Take a step back in time and follow the historic story of how the United States responded to Sputnik, the world's first Earth-orbiting satellite launched by the Soviets in 1957. JPL designed and built -- and, in cooperation with the Army, launched -- Explorer 1, the first U.S. satellite and the first spacecraft ever to return scientific data from space. + PDF (9.7Mb) - Requires Adobe Reader + Text version
Explorer 1 Spacecraft
Fifty years ago, on Jan. 31, 1958, the JPL-designed and -build Explorer 1 soared into space, becoming the first Earth-orbiting U.S. satellite. Take a look inside the spacecraft and learn how it worked.
+ Interactive feature