Mariner 7

The Mariner 7 spacecraft made a close flyby of Mars just five days after its twin spacecraft, Mariner 6, in 1969.

Although it had the same objective to study the surface and atmosphere of the Red Planet, Mariner 7 benefited from being the second to arrive at Mars. Scientists were able to use the spacecraft's reprogrammable command system to instruct it to take additional pictures of the Martian south pole, which had piqued their interest during Mariner 6's flyby. One photo even showed Mars' irregularly shaped moon, Phobos.