Interstellar travel is mostly a though experiment at this stage (although NASA will be launching the solar sail SunJammer in a couple of years). My question is a very broad one about what type of materials would be well-suited for structures to support interstellar travel. Any human habitat would be pressurized (to ~14-21 psia) and (probably) made out of steel (like the Centaur, the upper stage of the Atlas V rocket) or aluminum in the shape of a cylinder. What could be the expected life of such a structure in this environment (corrosion due to moisture, radiation, etc.). Is there an "ideal" material for this application? How might you estimate a usable life for the structure? I've never really seen much data where material performance is extrapolated to centuries (rather than years). When a structure of this sort does fail, what would be the failure mode?