It was the most famous step in history. When Neil Armstrong's shoe hit the lunar soil for the first time on July 20, 1969, the event was celebrated worldwide as a triumph for humanity. Yet the blurry televised images broadcast from space could not convey the true boldness-the enormous risks, the technological complexity, the complicated collaboration-the mission that brought two Americans to the moon.
Popular Mechanics set out to document the full and unvarnished story. July 16, 1969 marks the first day of the historic mission. Here sleepless news correspondents and field engineers, air traffic controllers and astronauts bring us to the point where the rocket clears the tower and the responsibility is shifted from the launch control in Cape Kennedy to Mission Control in Houston for the crew's coast to the moon.
** This post was originally published in the June 2009 issue by Popular Mechanics to celebrate the 40th birthday of Apollo 11 . Since then, the first man on the moon Neil Armstrong died in 2012. A new biopic with Ryan Gosling as Armstrong, called First Man will be released in October 2018.
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19659007] JULY 16, 1969: LAUNCH DAY
* JoAnn Morgan, Instrumentation Controller, Apollo Launch Control, Kennedy Space Center: The pad at night was just gorgeous to see with all the vehicle in these was bathed in huge xenon lights. Since I arrived there before 3 o'clock, it was almost at the end of the propellant charge; there was a small vent of the liquid oxygen. It was just an enchanting sight, and I had the most positive feeling that this launch would be successful from the moment I parked my car and walked to the firebox.
* Jackie Smith, 19659012 Spacecraft Testing and Launch Engine, Kennedy Space Center: Starting days were always a little unusual because you could get up in the middle of the night and go to work ,
* Jay Barbree, Correspondent, NBC News: I had radio commercials fed until about midnight, so I never went home – I slept there on a camp bed on Press Site 39.
*  Morgan: As an instrumentation controller, I monitored everything on the pad. It is extremely intense work. As you go through the countdown and start, you are very focused. Everything is planned – it's like a script in one piece.
* Smith: In the world of spacecraft, we did not have a sequence like the carrier rockets. We had to make sure our systems were working properly. Otherwise we had to call a time-out.
* William Lucas, Program Development Director, Marshall Space Flight Center: I was very tense. We knew that there were thousands of parts that needed to work, otherwise we would be in real trouble. And we knew that once we had given the signal, we could do nothing more. It had to go.
* Buzz Aldrin, Pilot of the Lunar Module, Apollo 11: I was the last, and so I was left on a landing one stop below the elevator, while [Neil Armstrong and Michael Collins] were in the capsule added. I stood on the edge of this rocker and looked at this rocket, and the waves came much deeper, and the sun was gradually rising, and it was really a very lonely, yet private, peaceful moment to get into this wondrous white machine before us should go down in history – we hoped.
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Morgan: Then the astronauts Deke Slayton and Alan Shepard came in and they sat directly behind me at the launch control. You knew when Deke and Alan showed up at take-off that the flight crew was ready.
* Robert Sieck, spacecraft test and launch operator, Kennedy Space Center: Since I was the backup engineer, I was not out at the Cape. I was able to watch the start with my wife and 1 year old daughter. The highway was an absolute transportation hub, and the cars and trucks were not trying to move. Everyone was there to see history. The sellers were sold out – no T-shirts, caps, buttons or pins anymore. People pulled grass cuttings from the roadside and stuffed them into zip-lock bags as souvenirs.
* Barbree: We're in the countdown, and I felt that little tap on my shoulder. I turned and looked up and it was Jimmy Stewart and his wife Gloria. And he said, "Is it all right if we watch from here?" And I said, "Mr. Stewart, you see from wherever you want."
* Morgan: It was a wonderful countdown – I felt pretty relaxed. Unless you come to the end, the last 30 seconds, just knowing the power of the fuels on board, and these three men are sitting up there.
* Lucas: The stack of the Saturn V weighed just over 6 million pounds, so when we took off we had about 7.5 million pounds of thrust. When you see how it lifts off, it looks like it will never clear the tower. But as it burns fuel, it gets faster – the weight on lift decreases, so it picks up speed.
* Morgan: It's a pretty physical experience, an Apollo launch because it's such a slow take-off – and then the shockwaves hit you. We could feel it in the firebox because we had those shutters and they were banging and chattering and the consoles vibrated.
