Mars Climate Orbiter Mishap Investigation Board Phase I Report

Stephenson, A. G. (1999). Mars Climate Orbiter Mishap Investigation Board Phase I Report.

Type

Report

Intellectual base

Grey literature

Year

1999

Link

https://llis.nasa.gov/llis_lib/pdf/1009464main1_0641-mr.pdf

Cited from

philosophy

Cited by

3 citations across 3 artifacts.

Each citation links to the sentence it supports in the citing article.

Primes

• Assumption
  • A navigation module computes thrust from a sensor reading, assuming the reading is in metric units; an upstream component, written by a different team, emits it in imperial units.

    This sourceDocuments the loss of the orbiter due to an unstated unit-convention assumption (pound-force seconds vs. newton-seconds) at a software interface between teams.

• Equivocation
  • The 1999 Mars Climate Orbiter loss is equivocation in a safety-critical software pipeline, with the token being a unit rather than a word.

    This sourceEstablishes that the spacecraft loss resulted from ground software producing impulse data in pound-force-seconds while the spacecraft navigation software consumed it as newton-seconds — a unit (referent) mismatch with no conversion at the boundary.

Mechanisms

• Unit Normalization Table
  • The most famous instance is the loss of NASA's Mars Climate Orbiter, where one system produced impulse in pound-force-seconds while another consumed it as newton-seconds, and the unconverted mismatch sent the craft into the atmosphere.

    This sourceDocuments a pound-force-second/newton-second mismatch that corrupted navigation and led to the Mars Climate Orbiter's loss.

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