A spome is any hypothetical system closed with respect to matter and open with respect to energy capable of sustaining human life indefinitely. The term was coined in 1966 by Isaac Asimov in a paper entitled, “There’s No Place Like Spome” in Atmosphere in Space Cabins and Closed Environments [1], originally presented as a paper to the American Chemical Society on September 13, 1965.

http://en.wikipedia.org/wiki/Spome

not to be confused with “spime”… .