NASA vows to fix "flying saucer" parachute problems
Recovery crews brought NASA's flying saucer-like test vehicle back to port in Hawaii Tuesday, along with critical high-resolution video and data that should help engineers figure out what went wrong with a supersonic parachute that ripped apart Monday in a dramatic high-altitude test of Mars landing technology.
It was the second parachute failure in a $230 million program calling for three flights to certify the technology for use in future Mars missions.
Given the back-to-back parachute malfunctions, and a requirement for at least two successful flights in a row before the system can be counted on for use at Mars, NASA will have to come up with the money to pay for at least one additional test flight.
"On this project, we're pushing the limits of our technologies, our engineering and our understanding of aerodynamic decelerators," said Ian Clark, the principal investigator at NASA's Jet Propulsion Laboratory. "This year, the physics of supersonic parachutes pushed back on us."
As an engineer, Clark told reporters, such failures can be a "humbling experience."
"But as a curious human, this can be extremely exciting," he said. "We don't conduct tests like this to show we know all the answers ahead of time. We conduct them to learn about what we didn't know. And I think that's something that certainly rings true with the results we're seeing this year."
The Low-Density Supersonic Decelerator, or LDSD, program was developed to test innovative technologies that could help NASA get larger payloads safety down to the surface of Mars using aerodynamic drag to slow down in the red planet's ultra-thin atmosphere.
Two such technologies were built into the LDSD test craft: an innovative doughnut-shaped airbrake, known as the Supersonic Inflatable Aerodynamic Decelerator, or SIAD, and the world's largest supersonic parachute.
Making its second test flight, the LDSD test vehicle was carried to an altitude of 120,000 feet above the Pacific Ocean west of Hawaii by an enormous helium-filled ballon.
The craft then was released and set spinning before ignition of a solid-fuel rocket motor that boosted it to more than 180,000 feet and a velocity of slightly more than four times the speed of sound. At that altitude and velocity, the conditions are similar to what a Mars-bound spacecraft would encounter during descent.
A few moments later, as planned, a large Kevlar torus inflated around a simulated heat shield, expanding the vehicle's cross section from 15-and-a-half feet to 20 feet and increasing its atmospheric drag. The SIAD appeared to work flawlessly, just as it did during the program's first flight last year.
The second major objective of the flight was to test the redesigned parachute.
During the first test flight last year, the parachute appeared to rip apart as soon as it began opening in the supersonic airflow. This time around, a redesigned version of the parachute appeared to inflate normally, quickly opening to its full diameter, or close to it, and briefly generating some 80,000 pounds of drag. But an instant later, a large tear developed and the parachute tore apart.
"The deployment of the parachute from the test vehicle appeared to go quite well, and the parachute began inflating uniformly up to the point of full inflation," Clark said. "At some point at or near full inflation, the parachute was damaged and the damage propagated further until the parachute could no no longer survive the harsh supersonic environment."
Despite the failure, Clark said large parachutes will be critical for future Mars missions.
"Parachutes are tremendously efficient decelerators," he said. "The parachute that we tested yesterday generated nearly 80,000 pounds of drag and itself weighs only about 200 pounds. That amount of deceleration for that small amount of mass, you cannot find with any other technology presently out there."
Parachutes, he said, were "critical for our missions to Mars since the Viking landers in the 1970s and I believe they will continue to be critical as efficient aerodynamic decelerators for the coming missions to Mars."
Mark Adler, the LDSD project manager at JPL, said the team would learn from the latest setback.
"Like any science experiment, it is successful if you are able to conduct the experiment, get the data you were looking for and then be able to make conclusions from that data," he said. "In the sense it was not successful -- we had a parachute that did not survive inflation -- we are now going to have to look at that data and see why that happened and remedy that and try again."