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ESRO 2 was a 75-kg spin-stabilized spacecraft that was launched on May 16, 1968, into a near polar orbit. The main objective of ESRO 2 was to conduct a study of solar astronomy and cosmic rays. The ESRO 2 experiments had their counterparts in the NASA-OSO series. The purpose of the spacecraft was to provide continuity to the solar radiation observations carried out by OSO D launched October 18, 1967. The particle experiments were designed to continue similar measurements carried out by the Ariel 1 (UK 1) satellite. The satellite had a spin rate of about 40 rpm and had completed 16,282 orbits of the earth before reentry on May 8, 1971, shortly after 0300 UT. No playback data has been available since December 10, 1968, following a mechanical failure of the onboard tape recorder. The failure reduced the data flow by about 80 percent, although a combination of Estrack (ESRO) and STADAAN (NASA) tracking stations were used.

Alternate Names

  • 03233
  • ESRO 2B
  • ESRO2
  • IRIS

Facts in Brief

Launch Date: 1968-05-17
Launch Vehicle: Scout
Launch Site: Vandenberg AFB, United States
Mass: 89.8 kg

Funding Agencies

  • NASA-Office of Space Science (United States)
  • European Space Agency (International)


  • Space Physics
  • Solar Physics
  • Astronomy

Additional Information

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



NameRoleOriginal AffiliationE-mail
Mr. L. Henry AndersonGeneral ContactNASA Goddard Space Flight Center
Mr. James L. MichaelGeneral ContactNASA Goddard Space Flight Center
Mr. Herbert L. EakerProject ManagerNASA Goddard Space Flight Center
Mr. Ants KutzerProject ManagerGes fur Weltraumforschung
Mr. James P. TalentinoGeneral ContactNASA Goddard Space Flight Center
Dr. D. Edgar PageProject ScientistESA-European Space Research and Technology Centre
Mr. Roger D. WerkingGeneral ContactNASA Goddard Space Flight
Dr. Leslie H. MeredithProject ScientistNASA Goddard Space Flight Center
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