Space Station design for growth

This paper reviews the current status of Space Station planning for growth as the basis of an assessment of potential Space Station evolution directions in the 21st Century to meet the challenges of the report of the U.S. National Commission on space, 'Pioneering the Space Frontier'. Thus future mission requirements are reviewed and assessed. Based on these requirements, evolution scenarios and potential configurations are developed. It is concluded that the Space Station, as a multipurpose facility, should evolve to a capability of 300 kW, crew of 18 and 5 lab modules. Beyond this capability it will be necessary to separate functions and establish two separate Space Stations, one for research and one for operational activities (e.g., transportation node, servicing, etc.). If the U.S. National Commission on space's recommendations are adopted, this separation or 'branching' could occur as early as 2005 to meet the needs of a permanent lunar base.