Mariner 4, first spacecraft to Mars, launched in 1965

Mariner 4, launched November 28, 1965, was the first spacecraft to perform a flyby past Mars, answering the burning questions about life on the Red Planet.  Mariner performed the flyby July 14-15, 1965, passing within 9,846 km from the surface of Mars.  Communications were terminated with the spacecraft on December 21, 1967.

The first close-up picture of the surface of Mars, courtesy Mariner 4.