Apollo Revisited

Looking back at the many people and feats of engineering that made it possible.

by Ed Butts, PE, CPI

Anyone who has read this column knows I am fascinated with science and the practical application of science and technology through engineering—so my interest in the U.S. space program should come as no surprise.

As a young kid in the 1960s and still today, I can state I am enamored with our space program. From my earliest recollections of the Gemini launches in the 1960s, to the Apollo missions that first landed on the moon a week before my 11th birthday in 1969, and up to the Space Shuttle missions I have always appreciated the science, engineering, and technology that many thousands of people invested to accomplish a goal established by President John F. Kennedy in 1961: “To send a man to the moon before this decade is out and return him safely to the earth.”

Even as much as I respect the accomplishments of the “many thousands,” I also appreciate the contributions made by a select few who were the true forces behind the moonmissions. This month, as a departure from my usual water well–related topics, I want to revisit some of the lore and incredible
engineering from those at Apollo for those who still remember, for those too young to remember, and most importantly,for those who still know how to dream.

The rocket had to be created.

Many thousands of engineers, scientists, and technicians made the many voyages to the moon and back possible. Here I want to give individual recognition to five of these people who are for the most part unknown.

Many people believe the space program began in 1961 with the launch of the first manned Mercury mission. But actually, it started in 1957 with the Soviet launch of the first artificial satellite, Sputnik. This single accomplishment was enough to strike fear in the hearts of many Americans who thereafter worried about possible Soviet invasions on American soil from armed Russian cosmonauts.

This also caused enough concern to the U.S. government that a new emphasis was applied towards accelerating exploration, notably with the creation of the National Aeronautics and Space Administration (NASA) in 1958 on the very day in July I was born!

Most people also think the United States’ dream of going to the moon began with Kennedy’s announcement to a joint session of Congress in May of 1961, although the discussions of this potential feat started back in the Eisenhower administration during the late 1950s.

What most do not know is just how woefully unprepared the United States was to make this type of journey. Not only didn’t our country have the technology in place to support a manned expedition to and back from the moon—we couldn’t even launch a man towards the moon with adequate velocity
to escape Earth’s formidable gravity at the time. In fact, many knowledgeable individuals did not think such a mission to the moon would even be possible until sometime during the mid or late 1970s due to the lack of adequate rocket technology.

Every argument and discussion during those initial days came down to one factor: enough rocket thrust. Getting a rocket off a launchpad with enough thrust to generate the lift required to elevate the roughly 6 million pounds of launch weight needed to overcome Earth’s gravity, which requires an escape velocity of about 25,000 miles per hour, would require about 7.5 million pounds of rocket thrust. During the early days of the space program, NASA was fortunate if they could launch a rocket with just 67,000 pounds of thrust from an Atlas rocket sufficient to take a single man into orbit in a Mercury space capsule.

In just a few years, however, we got there. The effort was led by replanted scientists from World War II Germany, notably Wernher von Braun, who would later become the director of NASA’s Marshall Space Flight Center. These scientists led the effort to develop first the single-stage Saturn I and then the Saturn V (“the Saturn five”) rocket, a three-stage behemoth that never incurred a failure on the launchpad or
in space during a manned mission.

Many people felt von Braun and other German engineers should be held responsible for their actions during the war, but his subsequent peacetime service in the development and creation of liquid-fueled rocket technology that would ultimately get the United States to the moon first underscored his
devotion to his new country.

Figure 1. The Saturn V rocket.

The Saturn V rocket (Figure 1) was a huge technological step ahead in rocket science that used liquid fuel propellants through a combination of five Model F-1 engines in the first stage (the lowest stage), each creating the needed 1.5 million pounds of thrust, as opposed to the later solid-fueled rockets of the Space Shuttle era.

A mixture of a kerosene-based fuel combined with liquid oxygen as an oxidizer was needed since there’s no air (i.e., oxygen) available in space as with jet engines that fly in the oxygen-rich atmosphere. This development of the combination of these five reliable engines into a single Saturn V rocket turned out to be a needed watershed moment in space exploration, helping chart our path to the moon.

But how do we get there?

Another person who played quite a pivotal role in landing on the moon was John Houbolt, an aerospace engineer.

In the early days of the Apollo program, fierce debate raged as to the best way to travel to and land on the moon. In the beginning, many engineers favored the more commonly accepted methods of using either direct ascent or earth orbit rendezvous as the only way to land on the moon (Figure 2).

Figure 2. The early Apollo configuration for direct ascent and earth orbit rendezvous.

