The detection of ultra-relativistic electrons in low Earth orbit
Dammasch, Ingolf E.; Berghmans, David; Dominique, Marie; Pierrard, Viviane; Katsiyannis, Athanassios C.; Rosson, Graciela Lopez; Keyser, Johan De; Kruglanski, Michel; Donder, Erwin De
Abstract
Aims: To better understand the radiation environment in low Earth orbit (LEO), the analysis of in-situ observations of a variety of particles, at different atmospheric heights, and in a wide range of energies, is needed.
Methods: We present an analysis of energetic particles, indirectly detected by the large yield radiometer (LYRA) instrument on board ESA's project for on-board autonomy 2 (PROBA2) satellite as background signal. Combining energetic particle telescope (EPT) observations with LYRA data for an overlapping period of time, we identified these particles as electrons with an energy range of 2 to 8 MeV.
Results: The observed events are strongly correlated to geo-magnetic activity and appear even during modest disturbances. They are also well confined geographically within the L = 4-6 McIlwain zone, which makes it possible to identify their source.
Conclusions: Although highly energetic particles are commonly perturbing data acquisition of space instruments, we show in this work that ultra-relativistic electrons with energies in the range of 2-8 MeV are detected only at high latitudes, while not present in the South Atlantic Anomaly region.