AN ALTERNATIVE CONCEPT FOR AEROASSISTED ORBITAL TRANSFERS

RECENT RESEARCH HAS INDICATED THE POTENTIAL BENEFITS OF AEROASSISTED ORBITAL TRANSFER MANEUVERS FOR REALIZING SIGNIFICANT FUEL SAVING OVER PURELY PROPULSIVE MANEUVERS FOR BOTH COPLANAR AND PLANAR TRANSFER USING APPROXIMATE CLOSED-LOOP GUIDANCE LAWS AND/OR NUMERICAL OPTIMIZATION ALGORITHMS. THIS RESEARCH HAS FOCUSED ON CURRENTLY ENVISAGED TRANSATMOSPHERIC VEHICLES. BASIC RESEARCH IS NEEDED TO INVESTIGATE OTHER POTENTIAL APPLICATIONS OF AEROASSISTED ORBITAL MANEUVERS AND TO ADDRESS THE ON-LINE IMPLEMENTATION FEASIBILITY OF SUCH ATMOSPHERIC TRAJECTORY/GUIDANCE SCHEMES. IN PARTICULAR, THERE IS A NEED TO IDENTIFY VEHICLE AND ORBITAL PARAMETERS/GEOMETRIES THAT ARE THE DESIGN DRIVERS FOR ALLOWING APPLICATION OF AEROASSISTED MANEUVERS AND FOR DETERMINING OVERALL TRANSFER PERFORMANCE OF FUEL REQUIREMENTS. AS FOR ON-LINE IMPLEMENTATION OF TRANSATMOSPHERIC GUIDANCE SCHEMES, ARTIFICIAL NEURAL NETWORKS OFFER AN ATTRACTIVE ALTERNATIVE APPROACH THAT MAY AMELIORATE THE ASSOCIATED COMPUTATIONAL BURDENS AND BE READILY ADAPTABLE TO ENVIRONMENTAL UNCERTAINTIES ENCOUNTERED DURING ATMOSPHERIC MANEUVERS. IN THIS STUDY, WE PROPOSE TO INVESTIGATE AND IDENTIFY THE POSSIBLE APPLICATION OF AEROASSISTED MANEUVERS TO OTHER VEHICLE/MISSION ELEMENTS, DETERMINE THE BASIC DESIGN DRIVERS, AND FORMULATE A SPECIFIC SCENARIO USING A NEURAL NETWORK APPROACH TO THE ON-LINE IMPLEMENTATION OF A GUIDANCE SCHEME. ANTICIPATED BENEFITS/POTENTIAL COMMERCIAL APPLICATIONS - WE SEE SEVERAL POTENTIAL COMMERICIAL APPLICATIONS OF OUR PROPOSED STUDY. FOR ALTERNATIVE AEROASSISTED TRANSFER CONCEPTS, WE SEE POTENTIAL BENEFIT TO COMMERCIAL AS WELL AS TO CIVILIAN GOVERNMENT AGENCIES. FOR INSTANCE, RESULTS OF THE STUDY MAY MAKE EASIER THE DEBOOST OF HEO SATELLITES TO LEO FOR EITHER SHUTTLE, OR IN THE FUTURE, SPACE STATION-BASED REPAIR/REFURBISHMENT. APPLICATIONS ARE ALSO TO THE NASP AND NASA'S OTV PROGRAM. THE NEURAL NETWORK COMMERCIAL