In direct ascent, a single rocket ship would be launched, transported to the moon, land, and then relaunch and return to Earth. The proposed rocket ship was up to 100 feet in height for storage of the fuel and oxidizer and required an elevator-type device to transport the astronauts down to the moon’s surface and back up into the mother ship. The proposed vehicle would consist of an enormous rocket, much larger than the Saturn V (then under development).

In earth orbit rendezvous, the program would have called for at least two launches needed to assemble both crafts in earth orbit: one the direct-landing vehicle, the other the return vehicle.

In virtually no realm at the time was the possible choice of a lunar orbit rendezvous ever considered. During the early 1960s, it appeared either direct ascent or earth orbit rendezvous would be selected the way to go to the moon, ignoring the costs and lack of feasibility. This is when Houbolt, who had been independently evaluating both proposed methods, suggested a third but often ignored approach—lunar orbit rendezvous—be adopted, not only as one way to land on the moon, but as the only practical way to get to the moon.

For Houbolt, it all came down to weight and keeping the weight as low as possible. The lower you can keep the weight of the rocket itself and its components, the less fuel it would require.

Figure 3. A lunar flight profile.

In lunar orbit rendezvous (Figure 3), a command module, where three astronauts would ride to the moon and back to Earth, would be connected to a service module housing the needed consumables
such as water, fuel, and oxygen for use during the mission. The command module and service module would be docked to a lunar excursion module (LEM) all the way to the moon and undock just before the LEM made the descent to the surface of the moon. The LEM would land on the moon, support two astronauts on the moon for the entire lunar stay, and then ascend and dock with the command module for the trip back to Earth, subsequently disposing of the LEM in lunar orbit.

When proposing this idea to the powers-that-be, Houbolt received an almost unanimous outcry: “But this would mean the astronauts would have to undock and then dock again in space—around the moon no less!” At the time this had not even been envisioned or accomplished in earth orbit. In a typical engineer’s response, Houbolt and his supporters retorted, “Sure they will need to dock in space,
but astronauts are smart people. They will figure it out.”

The solution was obviously somewhat more involved than that and required years of extensive training and a plethora of new and old technologies, such as tracking radar and celestial navigation. But Houbolt was vindicated. Lunar orbit rendezvous would be used on every manned mission.

What if they get lost?

Although the distance varies, the mean distance between Earth and the moon averages around 250,000 miles. Knowing both are in constant rotation and travelling through space at the same time required some more planning than the attitude that “We will simply point our rocket ship to the moon.” In fact,
knowing this represented the most critical aspect of the entire Apollo program, the first contract NASA awarded for the Apollo program was to the Massachusetts Institute of Technology (MIT) for the guidance system to enable and chart the trip to the moon and back.

This is where our next notable person comes in, Dr. Charles Stark “Doc” Draper. He was an accomplished American scientist and engineer, known as the “father of inertial navigation.” He was also the founder and director of the MIT Instrumentation Laboratory, later renamed the Charles Stark Draper Laboratory, which made the Apollo moon landings possible through its Apollo guidance computer.

The guidance computer used for each moon landing was truly a rudimentary,  although ingenious, machine with limited memory and computing function. In fact, today’s handheld calculators and
iPads have more computing ability than the original Apollo guidance computer!

The concept Draper used in developing the basic guidance program was based on the now fundamental concept of inertial guidance. During the 1950s, Draper commissioned a cross-country flight from the east coast of the United States to the west coast—using only a gyroscope and inertial guidance to perform
the needed navigation to keep the plane on course. After a flight of many hours the plane landed safely in Los Angeles, the intended destination, with only minor course corrections automatically made during the journey.

Today, this seems like old hat technology with most planes now equipped with either autopilot or global positioning satellite controls, but this was a revolutionary method of guidance at the time. In fact, this guidance computer was later instrumental in keeping the command module on course on the way
to the moon and the lunar module during the landing itself.

So how are we going to land on the moon?

Figure 4. Lunar module cutaway illustration.

Our fourth often unsung hero of the Apollo program is Thomas Kelly, an engineer for Grumman Corp., the firm that developed the lunar lander. Kelly was an aerospace engineer who mainly worked on jet fighters for the U.S. Air Force but was assigned as chief engineer for the LEM (Figure 4) project,
which later earned him the name “Father of the Lunar Module.”

Development of the LEM was not simply a matter of building a space vehicle with the capability of setting down on another celestial body. Right from the beginning, a whole host of problems confronted the design team of the LEM. To start with, no manned vehicle had ever been designed or intended to fly
through space, land, and then launch from another planet.

