Failed U.S. Missions

Mariner 3: Mars flyby attempt. Solar panels did not open, preventing flyby. Mariner 3 is now in a solar orbit.

Mariner 8: It failed to reach Earth orbit.

Mars Observer: Communication was lost with Mars Observer on August 21, 1993, just before it was to be inserted into Mars orbit. It was believed that Mars Observer developed a major leak in its propulsion system, sending it out of control.