Mariner 4 made the first successful flyby of Mars in 1965 and sent the first close-up images of the planet back to Earth.
NASA launched Mariner 4 on 28 November 1964 from Cape Canaveral. It passed Mars on 14 July 1965, coming within about 9,846 kilometres of the surface. The probe returned 21 photographs, covering only a small portion of Mars but revealing a cratered, Moon-like landscape that challenged hopes of finding a planet covered by canals or abundant vegetation.
The mission was a major early success in interplanetary exploration and demonstrated that a spacecraft could navigate to another planet, survive the journey and transmit scientific data across interplanetary distances. Mariner 4 continued sending engineering data after the encounter before radiation damage eventually ended communications.
Mariner 9 is sometimes confused with it, but Mariner 9 arrived at Mars in 1971 and became the first spacecraft to orbit another planet. Viking 1, launched in 1975, later became the first American mission to land successfully on Mars.