* Sieck: When you are in the control room For the number of launches, focus on the technical data. [Standing outside] was like the difference between a sports event on TV and the crowd in the stadium. The people hopped up and down, shouting and shouting and honking. It was great.
* Lucas: The first stage burned for about 2 to 3 minutes, then it was consumed, and the second stage and everything flew over it. The second stage had five J-2 engines, each with about 150,000 pounds of thrust. Burning out this stage ignited the third stage, the S-IVB stage. It had a J-2 engine of about 200,000 pounds of thrust.
* Jay Finst, Saturn V IBM Flight Computer : I think it's a track relay. You have a runner and he runs and hands the wand to the next runner, and that runner runs and passes the baton to the next runner. And the race is not over until the baton is handed over to the last man and he crosses the finish line. This start is the same way. The first stage, the S-IC, has to work, and the staff goes to the next stage; the S-II stage has to work and deliver the staff to the S-IVB stage – that must work. And you give the baton back to the S-IVB stage, and that must work. You have the staff four times to have a successful mission.
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* Lucas: The second and third stages were hydrogen-fueled, the first time that hydrogen was successfully deployed in a rocket stage. You may be wondering why we did not use that for the first stage – because it's so light that it would require too much tankage volume. The kerosene fuel was more effective for the first stage when you were still in the Earth's atmosphere.
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* Bales: Sobald es verschlossen war Weiter sah das Radar, dass wir in Radialgeschwindigkeit ein wenig schnell waren und korrigierte den Computer. Zu dieser Zeit dachte ich, unser schlimmstes Problem sei vorbei. Es stellte sich heraus, dass unser schlimmstes Problem gerade erst begonnen hatte.
* Aldrin: Wir haben den ersten 1202-Alarm erhalten. Also schauen wir uns gegenseitig an, und wir wissen, dass es in dem Führungs- und Navigationswörterbuch ist, aber anstatt es auszuprobieren, während das Modul einen motorisierten Abstieg macht, fragte Neil sie, was auf dem 1202-Alarm zu lesen sei. Dann bekamen wir einen 1201.
* Charlie Duke,  Astronaut, Kapsel-Kommunikator (CAPCOM), Weißes Team, Mission Control: Ich war schockiert. Eigentlich ist "betäubt" ein besseres Wort. Ich fing an, nach meiner Anleitung und Navigations-Checkliste zu greifen, um zu sehen, was ein 1201 und ein 1202 war. Und natürlich wusste Steve Bales sofort und zögerte nicht lange zu sagen: "Wir gehen auf diese Alarme, Flight."
* Bales: Ich hörte ihn kaum. Wenn Sie die [voice] Loops hören, ist viel los. Und dann kommen endlich die Daten rein und wir sehen den 1201, und Jack [Garman] schreit – ich meine fast schreiend: "Es ist okay! Es ist okay, solange es nicht weitergeht!"
Garman: Es gab ein Team von Fluglotsen, deren Aufgabe es war, Simulationsprofile zu entwickeln, die Fluglotsen und Astronauten zusammen trainieren, um zu überleben und Dinge zu reparieren. Irgendwann hatten sie mich gebeten, einen Fehler zu machen, der völlig softwarebezogen war. Ich habe das schon Monate zuvor gemacht und sie haben das während einer der Simulationen festgehalten.
* Liebergot: Es gab normalerweise eine ziemlich feindselige Beziehung zwischen den Simulationstrainern und uns Fluglotsen, weil sie es versuchten um zu sehen, ob sie uns überlisten können. But they were pretty important. They trained us to respond to most of the problems we would ever see.
* Kranz: Dick Koos, our simulation supervisor, gave us the 1201 and 1202 alarms. Steve [Bales] had never seen this before. During the simulation, they had an abort, which was his call.
* Bales: There's a general rule in flight control: If you don't know what to do, don't do anything. The problem is, in the middle of a lunar landing, not doing anything is not an option.
* Garman: Gene Kranz sat us all down and said, "I want you to figure out every possible alarm code that can happen in flight so that we're prepared." In those days, there was no such thing as desktop computers. So I wrote down all the alarm codes on a sheet of grid paper, with crib notes on what they meant and what our response should be. And I stuck it under the plexiglass of the console I was to sit at. And, lo and behold, one of them–well, a couple of them–popped up during the actual landing.
