environment Experiment (MARIE).