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Inflatable aeroshell succeeds in suborbital test

Posted: August 17, 2009

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Data from today's "IRVE" Inflatable Reentry Vehicle Experiment indicate the NASA flight test was a complete success, with the aeroshell system inflating properly to 10 ft. dia. then performing as expected from both a thermal and deceleration loading standpoint during its descent from about 130 mi. altitude.

The 15 in. diameter IRVE canister was fired aloft on a Canadian Black Brant 9 sounding rocket at 8:52 a.m. from the Wallops Flight Center, Va. The launcher dublicated the Black Brant configuration shown below.

Credit: NASA
The long range objective of the technology demonstration is the development of much lighter more capable reentry systems to lower multiton payloads to Mars and other planetary bodies with atmospheres, such a Saturn's moon Titan.

"We're really excited today because this is the first time anyone has successfully flown an inflatable reentry vehicle," said Neil Cheatwood, IRVE principal investigator and chief scientist for the Hypersonics Project at NASA's Langley Research Center in Hampton, Va. Computer graphics aided the design of the system shaped like an inverted mushroom with multiple gas cells for rigidity.

On Mars it could open the entire higher elevation southern hemisphere to exploration by landers. That is not possible now because with the higher elevation and lower density atmosphere parachutes do not function nearly as well as in the northern hemisphere where atmospheric density is greater.

The situation at Mars is barely possible even in the northern hemisphere where sandstorms can lower atmospheric density. As a result of a the dust storm effect the Spirit rover nearly crashed in January 2004 because it's parachute slowed the spacecraft to separation altitude with only a few feet to spare. It is also possible the British Beagle lander crashed because of the same situation in December 2003.

Credit: NASA
The 10-foot diameter IRVE heat shield, made of several layers of silicone-coated industrial fabric, was inflated with nitrogen to a mushroom shape several minutes after liftoff. Computer graphic shows the nitrogen cells and major structural elements of the aeroshell.

The Black Brant 9 rocket took approximately four minutes to lift the experiment to an altitude of 131 miles. Less than a minute later IRVE was released and started inflating. The inflation of the shield took less than 90 seconds.

"Our inflation system, which is essentially a glorified scuba tank, worked flawlessly and so did the flexible aeroshell," says Cheatwood.

According to imagery and data from the cameras and sensors on board, the heat shield expanded to its full size and went into a high-speed free fall. The key focus of the research came about six and a half minutes into the flight, at an altitude of about 50 miles, when the aeroshell re-entered Earth's atmosphere and experienced its peak heating and pressure measurements for a period of about 30 seconds. This took place at a velocity of about Mach 2.5.

An on board telemetry system captured data from instruments during the test and broadcast the information to engineers on the ground in real time. The technology demonstrator splashed down and sank in the Atlantic Ocean about 90 miles east of Virginia's Wallops Island.

"This was a small-scale demonstrator," said Mary Beth Wusk, IRVE project manager, based at Langley. "Now that we've proven the concept, we'd like to build more advanced aeroshells capable of handling higher heat rates, " she said.