The space environment particle density in Low Earth Orbit based on two decades of in situ observation

Abstract

Currently the only method to establish the prevalence of particles, space debris or meteoroids, sized between 1 micrometre and a few centimetres, in Earth orbit is by instruments or witness plates dedicated to in situ detection. Derived usable datasets are remarkably scarce and cover varying time periods and constrained orbital regions. Nonetheless, space environment models use those limited datasets as anchor points to extrapolate results to the entirety of Earth orbit, from the beginning of the space age to decades into the future. Here we present a readout of over 20 years of Sensor Unit 1 (SU-1) of DEBris In orbit Evaluator 1 (DEBIE-1), an in situ detector that was launched in October 2001, providing the longest continuous set of measurements available to date. The dataset has not been used in the generation of space environment models and hence provides a first independent source for the detection of environment changing events and for the calibration of long term evolution models. The DEBIE-1 SU-1 measurements, which primarily capture ejecta, meteoroids, and small debris fragments, were compared with predictions from ESA’s MASTER model. While general alignment in flux trends was observed, notable deviations occurred during certain periods. DEBIE-1 SU-1 recorded increased impact rates following major fragmentation events. However, no direct correlation was established.