Mariner-71H (also called Mariner-H) was the first of a pair of American spacecraft intended to explore the physical and dynamic characteristics of Mars from Martian orbit. The overall goals of the series were to search for an environment that could support life; to collect data on the origin and evolution of the planet; to gather information on planetary physics, geology, planetology, and cosmology; and to provide data that could aid future spacecraft such as the Viking Landers.
Date: 9 May 1971
Launch of Mariner-71H was nominal until just after separation of the Centaur upper stage, when a malfunction occurred in the stage's flightcontrol system, leading to loss of pitch control at an altitude of 148 kilometers at T+4.7 minutes. As a result, the stack began to tumble and the Centaur engines shut down. The stage and its payload reentered Earth's atmosphere approximately 1,500 kilometers downrange from the launch site.
Credit: NSSDC Photo Gallery