On November 28, 1964, the Mariner 4 probe launched from Cape Canaveral and began its 7 month journey to Mars. When we think of the space race in the 1960’s, most consideration is given to the effort to put a man on the moon. And while landing on the moon is certainly deserving of the lion’s share of recognition, there was a vibrant effort from both the United States and the USSR to reach and explore our nearest planetary neighbor, Mars.
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By the time Mariner 4 launched in November of 1964, there had been numerous attempts and subsequent failures at reaching Mars. The Soviets had sent over 6 probes by this time, some of which failed to achieve flight, and others which made it to space but lost communication. The United States launched Mariner 3 earlier that November, which was intended to complete a flyby of the red planet, but failed to properly separate from its launch vehicle and was unable to complete the mission. Mariner 4, which would follow the same mission plan as Mariner 3, successfully launched on November 28 and began its long journey to Mars.
Mariner 4 successfully reached Mars by July 1965, and soon started snapping pictures and gathering data. The first picture sent back was unable to be fully processed, and so NASA technicians used a store bought art set to essentially paint by numbers over the raw data. Subsequent transmissions improved and NASA received digital pictures of the martian surface for the first time, covering a sweeping swath of the planet as the probe sped past without entering orbit. Ultimately, Mariner 4 relayed back around 12 low-resolution images of the planet, comprising just 634 kilobytes of data, a meager amount for such an important mission.
But Mariner 4 wasn’t underwhelming in context. At this point in time, we didn’t have a very good idea of what Mars was like beyond what we could see through a telescope. There was still widespread hope and belief that Mars even harbored life, and much of the science fiction up until the Mariner mission focused on the discovery of life on Mars. When Mariner 4 used its numerous scientific instruments to gauge the composition of the Martian atmosphere, we found that without a magnetic field or robust atmosphere, there was little chance that Mars could support life with its exposed, dead surface. While we didn’t get a very good picture of what this nearby planet was like, Mariner 4 rapidly changed our global perceptions of Mars, and forever altered how we view our place in the universe.