The process of slowing the Space Shuttle from orbital speeds in excess of 25,000 kilometers per hour (15,000 miles per hour) to about 350 kilometers per hour (215 miles per hour) at touchdown produces heat that would normally destroy the spacecraft without the use of thermal protection systems. During re-entry, the shuttle must pass through Earth's atmosphere which increases the heat load on the vehicle to approximately 1,600°Celsius (3000° Fahrenheit).

As the shuttle travels at supersonic speeds through the upper atmosphere, the air passing over its forward-facing surfaces produces the immense heat. Thanks to the heat shield and other thermal protection, the heat is largely absorbed and radiated and does not heat the entire vehicle.