W Gaubatz, May 24-31, 1998, "Reusable Space Transportation - The Key Infrastructure Element In Opening the Space Frontier To the Public", Invited Paper 98-o-1-O1V. 21st International Symposium On Space Technology and Science, May 24-31, 1998,Sonic City, Omiya, Japan. Re-usable Space Transportation System Session. Also downloadable from http://www.spacefuture.com/archive/reusable space transportation the key infrastructure element.shtml