A view toward future launch vehicles - A civil perspective
Prospective NASA launch vehicle development efforts, which in addition to follow-on developments of the Space Shuttle encompass the Shuttle-C cargo version, various possible Advanced Launch System (ALS) configurations, and various Heavy Lift Launch System (HLLS) design options. Fully and partially reusable manned vehicle alternatives are also under consideration. In addition to improving on the current Space Shuttle's reliability and flexibility, ALS and HLLV development efforts are expected to concentrate on the reduction of operating costs for the given payload-launch capability.
Darwin, Charles R.↗