Uncertainties in Satellite Drag Associated with Variations in Atmospheric Conditions

An uncertainty quantification (UQ) computational technique based on principles of importance sampling is applied to Space Environmental NanoSat Experiment (SENSE) satellite aerodynamic studies. Computational simulations are performed at an altitude of 100 km using a DSMC solver that is coupled with the UQ technique, allowing for automated variation of DSMC input parameters and propagation of input uncertainties through the flow solution. Satellite drag is identified as the parameter of interest because of its role in defining the trajectory and eventual lifespan of the satellite. Contributions of the ambient flow temperature and density uncertainties on the resulting satellite drag uncertainty are studied in detail. Two types of uncertainties, epistemic and aleatory, are considered and resulting probability boxes for satellite drag are presented. DSMC calculations incorporating UQ are applied to this configuration for the collisional flow at 100 km altitude. It is found that the nominal value of the computed drag guarantees reentry of a SENSE type satellite within a very small fraction of an orbit. This is an expected result for small satellites orbiting around 100 km altitude.