Mars Climate Orbiter
Date: 27 May 1998
The Mars Climate Orbiter spacecraft is shown here during acoustic tests that simulate launch conditions. The orbiter was to conduct a two year primary mission to profile the Martian atmosphere and map the surface.
Unfortunately, Mars Climate Orbiter burned up in the Martian atmosphere on September 23, 1999, due to a metric conversion error that caused the spacecraft to be off course.
Image Credit: NASA