NASA celebrated April Fool’s Day by telling the world that they found water on Mars.
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America's robot spacecraft, the Viking I, successfully landed on Mars.
The mapping of Mars' surface began.
The USSR launched the Mars 7 spacecraft from the Baikonur Cosmodrome in modern-day Kazakhstan.
NASA's Mars Odyssey completed its 60,000th orbit around Mars.
NASA's Mariner 9 became the first spacecraft to orbit another planet when it entered Mars' orbit.
