This report highlights on run-up to success, the American space program that had absorbed a series of high-profile embarrassments as the Soviet Union, with which the United States was competing in a so-called Space Race, seemed to remain one step ahead. To declare so publicly the goal to land a man on the moon before the end of the decade was to risk another humbling loss. At the time, the public spotlight shined on the face of the space program, the astronauts who had already become national heroes. One of the biggest issues to settle was the mission architecture—the steps through which spacecraft would be launched, landed on the moon, and returned safely. The engineers who designed the remarkable pieces of space hardware were only a part of the overall Apollo team. Thousands of engineers were involved in launch processing and monitoring the flights. In an era when computer systems were primitive compared to what we have today, constant communication between the astronauts and an army of engineers back in Houston was critical to ensure the safety of the astronauts as well as the success of the mission.
When President John F. Kennedy announced in May 1961 his goal to send a man to the moon, the United States had accomplished exactly 15 minutes of human spaceflight time, Alan Shepard’s suborbital flight in the Mercury space capsule, Freedom 7. In the run-up to that success, the American space program had absorbed a series of high-profile embarrassments as the Soviet Union, with which the U.S. was competing in a so-called Space Race, seemed to remain one step ahead. To declare so publicly the goal to land a man on the moon before the end of the decade was to risk another humbling loss.
“We choose to go to the moon in this decade and do the other things,” Kennedy said in a speech at Rice University in September 1962, “not because they are easy, but because they are hard.” And it was hard. The motive for the President’s goal may have been politics and prestige during the Cold War, but America’s political fortunes were now in the hands of its top engineers. At the moment of Kennedy’s announcement, the technology, the infrastructure, the hardware, and the technical workforce needed to achieve this goal did not yet exist.
At the time, the public spotlight shined on the face of the space program, the astronauts who had already become national heroes. What most people didn’t realize was the massive harnessing of America’s technological resources that occurred to make the moon landing possible. In all, more than 400,000 engineers, scientists, and technicians working for more than 20,000 companies and universities contributed to Apollo’s success. The engineers are not household names. Collectively, however, they overcame enormous technological challenges with creativity, innovation, and persistence. Their decisions and designs were sometimes risky, but always well thought out and, on occasion, elegantly simple.
This month we celebrate the 40th anniversary of the achievement of President Kennedy’s bold goal—Apollo It’s historic landing on the moon. And while most of the commemorations will feature Armstrong and Aldrin, who went to the moon, it took the efforts of Houbolt, Mueller, Castenholz, McClure, Kelly, Rathke, Carbee, Rigsby, Harms, Sherman, Bales, Garman, and thousands of engineers just like them to make it possible.
Speaking as an engineer, it is impossible not to be in awe of what they accomplished in just eight years. I’d like to share a few stories about their remarkable achievements.
Burton Dicht is Managing Director of ASME's Knowledge and Community Sector. His lifelong interest in aerospace history has made him a frequent lecturer at ASME’s sections and student sections.
Immediately following Kennedy’s announcement, NASA managers asked themselves, “How do you get to the moon?” It wasn’t the first time that engineers had speculated on the problem: In the early 1950s, for instance, Collier’s magazine had published a famous series of articles by leading scientists and engineers detailing a plan to send men to the moon and Mars. But suddenly the question had turned from being an academic exercise to a matter of national importance.
One of the biggest issues to settle was the mission architecture—the steps through which spacecraft would be launched, landed on the moon, and returned safely. For instance, one potential mission architecture involved launching a single manned vehicle directly to the moon and returning the entire spacecraft to Earth. Although straightforward, such a mission would be require launching a prohibitively large mass with a single rocket and was beyond the scope of what was possible in the 1960s.
Instead, the mission concept initially embraced by NASA was called Earth Orbit Rendezvous. EOR involved the launch of two rockets with all of the components needed for a lunar mission. In Earth orbit, the two rockets would rendezvous and dock, and then the combined spacecraft would continue onto the moon. This entire spacecraft would land on the moon and return to Earth when the mission was completed.
