Geo-lunar shuttle: direct flight vs. near-earth operations all engines reused

摘要

This paper develops analytical and design comparisons among a range of geo-lunar shuttle alternatives. These variations are generated by considering two flight modes: 1) direct; 2) near-Earth operations; and Earth launcher engine recovery from: 1) near-Earth orbit; 2) lunar orbit; and 3) other orbits within geo-lunar space. From near-Earth orbit, Earth launcher engines are recovered in the cargo bay of a near-Earth shuttle, such as the current NASA shuttle or a "Venture Star"-class vehicle. From far-Earth or lunar orbit, Earth launcher engines are recovered in the cargo bay of the shuttle itself. The shuttle engines, integral with the shuttle itself, are recovered by virtue of the shuttle's direct Earth re-entry capability. for direct flight all-up Earth launch is provided by single-stage and 1~1/2-stage launch vehicles, from which launcher tankage is jettisoned. For near-Earth fueling, Earth launch could also be provided by multiple launches of "Venture Star" -class vehicles, launching the mepty lunar shuttle, and its fuel separately, to near-Earth orbit fueling operations, possibly at an International Space Station. Chemical propulsion is assumed. Comparison is made between single-mode O_2/H_2 (SSME/RD-120 class) and mixed-density O_2/hydrocarbon/H_2 engines (RD-704 and DF/DX), for Earth-to-near-orbit launch. All-O_2/H_2 is shown to be preferable beyond near-Earth orbit. Results are evalauted in relation to lunar facility and operationla logistic requirements, and economic considerations.