>"By the 1990s, the term was widely used, including formal engineering papers. (As an example, Towards unobtainium [new composite materials for space applicati

>"By the 1990s, the term was widely used, including formal engineering papers. (As an example, Towards unobtainium [new composite materials for space applications], by Misra and Mohan describes how the ideal material (unobtainium) would weigh almost nothing, but be very stiff and dimensionally stable over large temperature ranges.)" Addendum: Perhaps Carbon Nanotube Fibers -- are one potential candidate for "Unobtainium": https://en.wikipedia.org/wiki/Carbon_nanotube https://en.wikipedia.org/wiki/Carbon_nanotube