Rare ed Aerothermodynamic Predictions for Mars Global Surveyor

Mars Global Surveyor (MGS) successfully completed its rst phase of aerobraking in early 1998 and is the rst planetary mission to use aerobraking as a primary means of customizing its orbit to achieve its mission objectives [1]. The aerobraking requirements together with post-launch anomalies [2] presented a unique challenge to provide accurate predictions of the aerothermodynamic environment of the spacecraft in the rare ed transitional ow regime. Direct Simulation Monte Carlo (DSMC) and freemolecular techniques were used to provide heating and aerodynamic predictions and to investigate a variety of rare ed ow phenomena across the ight regime [3, 4, 5]; MGS is the rst major planetary mission in which rare edow predictions have played such a critical role all the way through the design, mission planning, and operational phases. This paper summarizes these studies with emphasis on transitionalow and gas-surface interaction phenomena.