Mars Odyssey

2001 Mars Odyssey

Agency

NASA

Country

🇺🇸 USA

Launched

2001-04-07

Status

Ongoing

Mass

725.9 kg

Instruments

3 science instruments

THEMIS thermal imaging system, GRS/HEND gamma ray and neutron spectrometer suite, MARIE radiation environment (failed 2003)

Orbit

Sun-synchronous polar mapping orbit, ~400 km altitude, 2-hour period

Key Findings

1.THEMIS produced the first comprehensive global map of surface mineralogy, identifying volcanic and water-altered rock types across the entire planet
2.GRS and HEND instruments discovered hydrogen-rich (water-ice) deposits in the shallow subsurface at latitudes above 60°, later confirmed by Phoenix lander
3.Longest-operating Mars spacecraft in history as of 2026, surpassing its original 917-day design life by more than 20×
4.Serves as the primary UHF relay satellite for Spirit, Opportunity, Phoenix, Curiosity, and InSight surface missions

Mission Outcome

Mars Odyssey has operated continuously since October 2001, making it the longest-lived Mars spacecraft ever flown. Its discovery of near-surface water ice fundamentally altered landing site selection for all subsequent missions. The spacecraft continues to serve as a critical communications relay for surface assets as of mid-2026.

Sources

[1] NASA Mars Exploration Program — retrieved 2026-06-01
“Mars Odyssey launched April 7, 2001 and is the longest-operating spacecraft ever sent to Mars.”
[2] NASA NSSDCA — retrieved 2026-06-01

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