Early Measurements of Electron Precipitation Using the Firebird Cubesats

We present measurements from energetic particle detectors from the FIREBIRD CubeSats. FIREBIRD is a pair of 1.5U CubeSats equipped with a pair of energetic electron detectors measuring electrons from 200 keV to 1 MeV in energy with 18.75ms time resolution for targeted intervals, as well as producing a lower time resolution (6s) continuous data product of 1 MeV electron precipitation. Although the two spacecraft were unable to operate simultaneously we present measurements from both spacecraft of energetic electrons in low-earth orbit, specifically near the bounce and drift loss cones. We present an analysis of the energy characteristics of the precipitation observed on the spacecraft looking at variations in the energy spectra, both in terms of location but also taking into account the slow rotation of the spacecraft owing to its passive magnetic stabilization. This slow rock results in a sampling of a range of pitch angles with the detectors, and a consequent variation in energy spectra. We discuss both the physical ramifications of the measurements as well as instrumental challenges and opportunities intrinsic to making the measurement in a CubeSat.