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 Feelings Against
Lunar-Orbit Rendezvous

The basic premise of the LOR concept, which NASA would eventually develop as Project Apollo, was to fire an assembly of three spacecraft into Earth’s orbit on top of a single powerful (three-stage) rocket, the Saturn V. This 50,000-pound-plus assembly would include: a mother ship or command module; a service module containing the fuel cells, attitude control system, and main propulsion system; and a small lunar lander or excursion module. Once in Earth’s orbit, the last stage of the Saturn rocket would fire and expend itself, boosting the spacecraft—and its crew of astronauts—into its trajectory to the Moon. After braking into lunar orbit via the small rockets aboard the service module, two of the crew members would don space suits and climb into the lunar excursion module (LEM), detach it from the mother ship, and descend to the lunar surface. The third crew member would remain in the command module, maintaining a lonely but busy vigil in lunar orbit. If all went well, a top half, or "ascent stage," of the LEM would rocket back up, using the ascent engine provided, and redock with the command module. What remained of the lander would then be discarded to the vast darkness of space—or crashed onto the Moon, as was done in later Apollo missions for seismic experiments—and the astronauts would return home in their command ship.

One can summarize the LOR concept by referring to three "only" statements:

  1. Only a specially designed lunar module (the LEM) would actually descend to the Moon's surface.

  2. Only a portion of that LEM, the so-called "ascent stage," would return to dock with the command module in lunar orbit.

  3. Only the command module, the Apollo capsule itself, with its protective heatshield, would fall back to Earth.

Knowing what we know now—that Americans would land on the Moon and return safely before the end of the 1960s, using the LOR method—it might be hard to imagine and appreciate the strength of feeling against the LOR concept in the early 1960s. In retrospect, we know that LOR enjoyed—as Brown, Michael, Dolan, and especially John Houbolt had said—several advantages over competitor methods. It required less fuel, only half the payload, and less brand-new technology; it did not need a monstrous rocket, such as the proposed Nova for a direct flight; and it called for only one launch from the Earth, whereas one of LOR's chief competitors, "Earth-orbit rendezvous," required two. Only the small, lightweight LEM, not the entire spacecraft, would have to land on the Moon; this perhaps was LOR's major advantage. Because the lander would be discarded after use and would not return to Earth, NASA could customize the LEM’s design for maneuvering flight in the lunar environment and for landing softly on the Moon. In fact, NASA could tailor all the modules of the Apollo spacecraft independently—and without those tailorings compromising each other. One spacecraft unit performing three jobs would have forced some major compromises. But three units performing three jobs, without compromise, was another LOR advantage that no one at NASA could overlook.

In the early 1960s, however, all these advantages were merely theoretical. On the other hand, the fear that American astronauts might be left in an orbiting coffin some 240,000 miles from home was quite real. If rendezvous had to be part of the lunar mission, many felt it should be conducted only in the Earth’s orbit. If that rendezvous failed, the threatened astronauts could be brought back home simply by allowing the orbit of their spacecraft to deteriorate. But if a rendezvous around the Moon failed, the astronauts would be too far away to be saved, because nothing could be done. The morbid specter of dead astronauts sailing around the Moon haunted the dreams of those responsible for the Apollo program. It was a nightmare that made objective evaluation of the LOR concept by NASA unusually difficult.

It also was a nightmare that John Houbolt understood all too well, but he recognized that all the alternative schemes had serious pitfalls and dreadful possibilities. In fact, he was certain that all the other options involved even more perils. None of them offered a rescue possibility. In contrast, LOR offered the chance of a rescue by having two small landing modules, if NASA wished, rather than just one. One lander could be reserved with the orbiting mother ship and used only if the number-one lander encountered serious trouble. Or, in the case of an accident inside the command-and-service module, even one attached LEM could serve as a type of "lifeboat." (This actually did happen during Apollo 13, when, while the spacecraft was outward bound and 200,000 miles from the Earth, an explosion in one of the oxygen tanks within the service module caused a leak in another oxygen tank. NASA had an urgent life-threatening problem that it could only solve because it had the LEM. The astronauts headed home, without landing, temporarily occupying the LEM.) Therefore, Houbolt could not accept the charge that LOR was inherently more dangerous, but neither could he easily turn that charge aside.

