Building Saturn

NASA inherited the effort to develop the Saturn family of boosters used to launch Apollo to the Moon in 1960 when it acquired the Army Ballistic Missile Agency under Wernher von Braun.⁶⁸ By that time von Braun’s engineers were hard at work on the first generation Saturn launch vehicle, a cluster of eight Redstone boosters around a Jupiter fuel tank. Fueled by a combination of liquid oxygen (LOX) and RP-1 (a version of kerosene), the Saturn I could generate a thrust of 205,000 pounds. This group also worked on a second stage, known in its own right as the Centaur, that used a revolutionary fuel mixture of LOX and liquid hydrogen that could generate a greater ratio of thrust to weight. The fuel choice made this second stage a difficult development effort, because the mixture was highly volatile and could not be readily handled. But the stage could produce an additional 90,000 pounds of thrust. The Saturn I was solely a research and development vehicle that would lead toward the accomplishment of Apollo, making ten flights between October 1961 and July 1965. The first four flights tested the first stage, but beginning with the fifth launch the second stage was active and these missions were used to place scientific payloads and Apollo test capsules into orbit.⁶⁹

The next step in Saturn development came with the maturation of the Saturn IB, an upgraded version of earlier vehicle. With more powerful engines generating 1.6 million pounds of thrust from the first stage, the two-stage combination could place 62,000- pound payloads into Earth orbit. The first flight on 26 February 1966 tested the capability of the booster and the Apollo capsule in a suborbital flight. Two more flights followed in quick succession. Then there was a hiatus of more than a year before the 22 January 1968 launch of a Saturn IB with both an Apollo capsule and a lunar landing module aboard for orbital testing. The only astronaut-occupied flight of the Saturn IB took place between 11 and 22 October 1968 when Walter Schirra, Donn F. Eisele, and R. Walter Cunningham, made 163 orbits testing Apollo equipment.⁷⁰

The largest launch vehicle of this family, the Saturn V, represented the culmination of those earlier booster development and test programs. Standing 363 feet tall, with three stages, this was the vehicle that could take astronauts to the Moon and return them safely to Earth. The first stage generated 7.5 million pounds of thrust from five massive engines developed for the system. These engines, known as the F-1, were some of the most significant engineering accomplishments of the program, requiring the development of new alloys and different construction techniques to withstand the extreme heat and shock of firing. The thunderous sound of the first static test of this stage, taking place at Huntsville, Alabama, on 16 April 1965, brought home to many that the Kennedy goal was within technological grasp. For others, it signaled the magic of technological effort; one engineer even characterized rocket engine technology as a “black art” without rational principles. The second stage presented enormous challenges to NASA engineers and very nearly caused the lunar landing goal to be missed. Consisting of five engines burning LOX and liquid hydrogen, this stage could deliver 1 million pounds of thrust. It was always behind schedule, and required constant attention and additional funding to ensure completion by the deadline for a lunar landing. Both the first and third stages of this Saturn vehicle development program moved forward relatively smoothly. (The third stage was an enlarged and improved version of the IB, and had few developmental complications.)⁷¹

Despite all of this, the biggest problem with Saturn V lay not with the hardware, but with the clash of philosophies toward development and test. The von Braun “Rocket Team” had made important technological contributions and enjoyed popular acclaim as a result of conservative engineering practices that took minutely incremental approaches toward test and verification. They tested each component of each system individually and then assembled them for a long series of ground tests. Then they would launch each stage individually before assembling the whole system for a long series of flight tests. While this practice ensured thoroughness, it was both costly and time-consuming, and NASA had neither commodity to expend. George E. Mueller, the head of NASA’s Office of Manned Space Flight, disagreed with this approach. Drawing on his experience with the Air Force and aerospace industry, and shadowed by the twin bugaboos of schedule and cost, Mueller advocated what he called the “all-up” concept in which the entire Apollo-Saturn system was tested together in flight without the laborious preliminaries.⁷²

A calculated gamble, the first Saturn V test launch took place on 9 November 1967 with the entire Apollo-Saturn combination. A second test followed on 4 April 1968, and even though it was only partially successful because the second stage shut off prematurely and the third stage—needed to start the Apollo payload into lunar trajectory—failed, Mueller declared that the test program had been completed and that the next launch would have astronauts aboard. The gamble paid off. In 17 test and 15 piloted launches, the Saturn booster family scored a 100 percent launch reliability rate.⁷³