Brown had studied the 1920s writings of German physicist Hermann Oberth and other early space theorists. Brown concluded that just building a space station after Mercury wouldn’t be considered a significant advancement in the United States’ activity in space. So he started a group with fellow engineers William Michael Jr., John Bird, Ralph Stone and Max Kurbju who studied not only a circumlunar trip around the Moon but also a rendezvous to facilitate a lunar landing. Then, during an offhand discussion with Tom Dolan, a representative from one of Langley’s aircraft contractors, the Chance Vought Aircraft Corporation, Brown found a compatriot for early ideas about LOR. Brown and Dolan were actually studying two different things—the mechanics of a trip to the Moon and the procedures for a rendezvous in space. During subsequent conversations, noodling sessions, shared scratch-paper sketches and then official meetings, they put their two analyses together to create the idea of LOR for a human lunar mission. But the idea couldn’t seem to gain traction with the Direct Ascent and EOR crowds.
Then along came John Houbolt, another engineer at Langley who was working on understanding rendezvous in Earth orbit. The story goes that Houbolt attended a presentation on LOR by Clinton Brown’s group sometime in 1960 and it was like a bolt of lightning hit him. He was an instant convert.
Engineer John C. Houbolt explains the Lunar Orbit Rendezvous concept at the Langely Research Center. Credit: NASA.
The more Houbolt studied LOR, the more he was convinced it was the only way NASA could get to the Moon. LOR required less fuel, only half the payload and not as much new technology compared to the other methods. It would take just one launch from Earth, as opposed to EOR’s two or more. Only a small, lightweight Lunar Module would land on the Moon instead of a massive rocket ship. And because the lander could be discarded after use, it wouldn’t have to be built to withstand the fiery return through Earth’s atmosphere. Instead, it could be designed for maneuvering in the lunar environment, which had no atmosphere and only one-sixth the gravity of Earth.
Houbolt became a fervent champion of LOR. Charlie Donlan, then one of the leaders at Langley, equated Houbolt to John the Baptist, traveling the wilderness of ad hoc committee meetings and scientific conferences, passionately preaching the LOR gospel to anyone who would listen. He was trying to save the souls of everyone at NASA because he was sure the only way to attain the salvation of landing on the Moon was through LOR.
Houbolt first proposed the idea of LOR to a larger group of engineers during a Space Task Group meeting at Langley in early 1961. He was told he didn’t know what he was talking about. In a later meeting, Houbolt was told the numbers he presented were lies.
The reluctance about rendezvous in general continued. At one meeting in June 1961, Abe Silverstein, who was now director of the Office of Space Flight Programs at NASA Headquarters, emphatically said there was no way rendezvous should be part of getting to the Moon.
“Look, fellas, I want you to understand something,” he said, starting the meeting. “I’ve been right most of my life about things, and if you guys are going to talk about rendezvous, any kind of rendezvous, as a way of going to the Moon, forget it. I’ve heard all those schemes, and I don’t want to hear any more of them, because we’re not going to the Moon using any of those schemes.”
But that didn’t stop Houbolt. He kept evangelizing for LOR, and when he was summarily dismissed, he refined his presentations, making them more precise and emphatic.
In the meantime, as engineers continued to study and work out the rendezvous concept, it became apparent that it wasn’t going to be as impossible as it first seemed. The realization hit that any missions subsequent to Mercury were going to require it, so they better damn well figure it out. Little by little, the prevailing perceptions against rendezvous began to change. EOR now moved ahead and became the leading candidate for landing on the Moon, even though there wasn’t a clear concept of how to set down a large vehicle on the then-unknown lunar surface and then boost it from the Moon’s surface back to Earth.
After even further study, some engineers admitted that a rendezvous around the Moon might not be as dangerous as everyone first thought. Early comments about LOR basically being a death sentence for a crew were softened when John Bird from the LOR team refined his comeback: “No, it’s like having a big ship moored in the harbor while a little rowboat leaves it, goes ashore and comes back again.”
