6Lindenmoyer A.Commerical crew and cargo program[R].Washington D.C.:NASA,2010.
7Daniel J,Bruce P,Mark E N.The reusable launch vehicle challenge,AIAA 2006-7208[C]//AIAA Space 2006Conference.Washington D.C.:AIAA,2006.
8Smitherman D,Woodcock G.Future concepts for integrating the space launch system and the multi-purpose crew vehicle into a reusable space transportation infrastructure,AIAA 2012-14533[R].Huntsville:NASA Marshall Space Flight Center,2012.
9Musk E.COTS status update&crew capabilities[R].Hawthorne:Space X,2009.
