The Apollo Lunar Module: Part One

By Michael Jarema, contributing writer

I tell you, Houston, I sure do enjoy flying this thing.

Apollo 12 Mission Commander Charles “Pete” Conrad made the above comment regarding the Intrepid, the mission’s Lunar Module, as the craft’s ascent stage blasted off the surface of the Moon.

In a 2019 issue of Astronomy¹, writer Amy Teitel explained that Conrad and Lunar Module Pilot, Alan Bean, planned to rocket into lunar orbit where they’d dock with Richard Gordon, piloting the Command/Service Module. The date was November 20, 1969, and the mission marked the second time one of NASA’s Lunar Modules carried two astronauts to the surface of the Moon then safely returned to their waiting mothership.

Conrad’s statement was a simple testament to the performance of the singular spacecraft.

To go to the Moon

We choose to go to the Moon in this decade...

When President John F. Kennedy announced this directive to the American people in September of 1962, the barely-four-year-old National Aeronautics and Space Administration (NASA) had little idea how they were going to do it. It was an extraordinary task.

Not only did the science needed to accomplish it not yet exist, scientists didn’t even know what they needed to know. NASA’s initial plan, in fact, differed significantly from how the monumental undertaking was eventually achieved, primarily in that mission planners considered the optimum mission profile to be direct ascent – a craft that would lift off from Earth, travel to the Moon, land, then take off and return.

Teitel detailed some of the challenges to this plan:

The entire spacecraft would have to land upright on the Moon; that single spacecraft would also have to carry the propellant necessary to launch from the Moon's surface and generate enough velocity to return to Earth. Not only was this option complicated, but it involved a heavy payload that would need a massive, not-yet-developed rocket.

NASA released a first call for proposals for a direct ascent craft on July 28, 1961. Based largely on the aerospace knowledge gained from designing and building their highly-regarded X-15 rocket-powered spy plane, North American Aviation won the contract. The craft was to be called Nova.

Nova was to be, as Teitel described it, “mindblowingly large.” Saturn V, the rocket NASA eventually used for all Apollo lunar launches, was 363 feet tall, 33 feet in diameter at its base, and employed a total of eleven engines in its three stages. Its five first-stage engines delivered a total of 7.5 million pounds of thrust on launch. While the largest of the series of proposed Nova rockets, the Nova C8, was only marginally taller than the Saturn V, it was 50 feet in diameter at its base, and employed thirteen engines in its three stages. Its eight first-stage engines delivered a total of 12 million pounds of thrust on launch.

The Nova C8 was never built, though. By early 1962, Teitel said NASA was considering another mission mode – Lunar Orbit Rendezvous. This plan kept a mothership with its heavy load of fuel in orbit around the Moon, while a landing craft descended to the lunar surface and then returned to rendezvous with the mothership. Teitel again detailed the thinking behind the plan:

Though the rendezvous made the mission more complicated, it also made the payload lighter, because the lander could be smaller and thus require less fuel to escape the Moon's gravity. The whole payload would be light enough to launch on a single Saturn V rocket, which was simpler to develop and gave NASA the best chance at meeting Kennedy's end-of-decade deadline.

Lunar Orbit Rendezvous quickly became the favored mission mode, with NASA committing to it on July 11 of 1962.

The genesis of the Lunar Module

With Lunar Orbit Rendezvous came the genesis of the Lunar Module. NASA now needed a small, light spacecraft that had a relatively simple dual purpose – land a man on the Moon, then return him to an orbiting mothership. And the vehicle had to be carried from the Earth to lunar orbit by a Saturn V rocket.

Tom Kelly was the Engineering Director of the Grumman Aircraft team that developed the Lunar Module. He didn’t start his career at Grumman in that position, though. The aircraft manufacturer had another, more relaxed objective in 1959 when they hired him away from Lockheed, the aerospace company where he worked on rocket engines.

The New York Times’ Linda Saslow wrote an article² profiling Kelly in which he explained.

They told me that they were going to set up a design group to look for business in space, and they wanted me to help them...At that time, we were only in a 'what if' stage, and I was one of only two men working on a lunar project to explore the technical issues of getting to the moon.

But that all changed in 1961, when the Soviet Union launched cosmonaut Yuri Gagarin into Earth orbit. It was the first-ever manned space flight. A year-and-a-half later, President Kennedy announced America’s ambitious response.

