Medium‐Energy Electron Detector Onboard the FY‐3E Satellite

The Medium‐Energy Electron Detector (MEED), a space weather monitoring instrument on the Fengyun‐3E (FY‐3E) satellite, is introduced in this paper. The MEED utilizes pin‐hole imaging technology on low‐orbit satellites for medium‐energy electron detection. Two orthogonal sensor heads enable the MEED to measure electrons from 18 directions simultaneously in the energy range of 30–600 keV (divided into eight exponentially distributed energy channels). The instrument has a ∼12° angular resolution and covers two 180° × 30° fields of view. With the magnetometer onboard the same satellite, the pitch angle distribution of medium‐energy electrons can be obtained with good angular resolution. This paper presents the design principle, ground calibration results, and preliminary on‐orbit test results of the FY‐3E MEED. The on‐orbit test results show that the medium‐energy electron fluxes, geographical distribution, energy spectrum, and pitch angle observed by the MEED are in agreement with the expected results. The MEED provides a new method to observe the low‐orbit energetic electron radiation environment from the FY‐3E satellite. Its successful in‐orbit operation will enable the theoretical study of radiation belts and improve space weather research. Plain Language Summary The Medium‐Energy Electron Detector (MEED) is a space weather monitoring instrument onboard the FY‐3E satellite. The MEED utilizes pin‐hole imaging technology on a low‐orbit satellite for medium‐energy electron detection for the first time. The MEED has two orthogonal sensor heads that can measure 30–600 keV electrons from 18 directions simultaneously. With the magnetometer onboard the same satellite, high‐resolution observations of the electron pitch angle distribution can be derived. The ground calibration and the preliminary in‐orbit measurements verify the good performance of the MEED. The MEED data will be of great importance for radiation belt research and space weather applications. Key Points The Medium‐Energy Electron Detector (MEED) on the FY3E satellite measures 30–600 keV electrons from 18 directions with two orthogonally‐mounted pin‐hole imaging sensor heads The first results of the MEED are in agreement with the AE9 model and DEMETER observations The high‐quality data of MEED will contribute to space physics and space weather research