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

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

NSSDCA ID: 1971-109A-04

Mission Name: Ariel 4
Principal Investigator:Prof. Louis A. Frank


A Low-Energy Proton and Electron Differential Energy Analyzer (LEPEDEA) measured the differential energy spectra of proton and electron intensities, in the energy range 5 keV to 50 keV, at low altitudes within the outer radiation zone and over the auroral zones and polar caps. The angular distribution and temporal variations of these particles were also considered. The data obtained were correlated with data from the onboard VLF and plasma experiments. The LEPEDEA was composed of curved plate electrostatic analyzers and continuous channel multipliers and had 45 energy channels. The detector also had an Eon Type 213 Geiger-Mueller tube (with collimated field of view directed parallel to those of the LEPEDEA) to provide background measurements for the LEPEDEA channels and to survey directional intensities of protons (E>500 keV) and electrons (E>45 keV). The experiment operated normally from launch until April 29, 1972, when a transistor failure caused certain energy level and experiment mode identification to be lost in the high speed telemetry. However, all but one of the functions lost because of the failure (experiment temperature) were recovered in the spacecraft low speed encoder mode. Some details of high-energy electron intensities were lost due to the lower temporal resolution.

Alternate Names

  • Ariel4/LEPEDEA


  • Space Physics: Magnetospheric Studies

Additional Information

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



NameRoleOriginal AffiliationE-mail
Dr. John D. CravenOther InvestigatorUniversity of
Dr. M. A. SchieldOther InvestigatorUniversity of Iowa
Mr. David M. YeagerOther InvestigatorUniversity of Iowa
Prof. Louis A. FrankPrincipal InvestigatorUniversity of
[] NASA Logo -