Brown's Lunar Exploration Working Group

Michael's Paper on a "Parking Orbit"

The Rendezvous Committees

Houbolt's First Crusade

The Feelings Against Lunar-Orbit Rendezvous

The Space Task Group's Early Skepticism

Mounting Frustration

President Kennedy's Commitment

Houbolt's First Letter to Seamans

A Voice in the Wilderness

The LOR Decision



Key Documents
(pdf version)


 The Space Task Group's
Early Skepticism

In the early months of 1961, the STG, still at Langley, was preoccupied with the first Mercury flight and the hope—soon to be crushed by Vostok 1—that an American astronaut would be the first human in space. When any of its members had a rare moment to consider rendezvous, it was thought of "as one of several classes of missions around which a Mercury program follow-on might be built."44

On 10 January 1961, four days after the meeting of the Space Exploration Program Council, Houbolt and three members of the Theoretical Mechanics Division—division chief Clint Brown, Ralph Stone and Manuel J. "Jack" Queijo—attended an informal meeting at Langley with three members of STG's flight systems division—H. Kurt Strass, Owen E. Maynard, and Robert L. O'Neal. Langley Associate Director Charles Donlan, Gilruth's former chief assistant, also attended. It was at this meeting that Houbolt, Brown, and the others tried to persuade the men from the STG (Donlan had only recently been reassigned to Langley from the STG) that a rendezvous experiment belonged in the Apollo program and that LOR was preferable if any realistic plans for a lunar landing were to be made.45

They were not persuaded. Although the STG engineers received the analysis more politely than Max Faget had the month earlier, all four admitted quite frankly that the claims about the weight savings were "too optimistic." Owen Maynard remembers that he and his colleagues initially viewed the LOR concept as "the product of pure theorists' deliberations with little practicality." In essence, they agreed with Faget's charge, although they did not actually say it, that Houbolt's figures did "lie." In advertising the Earth-weight savings of LOR and the size reduction of the booster needed for the lunar mission, Houbolt and the others were failing to factor in, or at least greatly underestimating, the significant extra complexity, and thus added weight, of the systems and subsystems that LOR's modular spacecraft would require.46

This criticism was central to the early skepticism toward the LOR concept—both inside and outside the STG. Even Marshall's Wernher von Braun initially shared the sentiment: "John Houbolt argued that if you could leave part of your ship in orbit and don't soft land all of it on the moon and fly it out of the gravitational field of the moon again, you can save takeoff weight on earth." "That's pretty basic," von Braun recalled later in an oral history. "But if the price you pay for that capability means that you have to have one extra crew compartment, pressurized, and two additional guidance systems, and the electrical supply for all that gear, and you add up all this, will you still be on the plus side of your trade-off?" Until the analysis was performed (and there are some former NASA engineers who still argue today that "this trade-off has never been realistically evaluated"),47 no one could be sure—but many NASA people suspected—that LOR would prove far too complicated. "The critics in the early debate murdered Houbolt," von Braun remembered sympathetically.48

Houbolt recalls this January 1961 meeting with the STG as a "friendly, scientific discussion." He, Brown, and the others did what they could to counter the argument that the weight of a modular spacecraft would prove excessive. Using an argument taken from automobile marketing, they stated that the lunar spacecraft would not necessarily have to be "plush"; an "economy" or even "budget" model might be able to do the job. One such "budget model," which the STG engineers did not seriously consider, was one of John Bird's lunar bugs, "a stripped-down, 2,500-pound version in which an astronaut descended on an open platform."49 In answer to the charge that a complicated modular spacecraft would inevitably grow much heavier than estimated, Houbolt retaliated that the estimated weight of a direct-ascent spacecraft would no doubt increase during development, making it a less competitive option in comparison with rendezvous.

But in the end, all the substantive differences between the two groups of engineers went out the window. All Houbolt could say to the STG representatives was "you don't know what you're talking about," and all they could say to him was the same thing. "It wasn't a fight in the violent sense," reassures Houbolt. "It was just differences in scientific opinion about it."50

Whether or not this skeptical response to that day's arguments in favor of LOR indicated any general STG sentiment in early 1961 has been a matter of serious behind-the-scenes debate among the NASA participants. Houbolt has argued that the STG consistently opposed LOR and had to be convinced from the outside, by Houbolt himself, after repeated urgings, that it was the best mission mode for a lunar landing. Leading members of the STG, notably Gilruth and Donlan, have argued that that was not really the case. They say that the STG was too busy preparing for the Mercury flights even to bother thinking seriously about lunar studies until after Kennedy's commitment. Gilruth recalls that when Houbolt first approached him "with some ideas about rendezvousing Mercury capsules in earth orbit" as "an exercise in space technology," he did react negatively. It was a "diversion from our specified mission," according to Gilruth, and therefore not something on which he, as the head of Project Mercury, had any time to reflect.51

