New Magnetospheric Substorm Injection Monitor: Image Electron Spectrometer On Board a Chinese Navigation IGSO Satellite

Substorm injections are one of the most dynamic processes in Earth's magnetosphere and have global consequences and broad implications for space weather modeling. They can be monitored using energetic electron detectors on geosynchronous satellites. The Imaging Electron Spectrometer (IES) on board a Chinese navigation satellite, launched on 16 October 2015 into an inclined geosynchronous satellite orbit (IGSO), provides the first energetic electron measurement in IGSO orbit to the best of our knowledge. The IES was developed by Peking University and is named hereafter as BD‐IES. Using a pin‐hole technique, the BD‐IES instrument measures 50–600 keV incident electrons in eight energy channels from nine directions covering a range of 180° in polar angle. Data collection by the BD‐IES instrument have recently passed the 1 year mark, which reflects a successful milestone for the mission. The innermost and outermost signatures of substorm injection at L  ~ 6 and 12 have been observed by the BD‐IES with a high L shell spatial coverage, complementary to the existing missions such as the Van Allen Probes that covers the range below L  ~ 6. There are another two BD‐IES instruments to be installed in the coming Chinese Sun‐synchronous and geosynchronous satellites, respectively. Such a configuration will provide a unique opportunity to investigate inward and outward radial propagation of the substorm injection region simultaneously at high and low L shells. It will further elucidate potential mechanisms for the particle energization and transport, two of the most important topics in magnetospheric dynamics.