* Eyles: What led to [the alarms] was an obscure mismatch deep in the electronics–two signals that should have been locked together in phase were only locked together in frequency. That hardware glitch involved the rendezvous radar, which really wasn't needed during the descent to the moon.
* Aldrin: I left it on. That turned out to be the main cause, and maybe the cause, of the program alarms.
* Eyles: Based on a random-phase relationship between those two signals, the rendezvous radar electronics were sending pulses to the computer at a very high rate.
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* Ward: The computer was simply saying, "Hey, I've got more than I can handle, but I'm gonna do the important things, so don't worry about it."
* Eyles: Under the software control, it did a software restart. Five times during the landing, the whole software was flushed and reconstructed in terms of what was being executed. And that load shedding was what allowed us to complete the landing without any appreciable glitches in the way the guidance system worked. Without quite knowing it, we had built a fault-tolerant computer.
* Garman: The problem is that those program alarms set off what is called the "master caution and warning," which is red lights and very large klaxon sounds–if you've seen submarine movies, kind of like the klaxon that goes off when they say, "Dive! Dive!" And as I gathered from after-flight readings, the heart rates for Neil Armstrong and Buzz Aldrin went up just a bit.
* Armstrong: The powered descent was the most challenging segment of the flight. The systems were heavily loaded, the margins were slim, and this would be the first time that the entire descent strategy would be fully tested. A decade earlier, while I was flying in the X-15 program, we learned, surprisingly, that all the pilots, while flying the X-15, had heart rates between 145 and 185. It reflected the mental intensity appropriate for a challenging situation. The Apollo data seemed to correlate well with our prior experience.
* Duke: I didn't notice anything panicky, any tension at all in them. We just kept feeding them the information, trying to be as professional about it as possible. I don't think I was relaying any anxiousness in my voice–I tried not to, anyway–but tension was building.
* Aldrin: As long as you've got communication, Houston knows what [the problem] is, and they have more information, so they're going to be the ones that call the shots.
* Liebergot: We weren't exhaling, but very businesslike. And that's not to say the job was just ho-hum; it was not. It's that we, with hearts racing, did our job.
* Eyles: The first two [landing] phases were very much under the computer's control using different targets. The final landing phase was the point where the astronauts took over semimanually to maneuver the spacecraft like a helicopter. When I say semimanually, I mean that the automatic system was controlling the throttle to maintain a commanded descent rate while the astronaut commanded the attitude of the spacecraft in order to scoot along the surface in whatever direction he needed to go.
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* Bruce McCandless, astronaut (CAPCOM), Green Team, Mission Control: Neil was flying, looking for a boulder-free spot. It's fair to say people were holding their breath. But Neil had a considerable amount of experience in the lunar module simulator and in the lunar-landing research training vehicle.
* Armstrong: Every flying machine has its own unique characteristics, some good, some not so good. Pilots naturally fly the craft in such a manner as to take advantage of its good characteristics and avoid the areas where it is not so good. In the case of the lunar module, surprisingly, it flew much more smoothly than I had expected based on all the simulator work we had done. It was a welcome surprise.
* Gavin: The lunar module had the first really throttle-able descent engine. When it first fired, it had to operate at about 10,000 pounds of thrust. But as they approached the lunar surface, the vehicle became much lighter, having burned up a lot of fuel, and they had to get the thrust down to maybe 2000 pounds. So it was quite a development to get a rocket engine that would not only do this, but would operate smoothly in either range.
* Bales: There wasn't a lot being said, but we had a lot of data. I was thinking, "What in the bloody heck is going on?" Normally, in the simulations, once [Armstrong] got on a path to come down, he killed all the velocities but altitude rate and pretty much just came straight down. But he wasn't. He had a forward velocity of 20 feet per second. And, of course, that was eating up fuel.
* Gavin: In an airplane you usually have, oh, at least an hour's extra fuel in case the airport is closed where you're going. But in the case of the lunar module, we had about 120 seconds of margin.
* Kranz: We got what we call "low level" in the propellant tank. Once we got that indication, we knew we'd have roughly 120 seconds of propellant remaining at a hover throttle setting.
* Carlton: We had never seen that light, never expected to see it. In all of the sims, we had so much margin, that wasn't normally a factor.
