NASA engineers have redesigned these explosive bolts that fire soon after liftoff to separate the solid rocket boosters from the external fuel tank. Investigations have found that bolt debris could strike the orbiter causing damage. By making the new bolts out of a single piece rather than two welded pieces, engineers hope to reduce the danger.		Main: Return to Flight Making the Shuttle Fit to Fly Risks of Manned Spaceflight Next Generation Space Vessel Slide Show: Evolution of Spaceflight Interactive: Shuttle Upgrades Lesson Plan Archive