From Wikipedia, the free encyclopedia
Jump to navigation Jump to search
S-45 1.jpg
An S-45 satellite before launch
Mission typeIonospheric
Mission durationFailed to orbit
Spacecraft properties
Launch mass33.6 kilograms (74 lb)
Start of mission
Launch date24 May 1961, 19:48:05 (1961-05-24UTC19:48:05Z) UTC
RocketJuno II AM-19G
Launch siteCape Canaveral LC-26B
Orbital parameters
Reference systemGeocentric
RegimeHighly elliptical (planned)
S-55 →

S-45A was an American satellite, which was lost in a launch failure in 1961. The satellite was intended to operate in a highly elliptical orbit, from which it was to have provided data on the shape of the ionosphere,[1] and on the Earth's magnetic field.[2] It was part of the Explorer programme, and would have been designated Explorer 12 had it reached orbit. It was the second of two identical satellites to be launched; the first, S-45, had also been lost in a launch failure, earlier in the year.[2]

S-45A was launched aboard a Juno II rocket, serial number AM-19G. It was the final flight of the Juno II.[3] The launch took place from Launch Complex 26B at the Cape Canaveral Air Force Station at 19:48:05 UTC on 24 May 1961.[3] The system which was intended to ignite the second stage malfunctioned, and as a result that stage failed to ignite.[4] The rocket failed to achieve orbit.[5]


  1. ^ "Explorer S45A". NSSDC Master Catalog. NASA. Retrieved 14 July 2010.
  2. ^ a b Wade, Mark. "P-14". Encyclopedia Astronautica. Archived from the original on 13 June 2010. Retrieved 14 July 2010.
  3. ^ a b McDowell, Jonathan. "Launch Log". Jonathan's Space Page. Retrieved 14 July 2010.
  4. ^ Krebs, Gunter. "Explorer: S-45". Gunter's Space Page. Retrieved 14 July 2010.
  5. ^ "Explorer Program". Mission and Spacecraft Library. NASA. Archived from the original on 27 January 2008. Retrieved 14 July 2010.