Mars Climate Orbiter

Agency

NASA

Country

🇺🇸 USA

Launched

1998-12-11

End Date

1999-09-23

Mass

629 kg

Instruments

2 instruments (never returned Mars data)

PMIRR pressure modulator infrared radiometer, MARCI wide-angle camera — neither returned science data

Orbit

Never achieved stable orbit — entered Martian atmosphere due to navigation error

Key Findings

1.No science data returned — spacecraft was destroyed on September 23, 1999 when it entered the Martian atmosphere
2.Root cause: Lockheed Martin engineering team provided thruster impulse data in pound-force seconds (imperial) while NASA navigation team expected newton-seconds (metric)
3.The 327 km closest approach altitude was far below the 80 km survivable minimum; the spacecraft either burned up or skipped out of the atmosphere
4.The incident led to mandatory unit-standardization protocols across all NASA missions and contractors

Mission Outcome

Mars Climate Orbiter was lost on September 23, 1999, when a unit mismatch between metric and imperial measurements caused the spacecraft to approach Mars 170 km lower than planned and disintegrate in the atmosphere. The $327 million failure became one of the most-cited examples of engineering process failure in aerospace history. Its MARCI camera was successfully re-flown on Mars Reconnaissance Orbiter.

Sources

[1] NASA NSSDCA — retrieved 2026-06-01
“Mars Climate Orbiter was lost on September 23, 1999 due to a navigation error caused by a units mismatch between metric and English data between a Lockheed Martin contractor and NASA.”

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