The Radiation Environment and Effects Analysis of the LUMIO Mission

The Lunar Meteoroid Impact Observer (LUMIO) is a mission designed to observe, quantify, and characterise the impacts of meteoroids by detecting their flashes on the far side of the moon. These Lunar-based observations offer the opportunity to perform longer data taking compared to Earth-based ones thanks to the fact that they are not limited by illumination, weather and geometry conditions. LUMIO is a 12U CubeSat, with a mass of less than 22 kg, which will be placed on a halo orbit about the Earth-Moon L2 point, where permanent full-disk observation of the Lunar far side can be performed in absence of background noise due to the Earth. Besides the principal instrument of the mission, the LUMIO-Cam, an optical instrument capable of capturing the light flashes in the visible spectrum, which is custom-designed, all other subsystems (e.g. On-board Computer, Propulsion System, Communications, Attitude Determination and Control System, Electrical Power System etc.) are heavily relying on COTS parts. Radiation effects represent already a great concern for any small satellite mission in Low Earth Orbit and in the case of a lunar mission such as LUMIO, it becomes of paramount importance to analyse the harsh radiation environment this mission will face in order to design a radiation-tolerant spacecraft. In this paper we will present the detailed radiation analysis performed during Phase A. A Monte Carlo simulation based on GEANT4 was performed which includes a simplified 2D model of the spacecraft and the predicted fluxes of trapped particles, solar particles and cosmic rays fluxes for the selected orbit. The analysis included Total Ionising Dose and Single Event Effects predictions for the most critical electronic components. Recommendations for the LUMIO system design were drawn and will be used as input for the Phase B spacecraft and mission detailed design.