Follow this link to skip to the main content
NASA Logo - Jet Propulsion Laboratory + View the NASA Portal
homeearthsolar systemstars galaxiestechnology
JPL History banner
The 90s
1991 - present
Home History
Early History
First Space Missions
New Directions
Grand Voyages
the 80s
the 90s
Mars 1998/1999
  printer-icon  Print this page

On Dec. 11, 1998, the Mars Surveyor program launched the first of its two missions for the 1998/1999 launch window. Named the Mars Climate Orbiter, the spacecraft carried two more Mars Observer instruments. During its orbit insertion on Sept. 23, 1999, Climate Orbiter disappeared. Unlike the Mars Observer case, JPL knew within hours what had happened. A computer program in the ground control system had been written to use English Engineering Units (feet, pounds, etc.) instead of NASA-mandated metric (meters, kilograms, etc.). This had caused the spacecraft to be just far enough off course to hit the atmosphere while going into orbit.

The Climate Orbiter was the first mission JPL had ever lost to a navigation error. Director Ed Stone had John Casani, who had been project manager for Voyager and Galileo, immediately start a detailed review of the second mission, which was already on its way to Mars. This was the Mars Polar Lander, launched Jan. 3, 1999. Stone hoped Casani and the small team he assembled would be able to identify and fix anything that might be wrong with Polar Lander in the short period of time before it reached Mars.

The Polar Lander's target was the south polar region of Mars. It used a Viking-like lander equipped with a landing rocket and legs. In addition to the lander, it consisted of a cruise stage that would fly past Mars after releasing the lander, and two Deep Space 2 surface penetrator probes. They were also released by the cruise stage and entered the atmosphere independently of the lander.

The Polar Lander disappeared Dec. 3, 1999, apparently crashing onto its landing site. The spacecraft had not been designed to provide telemetry during its descent so a definitive cause could not be found. But a test on duplicate hardware at Lockheed suggested that the most likely cause was a software fault that had shut off the descent rocket too early, causing the spacecraft to fall the last 60 meters (about 65 yards) or so to the surface. The penetrator probes were also lost without a trace.

After these losses, NASA overhauled the Mars program, adding more money while reducing the objectives for the 2001 mission to a single orbiter. This marked the end of Faster/Better/Cheaper management for Mars.


artist concept of Mars Climate Orbiter


Artist's concept of Mars Climate Orbiter.
+ Full image

  artist's concept of Mars Polar Lander
Artist's concept of Mars Polar Lander.
+ Full image
    Next >
Privacy / Copyrights    FAQ   Contact JPL
Link to + Freedom of Information Act View NASA Home Page    
JPL Historian: Erik Conway
Site Manager: Susan Watanabe
Webmasters: Tony Greicius, Martin Perez