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Brown's Lunar Exploration Working Group Michael's Paper on a "Parking Orbit" The Feelings Against Lunar-Orbit Rendezvous The Space Task Group's Early Skepticism President Kennedy's Commitment Houbolt's First Letter to Seamans
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The
Rendezvous Committees
There was a growing feeling within NASA in late 1959 and early 1960 that a rendezvous in space was going to be a vital maneuver no matter what the agency's mission after Project Mercury might be. If it were a space station, travel vehicles would have to meet and dock with that station and then leave it. Thus NASA had to be able to bring two vehicles together in space. A lunar mission, too, would require some sort of rendezvous either in lunar orbit, as Michael's study suggested, or around the Earth from an orbital base—perhaps the space station itself—where a lunar-bound spacecraft might be assembled or at least fueled. Even if neither were done, there would still be communications and military "reconnaissance" satellites to inspect and repair, which would also require rendezvous maneuvers. Rendezvous had to be a central element of all future flight endeavors—whatever they might be. By the late summer of 1959, Langley's senior staff was ready to proceed with detailed studies of how best to perform rendezvous maneuvers in space. Two rendezvous study committees eventually came to life, both chaired by Dr. John C. Houbolt, the assistant chief of Langley's Dynamic Loads Division. Houbolt (with a B.S. and M.S. in civil engineering from the University of Illinois) was an aircraft structures expert who began working at Langley in 1942. In contrast to most Langley researchers, he had some significant foreign experience, having been an exchange research scientist at the British Royal Aircraft Establishment at Farnborough, England, in 1949. In 1958, he had only recently returned from a year's education at the Swiss Federal Polytechnic Institute in Zurich, where his dissertation on the heat-related aeroelastic problems of aircraft structure in high-speed flight had earned him a Ph.D.18 After returning from his graduate work in Switzerland, Houbolt and many other Langley researchers in the post-Sputnik phase became increasingly curious about spaceflight. Largely independent of the conversations taking place within Brown's group, Houbolt was on his own. He said years later, "I racked down and went through the whole analysis of orbital mechanics so I could understand it." From his own preliminary studies of trajectories, he saw the vital importance of rendezvous and began to recognize and evaluate the basic problems associated with it. During the STG's training of the Mercury astronauts at Langley, Houbolt was the one who presented their course of lectures on space navigation.19 Houbolt especially studied one particular problem related to rendezvous in space—the timing of the launch. NASA could not launch a mission at any arbitrary time and be assured of effecting a rendezvous with an orbiting spacecraft. To visualize the problem, Houbolt built a gadget with a globe for the Earth and a small ball on the end of a short piece of coat hanger, all connected to a variable-ratio gearbox. It simulated a satellite at different altitudes and in different orbital planes, enabling him to calculate the varying amounts of time it would take for the satellite to orbit around the revolving Earth. From his considerations of orbital mechanics, he knew that a change in orbital plane at 25,000 feet per second without the help of any sort of aerodynamic lift would require an enormous amount of energy and realistically could not be made. With this simple but ingenious model, Houbolt saw how long one might have to wait—a period of perhaps many days—to launch a rendezvous mission from Cape Canaveral. But he also found a way to circumvent the problem: if the orbital plane of the satellite could be made just one or two degrees larger than the latitude of the launch site, one could extend the launch "window" to four hours every day. Thus, he began to understand how NASA could get around the long waiting periods.20 The word quickly spread around Langley that Houbolt, the aircraft structures specialist, was now "the rendezvous man." He even had a "license to rendezvous." The Rand Corporation, a nonprofit think-tank organization in southern California connected to Douglas Aviation and interested in space rendezvous, presented it to a visiting Houbolt in early November 1959 as a jovial "pat on the back" after he had made a successful rendezvous in Douglas's rendezvous simulator.21 Thus when NASA Langley created its steering groups to study the problems of orbital space stations and those of lunar exploration missions, Houbolt, already recognized as a brilliant analyst, naturally emerged as the one to provide the input about rendezvous. The first of Houbolt's rendezvous committees was tied to the laboratory's Manned Space Laboratory Group. Headed by the Full-Scale Research Division’s Mark R. Nichols, an aerodynamics specialist who was reluctant to accept the assignment, this group came to life in the late summer of 1959. It was similar to Brown's interdivisional Lunar Exploration Working Group, except that it was larger and had committees of its own. One of them, Houbolt's committee, was supposed to investigate the matter of rendezvous as it pertained to Earth-orbital operations. And it did—in a "loosely organized and largely unscheduled" way—into the first months of 1960. Serving on the committee were John M. Eggleston, Arthur W. Vogeley, Max C. Kurbjun, and W. Hewitt Phillips of the Aero-Space Mechanics Division; John A. Dodgen and William C. Mace of the Instrument Research Division; and John Bird and Clint Brown of the Theoretical Mechanics Division.22 Given the overlapping memberships and responsibilities of the different committees and study groups created during this increasingly busy and chaotic period, it is no wonder that there has been so much confusion in the historical record about how the concept of lunar-orbit rendezvous first germinated in NASA and about who deserves credit for what. At one of the early meetings of the Manned Space Laboratory Group on 18 September 1959, Houbolt made a long statement on the rendezvous problem, one of the first made anywhere inside the NASA family. He insisted that his committee be allowed to study rendezvous "in the broadest terms" possible because, as he presciently argued, the technique was bound to play a major role in almost any advanced space mission NASA might initiate.23 Three months later, in December 1959, Houbolt appeared with other leading members of the Manned Space Laboratory Group before a meeting of the Goett Committee studying NASA's long-term plans. He urged the adoption of a rendezvous-satellite experiment that could "define and solve the problems more clearly"—something similar to the essence of NASA's later project, Gemini. Most members of the Goett Committee were still focusing more narrowly on a space station and a circumlunar mission; they showed little interest at that time in his experiment idea.24
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