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AAS 12-035TUTORIAL: THE NEUTRAL ATMOSPHERE ANDTHE SATELLITE DRAG ENVIRONMENTGeoff Crowley, * Marcin Pilinski † and Irfan Azeem ‡Satellite drag is the primary non-gravitational force acting on satellites below 500km altitudes and continues to be an important orbital perturbation up to 800-1000 kmaltitudes. Recent developments in the understanding of upper atmospheric physics aswell as the availability of high-resolution satellite drag data are motivating a transitionfrom empirical models to physics based assimilative models as the primary tools forsatellite drag specification. The motivation, current progress and future challenges associatedwith this effort are described in this paper. First principles models, such asTIMEGCM are described and their ability to specify satellite drag is demonstrated.Since the prediction of satellite ballistic coefficients limits the ability to forecast satellitedrag almost as much as atmospheric density, physics-based atmospheric models willlikely be coupled with physics-based ballistic and drag coefficient specification. Thiscomplete approach to the satellite drag problem has the potential to be the first systemto achieve the 5% drag specification goal prescribed by the Air Force Space Command.[View Full Paper]* Chief Scientist and CEO, Atmospheric and Space Technology Research Associates (ASTRA), Boulder,Colorado 80301, U.S.A. Tel: 210-834-3475.† Postdoctoral Researcher, Atmospheric and Space Technology Research Associates (ASTRA), Boulder, Colorado80301, U.S.A. Tel: 210-834-3475.‡ Chief Engineer, Atmospheric and Space Technology Research Associates (ASTRA), Boulder, Colorado 80301,U.S.A. Tel: 210-834-3475.14