Said Kelly:

It was no longer a 'what if,' but a requirement and a huge challenge...We were hand-building the world's first spacecraft and had no guidelines to follow, so we just made the whole thing up as we went along. From propulsion to life support...Nobody knew what a manned lunar landing spacecraft should look like, so we just let function determine form, and ended up with the spindly insect-like creation...

Kelly was referring to the LEM, as NASA called it at the time – the Lunar Excursion Module. (They later dropped the “Excursion” because they thought the word suggested schoolkids on a field trip; LEM became LM.)

Grumman won the contract to build the LM on November 7, 1962, and Kelly’s little team of “what if” thinkers grew from himself and one other to over 7000 engineers working with NASA, studying how to design something that could land men on the Moon. Saslow again quoted Kelly:

Nobody at Grumman who worked on the lunar module will ever forget it...We all knew that we were part of a majestic endeavor, and that we were making history happen.

What it was

NASA and Kelly’s Gumman team conceived the LM as a two-stage spacecraft. The full ship would land on the Moon, using a large rocket engine to slow its descent. The upper-stage crew compartment would later blast off with its smaller engine, launching the two astronauts inside back into space to rendezvous with the orbiting Command Module.

Charles Fishman described some of the landmark features of those rocket engines in a comprehensive article on the space race published in a 2019 issue of Smithsonian magazine³.

Each of those rocket engines weighed less than the engine in a typical midsize car-and each was a marvel. The descent engine could be throttled: powerful thrust to bring the lunar module down to the Moon from orbit, and lower thrust to allow the LM to hover near the surface of the Moon while the astronauts picked a final landing spot. No rocket engine before had ever had variable power. The smaller engine...absolutely had to work when the launch command was given. If it didn't ignite, the astronauts were trapped on the Moon. So the ascent engine was a study in simplicity to reduce the number of ways it could fail.

Teitel documented the development of other key features of the LM in her article, noting the LM was originally patterned after a helicopter since that type of aircraft landed and ascended vertically – that is, the LM was to have huge bubble-like windows for visibility, behind which the pilot and co-pilot were seated. But the windows caused problems – they were heavy. And the seated position necessitated greater interior space.

Teitel explained the solutions:

To solve this problem, engineers...realized that there was no rule saying astronauts had to fly sitting down. Standing closer to smaller windows would give the same visibility and in the Moon's lower gravity field, just one-sixth what we feel on Earth, human legs would be more-than-adequate shock absorbers for the moment of lunar touchdown.

So, the astronaut pilots flew standing up, attached to the cabin floor by hook-and-loop fasteners and tethered to its inner structure by cables, navigating to the lunar surface by peering out two small triangular windows.

Other weight and space savings resulted from the craft’s never having to fly through an atmosphere. It didn’t need to be structurally robust or even aerodynamic. As Kelly said, its final form resulted entirely from function. The crew compartment, life-support systems, fuel tanks, engines, landing gear – everything needed to make the LM work – was determined, and then sheathed in a thin metal skin.

In the end, with its octagonal, four-legged descent stage and lumpy, irregular ascent stage/crew compartment, the LM ended up looking like a bug – so much so that the crew of Apollo 9, the first team to fly a LM (not landing it on the moon, but testing its engines, maneuverability, docking capability, and other functions), named their Lunar Module, Spider.

Read the rest of the story: The Apollo Lunar Module Part 2 - Remembering history’s most unique spacecraft: From unenthused astronauts to flying the dream.

Learn more about ProQuest's Global Challenges initiative.

Notes:

1. Teitel, A. (2019, Jul). Building Apollo. Astronomy. Available from ProQuest One Academic.
2. Salow, L. (1999, Jul 18). The Man Whose Stuff is Still on the Moon. New York Times. Available from ProQuest One Academic.
3. Fishman, C. (2019, Jun). Inside America’s Greatest Adventure. Smithsonian. Available from ProQuest One Academic.

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Michael Jarema is an Ypsilanti, Michigan-based writer, filmmaker, sometime-foodie, and full-time craft beer enthusiast. He regularly incorporates the latter when working on his current pet writing project – a graphic novel titled, I Kill Nazis with Dinosaurs.