SAN FRANCISCO — NASA’s huge supersonic parachute isn’t ready to land astronauts on Mars just yet.
The 30-meter-wide chute — the biggest supersonic parachute ever deployed — was apparently torn apart June 8 during the second flight test of NASA’s Low-Density Supersonic Decelerator (LDSD) vehicle, which the space agency built as part of an ongoing effort to learn how to get superheavy payloads such as habitat modules down softly on the surface of Mars.
“Chute deployed, but did not inflate. We’ll study data from this test to learn & improve,” NASA officials said June 8 via the agency’s Twitter account, @NASA.
Yesterday’s test, which lifted off from the Pacific Missile Range Facility on the Hawaiian island of Kauai at 1:45 p.m. EDT (1745 GMT; 7:45 a.m. local time in Hawaii), was similar to the first LDSD flight. That June 2014 test also went well until it was time for the supersonic chute to catch the fast-moving air.
New landing tech needed
The 1-ton Curiosity rover is the heaviest object NASA has ever put down on Mars. Curiosity landed in August 2012, pretty much maxing out the capabilities of its rocket-powered “sky crane” and 15-meter-wide parachute.
“Right now, we are kind of at the technological limit of what we can land on Mars in terms of size and weight,” Steve Jurczyk, associate administrator of NASA’s Space Technology Mission Directorate, said during a prelaunch news conference June 1.
“So this new technology is required to land 5 metric tons for human missions, maybe 30 [metric tons] and beyond,” he added, referring to the LDSD system.
That system consists of a saucerlike “supersonic inflatable aerodynamic decelerator” (SIAD) and the 30-meter chute. The SIAD is designed to fit around the rim of an atmospheric entry vehicle, slowing it down by increasing its surface area and thus its drag. NASA engineers are developing two SIAD versions; one is 6 meters wide when inflated, and the other measures 8 meters across.
The LDSD team has devised a high-altitude test for this gear, taking advantage of the fact that the thin air far above Earth’s surface is a good analogue of the Martian atmosphere.
A 121-meter-wide balloon lofts the LDSD test vehicle up to an altitude of about 37 kilometers from the Pacific Missile Range Facility. The 3,175-kilogram craft is dropped; it then fires up its onboard rocket engine, which blasts the vehicle to supersonic speeds and a height of 55 km or so.
Then, the SIAD inflates. This maneuver slows the LDSD craft down from about four times the speed of sound (Mach 4) to Mach 2.35 — slow enough, theoretically, for the huge parachute to deploy safely and guide the vehicle down to a soft splashdown in the Pacific Ocean.
Flight test No. 2
The LDSD system’s first such flight test was on June 28, 2014. Everything went well that day until it was time for parachute deployment; the supersonic chute was quickly destroyed.
Nevertheless, LDSD team members declared the trial a success, saying they had learned a great deal that would help them improve the landing technology. Indeed, yesterday’s flight featured a new and improved supersonic chute, said LDSD project manager Mark Adler, of NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California.
“Now, we’ve developed a much more robust, stronger parachute they’re going to be able to test this time,” Adler said during the June 1 news conference. This second test centered primarily on the new chute, since the SIAD and other aspects of the test vehicle worked well the first time around, mission team members said.
So the groans that that could be heard in mission control after yesterday’s apparent parachute failure made a great deal of sense. Once again, everything worked well — the test vehicle separated as planned at 5:35 p.m. EDT (2135 GMT); the rocket engine fired, accelerating the craft up to Mach 4 — except the revamped chute.
The full details of what happened probably won’t be known for a while; engineers will need to examine the data stored on the LDSD test vehicle’s “black box.” (Recovery boats were standing by in the Pacific, ready to retrieve the saucer-shaped craft and haul it back to land.)
Though the parachute didn’t work as hoped, yesterday’s test will still return valuable information, mission team members said.
“This is exactly why we do tests like this before we send things to Mars, so that we can understand exactly how they work, or don’t work,” said JPL engineer Dan Coatta.
“Then we can improve on our designs to make sure that, when we’re actually ready to send [heavy] spacecraft to Mars, we know that they’re going to work when that big mission is on the line,” Coatta said during the webcast of the June 8 test, which aired on NASA TV.
The cost of the LDSD program is about $230 million, Adler said. A third test flight, also planned to launch from Kauai, is tentatively scheduled for next year.
The June 8 test flight was originally scheduled for June 2, but strong winds and rough seas that could have hampered recovery of the LDSD vehicle delayed the liftoff by nearly a week.