NASA’s Mariner 4 mission first photographed Mars close-up, returning images in 1965.
Mariner 4 launched on November 28, 1964, and flew past Mars on July 14, 1965. It transmitted 22 television pictures of the planet’s surface, making them the first close-up images of Mars and the first photographs of another planet returned by a spacecraft during a flyby.
The pictures showed heavily cratered terrain that looked more Moon-like than many scientists had expected. Mariner 4 also measured the Martian atmosphere and found it to be extremely thin, an important result for understanding the planet’s surface environment.
Because the spacecraft stored its images and transmitted them slowly, the complete set took several days to reach Earth. Mariner 4 did not land or enter orbit around Mars; it was a flyby mission. Later Mariner and Viking missions revealed a more geologically varied planet than the first images suggested.