The Mars Exploration Program itself was formed officially in the wake of the failed Mars Observer in September 1992, which had been NASA's first Mars mission since the Viking 1 and Viking 2 projects in 1975. The spacecraft, which was based on a modified Earth-orbiting commercial satellite, carried a payload of instruments designed to study the geology, geophysics, and climate of Mars from orbit. The mission ended in August 1993 when communications were lost three days before the spacecraft had been scheduled to enter orbit.