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Explorer 35



Explorer 35 was a spin-stabilized spacecraft instrumented for interplanetary studies, from lunar orbit, of the interplanetary plasma, magnetic field, energetic particles, and solar X rays. It was also designed to study the Moon's gravity field, ionosphere and micrometeorite and dust distribution. It was launched into an elliptical lunar orbit. The spin axis direction was nearly perpendicular to the ecliptic plane, and the spin rate was 25.6 rpm. Mission objectives were achieved. After successful operation for 6 years, the spacecraft was turned off on June 24, 1973. The orbit would have naturally decayed after this point, resulting in an impact on the Moon at an unknown time and location. Explorer 35 (or Explorer XXXV) was also known as the Anchored Interplanetary Monitoring Platform E (AIMP-E, or just IMP-E).

Spacecraft and Subsystems

Explorer 35 was similar to the earlier Explorer 33. Spacecraft mass was 93.5 kg. The main body of the spacecraft was an octagonal prism, 71 cm (28 in) across and 20.3 cm (8 in) high. Four arrays containing 6144 n/p solar cells, providing an average of 70 W power, extended from the main bus, along with two 183 cm (6 ft) magnetometer booms. Four whip antennas are mounted on top of the spacecraft. A retrorocket was mounted on top of the bus. Power was stored in silver-cadmium (Ag-Cd) batteries. Communication (PFM telemetry) was via a 7-W transmitter and a digital data processor.

The science payload had a mass of 23.1 kg (51 lb) and included two 3-axis magnetometers, low energy protons and alpha energy analyzer, low energy protons and electrons detector, energetic particle detector, plasma probe, a micrometeorite detector, a solar cell damage experiment, and gravity field and bistatic radar experiments.

Mission Profile

Explorer 35 was launched on 19 July 1967 at 14:19:02 UT from the Eastern Test Range of Cape Kennedy, Florida on a Thor Delta E-1 (Thrust Augmented Delta). It went on a direct ascent trajectory, reaching the Moon on 22 July. It entered an initial 800 x 7692 km altitude elliptical lunar orbit at 147 degree inclination after a 23 second retrorocket burn. The main engine separated 2 hours later. Explorer 35 operated normally in lunar orbit for 6 years until shut off on 24 June 1973.

Alternate Names

  • 02884
  • AIMP 2
  • AIMP-E
  • Anchored IMP 2
  • Explorer35
  • IMP-E

Facts in Brief

Launch Date: 1967-07-19
Launch Vehicle: Thrust Augmented Delta
Launch Site: Cape Canaveral, United States
Mass: 93.5 kg
Nominal Power: 70 W

Funding Agency

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


  • Planetary Science
  • Space Physics
  • Solar Physics

Additional Information

Questions and comments about this spacecraft can be directed to: Dr. David R. Williams



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. Frank W. GaetanoGeneral ContactNASA Headquarters
Mr. Paul L. HeffnerGeneral ContactNASA Goddard Space Flight Center
Mr. Paul G. MarcotteProject ManagerNASA Goddard Space Flight Center
Dr. Norman F. NessProject ScientistNASA Goddard Space Flight Center
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