
NASA built a supersonic brake for landing on faraway planets, and it's amazing. Courtesy JPL
Landing safely on an alien planet requires drastic braking at hypersonic speeds. To practice techniques for slowing down, NASA’s Jet Propulsion Laboratory built the LDSD, which inflates a 20-foot-wide tube-shaped balloon to increase a craft’s atmospheric drag, slowing the LDSD until its parachute deploys.