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The Apollo Lunar Module: Part II
29 Aug 2019

The Apollo Lunar Module: Part II

Remembering history’s most unique spacecraft: From unenthused astronauts to flying the dream

By Michael Jarema, contributing writer

Part 1 of The Apollo Lunar Module appeared on August 23, 2019. The story follows the development of the Lunar Module, the extraordinarily unprecedented craft NASA developed to land the Apollo astronauts on the surface of the Moon.

A source of uncertainty

By fall of 1964, two years after receiving the contract to build the Lunar Module (LM), Grumman had finalized the design. In an article for Astronomy, Amy Teitel1 noted that NASA astronauts were less than enthused.

“...[U]sed to streamlined, aerodynamic planes,” she wrote, “they thought the buglike spacecraft looked more gangly than flight-worthy.”

Adding to their dissatisfaction, and a source of nerve-wracking uncertainty in NASA engineers and astronauts alike, was the fact that the LM couldn’t be test-flown before it was used. It was designed for use only in a zero-gravity vacuum; there was no place on Earth to test it. Joe Gavin, Grumman’s Director of the Lunar Module Program, explains in an uncredited series of interview clips published in Popular Mechanics2:

The whole thing was tense, because we were basically aircraft designers. In the aircraft business you always flight tested something before you delivered it. In the case of the lunar module, you couldn't flight test it. Every launch was a brand-new vehicle.

There were other, even more significant unknowns, for which no one could prepare. NASA knew very little about the environment of the lunar surface. Would the Moon’s surface support the weight of a LM? What was the composition of lunar dust?

Don Beattie, Program Manager for Apollo Lunar Surface Experiments, is quoted in the Popular Mechanics piece:

One scientist had projected that when the lunar module landed it would disappear into levitated dust. Even though we landed the Surveyor spacecraft successfully, that was a real concern. Another was that the dust would be pyrophoric – that when they opened the cabin of the lunar module, oxygen would react with dust and explode. There was no way we could be sure until the guys opened up the door and the oxygen flowed out.

Landing on the Moon

Neil Armstrong and Buzz Aldrin landed Apollo 11’s LM on the Moon on July 20, 1969, at 20:17 Greenwich Mean Time. They didn’t sink and disappear into the lunar dust. They were scheduled for a five-hour rest but, unable to sleep, convinced Mission Control to let them start their moonwalk early.

Armstrong was the first to step out of the LM and onto the surface of the Moon at 02:56 on July 21. Aldrin joined him 19 minutes later. The Moon dust didn’t explode, although, as Charles Fishman noted in his article, both astronauts reported that it has a curious smell – "the scent of wet ashes,” as Armstrong described it. Like "the smell in the air after a firecracker has gone off,” said Aldrin. The smell has never been figured out – all astronauts who walked on the Moon noted it, but there’s nothing in the composition of Moon dust to account for it.

The LM’s performance was not without some surprises. During the descent to the Moon, the LM’s guidance computer sent several 1201 and 1202 program alarms to Mission Control – notices that the computer was overloaded and couldn’t keep up with incoming information. But the computer re-prioritized its tasks and the landing was unaffected. The problem was later diagnosed as a hardware glitch that fed the computer information from two sources.

The real nail-biting came when Armstrong, looking out one of the LM’s windows, noticed the computer’s selected landing site was strewn with boulders. So, he took over control of the LM and, with Aldrin calling out surface details from the other window, navigated to a clearer site.

250 feet above the surface, Armstrong saw a crater in his selected site. He moved past that, selected another site and, now 100 feet above the surface with 90 seconds of propellant remaining, began a direct descent. As they got lower, dust kicked up from the surface began to restrict visibility and Armstrong navigated using Moon rocks to reference altitude.

At 67 inches above the surface, a probe hanging from one of the LM’s footpads notified Armstrong to shut the engine down – a precaution NASA implemented due to concerns that the thrust from the descent engine could ignite the lunar surface. But Armstrong forgot. He didn’t shut the engine down until the LM landed.