The other concept, which was not given much credence by the NASA hierarchy, was Lunar Orbit Rendezvous. In that mission architecture, a single launch vehicle would send a mother ship and a landing craft directly to the moon. In lunar orbit, the lander would separate from the mother ship and descend to the surface. On return the lunar lander would rendezvous and dock with the mother ship; the lander would then be discarded and the astronauts would return to Earth in the mother ship.
NASA’s opposition to LOR centered on the complexity and danger associated with spacecraft that must rendezvous in lunar orbit. But John Houbolt, an engineer at NASA’s Langley facility in Virginia, was a passionate advocate for LOR. Houbolt crunched the numbers for both concepts in what he called “back of the envelope calculations.”
The results to Houbolt were irrefutable. LOR made it possible to use smaller and lighter spacecraft, thus making the scale of the entire project simpler. But Houbolt could not convince his own bosses, and he did what most would consider career suicide by going around them directly to NASA’s leaders in Washington.
Houbolt’s stubborn persistence in the face of great opposition and the validity of his engineering calculations finally won the day. NASA leadership slowly came around, and by the fall of 1962 it had adopted the LOR mission architecture. With the concept set, NASA moved to develop the hardware necessary to make the lunar flight.
The linchpin of the Apollo program was a launch vehicle powerful enough to propel the mother ship and lunar landing craft to the moon. Without that critical piece, all other parts of the effort would be useless.
Tackling the problem was the brilliant German-born rocket engineer Wernher von Braun and his team at the Marshall Spaceflight Center in Huntsville, Alabama. Their solution, the engineering masterpiece known as the Saturn V, was a technological leap over anything the United States had in its inventory at the time.
Consisting of three stages possessing more than 3 million parts in total, the Saturn V would tower some 363 feet when fully stacked. As designed, the behemoth weighed more than 6 million pounds and its five F-l engines would produce 7.5 million pounds of thrust.
One day it would be the most powerful rocket ever launched. But in 1962 it was just a concept on a drawing board. Over the next five years, von Braun and his team, along with prime contractors Boeing, North American, Douglas, and Rocketdyne worked to design, manufacture, and test the Saturn V. It was a massive engineering project that pushed the boundaries of the technology and manufacturing methods.
In 1963, George Mueller, an engineering manager from industry who had helped develop the Minuteman ballistic missile for the Air Force, was brought in as the associate administrator for manned space flight. Mueller conducted a top-to-bottom review of the Saturn V program and grew concerned over von Braun’s testing plan. Von Braun was meticulous and proposed testing the rocket’s first stage by launching it with dummy upper stages. If that flight succeeded, the tests would proceed incrementally from there with dummy stages being replaced by live ones. Discounting the additional cost of manufacturing multiple test stages, Mueller questioned the time it would take to conduct all of the launches von Braun proposed. NASA would never achieve the “end of the decade” deadline set forth by Kennedy.
Mueller instead pitched to von Braun what was called the “all up testing” concept: launching a fully assembled Saturn V with all of the stages stacked and fueled. This was an approach Mueller used on the Minuteman project and while it was much riskier, it would enable the team to meet Kennedy’s timetable. Mueller, using strong engineering arguments, ultimately persuaded von Braun.
The all up testing concept was put to its first test in November 1967 when the Saturn V made its debut launch. Except for vibration problems (which would be corrected) the rocket performed so well that some testing instrumentation was removed for the second flight in April 1968.
That test, designated Apollo 6, did not go well. The five first stage F-l engines experienced some minor problems, but two of the five J-2 engines on the second stage failed, as did the single J-2 on the third stage. The Saturn V successfully achieved orbit, but had this been a manned mission, the failure of the J-2 engines would have put a moon landing in jeopardy.
The engineers at Rocketdyne, the engine manufacturer, worked overtime to determine the cause of the problem. The J-2 had never failed in any ground tests, and making a diagnosis of the problem next to impossible was the fact that the engineers did not have any hardware to examine. The only clue to work from was some telemetry data that pointed to a possible rupture of an auxiliary fuel line. Paul Castenholz, the J-2 project manager at Rocketdyne, led the investigation, and his team tested the engine again and again without failure.
