The key to high-energy stages was to use liquid hydrogen as the fuel. Liquid hydrogen fuel appealed to rocket designers because of its high specific impulse, which is a basic measure of rocket performance. Specific Impulse is the impulse delivered per unit of propellant consumed. You might think of it as the efficiency of the rocket. Compared to an RP-1 (kerosene) fueled engine of similar size, liquid hydrogen fuel could increase the specific impulse or efficiency of an engine by 40 percent. The combination of hydrogen and oxygen for propellants made the moon shot feasible.
A few seconds after liftoff, a fin-vane at the base of the booster stuck and started the 13-meter-tall spacecraft-booster combination spinning like a bullet. Twenty-six seconds into the flight the vehicle started coming apart. The abort-sensing system signaled the launch escape tower rocket to fire and pull the spacecraft away…
In May 1961, NASA was not really prepared to direct an enormous Apollo program designed to fly its spacecraft to the moon. New and special facilities would be needed and the aerospace industry would have to be marshaled to develop vehicles not easily adapted to production lines, but at this point no one had even decided just what Apollo’s component parts should be or how they should look.
In January 1960, President Eisenhower directed NASA Administrator Glennan to accelerate the Super Booster Program that had recently been assigned to NASA. This order ensured the transfer of the von Braun group from the Army Ballistic Missile Agency to NASA, and it gave Glennan the launch vehicle development and management capability that he needed.