Delays in Picking a Launch Vehicle
Wiesner in his memorandum to Sorensen noted that “the major decisions have not been announced as to what extent rendezvous will be employed, what Advanced Saturn vehicle will be built (probably C-4), and what will be the characteristics of the so-called Nova that could put man on the Moon by direct ascent. The relative emphasis of rendezvous versus direct ascent is a key to the entire program.”
There were two reasons for the delay in selecting the launch vehicle for the lunar mission. One was that the “national space plan” called for in the May 8 Webb-McNamara memorandum had anticipated a collaborative NASA-DOD effort to define a family of launch vehicles that could meet both agencies’ requirements and advance the development of both liquid fuel and solid fuel propulsion systems. The focus of this planning effort was a “NASA-DOD Large Launch Vehicle Planning Group.” The group was directed by Nicholas Golovin, then with NASA; its deputy director was Lawrence Kavanaugh of DOD. The group started work in July 1961, and by the fall had become bogged down in very detailed studies and deadlocked over the relative roles of liquid-fueled and solid-fueled boosters in the lunar landing program. Rather than come up with an integrated plan, the group had suggested a new Air Force-developed launch vehicle, called Titan III, with lift capabilities closely resembling the Saturn 1 vehicle that NASA was developing. The group’s final recommendations attempted to satisfy both NASA and DOD, and ended up pleasing neither agency.23
The second reason for the delay in selecting a launch vehicle for the lunar mission was NASA’s difficulties during the May-November period in deciding its preferred approach to sending men to the Moon.24 Indeed, this uncertainty would continue well into 1962 and become a focus of NASA-White House controversy.
Beginning on May 2, even before a final decision on whether to approve a lunar landing effort had been made, there were a series of NASA studies examining alternatives for accomplishing the lunar mission. The first of these studies took as its starting point a “direct ascent” approach, in which the spacecraft for the lunar mission would be launched by a giant booster with eight F-1 engines in its first stage. The spacecraft would fly directly to the Moon and land intact on the lunar surface. A portion of the spacecraft would then take off from the Moon after the astronauts had completed their exploration, and return directly to Earth. This approach meant designing a seventy-five-ton spacecraft, almost forty times the weight of the Mercury capsule, that would “back down” to a lunar landing, using rocket firings to slow the craft to landing speed; during the landing, the astronauts would be on their backs at the other end of the craft, more than eighty feet above the surface and with no or very limited direct visibility of the landing site. The direct ascent approach also required that the fuel for the return journey and the heat shield needed for reentry into the Earth’s atmosphere, both of which were heavy, would have to be carried to and then launched from the lunar surface. All of this would require a large and heavy spacecraft, and thus a very powerful booster NASA called Nova to send it to the Moon in a single launch. The more NASA, and especially von Braun and his team at Huntsville, thought about the technological leap required to develop the gigantic Nova vehicle, the more it looked for alternatives to making such a jump.
NASA during the summer of 1961 began to look harder at an approach called Earth-orbit rendezvous (EOR). This approach would allow the lunar spacecraft and the rocket stage needed to send it toward the Moon to be divided into two or more pieces, each piece launched separately. One or more rendezvous in Earth orbit would then be needed to assemble the pieces into a single spacecraft. An alternative EOR approach was to send the complete spacecraft and its Earth departure stage fueled with light liquid hydrogen into Earth orbit with one launch. Then a second launch would carry into orbit the comparatively heavy liquid oxygen used as the oxidizer for burning the hydrogen fuel; the oxygen would then be transferred to the lunar – bound rocket stage. Using an EOR approach meant that a launch vehicle significantly smaller than the Nova could be developed for the lunar mission. However, it did not solve the problem of how to land a single large spacecraft on the lunar surface.
Several versions of a smaller launch vehicle were proposed during the 1961 studies. The Saturn C-2 that had been part of NASA’s plans in the spring was soon abandoned, and an “Advanced Saturn” with several powerful F-1 engines in its first stage became the focus of attention; the issue was how many of the large engines to use. The two-engine version became known as the Saturn C-3 and the four-engine version the C-4. This was the vehicle Wiesner mentioned in his November 20 memorandum to Sorensen.25
When he wrote that memorandum, Wiesner was apparently not aware of the latest NASA study of the launch vehicle issue. On November 6, Milton Rosen of NASA headquarters, reflecting the deadlock in the Golovin – Kavanau group, had organized a separate two-week study to recommend to the NASA leadership “a large launch vehicle program” which would “meet the requirements of manned space flight” and “have broad and continuing national utility.” Rosen reported that “to exploit the possibility of accomplishing the first lunar landing by rendezvous,” NASA should develop an “intermediate vehicle” that had five F-1 engines in the first stage, four or five J-2 engines in its second stage, and one J-2 in its third stage. (The J-2 was an engine powered by high-energy liquid hydrogen fuel that would have the capability to be stopped and restarted.) The four-engine Saturn C-4 had a “hole” in the center of its four first-stage F-1 engines; adding a fifth F-1 would thus be relatively straightforward. Rosen argued that NASA should build the most powerful rocket possible short of a Nova, and von Braun agreed that “the hole in the center was crying out for another engine.” Adding a fifth engine would increase first stage thrust at liftoff to 7.5 million pounds. Since a direct flight to the Moon was at this point still NASA’s officially stated preference for the lunar landing mission, Rosen also recommended that “a NOVA vehicle consisting of an eight F-1 first stage” should be developed on a “top priority basis.” He added that “large solid rockets should not be considered as a requirement for manned lunar landing.” The recommendation for a five-engine first stage for the launch vehicle, soon called the Advanced Saturn C-5 and ultimately the Saturn V, was quickly accepted by the NASA leadership. Within a few weeks, some form of rendezvous using the Saturn V replaced direct ascent as NASA’s preferred approach to getting to the Moon, although design work on the Nova vehicle continued for some months.26
Wiesner likely also was not aware of a November 6 meeting between the NASA and Department of Defense space leadership at which there was agreement to “cancel the development of very large (240” class) solid rocket as a backup for NOVA,” since “the work of the past six months shows that the reliability and potential of NOVA will be sufficient to make unnecessary the parallel development of the large solids on identical time scales,” as had been called for in the May 8 Webb-McNamara memorandum.27 Overall, the situation with respect to a launch vehicle for Apollo was not in as bad a shape as the Wiesner memorandum suggested; however, Wiesner was correct in his assessment that “the relative emphasis of rendezvous versus direct ascent is a key to the entire program.”