Electron Losses and Fields Investigation (ELFIN)

The Electron Losses and Fields Investigation (ELFIN) was a UCLA-led twin-CubeSat mission studying how energetic electrons escape Earth’s radiation belts into the atmosphere. Its two spacecraft helped distinguish spatial structure from time variation in electron precipitation, supporting research on space weather and magnetosphere–ionosphere coupling. Each spacecraft carried electron and ion energetic-particle detectors and a boom-mounted fluxgate magnetometer. UCLA students and staff designed, built, tested and operated the mission, combining instrument development with spacecraft systems and ground operations. ELFIN launched aboard a Delta II from Vandenberg on 15 September 2018. The mission continued for just over four years. ELFIN-A reentered on 17 September 2022 and ELFIN-B on 30 September 2022; the university reported that the mission met or surpassed its objectives. Publications, science data and analysis software remain available through the official mission website.