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Low-Energy Proton and Electron Differential Energy Analyzer (LEPEDEA)

NSSDCA ID: 1977-102A-03

Mission Name: ISEE 1
Principal Investigator:Prof. Louis A. Frank


This experiment was designed to study, by means of identical instrumentation on the mother/daughter spacecraft, the spatial and temporal variations of the solar wind and magnetosheath electrons and ions. Protons and electrons in the energy range from 1 eV to 45 keV were measured in 64 contiguous energy bands with an energy resolution (delta E/E) of 0.16. A quadrispherical low-energy proton and electron differential energy analyzer (LEPEDEA), employing seven continuous channel electron multipliers in each of its two (one for protons and one for electrons) electrostatic analyzers was flown on both the mother and the daughter spacecraft. All but 2% of the 4-pi-sr solid angle was covered for particle velocity vectors. A GM tube was also included, with a conical field of view of 40-deg full-angle, perpendicular to the spin axis. This detector was sensitive to electrons with E>45 keV, and to protons with E>600 keV.

Alternate Names

  • FRM
  • Hot Plasma

Facts in Brief

Mass: 5 kg
Power (avg): 5 W

Funding Agency

  • NASA-Office of Space Science (United States)


  • Space Physics: Magnetospheric Studies
  • Space Physics: Heliospheric Studies

Additional Information

Questions and comments about this experiment can be directed to: Dr. H. Kent Hills



NameRoleOriginal AffiliationE-mail
Prof. Charles F. KennelOther InvestigatorUniversity of California, Los
Prof. Vytenis M. VasyliunasOther InvestigatorMax-Planck-Institut fur
Prof. Louis A. FrankPrincipal InvestigatorUniversity of

Selected References

  • Frank, L. A., et al., Three-dimensional plasma measurements within the earth's magnetosphere, Space Sci. Rev., 22, No. 6, 739-763, doi:10.1007/BF00212621, Dec. 1978.
  • Frank, L. A., et al., Quadrispherical LEPEDEAS for ISEE's-1 and -2 plasma measurements, IEEE Trans. Geosci. Electron., GE-16, No. 3, 221-225, doi:10.1109/TGE.1978.294551, July 1978.
  • Frank, L. A., Technical progress report on data reduction and analysis for the International Sun-Earth Explorer A and B (ISEE-1+2) magnetospheric and interplanetary plasma instruments, U. of Iowa, Dept. Phys. Astron., Iowa City, IA, March 1982.
  • Frank, L. A., et al., Currents in the earth's magnetotail, in Magnetospheric Currents, 147-157, Ed. T.A. Potemra, AGU Geophys. Mono. 28, Washington, DC, doi:10.1029/GM028p0147, 1984.
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