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How does the Thermal Protection System on the Space Shuttle work?
The Thermal Protection System of the Space Shuttle is actually composed of the tile and thermal blankets
used on the orbiter. Now originally, there were over 30,000 tile used on the orbiter, but we reduced that
number to just a little over 25,000 through the use of heat-resistant blankets in some of the cooler areas
like along the top of the wings or the sides of the payload bay.
Now what these tile and these blankets must do is protect the orbiter from the heat of reentry and the heat
of just being in space. Because when you're in space and you hold your hand up there, the side that's
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.
Now the black tile on the bottom of the orbiter have to be able to withstand about 2,000 degrees Fahrenheit
during a reentry. Along the wing's leading edges and on the nose cap, that's called Reinforced
Carbon-Carbon, or RCC. Those have to be able to take about 3,000 degrees.
Now what happens during reentry is a shockwave is set up right in front of the orbiter, and those tile and
those RCC have to protect the aluminum skin of the orbiter. The skin of the orbiter, as I said, is made up
of a very unexotic aluminum. It will begin to actually bend and anneal at around 350 degrees.
Now the temperature on the tile can get as high as, oh, 2,000 degrees. So what they have to do, those
4-inch-thick tile in some areas, have to dissipate as much as 1,700 degrees of heat. And they're bonded to
the orbiter's aluminum structure with what's called a "strain isolation pad," because the tile are very
brittle and the orbiter's structure can flex and move quite a bit.
And that's how the tile work on the orbiter.
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