A 'Worst Case' Spacecraft Environment as Observed by SCATHA on 24 April 1979
Abstract
A survey of data from the first year of the P78-2 SCATHA satellite operations showed that a highest level spacecraft frame charging (phi sub f) both in sunlight (-340 V) and in eclipse (> -8 kV) occurred on 24 April 1979. Analysis of the data indicates that if the sunlight charging environment had been present during eclipse, the vehicle would have charged in excess of 15 kV which is above any known charging level observed to date for the SCATHA satellite. Therefore, the environment at the peak of the sunlight charging at approx. 0650 UT 24 April 1979 was chosen for this worst case study. The environment at this time is characterized by an injection of high energy (30-335 keV) electron fluxes whose combined current correlates with phi sub f with a correlation coefficient of 0.95. The fluxes were highly anisotropic, maximizing perpendicular to the magnetic field. The low energy (< 4 keV) electron population had a density < 1/cc and the low energy ions were near background. The measured electron distribution functions, when fit to double Maxwellians by a least squares technique, show that throughout the sunlight charging the high and low temperatures remained nearly the same, while the density of the high energy component followed the charging levels. The injection occurred simultaneously with the rapid return of the magnetospheric magnetic field to a more dipole-like configuration.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 31, 1981
- Accession Number
- ADA108680
Entities
People
- E. G. Mullen
- H. B. Garrett
- M. S. Gussenhoven
Organizations
- University of Maryland