A document by Mykhaylo Shumko. Click on the document to view its contents.

This study investigates the energy spectrum of electron microbursts observed by the Focused Investigations of Relativistic Electron Burst Intensity, Range, and Dynamics II (FIREBIRD-II, henceforth FIREBIRD) CubeSats. FIREBIRD is a pair of CubeSats, launched in January 2015 into a low Earth orbit, that focus on studying electron microbursts. High resolution electron data from FIREBIRD-II consists of 5 differential energy channels between 200 keV and 1 MeV and a $>$1 MeV integral channel. This covers an energy range that has not been well studied from low Earth orbit with good energy and time resolution. This study aims to improve understanding of the scattering mechanism behind electron microbursts by investigating their spectral properties and their relationship to the equatorial electron population under different geomagnetic conditions. Microbursts are identified in the region of the North Atlantic where FIREBIRD only observes electrons in the bounce loss cone. The electron flux and exponential energy spectrum of each microburst is calculated using a FIREBIRD instrument response modeled in GEANT4 (GEometry ANd Tracking) and compared with the near equatorial electron spectra measured by the Van Allen Probes. Microbursts occurring when the AE index is enhanced tend to carry more electrons with relatively higher energies. The microburst scattering mechanism is more efficient at scattering electrons with lower energies, however the difference in scattering efficiency between low and high energy is reduced during periods of enhanced AE.

No existing instrument is capable of consistently measuring all three components of the DC and low frequency electric field (E-field) throughout the heliosphere with sufficient accuracy to determine the smallest, and most geophysically relevant component: the E-field component parallel to the background magnetic field. E-field measurements in the heliosphere are usually made on spinning spacecraft equipped with two disparate types of double probe antennas: (1) long wire booms in the spin plane, and (2) ~10 times shorter rigid booms along the spin axis. On such systems, the potential difference (signal + noise) is divided by the boom length to produce a resultant E-field component. Because the spacecraft-associated errors are larger nearer the spacecraft, the spin plane components of the E-field are well measured while the spin axis component are poorly measured. As a result, uncertainty in the parallel E-field is usually greater than its measured value. Grotifer leverages more than fifty years of expertise in delivering highly accurate spin plane E-field measurements, while overcoming inaccuracies generated by spin axis E-field measurements. Its design consists of mounting detectors on two rotating plates, oriented at 90° with respect to each other, on a non-rotating central body. Each rotating plate has two component measurements of the E-field such that the Twin Orthogonal Rotating Platforms (TORPs) provide four instantaneous measurements of the E-field, and the three E-field components are well-measured by the rotating detectors. Grotifer (Giant rotifer) is a reference to the rotifer, also known as the “wheel animalcule”, which has twin crowns of antenna-like cilia that appear to rotate in all directions. Grotifer marks a profound change in E-field instrument design that represents the best path forward to close the observational gap that currently hampers resolution of significant science questions at the forefront of space plasma physics research. Here, we present the Grotifer design concept implemented as a 27-U CubeSat, discuss the important features in the design and operation of Grotifer, and demonstrate the feasibility of implementing Grotifer using existing sub-systems and technologies.