Besides the obvious lack of aerodynamic considerations due to the fact the LEM was designed to only fly in space, there were other considerations. For instance, what was the type and composition of soil the craft would land on? Was it soft and the lander would simply sink into the lunar dust? Was it uneven, volcanic, and rocky where undue pressure on one of the lander’s footpads would cause the craft to tip or turn over? Was it so soft the lander would sink so deep and out of sight a return liftoff could not
be performed? Was the soil so corrosive even a stay of only a few hours would result in degradation of the metal pads? These all had to be factored in.

Additional considerations included the heat to cold variables experienced from the reverse exposure of sunlight to dark shadows—a possible swing of up to 525°F. In sunlight, the surface temperature
on the moon could reach 225°F, while in the dark shadows the temperature extreme could reach a low of
–300°F. This extreme variation in temperatures required the innovation of many new insulating fabrics and protective coverings, including Mylar—often seen as a gold-colored covering wrapped around the lower half of the lander.

As with all other elements of the mission, weight played an important and key factor in the design of the LEM. A critical early design factor by Kelly was the decision to leave behind the lower part of the LEM, with all of its no longer needed and mostly empty landing sequence engine, fuel and oxidizer tanks,
and other unneeded consumables. This would be done by using guillotines to sever the connections between the two portions of the lander and have the lower half act as a launchpad for the upper half, the manned crew compartment.

Another important design element overseen by Kelly was the decision to keep the astronauts in a standing position while in the LEM during docking and undocking, lunar orbit, landing, and lunar launch—avoiding the extra weight of unnecessary seats in the one-sixth gravity of the moon. This standing position afforded an ideal view of the moon’s terrain during landing that would not have been possible if the astronauts had been in a seated position. This had the added benefit of being able to use much smaller viewing windows for each astronaut during descent, saving substantial weight on the windows alone. Engineering in action!

Finally, although the descent engine in the lower half of the LEM used a fairly conventional liquid-fueled rocket design, the technology used for the ascent engine in the upper portion of the lunar module was truly a wonder of engineering as well as simplicity. The design of this engine was as close to “fail-safe” as could be envisioned with only two moving parts required to make the engine operate. This type of reliability was needed on the ascent engine since failure of this engine would have resulted in the definite stranding and eventual death of the two astronauts on the moon.

There was no direct ignition or the common lighting-the-candle sequence as with other rockets. The fuel and oxidizer mixture was known as a hypergolic propellant; in other words, the two components were designed to be stored separately up to the time of launch from the moon but to ignite immediately
upon contact within the engine.

In fact, each engine was regarded as one-time use, built for the single purpose to bring two men up from the surface of the moon and return them to the command module. They were so unique and simple in design and operation that pre-flight testing of the engines on Earth was not even possible since that would have resulted in the probable destruction of the engine. Obviously, this faith in the engines was justly rewarded since there was a 100% reliability of the Apollo descent and ascent engines in every mission.

What if they don’t pay the bill?

Our final unsung hero is one who some people may know, Frank Borman. He was an engineer and aeronautics professor, one of the second group of nine astronauts, a Gemini pilot, and the commander of the Apollo 8 mission in December 1968—seven months before the first lunar landing of Apollo 11.
His mission was the first manned flight to the moon and back and completed several orbits around the moon.

Even with all these accomplishments, what I am recognizing Borman for was his involvement as one of NASA’s representatives to investigate and provide testimony on the fire-ravaged Apollo 1 capsule in the 1967 disaster that killed three astronauts: Virgil “Gus” Grissom, Edward White, and Roger Chaffee.

Contrary to popular perception, the space program did not simply “pick up the pieces” and start over. There was a strong sentiment in Congress that space exploration was far too dangerous and not worth the risk to human life—and its funding should be curtailed.

Borman’s cool demeanor and rapid and honest appraisal of the circumstances surrounding the fire during powerful testimony to a congressional subcommittee investigating the fire was instrumental in reassuring Congress and the American public the risk was worth the potential price, and that any
advances in knowledge and science cannot be made without the fear of a potential loss of life.

In addition, Borman’s technical observations and admissions as to the exact cause of the fire were critical in making several design changes to the command module’s interior—modifying the environment of the cabin from a pure oxygen environment, a highly combustible situation, to one that used a mixture of oxygen and nitrogen similar to that found in Earth’s atmosphere; changing to an outward opening main hatch; as well as limiting the amount of combustibles to be permitted in the open
environment of the command and lunar modules.

This wraps up my discussion of the Apollo space program, which featured many thousands of people and feats of engineering. Next month, we will circle back around to the water well business.

Until then, work safe and smart.

Ed Butts, PE, CPI, is the chief engineer at 4B Engineering & Consulting, Salem, Oregon. He has more than 40 years of experience in the water well business, specializing in engineering and business management. He can be reached at epbpe@juno.com.

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