When NASA’s new associate administrator, Robert Seamans, came to visit Langley in September 1960, Houbolt intercepted him in a hallway to discuss LOR. Seamans had begun to understand how future missions would depend on the ability to rendezvous, and he invited Houbolt to present his ideas at NASA Headquarters in Washington.
His new report, Manned Lunar Landing through Use of Lunar Orbit Rendezvous, outlined the benefits and methodology of a Lunar Orbit Rendezvous mission. But again, his audience did not initially perceive the idea as a realistic and credible way to get to the Moon.
Houbolt continued his crusade throughout 1961 and, feeling desperate that NASA was about to make a disastrous decision, he a wrote a letter directly to Seamans, passing over all official channels. In the nine-page letter, Houbolt referred to himself “somewhat as a voice in the wilderness,” then proceeded to outline the challenges facing Apollo and highlight the simplicity, the cost-effectiveness and (most importantly) the timeliness of a lunar rendezvous mission.
“The greatest objection that has been raised about our lunar rendezvous plan is that it does not conform to the ‘ground rules,’“ Houbolt wrote. “This to me is nonsense; the important question is[:] Do we want to get to the Moon or not? Why is Nova, with its ponderous size simply just accepted, and why is a much less grandiose scheme involving rendezvous ostracized or put on the defensive?”
Seamans passed the letter along to others at NASA Headquarters, and a copy of it landed on the desk of Joe Shea. Shea’s boss, Brainerd Holmes, directed Shea to figure it out once and for all and Shea decided he just needed to go where the data took him.
In the months that followed, more than seven hundred scientists, engineers and researchers in government, industry and academia spent more than a million person-hours studying the various concepts. Decision makers dedicated meetings and conferences to considering the various mission proposals. The choice would have an impact on how the spacecraft and systems would be built and if NASA was going to meet the challenge of getting to the Moon by the end of the decade, the decision needed to be made soon.
NASA had been built on engineering. Since many of the organization’s top people were engineers, they couldn’t ignore what the numbers now proved. When Direct Ascent was finally examined realistically, it didn’t take much more than back-of-the-envelope calculations to determine the development of an enormous rocket would be prohibitively expensive. Plus, the Nova rocket was projected to be so powerful that it could not launch from Cape Canaveral (one engineer only half jokingly said the rocket would sink Florida’s Merritt Island). Additionally, the rocket would have to carry a massive amount of fuel to be able to land and then lift off from the Moon. And based on the limited success of the United States’ early small rockets, a Direct Ascent vehicle would probably take decades to design and build; it would not qualify for Kennedy’s challenge.
This artist’s concept illustrates the Nova launch vehicle concept, which, from 1960 to 1962, the Marshall Space Flight Center considered as the best means to achieve a human lunar landing with a direct flight to the Moon. Although the program was canceled after NASA planners selected the Lunar Orbit Rendezvous mode, the proposed F-1 engine would eventually be used in the Apollo Program to propel the first stage of the Saturn V launch vehicle. Credit: NASA/Marshall Space Flight Center (MSFC).
As the calendar turned to 1962, in many people’s minds, the decision was coming down to a battle between the strong cultures of the two NASA centers most involved: MSFC favored EOR since it meant constructing more rockets. MSC came to favor LOR because it meant developing lots of space
craft. It was going to come down to which strategy was more feasible: landing something big on the Moon or a risky lunar rendezvous.
On June 7, 1962, the Lunar Mode Decision Conference was held at MSFC. Representatives from Marshall spent four hours in the morning presenting their argument for EOR, and in the afternoon the Houston contingent spent another four hours stating their case for LOR. As the day wore on, it became apparent to most everyone which approach was more viable. In the end, von Braun stood up and, to the surprise of his Marshall colleagues, expressed support for LOR:
Catherine Osgood, NASA math aide and aerospace engineer. Credit: NASA.