* Garman: At that point there was nothing the ground could do except watch. It became a spectator activity. The tension went up noticeably. Very noticeably.
* Duke: When we got down to the last minute or so, it was real quiet. Everybody was glued to his monitor.
* Carlton: I had a stopwatch. I'm looking at it, and at the same time I'm looking at the altitude, and I can see it's still a long way down. I didn't know it, but the guys were flying over a crater. We call up 30 seconds. I'm thinking there's no way we're going to make it.
* Kranz: I'm a Catholic, and in the flight director business, you want all the help you can get.
* Carlton: When the engine shut down, I had 18 seconds to the point where we would have aborted.
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* McCandless: I was in the control center as a spectator, sitting right next to Charlie Duke, who was the CAPCOM. Once Neil came back with his transmission, "Tranquility Base here. The Eagle has landed," in spite of the earlier admonitions to maintain decorum, we burst into spontaneous cheers and applause.
* Duke: That's the first time he'd used that. The call sign was Eagle, so we'd just been using, "Eagle, this is Houston,"http://www.popularmechanics.com/"Houston, Eagle." As you can hear in the transcript, I was so excited, "tranquility" came out, "twank." I caught myself before I finished the word, "Twank–I mean, Tranquility. Roger, Tranquility, we copy you down."
* Ward: Kranz immediately got on the loop and said, "Everybody settle down. Settle down. We've got some critical calls to make, and we've got to focus on what's coming up here."
* Kranz: We had a job to do, because in the next 2 minutes, we had to make the first of our stay/no-stay decisions.
* Ward: But in the meantime we could hear this roar from the viewing room behind us. All of the politicians and top managers and astronaut families and so on were back there behind the glass.
* Aldrin: It was certainly momentous, but there were no trumpets blowing or cymbals crashing. We're there, we're two guys, and we're not the yippee type. We see something, absorb it, think about it and that's it, accept the way it is.
EXPLORING THE MOON
After an eventful descent to the lunar surface, Mission Control checked the spacecraft's systems and confirmed it was safe to stay on the moon. Here, the Green Team assumes the consoles so that an adrenaline-filled Aldrin and Armstrong can get a head start exploring the lunar surface. They pack in several experiments and a Presidential phone call before eventually lifting off to rendezvous with Collins, orbiting overhead in the command/service module.
* Bruce McCandless, astronaut (CAPCOM), Green Team, Mission Control: After they were given the "stay" call and shut down lunar-module systems, I headed for home, which was about 10 minutes away, to get a bite of dinner.
* Doug Ward, NASA public affairs officer: The original plan was that they weren't going to get out of the lunar module until the next day. They were going to get 8 hours of sleep and the next quote-unquote morning go do the first extravehicular activity.
* McCandless: But when I was pulling into the driveway, my wife came running out waving her arms. "They can't sleep! Go back!" So I turned around.
* Buzz Aldrin, lunar module pilot, Apollo 11:We wanted that to be the way the flight plan read, so that if we made a change, it was a change in the positive direction, not in the negative direction.
* Milt Windler, flight director (FLIGHT), Black Team, Mission Control: It was a pretty easy decision. You probably can't stop them, so why not go ahead and do it? Plus, we were all ready to get on the moon, too.
* McCandless: Driving back out to the center along NASA Road 1, it just so happened I was aimed right at the moon, which was nearly full. I had this eerie feeling that the moon didn't look any different to me from where I was here on Earth, and yet intellectually I knew the lunar module and Armstrong and Aldrin were on it and I'd be talking to them. It was one of those "This does not compute" type things. It wasn't until I got inside the control center and was talking to them that everything seemed to come back into the realm of reality.
* Don Beattie, program manager, Apollo Lunar Surface Experiments: 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.
* Joe Gavin, director, Lunar Module Program, Grumman Aerospace Corporation: When we started all this, we didn't know what the surface of the moon was like. We went ahead with a very conservative landing gear design because there never had been a rocket-propelled vertical-landing machine.
* McCandless: It was a relief that the dust on the lunar surface was actually only half an inch deep.
* Beattie: Another [concern] 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.
* McCandless: They depressurized the lunar module, opened the hatch and Neil came down the ladder. There was a crude black-and-white TV camera, which transmitted images along the lines of a white blob going down some sort of inclined structure. I remarked, "Okay, Neil, we see you now, we've got you on TV."
