Mars Climate Orbiter
Launch Date: December 11, 1998
Mission Project Home Page - http://mars.jpl.nasa.gov/missions/past/climorb.html
The Mars Surveyor '98 program is comprised of two spacecraft launched separately, the Mars Climate Orbiter (formerly the Mars Surveyor '98 Orbiter) and the Mars Polar Lander (formerly the Mars Surveyor '98 Lander). They were launched separately to study the Martian weather, climate, and water and carbon dioxide budget. The goal of MPL was to soft land, under propulsive power, near the edges of the South Polar ice cap on Mars, and to use cameras, a robotic arm and instruments to measure the Martian soil composition.
Unfortunately, the spacecraft failed to achieve orbit around Mars, and contact with it was lost on September 23, 1999.
This mission is part of the Mars Exploration Program.