NASA Logo, National Aeronautics and Space Administration
NASA Space Science Data Coordinated Archive Header




Interplanetary Monitoring Platform H (IMP-H, also Explorer 47, or IMP-7) continued the study begun by earlier IMP spacecraft of the interplanetary and magnetotail regions from a nearly circular orbit, near 37 Earth radii. It was designed to measure energetic particles, plasma, and electric and magnetic fields.

Spacecraft and Subsystems

IMP-H was a 16-sided drum-shaped spacecraft, 157.8 cm high and 135.6 cm in diameter, with a mass of 390 kg (860 lbs). It consisted of an aluminum honeycomb shelf supported by eight struts and a 46 cm diameter thrust tube on the underside. Experiment modules are mounted on the top side of the shelf, with the experiment section fully covered by metallic covers and side panels.

It had two approximately 3.35 meter long booms extending from the drum holding various experiment packages, and two 1.22 meter long booms holding the attitude control system. The spacecraft was powered by three solar array rings and a chemical battery, giving a maximum power of 152 W. Scientific data were telemetered at 1600 bps (with a secondary 400-bps rate available).

It carried eight particle experiments, two fields experiments, and three plasma experiments. It also carried three engineering tests: monitoring of 12 thermal coatings, newly developed integral glass solar cells, and new data multiplex and data processing units.

Mission Profile

IMP-H launched on 23 September 1972 at 01:20:00.559 UT (9:20 pm 22 September EDT)from Kennedy Space Center on a Delta 1640 with an extended first stage and TE 364-4 third stage. It went into a 201,599 x 235,639 km orbit with a period of 17,702 minutes and an inclination of 17.2 degrees. The spin axis was normal to the ecliptic plane, and the spin period was 1.3 s. The spacecraft was turned off on October 31, 1978.

Alternate Names

  • 06197
  • Explorer 47
  • IMP 7
  • PL-713A
  • imp7

Facts in Brief

Launch Date: 1972-09-23
Launch Vehicle: Delta
Launch Site: Cape Canaveral, United States
Mass: 390 kg

Funding Agency

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


  • Space Physics
  • Solar Physics

Additional Information

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



NameRoleOriginal AffiliationE-mail
Mr. John R. HoltzProgram ManagerNASA Headquarters
Mr. William R. LimberisProject ManagerNASA Goddard Space Flight Center
Dr. Norman F. NessProject ScientistNASA Goddard Space Flight Center
Dr. Erwin R. SchmerlingProgram ScientistNASA Headquarters
Dr. James H. TrainorGeneral ContactNASA Goddard Space Flight Center

Other IMP 7 Data/Information at NSSDCA

Retrieve/browse OMNI (hourly solar wind field/plasma) data with OMNIWeb

Related Data/Information at NSSDCA

Information on other Explorer spacecraft

Other Sources of IMP 7 Data/Information

Daily LEPEDEA (IMP 7 and IMP 8) spectrograms at U. Iowa

[] NASA Logo -