Energetic electron detection packages on board Chinese navigation satellites in MEO

Energetic electron measurements and spacecraft charging are of great significance for theoretical research in space physics and space weather applications.In this paper,the energetic electron detection package(EEDP)deployed on three Chinese navigation satellites in medium Earth orbit(MEO)is reviewed.The instrument was developed by the space science payload team led by Peking University.The EEDP includes a pinhole medium-energy electron spectrometer(MES),a high-energy electron detector(HED)based onΔE-E telescope technology,and a deep dielectric charging monitor(DDCM).The MES measures the energy spectra of 50−600 keV electrons from nine directions with a 180°×30°field of view(FOV).The HED measures the energy spectrum of 0.5−3.0 MeV electrons from one direction with a 30°cone-angle FOV.The ground test and calibration results indicate that these three sensors exhibit excellent performance.Preliminary observations show that the electron spectra measured by the MES and HED are in good agreement with the results from the magnetic electron-ion spectrometer(MagEIS)of the Van Allen Probes spacecraft,with an average relative deviation of 27.3%for the energy spectra.The charging currents and voltages measured by the DDCM during storms are consistent with the highenergy electron observations of the HED,demonstrating the effectiveness of the DDCM.The observations of the EEDP on board the three MEO satellites can provide important support for theoretical research on the radiation belts and the applications related to space weather.

Large-scale episodic enhancements of relativistic electron intensities in Jupiter's radiation belt

Previous studies indicate that,in the Jovian magnetosphere,the long-term trend of the radial profile of relativistic electron intensities is primarily shaped by slow radial diffusion.However,measurements by the Galileo spacecraft reveal the existence of transient increases in MeV electron intensities well above the ambient distribution.It is unclear how common such transient enhancements are,and to which dynamic processes in Jupiter's magnetosphere their occurrence is linked.We investigate the radial distributions of >11 MeV and >1 MeV electron intensities from 9R_(J) to 40R_(J)(R_(J)=71492km denotes the Jovian radius),measured by the Galileo spacecraft from 1996 to 2002.We find transient enhancements of MeV electrons during seven Galileo crossings,mostly occurring around~20R_(J).An apparent dawn-dusk asymmetry of their occurrence is resolved,with a majority of events discovered at dawn.This dawn-dusk asymmetry,as well as the average recurrence time scale of a few days,implies a potential relationship between the MeV electron transients and the storm-like dynamics in the middle and outer magnetosphere detected using a variety of Galileo,Juno and remote sensing aurora observations.We suggest that the observations of some of these transients in the inner magnetosphere may result from a synergy between the convective transport by a large-scale dawn-dusk electric field and the sources provided by injections in the middle magnetosphere.