The New York Times’ Linda Saslow3 quoted Tom Kelly on Armstrong’s landing: “By the time he touched down he had about 20 seconds of fuel remaining. He was supposed to have a full minute.''

...and taking off again

Armstrong and Aldrin lifted back off the Moon 21 hours and 31 minutes after landing, having spent two-and-a-quarter hours outside the LM collecting 47.5 pounds of lunar material. The Moon dust was pervasive – the two never removed their spacesuits after being outside the LM. The dust they brought in got onto everything, so much so that they were concerned about breathing it in. And the curious smell dissipated by the time they returned to Earth.

The ascent wasn’t without its own drama. Aldrin explained in the Popular Mechanics article what he noticed the night before he and Armstrong were to leave the Moon:

As I got down on the floor to sleep, I could see the broken head of a circuit breaker. It was the engine-arm circuit breaker – the one that's got to be in to get electricity to turn the ascent engine on. Since it was on my side, obviously I would have to take the blame for my backpack knocking against things clumsily and breaking it off...It looked as though there was enough left to push (the breaker) in. When the time came, I just said I was going to push it in with a pen.

And that’s what Aldrin did. It worked perfectly, although NASA determined that if it hadn’t, the circuitry could have been rerouted and the ascent engine fired in another manner.

Among the items the Apollo 11 astronauts left on the surface of the Moon – a medal commemorating Soviet cosmonaut Yuri Gagarin, the man whose historic Earth orbit had jump-started the space race had died in a plane crash on March 27, 1968. Ironically, the Soviet government feared for his safety and, as a hero of the Soviet Union, banned him from any future space missions. But Gagarin convinced them to let him fly military aircraft and died on a training mission.

In the end

Grumman ended up manufacturing 14 flight-ready Lunar Modules. Ten of those flew in space, and six landed on the Moon. Per Charles Fishman, the total cost of the LMs was $1.6 billion – about $11 billion today. Each one cost $110 million, although by the time they were flying to the Moon, Grumman said it could produce one for $40 million – “if,” noted Fishman, “anyone wanted one”.

The descent stages of the six LMs that landed on the Moon remain there to this day. (Saslow’s article refers to Tom Kelly as “The Man Whose Stuff Is Still on the Moon.”) The ascent stages, following their rendezvous with the Command Modules and after the two astronauts inside transferred from the LM, fell out of orbit and crashed into the Moon. The LM for the Apollo 10 mission – the practice run for a lunar descent – is still in orbit around the Moon. All other LMs burned up when they re-entered the Earth’s atmosphere inside the Saturn V.

In what’s referred to as NASA’s finest hour, dramatized in the popular film, Apollo 13, that mission’s LM became the lifeboat for three astronauts when their Command Module was disabled by a ruptured oxygen tank. After that, per the 2015 documentary, 13 Factors that Saved Apollo 134, “Apollo 13's mission priority was no longer lunar exploration, but survival.” Interviewed for the film, Mission Commander Jim Lovell concurred, “The only way to survive...was to transfer to the Lunar Module.” With Mission Control’s guidance, the crew used the LM’s oxygen and fuel to return to Earth.

Initially skeptical of the ugly little craft, the Apollo astronauts came to at least respect, if not love, the rugged LMs. According to Teitel, David Scott, Apollo 9 Command Module Pilot and Commander of Apollo 15, was asked which of all the planes he’d ever flown was his favorite. He replied, “The LM on fumes.” Teitel wrote, “he said it was so light and so responsive, it was an absolute dream to pilot.”


  1. Teitel, A. (2019, Jul). Building Apollo. Astronomy. Available from ProQuest One Academic.
  2. Uncredited. (2009, Jun). No Margin for Error: The Untold Story of Apollo 11. Popular Mechanics. Available from ProQuest One Academic.
  3. Salow, L. (1999, Jul 18). The Man Whose Stuff is Still on the Moon. New York Times. Available from ProQuest One Academic.
  4. Weaver, E., Weaver, Z. (2015, Jul 31). 13 Factors that Saved Apollo 13, Part 2: Safely Back to the Earth. Espresso TV. Available from ProQuest One Academic.


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.

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