Sometime before 2:30 p.m. CDT tomorrow, NASA will test a new way of landing heavy equipment on Mars using a ‘flying saucer’ design. It’s called the Low-Density Supersonic Decelerator (LDSD), and it’s designed to inflate into a large disk dragging a parachute behind it.
Whenever we launch a Mars landing mission, reaching the surface safely is critical. All the rovers and other Mars landing probes were packaged in heat-resistant aeroshells which protected their delicate instruments during the initial high-speed entry through the Martian atmosphere. Then, large parachutes were deployed in the thin Martian air to further slow the landers. Finally, rockets, or in the case of the Curiosity rover, a unique rocket-tether platform, slowed the descent to a gentle touchdown.
The Opportunity and Spirit rovers were protected in a cluster of airbags which dropped from the chutes and bounced many times on the surface until coming to a standstill.
LDSD: Supersonic Test Flight
All of this trouble comes from Mars’ paucity of good, thick air. On Earth, parachutes work fine because the density of the atmosphere is so much greater than Mars. On the airless moon, parachutes don’t work at all, and rocket-powered descent is the only option. Mars is somewhere in between with enough air for parachutes but not enough to slow a landing vehicle to a safe speed. The planet’s also missing those oceans for a more cushy landing.
Weighing in at a ton, the Curiosity mission pushed the limits of current technology. If we ever hope to send larger, more robust robotic labs to Mars and especially if we’re looking to get a crew of astronauts there, new ways of landing have to be invented. Enter the LDSD.
It comes in two parts — a supersonic inflatable aerodynamic decelerator (SIAD) that works in tandem with a 100-foot-wide (30 meters) supersonic parachute. During tomorrow’s test, a 400-foot-wide helium balloon will loft the LDSD test vehicle to about 120,000 feet (36,576 m). There it will fire its rocket engine to blast it further to 180,000 feet (54,865 m), where the air is about as thin as that on Mars.
Once at altitude, the SIAD will rapidly inflate to 20 feet (6 m) in diameter while dropping back to Earth at about 3 times the speed of sound (2,280 mph). The drag created by the plummeting donut will slow the package to around 1,788 mph, at which point a 110-foot-wide parachute — twice as large as that used for Curiosity — will release and slow the LDSD to a safe splashdown in the Pacific Ocean.
The rocket on the test vehicle is only there to send the LDSD up to a higher altitude. When used on Mars, the lander will be carefully protected in the center of the saucer and the entire thingamabob will descend without a rocket. With the new technology, the agency will be able to land probes weighing between 2 and 3 tons.