Chronology of Sputnik/Vanguard/Explorer Events 1957-58
- October 4, 1957 USSR: Sputnik 1 (83.6 kg) launched
- November 3 USSR: Sputnik 2 (508.3 kg), with dog Laika as passenger, launched
- December 6 USA: Vanguard TV-3 explodes on launch pad
- January 31, 1958 USA: Explorer 1 (14 kg), America's first satellite, discovers the Van Allen radiation belts
- February 3 USSR: First try to launch Sputnik 3 fails
- February 5 USA: A second Vanguard try fails
- March 5 USA: Explorer 2 fails to orbit
- March 17 USA: Vanguard 1 (1.47 kg) successfully orbits, establishes the pear-shapedness of the Earth
- March 26 USA: Explorer 3 orbits, collects radiation and micrometeoroid data
- April 28 USA: Another Vanguard fails to orbit (third failure)
- May 15 USSR: Sputnik 3 (1,327 kg) orbits, carrying large array of scientific instruments, but tape recorder fails, so it can't map Van Allen belts
- May 27 USA Vanguard fails for the fourth time
- June 26 USA Vanguard fails for fifth time
- July 26 USA Explorer 4 orbits and maps Van Allen radiation belts for 2 1/2 months
- August 24 USA Explorer 5 fails to orbit
- September 26 USA Vanguard fails for the sixth time
Source: James J. Harford, "Korolev's Triple Play: Sputniks 1, 2, and 3," adapted from James J. Harford, Korolev: How One Man Masterminded the Soviet Drive to Beat America to the Moon (John Wiley: New York, 1997).
For further information, please email histinfo@hq.nasa.gov
Last Updated: January 27, 2005.