Incident / 1999
Mars Climate Orbiter
A shared assumption can become a mission-level risk when it crosses an interface.
THE HISTORICAL RECORD
The interface is part of the mission
Mars Climate Orbiter launched in December 1998. Contact was lost on September 23, 1999 during arrival at Mars. NASA describes a navigation error involving a failure to translate English units to metric, leading to an incorrect trajectory.
Launch toward Mars.
Contact is lost during arrival.
The unit-conversion and interface failure is identified.
Primary sources
LESSONS TO INVESTIGATE
Carry the question into the next task.
- Make units and conventions explicit interface requirements.
- Check a signal’s meaning, not only its presence.
- Retain the evidence supporting an accepted calculation.
PROPOSED REHEARSAL · ORIGINAL EXERCISE
Practise the decision.
Two teams exchange a simulated actuator record using different conventions. Find the mismatch and demonstrate the corrected interface before release.
This is a proposed learning activity inspired by the case. It is separate from the historical record and is not an account of an EON mission deployment.
See Situation Room and Creator
