Review of US Concepts for Post-ISS Space Habitation Facilities and Future Opportunities

Abstract

Over the past decade, a modest number of groups has pursued concepts for future long-duration, highly capable human habitation systems in free space, building upon and following the International Space Station (ISS). In general, the designs have derived from the TransHab technologies and the Decade Planning Team architecture of the late-1990s and early-2000s: expandable habitation at an “operations node” – typically an Earth-Moon libration point or geosynchronous orbit – that enabled a wide range of science and human space flight activities via a single facility. This design work has direct applicability to future NASA plans for human space flight. Advocates for these systems point to (1) the importance of sustaining successful operation in free space if there are to be human missions to Mars; (2) continued development of key technologies beyond that which ISS alone will achieve; and (3) the value of a habitation system at a useful venue in cis-lunar space: e.g., support of lunar surface sorties, service and upgrade complex science facilities, maintenance of on-orbit depot systems. With the identification of Mars as the “ultimate destination” for human space flight, the capability to operate in free space comfortably and successfully for long periods of time remains a major priority. We close by summarizing some possible “next steps” that NASA might take with respect to long-duration human operations in space.