heat shield science definition

A barrier that prevents a substance from absorbing heat energy from an outside source by absorbing and dissipating, or simply reflecting, that heat. Heat shields are commonly used to protect parts of a device from heat generated by its energy source, as in isolating the cabin of a car from its motor. Many spacecraft dissipate heat generated by friction with the atmosphere upon reentry using heat shields that melt and vaporize, dissipating the energy back into the atmosphere.