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Mars Climate Orbiter Failure

Jul 23, 2025

Overview

The Mars Climate Orbiter mission, launched by NASA in 1998, failed due to a critical error involving incompatible measurement units in onboard software, resulting in the loss of the spacecraft and prompting a major investigation into project oversight and quality control.

Background and Mission Objectives

  • Mars Climate Orbiter (MCO) was designed to study Mars' climate and act as a relay for the Mars Polar Lander.
  • The mission aimed to collect data on Martian weather, water, and carbon dioxide.
  • MCO was built by Lockheed Martin under NASA contract, while NASA managed oversight and operations.
  • The project was part of NASA's effort to implement lower-cost, smaller spacecraft due to budget constraints.

Spacecraft Design and Mission Plan

  • The MCO had a single IBM processor, 128 MB RAM, 18 MB flash memory, and a solar array providing 500 W power.
  • The spacecraft used thrusters and reaction wheels for stabilization and maneuvering.
  • Mission plan included orbital insertion around Mars and aerobraking to achieve the final orbit.

Mission Timeline and Failure

  • MCO launched on December 11, 1998, and traveled to Mars over nine and a half months.
  • Navigation software issues arose during the journey, but no formal investigation was initiated.
  • On September 15, 1999, a trajectory maneuver left the MCO much closer to Mars than planned.
  • An emergency correction was considered but rejected to avoid impacting the Polar Lander.
  • On September 23, 1999, contact was lost earlier than expected and was never reestablished.

Investigation and Findings

  • NASA convened an investigation panel in October 1999 to determine the cause of the failure.
  • It was discovered that Lockheed Martin's software used English units, while NASA's systems used metric units, causing calculations to be off by a factor of 4.45.
  • The error was not caught due to lack of thorough end-to-end software testing and oversight.
  • Reports of discrepancies from staff were ignored due to improper reporting formats.
  • The investigation primarily blamed NASA for inadequate validation and rushed project management.

Decisions

  • No emergency trajectory correction maneuver was performed to avoid impacting the Mars Polar Lander's schedule.
  • Management did not pursue a formal investigation when software anomalies first appeared.

Recommendations / Advice

  • Independent verification and validation of software must be thorough on all mission-critical systems.
  • All measurements and unit standards must be explicitly verified throughout multidisciplinary projects.
  • Internal concerns and discrepancy reports should be formally documented and thoroughly investigated.

Questions / Follow-Ups

  • How can NASA ensure end-to-end validation and unit consistency in future multi-vendor projects?
  • What processes could be put in place to better capture and act upon internal discrepancy reports?

Full transcript