First, the space race took us to the moon. Next, we headed for Mars. NASA’s Mariner program ran in direct competition with USSR’s aptly-named Mars program. While we ultimately beat the Soviets in the race to establish a spacecraft in orbit around another planet, the real value of the Mariner missions was in getting there.

One big family

As Mariner 9’s name suggests, it was preceded by eight other spacecraft. Their goals varied from Venus and Mars flybys to established Mars orbits. Mariner 8 and 9 were physically identical, and both were intended to orbit Mars. The “younger” twin was lost in a launch failure, but the other craft went on to make history. Once in orbit around Mars, Mariner 9 took over 7,000 photos of the Red Planet, giving scientists their first clear and up-close view of Mars. After almost a year and a half in orbit, Mariner 9 was decommissioned and left in a gradually degenerating orbit around the planet. In 2020, the probe will begin to enter the atmosphere, where it will break apart.

The next generation

Following in Mariner 9’s footsteps, NASA launched Mariner 10, which used Venus’ gravitational pull to slingshot itself into a mercury flyby. It was the first probe to pass by two planets, and the only craft for 33 years to take up-close photos of Mercury. The 11th and 12th probes in the Mariner lineup were Mariner Jupiter-Saturn. This final addition to the Mariner family of spacecraft was approved in 1972. By the time the probes were launched in 1977, they had undergone significant mission modifications involving additional Uranus and Neptune flybys after passing Saturn and Jupiter. The probes would use Saturn’s moon Titan as a stepping stone to get there, if necessary. Shortly before their launch, the probes were renamed Voyager 1 and Voyager 2.