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ERS 21



OV5-4 (ERS 21) was a magnetospheric particle radiation satellite that was used to examine heat transfer in liquids in zero-G. It was launched by the US Air Force from Cape Canaveral aboard a Titan 3C rocket.

Alternate Names

  • 03430
  • ERS21
  • ORS 3(D)
  • OV5-4
  • PL-683I

Facts in Brief

Launch Date: 1968-09-26
Launch Vehicle: Titan III-C
Launch Site: Cape Canaveral, United States
Mass: 12.7 kg

Funding Agency

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


  • Microgravity

Additional Information

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



NameRoleOriginal AffiliationE-mail
Dr. Louis S. WalterProject ScientistNASA Goddard Space Flight Center
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