A "game changing" new foldable heat shield got its first flight test today, paving the way to larger, lighter deep space planetary missions. At Spaceport America in New Mexico, a test version of the umbrella-like shield called Adaptable Deployable Entry and Placement Technology (ADEPT) was one of NASA three technology demonstrators sent on a suborbital trajectory by a sounding rocket as part of UP Aerospace's SpaceLoft 12 mission.
One of the major hurdles faced by any planetary mission upon entering an atmosphere is that hitting even the thinnest of air at hypersonic speeds so compresses the molecules in front of the craft that it generates temperatures in excess of 3,000⁰ C (5,400⁰ F) – twice that of molten steel. The usual way to handle this is with a round shield made out of a special phenolic plastic that ablates like the pages of a book burning away one by one. As it does so, it carries away the heat before it can reach the spacecraft.
It's a system that has worked quite well for over 60 years, but such plastic shields are heavy, rigid, expensive to build, and much harder to do so as they grow larger. They also generate massive g forces and require supersonic parachutes to slow the craft enough to deploy regular chutes for the final phase of landing.
ADEPT gets around this by replacing the rigid plastic shield with one made of a thick mat of 3D-woven carbon fibers that's held rigid by a support structure of deployable ribs and struts. Unlike the ablative plastic shield, the carbon fabric keeps the payload cool by re-radiating the heat before it can pass through the insulating textile.
However, the big advantages are that the carbon fiber shield is much lighter than the plastic ones, and it's foldable. This means it can be used to build planetary probes that are larger than the present generation, yet weigh much less. This, in turn, means that rockets don't need to be much larger to launch them.
The ADEPT demonstrator was launched today on a 15-minute suborbital flight that lofted it to an altitude of 60 miles (96 km) before it separated from the sounding rocket and unfolded while traveling at over Mach 3 (2,300 mph, 3,700 km/h). This wasn't fast enough to cause much heating, but the purpose of the test was more to check the engineering and aerodynamics.
"For a deployable like ADEPT, you can do ground-based testing, but ultimately, a flight test demonstrates end-to-end functionality – surviving launch environments, deploying in zero gravity and the vacuum of space, holding that rigid shape and then entering, in our case, Earth's atmosphere," says Paul Wercinski, ADEPT project manager at NASA's Ames Research Center.
The space agency says that the next tests will involve subjecting the ADEPT shield to orbital speeds of over 17,000 mph (27,000 km/h).
Check out the foldable heat shield in the video below.
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