Designed to study Mars from orbit and serve as a communications relay for the Mars Polar Lander and Deep Space probes, the Mars Climate Orbiter was unsuccessful due to a navigation error caused by a failure to translate English units to metric.

Last contact with the spacecraft was on September 23, 1999, 9 months after launch, and an investigation found that the spacecraft burned up in Mars' atmosphere.

Scientific Instruments

- Mars Color Imager (MARCI)
- Pressure Modulated Infrared Radiometer (PMIRR)