Mars Observer

Launched from Cape Canaveral aboard a Titan 3 rocket on 9/25/92, this $900 million mission to Mars was the first in 17 years. The 450 million mile flight took 11 months. The 5,700 pound craft planned to arrive at Mars in August of 1993 and spend an entire Martian year, 687 Earth days, mapping the surface from an altitude of 240 miles. Unfortunately, this spacecraft failed and lost communications before orbital insertion.

The last U.S. mission to Mars before this mission was the landing of two Viking spacecraft in 1976.