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The simplest and cheapest type of heat shield is the ablative heat shield, which dissipates heat from the plasma by allowing its outer layers to vaporize.
All of the early spacecraft with the exception of the early Mercury capsules used ablative technologies to assist with the transition from high orbital speeds down to aerodynamic regimes where a spacecraft can be flown or parachuteApollo 15 capsule landed safely despite a parachute failure. A parachute is a device used to slow the descent of a falling body or load. The word parachute comes from the French words para, protect or shield, and chute, to fall. Therefore parachute actuald to safety.
Such heat shields are used on virtually all expendable spacecraft and on many ballistic missiles, since it doesn't matter whether they can withstand a second reentry.
When the reusable Space Shuttle system was designed, it was decided that a non-reusable heat shield would not be an efficient approach. Instead the Space Shuttle's underside was coated with thousands of ceramic tiles that were intended to be able to survive multiple reentries with only minor repairs between missions. However, the original design proved to be somewhat less robust than intended; the Shuttle suffered from frequent lost and damaged tiles, and ultimately the Space Shuttle ColumbiaShuttle Orbiter Columbia (NASA Designation: OV-102 was the first space shuttle in NASA's orbital fleet, first flying mission STS-1 from April 12 to April 14, 1981. It was lost with all crew when it disintegrated during re-entry on its 28th mission, STS-10 was destroyedSTS-107 on launch day STS-107 was a space shuttle mission by NASA using the Space Shuttle Columbia''. The entire seven member crew was killed on February 1, 2003, when the shuttle disintegrated over Texas during reentry into the Earth's atmosphere. This w with all hands when a piece of insulating foamThe most general definition of foam is a substance that is formed by trapping many gas bubbles in a liquid or solid. It can also refer to anything that is analogous to such a phenomenon, such as quantum foam. Often people mean polyurethane foam, Styrofoam from its external fuel tank fell off and damaged the heat shield on its left wing.