Its mission is to use spectrometers and a thermal imager to detect evidence of past or present water and ice, as well as study the planet's geology and radiation environment.

[9][10] Odyssey has also served as the primary means of communications for NASA's Mars surface explorers in the past decade, up to the Curiosity rover.

However, NASA e-mailed Arthur C. Clarke in Sri Lanka, who responded that he would be delighted to have the mission named after his books, and he had no objections.

Odyssey then spent about 76 days aerobraking, using aerodynamic drag from the upper reaches of the Martian atmosphere to gradually slow down and reduce and circularize its orbit.

[19] By planning to use the atmosphere of Mars to slow the spacecraft in its orbit rather than firing its engine or thrusters, Odyssey did not need an additional 200 kilograms (440 lb) of propellant on board.

[21] The payload's MARIE radiation experiment stopped taking measurements after a large solar event bombarded the Odyssey spacecraft on October 28, 2003.

[22] About 85% of images and other data from NASA's twin Mars Exploration Rovers, Spirit and Opportunity, have reached Earth via communications relay by Odyssey.

On September 30, 2008 (sol 2465) the spacecraft altered its orbit to gain better sensitivity for its infrared mapping of Martian minerals.

[29] Several days before MSL's landing in August 2012, Odyssey's orbit was altered to ensure that it would be able to capture signals from the rover during its first few minutes on the Martian surface.

[32] On February 11, 2014, mission control accelerated Odyssey's drift toward a morning-daylight orbit to "enable observation of changing ground temperatures after sunrise and after sunset in thousands of places on Mars".

[40] The ground truth for its measurements came on July 31, 2008, when NASA announced that the Phoenix lander confirmed the presence of water on Mars,[41] as predicted in 2002 based on data from the Odyssey orbiter.