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NASA has announced a successful live test of a prototype inflatable heat shield for re-entry to a planet's atmosphere. The blow-up shield could have important implications for future missions to Mars - and also, perhaps, for the nascent field of orbital spacesuit skydiving.
The test unit is known as the Inflatable Re-entry Vehicle Experiment, or IRVE. In packaged form its fabric is wrapped tightly around the gas cylinder used to inflate it - described as a "glorified scuba tank" by NASA engineers. The shield unit is 42cm in diameter and about a metre long on its own, and for this week's test another 50cm cylinder of electronics and telemetry gear was added.
After being fired 131 miles into space by a sounding rocket from NASA's Wallops Island test range, the IRVE then inflated its conical shield using nitrogen from the gas cylinder as it fell back towards the atmosphere. The fabric of the bladders uses silicone to provide gastightness, kevlar for strength and structure, and layers of "Kapton" film and "Nextel" fabric to resist the heat of re-entry.
The mushroom-cap-esque bag unit, when fully inflated, formed a circular heatshield 3 metres across. According to NASA, this successfully resisted the heat of re-entry at hypersonic speed - greater than Mach 5 - then slowed down through the supersonic realm and thus into the subsonic without difficulty.
"Everything performed well even into the subsonic range where we weren't sure what to expect," said NASA hypersonics boffin Neil Cheatwood. "The telemetry looks good. The inflatable bladder held up well."
"This was a small-scale demonstrator," added Mary Beth Wusk, IRVE project manager. "Now that we've proven the concept, we'd like to build more advanced aeroshells capable of handling higher heat rates."
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