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How does the Thermal Protection System on the Space Shuttle work?

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The Thermal Protection System of the Space Shuttle is actually composed of the tile and thermal blankets

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used on the orbiter. Now originally, there were over 30,000 tile used on the orbiter, but we reduced that

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number to just a little over 25,000 through the use of heat-resistant blankets in some of the cooler areas

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like along the top of the wings or the sides of the payload bay.

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Now what these tile and these blankets must do is protect the orbiter from the heat of reentry and the heat

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of just being in space. Because when you're in space and you hold your hand up there, the side that's

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facing the Sun can get up to 250 degrees and the side that's on the dark side, away from the Sun, can get to minus 150.

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Now the black tile on the bottom of the orbiter have to be able to withstand about 2,000 degrees Fahrenheit

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during a reentry. Along the wing's leading edges and on the nose cap, that's called Reinforced

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Carbon-Carbon, or RCC. Those have to be able to take about 3,000 degrees.

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Now what happens during reentry is a shockwave is set up right in front of the orbiter, and those tile and

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those RCC have to protect the aluminum skin of the orbiter. The skin of the orbiter, as I said, is made up

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of a very unexotic aluminum. It will begin to actually bend and anneal at around 350 degrees.

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Now the temperature on the tile can get as high as, oh, 2,000 degrees. So what they have to do, those

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4-inch-thick tile in some areas, have to dissipate as much as 1,700 degrees of heat. And they're bonded to

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the orbiter's aluminum structure with what's called a "strain isolation pad," because the tile are very

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brittle and the orbiter's structure can flex and move quite a bit.

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And that's how the tile work on the orbiter.

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