According to Gilruth, it was only later that he found out that Houbolt was interested in LOR. By that time, in early 1961, NASA had started studying the requirements of a manned lunar landing through such task forces as the Low Committee, and the STG did its best to follow suit. When it did think seriously about a lunar program, especially about that most critical operation of actually landing astronauts on the Moon, LOR gained "early acceptance
. . . notwithstanding the subsequent debates that erupted in numerous headquarters committees."52

"I was very much in favor of that mode of flight to the moon from the very beginning," Gilruth has since claimed. "I recall telling our people that LOR seemed the most promising mode to me—far more promising than either the direct ascent or the earth orbital rendezvous modes." The most important thing in planning for a lunar landing program was to minimize the risk of the actual operation. Thus, LOR was the best choice among the contending modes because it alone permitted the use of a smaller vehicle specifically designed for the job. In Gilruth's view, he was always encouraging to Houbolt. In his estimation, he felt all along that "the Space Task Group would be the key in carrying the decision through to the highest echelons of NASA" and "of course, this proved to be the case."53

Houbolt accepts little of these assertions; in fact, he "violently disagrees" with them. He points out that on several occasions in late 1960 he had briefed leading members of the STG about his LOR ideas. He also asserts that Gilruth had to know about them, that the STG had ignored and resisted them as too optimistic, and that the STG would continue to ignore and resist them and insist strongly on the need for developing large Nova-class boosters for a while. As evidence, he points to many subsequent instances where his ideas were summarily discounted by the STG and to different expressions of resistance from key STG members. One such statement came from Gilruth in an official letter as late as September 1961. "Rendezvous schemes are and have been of interest to the Space Task Group and are being studied," Gilruth informed NASA headquarters on 12 September. "However, the rendezvous approach itself will, to some extent, degrade mission reliability and flight safety." Rendezvous schemes such as Houbolt's "may be used as a crutch to achieve early planned dates for launch vehicle availability," Gilruth warned. Their advocates propose them "to avoid the difficulty of developing a reliable Nova class launch vehicle."54

Houbolt felt strongly that if he could just persuade Gilruth's people to "do their homework" on rendezvous, "then they too would become convinced of its merits." But for months, he could not get them—or anyone else—to do that. There was "virtually universal opposition—no one would accept it—they would not even study it." In his view, it was "my perseverance, and solely mine" that caused the STG and various other groups to study and realize finally "the far-sweeping merits of the plan." It was "my own in-depth analysis" and "my crusading" based on that analysis that, above all else, later "paved the way to the acceptance of the scheme." In Houbolt's view, if not for his constant badgering, NASA might have tried to reach the Moon some other way.55

In early 1961, when the Low Committee announced its plan for a piloted lunar landing and its aspiration for that bold mission to be made part of Project Apollo, it definitely seemed that NASA was still resisting LOR. In outlining the requirements for an ambitious lunar flight, the committee's chief recommendation was to focus on the direct approach to the Moon, leaving rendezvous out. LOR was not discussed at all. Low remembers that during the time of his committee's deliberations, he asked one of its members, E.O. Pearson, Jr., to visit John Houbolt at Langley and "to advise the Committee whether we should give consideration to the Lunar Orbit Rendezvous Mode." Pearson, the assistant chief of the Aerodynamics and Flight Mechanics Research Division at NASA headquarters, returned with the answer, "No," LOR "was not the proper one to consider for a lunar landing." A rendezvous 240,000 miles from home, when rendezvous had never been demonstrated—Shepard's suborbital flight had not even been made yet—seemed, literally and figuratively, "like an extremely far-out thing to do." Maybe LOR would save some weight; maybe it would not. But even if it did, it was not the best approach; too many critical maneuvers would have to be made after sending the spacecraft with its precious human cargo on its lunar trajectory. If any rendezvous had to be included, it would be much better in the Earth’s orbit, where everything about the spacecraft could be thoroughly checked out and the craft brought back safely with its human occupants if something went wrong.56

Thus the Low Committee, in early 1961, recognizing that it would be too expensive to develop and implement more than one lunar landing mission mode, made its "chief recommendation": NASA should focus on direct ascent. "This mistaken technical judgment was not Houbolt's fault," Low admitted years later, "but rather my fault in trusting a single Committee member instead of having the entire Committee review Houbolt's studies and recommendations."57


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John Houbolt explaining LOR principles at a briefing in 1962.