It was an amazingly tempestuous intellectual and emotional climate in which NASA would have to make perhaps the most fundamental decision in its history. It was a psychological obstacle that made the entire year of 1961 and the first seven months of 1962 the most hectic and challenging period of John Houbolt's life.40

On 5 January 1961, Houbolt again spoke about rendezvous in Washington during the first afternoon of an historic two-day meeting of the Space Exploration Program Council at the NASA headquarters. NASA had created this council for "smoothing out technical and managerial problems at the highest level." Chaired by Associate Administrator Seamans, this council meeting included, as it always did, all program office heads at headquarters, the heads of all NASA field centers, and their invited guests and speakers. The council had been meeting quarterly since early 1960, but this first meeting of 1961 was by far the most historic to date: it was the first inside NASA to feature a full-scale, agency-wide discussion of a piloted lunar landing.41

By the end of the first day of this meeting, everyone realized that the mission mode for a human landing on the Moon by NASA could be reduced to three major options: direct ascent, which was still the front-runner; Earth-orbit rendezvous (EOR), which was gaining ground quickly; and lunar-orbit rendezvous (LOR), the darkhorse on which only the most capricious gamblers in NASA would have ventured a bet.

A different speaker addressed each option. First, Marshall's impressive rocket pioneer from Germany, Wernher von Braun, reviewed NASA's launch vehicle program, with discussion on the advantages of Earth-orbit rendezvous. This option involved launching two pieces of hardware into space independently using advanced Saturn rockets that were then under development. The two pieces would rendezvous and dock in the Earth’s orbit. The modules that had joined up during the rendezvous would allow for the assembly, fueling, and detachment of a lunar mission vehicle. That augmented ship would then proceed directly to the surface of the Moon and, after exploration, return to the Earth. The immediate advantage of Earth-orbit rendezvous, as von Braun clearly pointed out, was that it required a pair of less powerful rockets that were already nearing the end of their development—in other words, twice as many of his early Saturns. The biggest pitfall, as with direct ascent, was that there was not yet any clear concept of how the spacecraft would actually make its landing. Of that essential maneuver, von Braun offered no details, admitting that serious study would have to be conducted very quickly.

Next, Melvyn Savage of the Office of Launch Vehicle Programs at NASA headquarters talked about direct ascent. This was basically the method that had been described in science fiction novels and shown in Hollywood movies. A massive rocket, roughly the size of a battleship, would be fired directly to the Moon, land, and then blast off for home directly from the lunar surface. The trip would be like that of a chartered bus, moving from point A to point B and back to A again in one huge booster vehicle, the proposed twelve-million-pound-thrust Nova rocket.

Late in the afternoon, Houbolt discussed rendezvous and highlighted the unappreciated wonders of his darkhorse candidate. To him, the advantages of LOR and the disadvantages of the other two options were clear. Any single big rocket, such as Nova, that had to carry and lift all the fuel necessary for leaving the Earth's gravity, braking against the Moon's gravity as well as leaving it, and braking back down into the Earth's gravity again was not the most practical, especially if the mission must be accomplished soon. The development of a rocket that mammoth would take too long, and the expense would be enormous. In Houbolt's opinion, Earth-orbit rendezvous was better than direct ascent but not nearly as good as LOR. Once the lunar-bound spacecraft left its rendezvous station around the Earth, the rest of its mission would be accomplished exactly as with direct ascent. NASA's astronauts would still have to land an incredibly heavy and large vehicle on the surface of the Moon. The business of backing such a large stack of machinery down to the Moon and "eyeballing" it to a pinpoint soft landing—on what at the time was still a virtually unknown lunar surface—would be incredibly tricky and dangerous. Those few NASA researchers, such as Arthur W. Vogeley of Langley's Aero-Space Mechanics Division, who had been thinking about the terrors of landing such a behemoth (and getting the astronauts down from the top of it using an inside elevator), understood that there were no satisfactory answers to that approach.42

There were other talks that day, including an introduction by George Low, head of NASA headquarters lunar landing task force, and a technical talk by Houbolt's nemesis Max Faget that outlined the hardware and booster requirements for several possible types of lunar missions. But everyone walked away from the meeting understanding that if the United States were to reach the Moon by the end of the decade, NASA would have to evaluate the comparative benefits and risks of these three major options and somehow quickly pick the one that would work.43 At this point, the odds were excellent that the choice—if one were to be made—would be either direct ascent, which seemed simplest in concept, or Earth-orbit rendezvous. The LOR concept was a "long shot"—almost not worthy of mention for many NASA officials.


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An early LOR spacecraft configuration.

A comparison of the proposed mammoth Nova rocket with the very large Saturn C-5 and C-1 launch vehicles

A diagram from 1962 demonstrating the three basic approaches considered for lunar landing missions.