NASA Awards Contract To Test Ballutes

What's that? What's a ballute? Well, it's a giant airbag is what it is, but the word "ballute" is actually a cross between balloon and a parachute... get it? And more importantly, NASA thinks it can use them for the atmospheric reentry of spacecraft.

NASA's Dryden Flight Research Center awarded Andrews Space of Seattle, WA a $600,000 Small Business Innovative Research (SBIR) contract to continue development of its ballute systems. Technically, the device is termed a "Flexible Transpiration Cooled Thermal Protection System for Inflatable Atmospheric Capture & Entry Systems." That's a lot of words... it's easier to say ballute!

The SBIR program is one our governments brighter ideas.  It provide a means for small, high technology companies and research institutions to participate in government-sponsored research and development efforts in key technology areas.

Andrews Space was founded in 1999. Its staff of 60 engineers, technicians and support personnel works with government and commercial customers developing technologies for space transportation systems.

So how does a ballute work? It's a pressure-stabilized, inflatable membrane that provides a large, blunt, high-drag surface for aero-braking systems.

Current reentry protection systems use either a material capable of withstanding the heat and pressure, such as the shuttle's reinforced carbon-carbon and ceramic tiles, or a layer of ablative material designed to burn off such as that used by older Apollo capsules and Russia's Soyuz. The criticality of these materials cannot be overemphasized -- the shuttle Columbia broke apart on reentry because its protective heat shield had been compromised.

One of the drawbacks to these shielding materials is weight -- they're heavy. Ever picked up a ceramic tile? All that weight must be carried aloft.

Ballutes offer significant advantages over rigid shells for aerocapture and re-entry of spacecraft by providing simplified packaging and lower total weight.

Andrews Director of Engineering Eric Wetzel says, "Ballutes offer substantial performance advantages for planetary capture and entry systems.  We are excited to help advance the state of the art to enable future spacecraft to include a ballute as a design solution."

Andrews' ballute would inflate just prior to reentry with an inert gas. Its design provides vents allowing some of the gas to escape as it heats up and expands.

So why doesn't the material just burn up? Well for one thing, the ballute has a much larger surface area over which to spread the heat and pressure. Also, the gas protects the material. Have you ever boiled water in a paper cup over an open fire? The paper won't burn as long as there is water in the cup to absorb the heat. The gas inside a ballute works just like the water in a paper cup; it absorbs the heat from the friction of reentry -- ingenious!

Using a ballute to aero-brake a spacecraft isn't a new idea -- although Andrews appears the to be the first to put the idea into practice. The concept was featured dramatically in the movie 2010:The Year We Made Contact, a sequel to 2001: A Space Odyssey. A scene in the movie shows the Russian spaceship Leonov performing a dramatic aero-brake maneuver to attain orbit around Jupiter. The craft used a ballute for drag and thermal protection.

The movies were based on science-fiction writer Arthur C. Clarke's novels. Clarke is a renowned author and futurist whose books have inspired a number of interesting ideas with real-world applications.

FMI: www.andrews-space.com