Voyager program (Mars)

The missions were planned, as part of the Apollo Applications Program, between 1966 and 1968 and were scheduled for launch in 1974–75.

[2] Originally, NASA had proposed a direct lander using a variant of the Apollo Command Module launched atop of a Saturn IB rocket with a Centaur upper stage.

With the discovery by Mariner 4 in 1965 that Mars had only a tenuous atmosphere, the mission was changed to have both an orbiter and lander.

Voyager was the first major space science project to be cancelled by the U.S. Congress.

The Saturn V had also been planned at one point as the launch vehicle for an upscaled probe for this mission.