NASA Launching High-Tech Inflatable Heat Shield TestSaturday

By Leonard David

Published July 17, 2012

When you think of the blistering, brutal re-entry temperatures generated by plowing through Earth'satmosphere, using fabric doesn't come quickly to mind.

But NASA is set to try some fabric out this Saturday (July 21), as part of a novel inflatable re-entryexperiment that could find a variety of uses, both off planet and possibly in returning payloads fromthe International Space Station as well.

The Inflatable Re-entry Vehicle Experiment III, or IRVE-3, has been years in the making for all of 20minutes of suborbital flight. It will be rocketed to high altitude above Earth from NASA's WallopsFlight Facility near Chincoteague Island, Va., then will dive into the Atlantic Ocean.

It's all "science friction" -- pushing the envelope, quite literally, while trying to beat the heat ofatmospheric re-entry.

Launching a space balloon

A three-stage Black Brant 11 suborbital rocket will hurl the 680-pound (309-kilogram) IRVE-3skyward, said F. McNeil "(Neil") Cheatwood, principal investigator for the IRVE program at NASA'sLangley Research Center in Hampton, Va. [Photos: NASA's Inflatable Heat Shield Ideas forSpaceships]

The uninflated IRVE-3 is carefully stuffed into a flight bag that fits inside the rocket's nose cone.Once IRVE-3 is released at its target altitude, its high-tech inner tubes will be inflated by nitrogen togive the experimental heat shield a mushroom shape.

The ready-for-re-entry contour is made of layers of silicone-coated industrial fabric. As the tubes areinflated, they stretch out a thermal blanket covering them to create a heat shield known as anaeroshell.

During re-entry, video cameras will transmit images to the Wallops control room to confirm that theIRVE-3 is holding up during its heat-defying trek. Instruments on board will also transmittemperature and pressure data to researchers for later analysis.

A rigorous ground test program of IRVE-3's thermal protection system has already been performedusing a number of facilities, Cheatwood told SPACE.com. But the upcoming flight will use theEarth's atmosphere as a wind tunnel in the sky for the ultimate test, he said.

IRVE-3 will be lobbed some 350 miles (560 kilometers) downrange into Atlantic Ocean waters.

A game- changing technology

NASA's Office of the Chief Technologist (OCT) is behind the Hypersonic Inflatable AerodynamicDecelerator (HIAD) project, under which the IRVE-3 experiment is being carried out. IRVE work isone venture within the office's OCT's Game Changing Development program for new spacetechnologies.

Testing of the IRVE over the years has seen both malfunction and success. A booster failure cutshort its first flight in September 2007.

"The original Inflatable Re-entry Vehicle Experiment was designed to demonstrate that inflatablestructures could inflate, remain inflated, and maintain stability," said Kathy Barnstorff, a Langleycenter spokeswoman for the project. "However, IRVE encountered a failure after launch in which theIRVE instrument was unable to separate from the metal payload cylinder surrounding it."

Building on success

In August 2009, IRVE scored its first success. Riding on a Black Brant 9 rocket, the booster reacheda high point of 131 miles (211 km), where it began its descent to supersonic speed. Less than aminute later the IRVE-2 was released to inflate in less than 90 seconds at an altitude of 124 miles(200 km).

Cheatwood recalls that the 2009 flight verified the IRVE was stable when it was inflated to itsprofile. It behaved like a rigid blunt body of the same shape, he said, making it through the heatpulse.

"The experiment really was ... just to take us through the heat pulse. It was like a 30-secondexperiment, officially," Cheatwood added. "It flew right through supersonic, transonic, intosubsonic."

IRVE-3 is the same size -- nearly 10 feet wide (3 meters) when inflated -- as the other two.

"IRVE-3 is launching on a larger rocket which will take it to a higher altitude," Barnstorff toldSPACE.com. "It will come back in with a higher velocity and more heating than IRVE-2 saw. IRVE-3will see about 10 times the heating that IRVE-2 did. It's a heavier payload, which also contributes tothe higher heat levels."

Using atmospheres on other worlds

Cheatwood said that work is ongoing in thermal protection materials that can take even greater heatloads. "That would let us handle higher heat rates, which means we could be smaller in diameter,"he said.

On the inflatable space structures side, there's also an eye toward building larger test articles,Cheatwood said.

HIAD-inspired technology is seen as ideal for use on NASA missions, be they to Mars, Venus or evenTitan -- the largest moon of Saturn. For example, far more precise landings on the Red Planet ofrobotic craft on the Red Planet are feasible. But the technology is envisioned to be scalable forpiloted expeditions to Mars, too.

Adopting inflatable heat shields could lead to landing more mass on Mars at higher surfaceelevations. The larger the diameter of a protective aeroshell, the bigger the payload can be.

The HIAD work can also be applied to Earth-returning payloads let loose from the InternationalSpace Station.

Already being sketched out is the High Energy Atmospheric Re-entry Test (HEART) -- a designconcept for a flight test that would utilize larger inflatable re-entry technology with a diameter ofalmost 30 feet (8 meters).

Here's the bottom line for Cheatwood: "If a planet has an atmosphere ... we can use it."

Leonard David has been reporting on the space industry for more than five decades. He is a winnerof last year's National Space Club Press Award and a past editor-in-chief of the National SpaceSociety's Ad Astra and Space World magazines. He has written for SPACE.com since 1999.