Development of the Energetic Charged Particle Instrument for the ESRA CubeSat Mission

The Experiment for Space Radiation Analysis (ESRA) is the first in a new series of demonstration and validation missions for the Los Alamos National Laboratory. This mission will utilize a 12U CubeSat platform and will be placed in a geosynchronous transfer orbit to make measurements of the dynamic charged particle populations in the Earth's radiation belts. Currently, there are no data from CubeSats operating in the radiation belts and this is an active space for CubeSat development. The Energetic Charged Particle (ECP) instrument on board the ESRA CubeSat is a particle telescope which aims to test and mature new technologies. The energy range of interest for the energetic charged particle sensor is from 100 keV to 1000 MeV for protons, and from 100 keV to 20 MeV for electrons. The instrument is comprised of five detection elements in a stacked configuration, surrounded with shielding to suppress spurious background events. We incorporate direct-to-digital readout electronics, with four channels served by a dedicated amplifier chain using Amptek A250 CSAs and one channel processed by the Amptek A121 CSA with an integrated discriminator. Signals are processed onboard using a Lattice FPGA, and commanding and monitoring is performed using a Vorago VA416x0 ARM Cortex-M4 Microcontroller. Data is sent to the space vehicle for downlinking through a SpaceWire interface. Selectable readout modes allow us to control data collection rates for dynamic radiation environments. The instrument design minimizes size, weight, and power requirements while pursuing an ambitious scientific measurement capability. This paper will present the instrument design, system architecture, initial laboratory results, and planned on-orbit scientific measurements.