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HEOS 2 was a spin-stabilized spacecraft with a highly eccentric orbit whose apogee occurred at high latitude. Its primary scientific mission was the investigation of interplanetary space and the high-latitude magnetosphere and its boundary in the region around the northern neutral point. HEOS 2 provided new data on the sources and acceleration mechanisms of particles found in the trapped radiation belts and in the polar precipitation regions and auroral zones. It also monitored solar activity and cosmic radiation. The satellite carried a magnetometer and particle detectors which covered a broad range from thermal to cosmic-ray energies. The satellite had three antennas to study extreme low frequency (ELF) waves and carried a sensitive micrometeorite detector. The spacecraft functioned normally until it reentered the Earth's atmosphere on August 5, 1974.

Alternate Names

  • 05814
  • HEOS-A2
  • HEOS2

Facts in Brief

Launch Date: 1972-01-31
Launch Vehicle: Delta
Launch Site: Vandenberg AFB, United States
Mass: 108 kg

Funding Agency

  • European Space Agency (International)


  • Space Physics

Additional Information

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



NameRoleOriginal AffiliationE-mail
Mr. C. W. ThomasGeneral ContactESA-European Space Research and Technology Centre
Dr. J. VandenkerckhoveProject ManagerESA-European Space Research and Technology Centre
Dr. Brian G. TaylorProject ScientistESA-European Space Research and Technology Centre
Mr. R. ColletteGeneral ContactESA-European Space Research and Technology Centre
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