End-to-End Optimization of Chemical-Electric Orbit-Raising Missions

摘要

A simple analytic multistage model is presented for combined chemical-electric orbit-raising missions. Expressions for transportation rates and optimum electric specific impulse are derived for two-stage, three-stage, variable-efficiency, and tank-limited missions of up to 100 days duration. The optimum electric specific impulse is shown to depend strongly on the specific impulse of the chemical thruster. A low-thrust-trajectory optimization model is combined with launch-vehicle performance data to derive end-to-end optimized three-dimensional chemical-electric orbit-raising profiles to geostationary orbit. Optimized profiles are derived for the Sea Launch, Ariane 4, Atlas Ⅴ, Delta Ⅳ, and Proton launch vehicles. Optimum electric orbit-raising starting orbits and payload mass benefits are calculated for each vehicle. The mass benefit is shown to be between 6.1 and 7.6 kg/day with two SPT-140 thrusters, or up to 680 kg for 90 days of electric orbit raising. The optimized profiles are combined with the analytic model to a create simple parametric performance model describing multiple launch vehicles. The model is a good tool for system level analysis of electric orbit-raising missions and is shown to match calculated performance to within 13%.