Aug. 19, 2009 -- After years of false starts, engineers have successfully tested an innovative technology to cushion a spacecraft's descent back to Earth or to land it on another planetary body using an inflatable heat shield.
During a demonstration flight Monday, a silicon-coated heat shield was launched into space, released from its rocket and inflated to its full 10-foot diameter in less than 90 seconds.
The point of the flight, which took place from Wallops Islands, Va., was to test the system's inflation mechanisms and determine if the shield would survive the fiery re-entry through Earth's atmosphere.
"Inflatables have been proposed for decades, but the materials weren't there back then," NASA's Neil Cheatwood, lead scientist for NASA's Inflatable Re-entry Vehicle Experiment, told Discovery News.
Spacecraft returning to Earth or flying through any planet's atmosphere need protection from the intense heat generated due to friction with particles in the atmosphere.
The space shuttle has heat-resistant tiles and carbon coatings to protect it during re-entry, where temperatures can reach 3,000 degrees Fahrenheit. But the shuttle's heat shield is extremely fragile, as NASA learned from the 2003 Columbia disaster, and it requires time-consuming maintenance and repairs.
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Other spacecraft, such as the Apollo-era capsules and the Russian Soyuz spaceships, use materials that ablate away during the fall through the atmosphere.
The Russians planned to use an inflatable heat shield on a Mars probe launched in 1996, but the spacecraft was lost due to an upper-stage rocket failure. NASA's first attempt to demonstrate an inflatable shield, likewise ended prematurely due to a problem with the launcher.
While engineers are happy to have finally tested an inflatable shield in orbit, much work remains before the technology is ready for operational missions.
In addition to making bigger shields needed to support heavier cargo, engineers are investigating lighter-weight, heat-resistant materials.
The shield tested this week was a sandwich of fabrics wrapped inside Nextel, an open-weave ceramic fiber that resembles white burlap.
Beneath the Nextel were three layers of Kapton film and a silicon-coated bladder that could hold air. The shield was inflated with nitrogen.
"This was a small-scale demonstrator," said project manager Mary Beth Wusk, with NASA's Langley Research Center in Hampton, Va. "Now that we've proven the concept, we'd like to build more advanced aeroshells."
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