X-33

Jump ahead now to the mid- to late 1990s, more than a decade after the Columbia lifted off on the first orbital space shuttle mission, and NASA was looking into designs for reusable launch vehicles that could eventually replace the shuttle fleet. This artist's conception shows the X-33 Advanced Technology Demonstrator, offered up by Lockheed Martin's Skunk Works operations. It never got too far past the drawing board, and NASA withdrew funds for the X-33 in 2001.