A spacecraft takes a hole-making hit from a meteoroid and repairs itself. Huge but super-thin solar sails en route to Alpha Centauri are imbedded with rip-stopping carbon nanotubes. Human waste is used as a death-defying way to shield Mars-bound astronauts against lethal blasts of radiation. Experts here at NASA’s Langley Research Center point to the physical fact: It’s a material world after all. These scientists are developing new, experimental materials that in the future could help protect astronauts and spacecraft from the harsh, often unpredictable world of deep space.