Mariner 4:
Goals: Like it predeccessor, Mariner 4 was designed to snap a series of photos of Mars after an eight month journey studying interplanetary space. The spacecraft was also equipped to study the Martian atmosphere as it flew past.
Accomplishments: Mariner 4 was one of the great successes of the early American space program. The spacecraft sent back 21 black and white images of the Martian surface -- the first pictures taken of another planet from space. The spacecraft found Mars was a battered, cold and barren world. Scientists learned they would need retro rockets in addition to parachutes to safely deliver a spacecraft through the planet's thin atmosphere to the surface. Mariner 4 also found Mars' weak radiation belt.
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Mariner 4 was the first successful mission to Mars -- a difficult science target.