We at the Marshall Space Flight Center readily admit that when first exposed to the proposal of the Lunar Orbit Rendezvous Mode we were a bit skeptical—particularly of the aspect of having the astronauts execute a complicated rendezvous maneuver at a distance of 240,000 miles from the earth where any rescue possibility appeared remote. In the meantime, however, we have spent a great deal of time and effort studying the [three] modes, and we have come to the conclusion that this particular disadvantage is far outweighed by [its] advantages.
We understand that the Manned Spacecraft Center was also quite skeptical at first when John Houbolt advanced the proposal of the Lunar Orbit Rendezvous Mode, and that it took them quite a while to substantiate the feasibility of the method and fully endorse it.
Against this background it can, therefore, be concluded that the issue of “invented here” versus “not invented here” does not apply to either the Manned Spacecraft Center or the Marshall Space Flight Center; that both Centers have actually embraced a scheme suggested by a third source … I consider it fortunate indeed for the Manned Lunar Landing Program that both Centers, after much soul searching, have come to the identical solutions.
Although there would be a few holdouts expressing their dissenting opinions well into the next few years, the final decision was that LOR provided the best solution for landing on the Moon before the decade was out. On June 22, 1962, the Manned Space Flight Management Council announced in favor of the LOR approach and the final paperwork went to NASA administrator James Webb for his signature.
WITH THE LOR DECISION NOW FIRMLY made, Ken Young and his compatriots in the Rendezvous Analysis Branch had an enormous task before them. They were starting with a blank sheet of paper, breaking new technical ground.
“In the beginning, we really didn’t know what we were doing,” Young said. “We knew how to work the equations of motion, and plan and maneuver the right orbits, but as far as rendezvous goes, we had to find a solution for relative motion.”
The questions of relative motion dealt with how two spacecraft moved in regard to one another and not how they were moving around Earth. But the fact that both vehicles would be moving at incredible speeds—about 17,500 miles per hour in low Earth orbit—created complications. In the unusual conditions of orbital flight, navigation is entirely different from navigation on Earth, and the differences are hard to reconcile with the everyday human experience; therefore, the team couldn’t use intuition to figure this out.
The intricacies of orbital mechanics meant that after a spacecraft reached orbit, the astronauts couldn’t just “floor it” and continuously fire their thrusters in order to meet up with another spacecraft. Doing so would quickly deplete the fuel, and they would likely never reach their target.
Orbital velocities are somewhat counterintuitive, as different orbital altitudes correlate to a certain orbital velocity: The lower the orbit, the higher the orbital velocity; and the higher the orbit, the slower the orbital velocity. If a spacecraft fires its thrusters—seemingly to speed up—and achieves a higher orbit, it ends up slowing down because higher orbits have a lower orbital velocity. And just the opposite—if the spacecraft decreases speed, it reaches a lower orbit, where it ends up going faster, relatively speaking.
The Rendezvous Analysis Branch had to account for Newton’s laws of motion and his law of gravity. The branch also had to understand the Hohmann transfer, a maneuver that moves a spacecraft from one orbit to another in the most efficient manner. Other specialized maneuvers, while not as efficient in fuel usage, had to be developed to put a spacecraft into the preferred position relative to another vehicle at a specific time or orbital position.
The key to orbital rendezvous maneuvers is timing the thruster firings so that the two spacecraft arrive at the same point in an orbit at about the same time. Deciding when to fire the thrusters takes quick calculations—somewhat similar to how a quarterback leads a receiver in a football game—to account for how fast and how far the spacecraft needs to go to make the rendezvous.
Equally as important as the orbital maneuvers is the precise timing of the launch of the second vehicle (called the chaser) since it must match the orbital plane of the first spacecraft (called the target vehicle) at the desired time of rendezvous. Thus, many other factors involving the launch window, the launch site, the range safety constraints, the booster lifting and steering capabilities and abort constraints must be researched and analyzed.
And working out the numbers would be very different whether you were computing for Earth orbit versus lunar orbit since the orbital periods and gravitational and environmental conditions were very different. For example, it takes ninety minutes to orbit the Earth and two hours to orbit the Moon.
