Space

New spin on heat shields could cut cost of spacecraft

Rui Wu's prototype spinning heat shield
Rui Wu's prototype spinning heat shield
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Rui Wu's prototype spinning heat shield
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Rui Wu's prototype spinning heat shield

If you're building a spacecraft that's going to be landing on a planet that has an atmosphere, then you'd better equip it with a heat shield. Although some approaches to such shields can be heavy and/or complex, a University of Manchester PhD student has developed one that's simple, cheap and lightweight.

As a spacecraft plummets through a planet's atmosphere, the friction of the air against the rapidly-passing underside of the craft causes heat to build up. Heat shields serve to dissipate that heat, keeping it from damaging the spacecraft itself, while also helping to slow the spacecraft's descent by creating aerodynamic drag.

Presently-used shields include ones that inflate when needed, or that are mechanically deployed. Rui Wu, however, created a prototype that's a little different.

Made of a flexible, strong and heat-resistant material that folds down into a spiral shape when not in use, his shield automatically starts spinning like a samara-type tree seed when exposed to the onrush of air that a spacecraft would experience when dropping through a planet's atmosphere.

As it spins, centrifugal force causes its skirt-like sides to flare out, flatten and stiffen. This creates the drag needed to help slow the descent, while also providing a large protective surface for the dissipation of heat. No additional machinery, other than the shield itself, is required for its deployment.

"Since this prototype is lightweight and flexible enough for use on smaller satellites, research could be made easier and cheaper," says Wu. "The heat shield would also help save cost in recovery missions, as its high induced drag reduces the amount of fuel burned upon re-entry."

Source: The University of Manchester

4 comments
piperTom
It's a superb idea, tho I'm not quite getting what makes it spin. Article states that friction is the cause of the heat; but it's mainly due to compression of the gas just in front of the object.
Skipjack
I am a bit concerned about the effect the spin will have on orientation of the rest of the spacecraft. Any force in one direction, will cause an equal force in the other direction. So theoretically, the rest of the spacecraft will start spinning in the opposite direction of the heat shield.
Expanded Viewpoint
No, Skipjack, you've got it wrong on the spin thing. Unless there's a friction free bearing involved, any spin in the shield will be imparted to some degree in the craft as well. It's called a heat SHIELD for a reason, it blocks heat, it can't possibly dissipate any heat. That would require a cooler place for the heat to flow into. Randy
Douglas Bennett Rogers
It will dissipate heat via radiant emittance according to the T**4 law. It looks like it will get very hot before it encounters the fluid flow condition required to spin a turbine.
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