The CELESTA CubeSat In-Flight Radiation Measurements and Their Comparison With Ground Facilities Predictions

The CELESTA CubeSat has employed radiation monitors developed by the Conseil Européen pour la Recherche Nucléaire (CERN) Centre, used for measuring the radiation environment at accelerators, to measure the space radiation field in a medium-Earth orbit (MEO). The technology is based on three static random-access memories (SRAMs) that are sensitive to single-event upsets (SEUs) and single-event latchups (SELs). The measurements were performed for the duration of two months. A statistically significant amount of SEUs and SELs was collected. No solar proton event effects were observed in the data during this period. The in-flight rates were compared with respect to estimations coming from the environmental space fluxes available in the Outil de Modelisation de l’Environmment Radiative Externe (OMERE) tool suite and ground facility measurements done with ions and protons. The analysis emphasizes the importance of employing more sophisticated satellite shielding models for the calculation of the fluxes reaching the detectors as well as the need to know accurately the proton energy threshold of the SEU cross section Weibull response of the devices. Both observations mainly arise from the peculiar spectral distribution of protons in this MEO peaking at 10–20 MeV, which differs from those of a low-Earth orbit (LEO) environment.