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Sputnik 1

Sputnik 1

Sputnik 1 was the first artificial Earth satellite. It was a 58 cm diameter polished metal sphere, with four external radio antennas to broadcast radio pulses. The Soviet Union launched it into an elliptical low Earth orbit on 4 October 1957. It was visible all around the Earth and its radio pulses were detectable. The surprise success precipitated the American Sputnik crisis and triggered the Space Race, a part of the larger Cold War. The launch ushered in new political, military, technological, and scientific developments. Sputnik itself provided scientists with valuable information. The density of the upper atmosphere could be deduced from its drag on the orbit, and the propagation ... more on Wikipedia