Solar Energetic Proton forecasting for Mars travel using SOHO and STEREO-A REleASE in fall 2024

Solar Energetic Ion Events (SEP) can have major impact on technology and human exploration of the Moon and Mars. Therefore warnings of an increased radiation exposure to electronics and astronauts would give sufficient time to take action like moving to a radiation shelter. The Relativistic Electron Alert System for Exploration (REleASE) has been succesfully developed to provide such early warnings for the Earth environment by exploiting the time difference of the arrival of SEP electrons and ions at 1 AU. Interplanetary travel to and from Mars using a Hohmann trajectory is not completely covered by the original REleASE forecast due to the longitudinal seperation between the spacecraft and Earth. The slow STEREO A fly by in 2023 allows to investigate longitudinal  dependencies of the REleASE forecast system. Here we investigate three SEP events observed by the Radiation Assessment Detector (RAD) on the Martian surface from September to December 2024 when the magnetic foot point separation in longitude of Mars and STEREO / Earth were between 77 and 36 degree / 96 and 62 degree, respectively. Applying REleASE for the three events we found a better forecast for STEREO closer to the magnetic field line to Mars than for Earth. 

The SOHO/EPHIN and STEREO/SEPT project is supported under Grant 50~OC~2302 by the German Bundesministerium für Wirtschaft through the Deutsches Zentrum für Luft- und Raumfahrt (DLR). This study has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 101004159 (SERPENTINE). The REleASE system is supported by NASA via the grant TXS0150642.