A recent report suggests using the hydrogen tank of an upper stage for the SLS as a space station:
Skylab II: A NASA 'Back to the Future' Concept to Open Up Space Exploration
By Mark Whittington | Yahoo! Contributor Network – Fri, Dec 21, 2012
http://news.yahoo.com/skylab-ii-nasa-back-future-concept-open-space-170200842.html
Note there had been suggestions before of using the space shuttle external tank(ET) as a space station:
The Space Island Project
http://www.youtube.com/watch?v=sYIo-0qo9FA
STS External Tank Station
www.astronautix.com/craft/stsation.htm
The External Tank Torus.
A Technical Review by David Buth
http://freemars.org/studies/torus/ettoru2.html
Using the External Tank From the Space Shuttle as a Space Station ...
aeromaster.tripod.com/grp.htm
At an empty tank mass of 26.5 metric tons(mT) this would be well within the
capability of the 70 mT SLS of getting this to LEO, as at least an outer hull
of a space station. Note for this purpose we could remove the ET bulkheads so
it would even weigh less than this.
This would have two and a half times the volume of the ISS.
And at the 130 mT payload capacity of the later SLS version, using Centaur
style in-space stages we could even transport this to the Moon.
Bob Clark
