Going to space is hard. Going to another world is even harder. Safely landing on another world is about as difficult as it gets. NASA pulled off a landing as clever as it was unlikely with the Curiosity rover in 2012, but it's going to need a much more effective way of slowing down heavier spacecraft whenever the time comes.
Enter the low-density supersonic decelerator, or LDSD. It's an inflatable device meant to add to a spacecraft's atmospheric drag, and — after a week of weather delays — NASA is performing the second major test of it today at 1:30PM ET. NASA will begin the broadcast at 1PM, and it can be seen above.
LDSD works in three stages. After being lifted to 120,000 feet (about 36,000 meters) by a high-altitude balloon, the test vehicle will be dropped and four small rocket motors will stabilizing the test vehicle through a controlled spin. Then, a separate rocket will propel the craft to 180,000 feet (about 55,000 meters) at more than 2,880 mph (4,635 km/h). It's at that point that the donut-shaped kevlar airbag that makes up the supersonic inflatable aerodynamic decelerator, or SIAD, will deploy. The SIAD decelerates the spacecraft to about 1,400 mph (2,253 km/h) when a massive parachute takes over, which slows the spacecraft to a safe speed for a water landing.
It was the parachute that failed during last year's test — supersonic winds tore it to shreds. This time around, NASA says the LDSD team "has been rewriting the book on high-speed parachute operations." Numerous changes were made to the parachute’s construction and geometry, and its ability to withstand the forces of deceleration will be the main focus of this particular test. The new parachute measures about 100 feet (30.5 meters) in diameter, which makes it more than twice as big as the one used to land Curiosity.