In April of 1960 the Douglas Aircraft Company was awarded a contract to develop the second and uppermost stage for the Saturn I space booster. In order to realize the high specific impulse available, this stage, called the S-IV, was to utilize liquid hydrogen and liquid oxygen as the propellants. After burn-out of the first stage, the S-IV Stage was to ignite its engines at an altitude of approximately 200,000 feet, burn for approximately 8 minutes, and inject a 20,000 lb spacecraft into a low earth orbit. This program represented Douglas's first major endeavor with liquid hydrogen. It was necessary to develop an insulation for the S-IV Stage that was capable of withstanding the thermal shock associated with loading, could provide adequate insulative properties to limit the flow of heat into the hydrogen, and was of minimum weight. This latter fact cannot be over emphasized because every extra pound of insulation is one less pound of available payload weight.
