Advanced Manned Launch System

Several alternatives exist for the development of the next manned launch system. The Advanced Manned Launch System (AMLS), which represents a clean-sheet replacement for the Space Shuttle, faces competition from concepts such as (1) the Personnel Launch System, which would serve as a personnel transport to complement the Space Shuttle, and (2) an advanced version of the existing Space Shuttle. An AMLS system could begin operations sometime between 2005 and 2020, depending upon the level of national interest and support. It would probably demonstrate a payload capacity less than that of the Space Shuttle, although performance specifications are far from certain. Even the form of the AMLS is still under discussion. Design studies have considered a wide variety of options including all levels of hardware reusability; single-, dual- and multiple-staging; and airbreathing vs. rocket propulsion. An evaluation of the relative cost-effectiveness of these options is impossible without guidance regarding basic mission requirements such as total number of launches over the system's life cycle and the date required. The availability of more advanced technologies will enable single-stage-to-orbit (SSTO) designs that are in general not feasible using current technology.