REAL: A CubeSat Mission to Study Energetic Electron Precipitation into Earth’s Atmosphere

Abstract:

REAL (Relativistic Electron Atmospheric Loss) is a CubeSat mission that will characterize different modes of atmospheric electron precipitation by making high time resolution measurements of precipitating electron pitch angle and energy distributions. Although significant progress has been made in identifying plasma waves that drive energetic electron precipitation (EEP) [e.g., Thorne, 2010 for review], there are missing links in our understanding, including the physical “modes” of wave–particle interactions. For example, electrons may be scattered slowly through a diffusive process [e.g., Shprits et al., 2008 review], or rapidly through nonlinear processes [e.g., Albert, 2000; Bortnik et al., 2008, Omura et al., 2015]. REAL will distinguish between these modes of precipitation by measuring electrons over a wide energy range, from 100 eV to 2 MeV. The 3U CubeSat incorporates low-, medium- and high-energy instrument heads, with 2, 5 and 4 look-directions respectively, making use of advances in sensor miniaturization. It operates in low Earth orbit (LEO), ideal for measuring precipitation since the atmospheric loss cone is larger (~60 deg) than at the equator (few degrees), with time resolution sufficient to resolve electron microbursts. The pitch-angle resolved measurements will also distinguish between precipitating, quasi- trapped, and trapped populations, thus more accurately quantifying the electron loss rate and the impact on Earth’s atmosphere.