Mariner 4

The Mariner 4 mission, launched by NASA in 1964, provided the first high-resolution images of Mars during its 1965 encounter. The spacecraft successfully executed a flyby of the planet, transmitting the historic photographs back to Earth. These images revealed a barren, cratered surface that changed scientific understanding of Mars.

The photographs transmitted by Mariner 4 revealed surface details and geological features that were previously unknown to scientists. Most notably, the images showed a heavily cratered, lunar-like landscape, debunking the popular theory of advanced life or oceans on Mars. The data also indicated that the planet had a very thin atmosphere and lacked a global magnetic field.

Mariner 4 was the first successful mission to complete a flyby of Mars and transmit close-up images of the planet. While earlier Soviet missions had attempted to reach Mars, they failed to return usable planetary data. Mariner 4's success in 1965 represented a pivotal moment in planetary exploration for NASA.

Mariner 4 transmitted a total of 21 complete images of the Martian surface during its 1965 flyby. While this seems like a small number by modern standards, these photographs took several days to transmit back to Earth using the technology of the time. The slow data rate meant the first images were initially rendered by hand-painting the digital values as they arrived.