CORK INSULATION IN NASA’S DELTA PROJECT
When a rocket ascends through the earth’s atmosphere it is subject to immense aerodynamic heating caused by the friction of the air against the fragile skin of the accelerating vehicle. Instead of running the risk of the heat piercing the skin of the rocket, the original Delta team used the typical engineer’s approach to “killing the problem”, putting in a layer of insulating material.
The insulator they chose was cork. It seemed to me a strange material to use in a launch vehicle. Cork in a spaceship? It was so ninetenth century. It made you think Where’s the gutta-percha? Where’s the beeswax? But cork really made sense if you thought about it. It’s a good insulator, it’s light and it’s cheap. It had worked well in the seventes, and when something really works in rockets, you tend to leave it alone unless you don’t have any choice.
The Delta family of rockets (supplied by the Boeing company) has been in service since August 1960 when Delta I was launched. When the shuttle programme began NASA proposed getting rid of all non-reusable craft, but after the Challenger accident all projects were renewed. In 1989 the new model of Delta rocket was launched, Delta II, designed to launch the satellites which would make up the GPS system. The United States needed bigger launchers for its spy satellites, and so in 1998 Delta III was created and in 2001 Delta IV.