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IE C (Injun 5, Explorer 40)

Explorer 40 (IE C, Injun 5) [NASA]

Injun 5 (Explorer 40) was a 71 kg magnetically oriented spacecraft and was launched by a Scout-B rocket, together with a 3.65-m inflatable balloon (Explorer 39) used for air density measurements. Injun 5 was designed to accomplish the following objectives:

  • comprehensive study of the downward flux of charged particles,
  • study of very low frequency (VLF) radio emission in the ionosphere associated with the downward flux,
  • study of geomagnetically trapped protons, alpha particles, and electrons,
  • observation of solar cosmic rays,
  • observation of the continuing decay of the Starfish artificial radiation belt, and
  • study of the temperature and density of electrons and positive ions of thermal and near thermal energy.

Following instruments were on board:

  • Low-Energy Proton and Electron Differential Energy Analyzer (LEPEDEA)
  • VLF Receiver
  • Solid-State Particle Detector
  • Spherical Retarding Potential Analyzer

The spacecraft systems performed normally except for the malfunction of the solar cell power dump device (shortly after launch) which caused the solar cells to deliver a lower power level to the experiments and reduced the time during which the onboard tape recorder could be run. The passive magnetic alignment became effective in mid-December 1968. The spacecraft was turned off from 31 May 1970, to 18 February 1971, after this period it was turned on again. The spacecraft was put in an operational off-mode in early June 1971, and became inoperable shortly thereafter.

A back up satellite was built, but not launched. It was donated to the Smithsonian National Air and Space museum.

Nation: USA
Type / Application: Research
Operator: NASA
Equipment: see above
Propulsion: None
Power: Solar cells, batteries
Mass: 71 kg
Orbit: 681 km × 2533 km, 80.67
Satellite COSPAR Date LS Launch Vehicle Remarks
Explorer 40 (IE C, Injun 5) 1968-066B 08.08.1968 Va SLC-5 Scout-B with Explorer 39
IE C back up - not launched Va SLC-5 Scout-B


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