The Mars Climate Orbiter was designed to study Mars from orbit. It was launched on December 11, 1998. The Climate Orbiter cost $193,100,000 to build and had an orbit height of 35 miles.
The purpose of the Climate Orbiter was a communications relay for the Mars Polar Lander and several Deep Space Probes. It carried an array of instruments used to study the geology, geophysics, and climate of Mars, like the Mars Observer did. The Climate Orbiter also studied the distribution of water on Mars and looked for any evidence of previous climate change.
The Climate Orbiter had its last contact with Earth when it burned up in Mars' atmosphere on September 23, 1999. The cause of its demise was because of a failure at a simple English to Metric unit conversion by the engineers of the Climate Orbiter. The failure caused the Climate Orbiter to fall into the Martian atmosphere, eventually leading to it burning up.