Low-Density Supersonic Decelerator

Real-life flying saucer

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.

the story here