“You start out with your equations of motion and how one vehicle moves and how the other one moves in relation to it,” said Catherine Osgood, who joined the group shortly after Young. “Then you just keep working on it until you’ve figured out how to lift off at the right time to rendezvous with a vehicle that’s already up there. You learned to keep your pencil sharp.”
Osgood worked at Langley as a math aide. Shortly before moving to Houston, she applied to become an aerospace engineer, based on all her work experience. She didn’t really expect to get her classification and job title changed since she had never taken any engineering classes.
“But then I actually got it,” she said. “I was really surprised, but there was no rough transition. It seemed if someone were capable of doing something, they’d be asked to do it, regardless of what their positions were. So I just sort of slid into it.”
Osgood’s husband, Donald, had worked for the Mercury Tracking and Ground Instrumentation Unit, setting up the communications network around the world for the Mercury flights. For Gemini and Apollo, he would be working with the instrumentation in the new Mission Control Center. The move to Houston meant new jobs, new challenges and living in a part of the country they’d never even visited. After living among the native Tidewater Virginians—who had the reputation of being a somewhat insular people—the Osgoods hoped that Houston might be a little more cosmopolitan.
But it meant moving their three children and finding new arrangements for their care. Both Catherine and Donald traveled for their jobs at various times, and their regular work schedules demanded long hours. They were eventually able to find a live-in nanny, and they also enlisted the help of the grandmas. Catherine’s mother came and stayed with the family in the summertime and Donald’s mother came in the winter. All the complications of moving, finding a place to live and getting the kids situated seemed to seamlessly work themselves out so Catherine could concentrate on her work with the rendezvous analysis team.
Bill Tindall, standing and Chris Kraft in Mission Control in Houston in 1973. Credit: NASA.
And this combination of math, physics and geometry took a tremendous amount of concentration. At this point, rendezvous was theoretical, because no one had actually performed any type of maneuver like this in space. In 1962, spaceflight was still in its infancy and humans had just recently made it to orbit. Nobody knew what the unknowns were, but the group at MSC knew rendezvous was going to require some new technologies and procedures. The Gemini spacecraft needed to be able to maneuver with incredible precision and communicate with a better ground tracking system. An in-flight radar system for the spacecraft would
need to be developed, and a small computer was going to be essential in calculating complicated rendezvous maneuvers and performing the precise thruster firings. Apollo would need an entirely new set of calculations, which meant the team needed to add all the elements of a new and different spacecraft flying in the lunar environment.
So the rendezvous analysis team worked their slide rules, argued regularly and then went back to working the numbers. While a few engineers at other NASA research centers also worked on resolving the theoretical complexities of rendezvous, the group at MSC had one person no one else had: Bill Tindall.
Tindall graduated from Brown University in 1948 after a stint in the Navy, uncertain what he wanted to do with his mechanical engineering degree. Either by luck or a stroke of kismet, he saw a brochure about the Langley Research Center; it immediately struck a chord. In his first job there, he figured out problems with aircraft wind tunnel instrumentation—but when Sputnik 1 launched, he felt pulled to the space side of Langley. He moved on to the Project Echo communications satellite, where his bent for dealing with sticky problems soon caught the attention of the Space Task Group. The way he could instinctively unravel a wide variety of issues made it seem like spaceflight was part of his soul.
Truly a man for all seasons, Tindall tooted the trumpet, acted in local theater, played a fiercely competitive game of tennis and unequivocally loved sports cars. Some called him Wild Bill; others thought he was the friendliest, funniest guy they’d ever met. But everyone considered him a genius.
“That guy was so dynamic, it was unbelievable,” Ken Young said. “He was an amazing first boss because he was a can-do, get-things-done, get-to-the-point kind of person. We had some great arguments trying to make plans for Gemini and get it done. But he was full of insights to help us younger guys with the subject of orbital mechanics.”
Eight Years to the Moon Page 6
