LASP Science Seminars

The discovery of Earth’s Van Allen radiation belts in 1958 revealed the hazardous radiative environment for spacecraft operating within. Understanding, modeling, and eventually predicting the dynamics of energetic electrons in the radiation belts have long been targets that space physicists have pursued. Since the launch of NASA Van Allen Probes in 2012, significant progress has been achieved in understanding the strong enhancement of relativistic electrons in the radiation belt. However, the fast radiation belt dropout remains unsolved, in which electron fluxes are observed to drop by orders of magnitudes in a few hours. Where do the electrons go during the dropout? This is one of the most important outstanding questions in radiation belt studies. In this talk, I will first briefly review the physical loss processes of energetic electrons that could be responsible for the fast radiation belt dropout. Then I will discuss our recent studies in modeling the loss of energetic electrons during the observed radiation belt dropout, either by transport across the magnetopause into interplanetary space or by precipitation into the atmosphere. Finally, I will discuss the future challenges and opportunities in understanding and modeling the mysterious dropout of radiation belt electrons.