Περίληψη:
Electric Orbit Raising (EOR) for telecommunication satellites
significantly reduced on-board fuel mass at the price of extended
transfer durations. These relatively long transfers, which usually span
a few months, cross large spans of the radiation belts, resulting in
significant exposure of the spacecraft to space radiations. Since they
are not very populated, the radiation environment of intermediate
regions of the radiation belts is less constrained than on popular
orbits such as low Earth orbit or geostationary orbit in standard
environment models. In particular, there is a need for more specific
models for the MeV energy range proton fluxes, responsible for solar
arrays degradations, and hence critical for EOR missions. ONERA has
developed a specification model of proton fluxes dedicated for EOR
missions as part of the ESA ARTES program. This model can estimate the
average proton fluxes between 60 keV and 20 MeV on arbitrary
trajectories on the typical duration of EOR transfers. A global
statistical model of the radiation belts was extracted from the Van
Allen Probes RBSPICE data. For regions with no or low sampling,
simulation results from the Salammbo radiation belt model were used.
Special care was taken to model the temporal dynamics of the belts on
the considered mission durations. A Gaussian Process model was
developed, allowing to compute the distribution of the average fluxes on
arbitrary mission durations analytically. Satellites trajectories can be
flown in the resulting global distribution, yielding the proton flux
spectrum distribution as seen by the spacecraft. We show the results of
the model on a typical EOR trajectory. The obtained fluxes are compared
to the standard AP8 model, the AP9 model and validated using the THEMIS
satellites data. We illustrate the expected effect on solar cell
degradation, where our model shows an increase of up to 20% degradation
prediction compared to AP8.
Συγγραφείς:
Brunet, Antoine
Sicard, Angelica
Papadimitriou, Constantinos and
Lazaro, Didier
Caron, Pablo
