Effect of rotating earth for analysis of aeroassisted orbital transfer vehicles

Abstract

Aeroassisted orbital transfer vehicles operate both in the endo- and exo-atmospheres. Although an orbital trajectory is shaped by the inertia! state variables, the aerodynamic maneuvering that induces trajectory perturbation is dictated by the relative velocity. The difference in relative velocities between a nonrotating and a rotating earth produces a substantial difference in the entry dynamic pressure. The exit-condition errors introduced at the edge of sensible atmosphere by the dynamic pressure difference produce significant deviations in the final orbit transfer. Endo-atmospheric flight control laws that tend to minimize the orbit reinsertion propellent requirement for orbit transfer and plane change are also demonstrated. In conclusion, aeroassisted orbital transfer vehicle analysis with an operational altitude constraint and a stationary earth assumption tends to underpredict the final low-earth orbit altitude and to overpredict the orbital inclination change. Because the turning radius is on the Order of a global scale, latitude positions may influence the effectiveness of orbit plane-change analysis.