Explorer S-46

Prototype satellite payload of the Explorer S-46 satellite (Gift of James A. Van Allen and the University of Iowa) [1]
Names	NASA S-46
Mission type	Earth science
Operator	NASA / JPL
COSPAR ID	EXS-46
Mission duration	Failed to orbit
Spacecraft properties
Spacecraft	Explorer S-46
Spacecraft type	Science Explorer
Bus	S-46
Manufacturer	Jet Propulsion Laboratory
Launch mass	41 kg (90 lb)
Dimensions	76 × 76 cm (30 × 30 in)
Power	100 watts
Start of mission
Launch date	23 March 1960, 13:35:11 GMT
Rocket	Juno II (AM-19C)
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	Medium Earth orbit
Perigee altitude	573 km (356 mi)
Apogee altitude	1,073 km (667 mi)
Inclination	50.27°
Instruments
Cadmium sulfide (CdS) Proton Detector Cadmium sulfide (CdS) Particle Detector Electron Spectrometer High Energy Geiger–Müller Tube Medium Energy Geiger–Müller Tube
Explorer program ← Explorer 7 Explorer 8 →

Explorer S-46 was a NASA satellite with a mass of 41 kg (90 lb). It was the last of the original series of Explorer satellites built, designed, and operated by the Jet Propulsion Laboratory and Army Ballistic Missile Agency (ABMA).^[2]

Its mission was to analyze electron and proton radiation energies in a highly elliptical orbit.^[2]

Explorer S-46 was a joint ABMA / NASA-JPL mission. The payload detector experiments were developed by the State University of Iowa. The detector assembly comprised five instruments: a Cadmium sulfide (CdS) broom low-energy proton detector, a Cadmium sulfide (CdS) low-energy particle detector; an electron spectrometer; a Geiger-Müller high-energy particle counter; and a Geiger-Müller medium energy particle counter. These were housed in the front of the Sergeant rocket engine that comprised the fourth (upper-stage) of the Juno II launch vehicle.^[2]

• Cadmium sulfide (CdS) Proton Detector
• Cadmium sulfide (CdS) Particle Detector
• Electron Spectrometer
• High Energy Geiger–Müller Tube
• Medium Energy Geiger-Müller Tube

The four-stage Juno II launch vehicle used a Jupiter missile as the first stage. The second stage was assembled as a circumferential "tub" of 11 scaled-down Sergeant rocket engines (solid propellant), the third stage was assembled as three scaled-down Sergeant rocket engines nested in the center of the "tub", and a single modified Sergeant rocket engine and casing comprising the fourth stage was mounted on top of this.^[2]

Explorer S-46 was launched using a Juno II launch vehicle on 23 March 1960, at 13:35:11 GMT, from LC-26B. Telemetry was lost shortly after the first stage burnout and one second stage motor failed to ignite, resulting in imbalanced thrust and inability to reach orbital velocity. The spacecraft did not achieve orbit.^[2]

• Explorer 8
• Explorer program