<Li> Reusable . Previous spacecraft generally used ablative heat shields which burned off during reentry and so couldn't be reused . This insulation was robust and reliable, and the single - use nature was appropriate for a single - use vehicle . By contrast, the reusable shuttle required a reusable thermal protection system . </Li> <Li> Lightweight . Previous ablative heat shields were very heavy . For example, the ablative heat shield on the Apollo Command Module comprised about 1 / 3 of the vehicle weight . The winged shuttle had much more surface area than previous spacecraft, so a lightweight TPS was crucial . </Li> <Li> Fragile . The only known technology in the early 1970s with the required thermal and weight characteristics was also so fragile, due to the very low density, that one could easily crush a TPS tile by hand . </Li> <P> The orbiter's aluminum structure could not withstand temperatures over 175 ° C (347 ° F) without structural failure . Aerodynamic heating during reentry would push the temperature well above this level in areas, so an effective insulator was needed . </P>

Who invented the heat shield for the space shuttle