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S 46A



Explorer (S-46) was launched using a Juno II rocket. Its mission was to analyze electron and proton radiation energies in a highly elliptical orbit. Launch took place at 13:35:11 UT on 23 March 1960 from Cape Canaveral. Telemetry was lost shortly after the first stage burnout and one of the upper stages failed to fire. The spacecraft did not achieve orbit.

Spacecraft and Subsystems

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

Launch Vehicle

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

Alternate Names

  • Explorer S-46
  • IE-B
  • S46A

Facts in Brief

Launch Date: 1960-03-23
Launch Vehicle: Juno 2 (Juno II)
Launch Site: Cape Canaveral, United States
Mass: 15.7 kg

Funding Agency

  • Department of Defense-Department of the Air Force (United States)


  • Space Physics

Additional Information

Questions and comments about this spacecraft can be directed to: Dr. David R. Williams



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