* Ward: I was very conscious of the fact that what the crew said was extremely important historically. The commentator stepped on a foot switch that interrupted the air to ground, so anytime we talked it obliterated whatever the crew was saying.
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* Jay Barbree, correspondent, NBC News: He gets to the bottom of the stairs, takes a step on the moon to make sure he can, steps back up and says, "That's one small step for [a] man, one giant leap for mankind." *
* McCandless:I had asked [Neil] before the mission launch several times what he was going to say on the occasion of this historic moment, setting foot on the lunar surface, and he always replied, "I'm a test pilot, I'll probably just say how dusty it is or something like that. Don't worry." But he came back with his now famous [line]. The media immediately wanted to know if it was one small step for a man, or just man. There was a little bit of static, so it wasn't entirely clear.
* McCandless: The first order of business was collecting a contingency sample. Neil was supposed to scoop up whatever was near his feet, the first thing that was handy, so that in the event of an emergency they would have at least something to show for having been there.
* Beattie: The bulk sample had a different purpose–to make sure that we got a very wide variety of material.
* Harrison H. Schmitt, astronaut, mission scientist for Apollo 11: The Apollo astronauts were very well trained engineers to begin with, and they were test pilots as well, which meant that they had very, very good observational skills. So we tried to give them a fundamental understanding of what they were going to encounter and the types of samples that we hoped that they would be able to collect.
* McCandless: Then Buzz came down and the two of them set up EASEP, the Early Apollo Scientific Experiment Package–a stand-in for ALSAP [the Apollo Lunar Surface Experiment Package].
* Schmitt: The Apollo Lunar Surface Experiment Package contained a number of individual scientific experiment packages by principal investigators from around the country. As soon as we started to really concentrate on what might be required to deploy that instrument package, it became very clear that there wasn't enough time. Simultaneously, it was becoming clear they were gonna need every weight margin that they could get in order to add to the amount of time that the crew would have to find a good landing spot–hover time. So we developed as quickly as possible a much simpler, smaller package for that first mission that would contain the two experiments that seemed to be the kind of thing you would want to have put on the moon just in case you never got a chance to go back.
* Beattie: The most important was the seismometer. That was going to tell us whether there were moon quakes, and possibly also something about the internal structure of the moon. Then we had the lunar retro reflector, which was deployed in order for us to take accurate measurements of the Earth-moon distance.
* Chuck Berry, chief flight surgeon, NASA: We were concerned about the metabolic cost of working in the bulky suit. The best way to monitor them on the lunar surface turned out to be the change in water temperature in the water-cooled undergarments. We had sensors to measure that, and we could then sort of gauge how far they could go.
* Neil Armstrong, commander, Apollo 11: On the lunar surface we had both the 16-mm movie camera and the television camera in fixed positions so our surface activities would not be slowed by camera position and setting requirements.
* McCandless: The mission was about 2 hours and 20 minutes in duration. About 15 minutes into it, the flight director gave an advisory that President Nixon wished to speak with the Apollo crew. After a little consultation, we decided it was President Nixon's prerogative to talk to the crew, but we had a lot of work to do before we felt we could afford the time and the minor disruption to the schedule. So we basically put him off for a little over an hour. We got the impression he was getting increasingly unhappy. But slightly after the midway point, we did get him on. I got Neil and Buzz to stand near the flag, within view of the TV camera, and [Nixon] talked for a couple minutes.
* Schmitt: Once an extravehicular activity starts the crew is going to move along the timeline and get as much done as they possibly can. Buzz Aldrin was talking about a lot of things that he was checking, like mobility.
* Aldrin: After the flag was up, I made a point of being in front of the camera just demonstrating different means of moving around.
* Schmitt: While he was doing that we were all wondering what Neil was doing. Well, Neil was…collecting this very fine and diverse group of rocks and soil. Not only did he get a very wide distribution, but he also thought the box looked a little empty, so at the last minute he filled it with just the dirt, so to speak–what we call the lunar regolith. That sample turned out to be the best, most comprehensive sample of the lunar regolith that was ever taken on any of the Apollo missions.
* Armstrong's famous words have been the subject of much speculation. Lunar surface communications were voice-activated and subject to interference, so a vowel could easily have been dropped. Armstrong confirmed to Popular Mechanics that he did articulate the "a."
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