The first spacecraft to visit Mercury was NASA's Mariner 10 (1974–75).[99] The spacecraft used the gravity of Venus to adjust its orbital velocity so that it could approach Mercury, making it both the first spacecraft to use this gravitational "slingshot" effect and the first NASA mission to visit multiple planets.[131] Mariner 10 provided the first close-up images of Mercury's surface, which immediately showed its heavily cratered nature,...
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