NASA is
preparing to conduct the second test flight of its Low-Density Supersonic
Decelerator (LDSD) — but you can call it NASA’s “flying saucer.” This craft is
designed to deliver mission payloads to the surface of Mars without all the
risky rocket-powered sky crane maneuvers that were part of the Curiosity rover
landing. The LDSD is going to launch in just a few minutes, and you can watch
it live on NASA’s JPL Ustream channel:
The LDSD
includes a number of technologies that could make Mars landings considerably
easier. The main issue to overcome when landing on the Red Planet is that the
atmosphere is far thinner than it is on Earth — only about 1% as dense. That
means a craft coming in at Mach 3.5 (about 2,500 mph) can’t slow itself down
with just a parachute.
Around the edge
of the LDSD is an inflatable expanding airbrake called the Supersonic
Inflatable Aerodynamic Decelerator (SIAD). It’s basically a giant airbag that
deploys in a fraction of a second and vastly increases the surface area of the
craft, thus slowing its descent. This alone should be able to reduce the
craft’s speed to around Mach 2.
The second
technology at work in the LDSD is a huge Supersonic Disksail Parachute. This is
the largest parachute NASA has ever flown, at 30 meters in diameter, and it’s a
critical aspect of this test. In the first test of the LDSD system last June,
the parachute shredded itself just moments after being deployed. If it deploys
properly, the parachute should be able to slow the flying saucer down to
sub-sonic landing speeds.
The next full
launch test will take place at the US Navy’s Pacific Missile Range Facility in
Hawaii in June, and will be conducted in the same way as the first test. The
LDSD will be take up to an altitude of roughly 120,000 feet by a weather
balloon. Then it will fire a rocket booster that takes it higher still, and
accelerates it to the speeds it would encounter during a Mars landing. Earth’s
atmosphere is much thicker, of course, but the rocket will carry the craft to
an altitude of nearly 200,000 feet, where the atmosphere is of similar density
to that of Mars. This will allow NASA to get an idea of how the LDSD will
perform on a mission. Hopefully
the parachute deploys this time.
