COMPUTER-EFFICIENT MODELS OF THERMOSPHERIC DENSITY AND COMPOSITION

THE PROBLEM OF DEVELOPING COMPUTER-EFFICIENT THERMOSPHERIC DENSITY MODELS IS ADDRESSED, AND DESIGN INVESTIGATIONS FOR IMPROVING THE ACCURACY AND SPEED OF SATELLITE ORBITAL PREDICTIONS IN LOW EARTH ORBIT ARE PROPOSED. EARLY COMPUTER MODELS OF THE ATMOSPHERE WERE DERIVED USING QUASI-STATIC DIFFUSION MODELS, BASED PRIMARILY ON SATELLITE ORBITAL DECAY DATA. RECENT MODELS INCLUDE DATA FROM COMPOSITION MEASUREMENTS, AND MORE ELABORATE FIRST-PRINCIPLES CODES SUCH AS TIGCM, HOWEVER WITHOUT SATISFACTORY IMPROVEMENT IN DECAY PREDICTION CAPABILITY. THE LATEST MODELS PROVIDE THERMOSPHERIC WINDS, A FIRST ORDER EFFECT ON SATELLITE DRAG WHICH HAS GENERALLY BEEN IGNORED IN ORBIT PROPAGATION SOFTWARE. EXTENSIVE AND CORRELATED SATELLITE ORBITAL HISTORIES ARE AVAILABLE, AND MAY BE USED TO EVALUATE THESE MODELS FOR ACCURACY AND DESIGN. BOTH RESEARCH AND SOFTWARE ENGINEERING DEVELOPMENT APPROACHES ARE PROPOSED IN ORDER TO ESTABLISH BENCHMARKS, IMPROVE CODE EFFICIENCY, DEVELOP DIAGNOSTIC TOOLS, AND IDENTIFY DEFICIENCIES THRU TESTING AND THRU THEORETICAL CONSIDERATIONS. THIS IS PROPOSED IN PHASE I.