Frustrated, and with the weight of the entire Apollo program bearing down on them, Castenholz and his engineers met to see if they were missing something. Marshall McClure, an engineer on the team, posed a simple question that would lead them down the path to an answer—“Would it be different in space than on the ground?”
The engineers watched films of their tests and saw that ice was building up on the lines carrying super-cooled liquid hydrogen and liquid oxygen. The fluid lines were flexible and were susceptible to vibrations. Could the ice, which needed air to form, be protecting the lines during ground tests? Castenholz and McClure used a specialized test chamber to study the components under a vacuum and the fluid lines failed. A simple engineering fix that involved adding steel mesh around the lines would prevent future failures. The Saturn V was now ready to carry astronauts.
The Saturn V launch vehicle was just one of the necessary components needed for a Lunar Orbit Rendezvous-style mission. NASA also had to develop a landing craft to take a pair of astronauts down to the surface of the moon. The lander, known as the Lunar Module, would serve as a shelter and base of operations on the lunar surface, and then launch the astronauts back into lunar orbit to rendezvous with the mother ship, the Command/Service Module.
The responsibility for designing the LM fell to Thomas Kelly and his team of engineers at Grumman Aviation (now Northrop Grumman). Designing a spacecraft for a largely unknown environment presented the team with many engineering challenges. And they had to balance the imperative of maximizing the chance of a successful landing with ensuring the safety of the astronauts aboard.
In the initial designs, those goals were in conflict; the weight of the Lunar Module as first drawn up was beyond specifications. Looking for any place where weight could be cut, Kelly focused on the windows, which were large and heavy. Such large windows would provide the astronauts with a good field of view as they sat in their seats during the landing phase. Kelly assembled a team of his engineers, which included Bill Rathke, Bob Carbee, John Rigsby, Gene Harms, and Howard Sherman to discuss options. As the discussion progressed an important question was asked, “What if we get rid of the seats?”
Kelly called it “a brilliant, paradigm-shifting question.” Seats were not necessary given the engine thrusts needed to navigate in the weak gravity of the moon. The astronauts’ legs could support them well enough. Removing the seats and having the astronauts stand during the landing meant they could be closer to the windows, enabling a good view though a much smaller window.
Also, reducing the window size and removing the flight seats would not only greatly reduce the weight but also increase the usable volume inside the cabin for the astronauts. Several design problems could be solved in one stroke.
Rathke and Carbee spent that night developing drawings of the new LM design. The engineering team met again and made the decision to propose this modification, and the NASA leadership enthusiastically endorsed the change. From that point, the Lunar Module took on the angular shape that is so familiar today.
The engineers who designed the remarkable pieces of space hardware were only apart of the overall Apollo team. Thousands of engineers were involved in launch processing and monitoring the flights. In an era when computer systems were primitive compared to what we have today, constant communication between the astronauts and an army of engineers back in Houston was critical to ensure the safety of the astronauts as well as the success of the mission.
For instance, as the Lunar Module Eagle made its powered descent to the lunar surface, a program alarm sounded at an altitude of 33,000 feet. Commander Neil Armstrong called out, “It’s a 1202.”
Back at Mission Control in Houston, even with hundreds of simulated landings under their belts, no one was quite sure what a “1202” alarm meant. Would the landing need to be aborted? The engineers in Houston had about 15 seconds to make a decision.
The computers in the LM were incapable of printing out an error message in plain English; instead, they used a series of four-digit codes. There were hundreds of such codes and in some cases one had to look up what the code meant.
The person on the ground who was in charge of monitoring the Lunar Module’s guidance computer was a 26-year-old flight controller named Steve Bales. Bales, and his counterpart behind the scenes, Jack Garman, were both familiar with the “1202” code. The LM’s computer was being asked to do too much and was being intermittently overloaded.
After conferring, Bales and Garman agreed that as long as the overload was intermittent, there was no safety-of-flight issue. The landing could continue.
Just nine seconds after receiving Armstrong’s message, Bales asked the Capcom—the capsule communicator— to inform the astronauts, “We’re go on that alarm.” With Armstrong and Aldrin at the controls, the Lunar Module continued to descend until 3:20 in the afternoon, Houston time, on July 20, 1969.
The Eagle had landed.