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OSCAR 4 was a regular tetrahedron with edges 48 cm long. It had four independent monopole antennae and contained a tracking beacon transmitter and a communications repeater. It was powered by a solar cell array and batteries but an unplanned 161-x 33,000-km orbit prevented nominal use. Only about 12 two-way communications were established through the repeater, but one on December 22, 1965 was the first direct satellite communication between the United States and the USSR.

Alternate Names

  • 01902
  • COMSAT Navigational Sat
  • OSCAR4

Facts in Brief

Launch Date: 1965-12-21
Launch Vehicle: Titan III-C
Launch Site: Cape Canaveral, United States
Mass: 15 kg

Funding Agencies

  • Project Oscar Inc (United States)
  • Department of Defense-Department of the Navy (United States)


  • Communications

Additional Information

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



NameRoleOriginal AffiliationE-mail
Dr. Perry I. KleinGeneral ContactAMSAT
Mr. ProjoscarProject ManagerFoothills College
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