Sputnik 1
October 4, 1957 · Baikonur Cosmodrome
The first artificial Earth satellite, launched by the Soviet Union into low Earth orbit on 4 October 1957. The 58 cm polished sphere transmitted radio signals for about three weeks before its batteries died, giving scientists new data on the upper atmosphere; it burned up on reentry on 4 January 1958. Its unanticipated success triggered the American Sputnik crisis and the Space Race.
