Explorer S-45A (satellite)

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

Explorer S-45A satellite before launch
Names	S-45A NASA S-45A
Mission type	Ionosphere research
Operator	NASA
COSPAR ID	EXS-451
Mission duration	Failed to orbit
Spacecraft properties
Spacecraft	Explorer S-45A
Spacecraft type	Science Explorer
Bus	S-45
Manufacturer	Goddard Space Flight Center
Launch mass	33.6 kg (74 lb)
Power	Solar cells and batteries
Start of mission
Launch date	24 May 1961, 19:48:05 GMT
Rocket	Juno II (AM-19G)
Launch site	Cape Canaveral, LC-26B
Contractor	Army Ballistic Missile Agency
End of mission
Destroyed	Failed to orbit
Orbital parameters
Reference system	Geocentric orbit (planned)
Regime	Highly elliptical orbit
Perigee altitude	221 km (137 mi)
Apogee altitude	181,100 km (112,500 mi)
Inclination	33.0°
Period	5013.90 minutes
Instruments
Beacon
Explorer program ← Explorer 11 Explorer S-55 →

Launch

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]