Modeling and Predicting Down-link Tropospheric Channel above Ku Band for Interplanetary Exploration

In this work we propose a model chain for the prediction of the tropospheric channel for the downlink of interplanetary missions operating above Ku band We show the validation and online operation of the model-chain, already tested within a feasibility study applied to the BepiColombo mission to Mercury (operated by the European Space Agency), through Hayabusa2 mission cross-support data provided by the Japan Aerospace Exploration Agency (JAXA). The model-chain is composed by three modules. A weather forecast module for the prediction of the atmospheric state expected during the downlink transmission. A radiopropagation module to simulate radiopropagation variables generated by the predicted atmospheric state. A downlink budget module for the statistical optimization of the satellite-to-Earth link. The latter is realized exploiting the spatial grid domain and the temporal evolution of the predicted radiopropgation variables to compute statistics and uncertainties of the outputs operational parameters to use during the transmission. We have successfully validated the model-chain through the comparison of the simulated signal-to-noise ratio with the one received from Hayabusa2 with an average error of 0.16 dB. For the online operation we have provided JAXA with our predicted operational parameters to use during the transmission which revealed to be reliable and correct.