We looked at every ounce of nonmetallic material, removed much of it, and concocted new materials for insulation and for pressure suits. We invented an insulating coating that would not burn, only to find that it would absorb moisture and become a conductor so we had to invent another one. The solution was a coating for the alass cloth. We solved the problem of fire in the space atmosphere of 5 psi oxygen, but try as we might, we could not make the ship fireproof in the launch-pad atmosphere of 16 psi oxygen. Launch with an atmosphcre that was 60 percent oxygen and 40 percent nitrogen, and then slowly convert to pure oxygen after orbit had been reached and the pressure was 5 psi.
Weight is a problem in the design of any flying machine.
Apollo, with its many chances, was anything but an exception. Problems are always easier to solve if one can afford a little leeway for making a change, but difficult and expensive if there is no weight margin. This margin made other CM changes relatively simple, and certainly less costly and time consuming. For LM there was no such solution. We had to shave an ounce here, another there, to make room for the changes that had to be made.