Re-entry

Abstract

Arguably the most audacious feature of an Apollo flight was to have the crew re-enter Earth’s atmosphere in the manner that they did. In the final minutes of a mission, a lump of metal and plastic, three crewmen and a few dozen kilograms of moonrock, altogether weighing nearly 6 tonnes, came barrelling in from outer space as Earth’s gravity hauled it in at speeds approaching 11 kilometres per second. As it entered, the air in front of the blunt end of the command module was brutally compressed in a shock wave, generating temperatures approaching 3,000°C. All that stood in the way of the crew being incinerated by this extraordinary heat was a coating of resin and fibreglass that NASA’s engineers reckoned could withstand the punishment.