Explorer S-45A (satellite)

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Explorer S-45A
S-45 1.jpg
Explorer S-45A satellite before launch
Mission typeIonosphere research
Mission durationFailed to orbit
Spacecraft properties
SpacecraftExplorer S-45A
Spacecraft typeScience Explorer
ManufacturerGoddard Space Flight Center
Launch mass33.6 kg (74 lb)
PowerSolar cells and batteries
Start of mission
Launch date24 May 1961, 19:48:05 GMT
RocketJuno II (AM-19G)
Launch siteCape Canaveral, LC-26B
ContractorArmy Ballistic Missile Agency
End of mission
DestroyedFailed to orbit
Orbital parameters
Reference systemGeocentric orbit (planned)
RegimeHighly elliptical orbit
Perigee altitude221 km (137 mi)
Apogee altitude181,100 km (112,500 mi)
Period5013.90 minutes
Explorer program

Explorer S-45A was a NASA 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 program and would have been designated Explorer 12 had it reached orbit. It was the second of two identical satellites to be launched; the first, Explorer S-45, had also been lost in a launch failure, earlier in the year.[2]


Explorer S-45A was launched aboard a Juno II launch vehicle, serial number AM-19G. It was the final flight of the Juno II.[3] The launch took place from LC-26B at the Cape Canaveral Air Force Station (CCAFS) at 19:48:05 GMT 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 launch vehicle failed to achieve orbit.[5]

See also[edit]


  1. ^ "Explorer S-45A". NASA. 28 October 2021. Retrieved 4 November 2021. Public Domain This article incorporates text from this source, which is in the public domain.
  2. ^ a b Wade, Mark. "P-14". Encyclopedia Astronautica. Archived from the original on 13 June 2010. Retrieved 4 November 2021.
  3. ^ a b McDowell, Jonathan (21 July 2021). "Launch Log". Jonathan's Space Page. Retrieved 4 November 2021.
  4. ^ Krebs, Gunter. "Explorer: S-45". Gunter's Space Page. Retrieved 4 November 2021.
  5. ^ "Explorer Program". Mission and Spacecraft Library. NASA. Archived from the original on 27 January 2008. Retrieved 14 July 2010. Public Domain This article incorporates text from this source, which is in the public domain.