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Explorer 33



Explorer 33 was a spin-stabilized (spin axis parallel to the ecliptic plane, spin period varying between 2.2 and 3.6 s) spacecraft instrumented for studies of interplanetary plasma, energetic charged particles (electrons, protons, and alphas), magnetic fields, and solar X rays at lunar distances. The spacecraft failed to achieve lunar orbit but did achieve mission objectives. The initial apogee occurred at about 1600 h local time. Over the first 3-yr period, perigee varied between 6 and 44 earth radii. Apogee varied between 70 and 135 earth radii, and the inclination with respect to the equator of the earth varied between 7 and 60 deg. Periods of principal data coverage (essentially 100%) are July 1, 1966 (launch), to January 14, 1970; February 21, 1970, to March 6, 1970; July 31, 1970, to September 14, 1970; January 15, 1971, to February 28, 1971; March 23, 1971, to May 31, 1971; and August 23, 1971, to September 15, 1971. No data were obtained after September 21, 1971.

Alternate Names

  • AIMP 1
  • Anchored IMP 1
  • IMP-D
  • 02258
  • Explorer33

Facts in Brief

Launch Date: 1966-07-01
Launch Vehicle: Delta
Launch Site: Cape Canaveral, United States
Mass: 212 kg

Funding Agency

  • NASA-Office of Space Science Applications (United States)


  • Planetary Science
  • 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
Dr. Alois W. SchardtGeneral ContactNASA Headquarters
Mr. John J. BrahmGeneral ContactNASA Goddard Space Flight Center
Mr. Jerome BarskyGeneral ContactNASA Goddard Space Flight Center
Mr. Paul L. HeffnerGeneral ContactNASA Goddard Space Flight Center
Dr. Norman F. NessProject ScientistNASA Goddard Space Flight
Mr. Paul G. MarcotteProject ManagerNASA Goddard Space Flight Center
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