Thermal Soak (Tiles) Re-Entry
•The space shuttles used a system called thermal soak. It consisted of multiple shield types, but the best known is the first use of tiles, which is a trademark of the shuttle program.
•Without a TPS, the shuttle’s aluminum skin would fail at about 347 °F.
•The most common tile on the Shuttle’s was High-temperature reusable surface insulation (HRSI) pictured below.
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http://upload.wikimedia.org/wikipedia/commons/2/22/Space_Shuttle_%28HRSI_tile%29.png
•The tiles are so fragile that they can be easily  crushed by the strength of a human hand.

•The tiles would vary between 1 to 5 inches.

•Each tile can  absorb at least 1300 °F of heat.