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Solar and Van Allen Belt Protons

NSSDCA ID: 1968-041A-02

Mission Name: ESRO 2
Principal Investigator:Prof. Harry Elliot


This experiment was designed to measure the proton flux outside the earth's atmosphere in the energy range 2 to 100 MeV using a telescope consisting of 4 solid-state devices separated by small amounts of absorber and shielded at one end. The data were acquired on the spectral and intensity variations of three distant particle populations (galactic cosmic rays, solar flare particles, trapped radiation in the Van Allen belts), the geomagnetic cutoff rigidities, at higher latitudes, and the way in which these items changed during periods of geomagnetic activity. The telescope also was used to measure the flux of alpha particles (5 to 70 MeV, mainly of solar origin) in two energy channels, and protons (1 to 100 MeV) in five energy channels using coincidence-anticoincidence techniques. A bending magnet removed electrons of energy less than 200 KeV. The experiment was aligned so that its view was perpendicular to the satellite spin axis. The experiment performed normally throughout the mission, except for some difficulties encountered during the period July to September 1968. The spacecraft decayed from orbit on May 8, 1971.

Alternate Names

  • ESRO2/SolarandVanAllenBeltProtons
  • S-27


    Additional Information

    Questions and comments about this experiment can be directed to: Coordinated Request and User Support Office



    NameRoleOriginal AffiliationE-mail
    Dr. Robert J. HyndsOther InvestigatorImperial
    Dr. John J. QuenbyOther InvestigatorImperial
    Prof. Harry ElliotPrincipal InvestigatorImperial College
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