Saturday Night Science: Apollo 11 at 50 I: Apollo

Apollo 11 “everyone elsie” by Michael Collins, 1969-07-21, AS11-44-6643.On November 5, 1958, NASA, only four months old at the time, created the Space Task Group (STG) to manage its manned spaceflight programs. Although there had been earlier military studies of manned space concepts and many saw eventual manned orbital flights growing out of the rocket plane projects conducted by NASA’s predecessor, the National Advisory Committee for Aeronautics (NACA) and the U.S. Air Force, at the time of the STG’s formation the U.S. had no formal manned space program. The initial group numbered 45 in all, including eight secretaries and “computers”—operators of electromechanical desk calculators, staffed largely with people from the NACA’s Langley Research Center and initially headquartered there. There were no firm plans for manned spaceflight, no budget approved to pay for it, no spacecraft, no boosters, no launch facilities, no mission control centre, no astronauts, no plans to select and train them, and no experience either with human flight above the Earth’s atmosphere or with more than a few seconds of weightlessness. And yet this team, the core of an effort which would grow to include around 400,000 people at NASA and its 20,000 industry and academic contractors, would, just ten years and nine months later, on July 20th, 1969, land two people on the surface of the Moon and then return them safely to the Earth.

Ten years is not a long time when it comes to accomplishing a complicated technological project. Development of the Boeing 787, a mid-sized commercial airliner which flew no further, faster, or higher than its predecessors, and was designed and built using computer-aided design and manufacturing technologies, took eight years from project launch to entry into service, and the F-35 fighter plane only entered service and then only in small numbers of one model a full twenty-three years after the start of its development.

In November, 1958, nobody in the Space Task Group was thinking about landing on the Moon. Certainly, trips to the Moon had been discussed in fables from antiquity to Jules Verne’s classic De la terre à la lune of 1865, and in 1938 members of the British Interplanetary Society published a (totally impractical) design for a Moon rocket powered by more than two thousand solid rocket motors bundled together, which would be discarded once burned out, but only a year since the launch of the first Earth satellite and when nothing had been successfully returned from Earth orbit to the Earth, talk of manned Moon ships sounded like—lunacy.

The small band of stalwarts at the STG undertook the already daunting challenge of manned space flight with an incremental program they called Project Mercury, whose goal was to launch a single man into Earth orbit in a capsule (unable to change its orbit once released from the booster rocket, it barely deserved the term “spacecraft”) atop a converted Atlas intercontinental ballistic missile. In essence, the idea was to remove the warhead, replace it with a tiny cone-shaped can with a man in it, and shoot him into orbit. At the time the project began, the reliability of the Atlas rocket was around 75%, so NASA could expect around one in four launches to fail, with the Atlas known for spectacular explosions on the ground or on the way to space. When, in early 1960, the newly-chosen Mercury astronauts watched a test launch of the rocket they were to ride, it exploded less than a minute after launch. This was the fifth consecutive failure of an Atlas booster (although not all were so spectacular).

Doing things which were inherently risky on tight schedules with a shoestring budget (compared to military projects) and achieving an acceptable degree of safety by fanatic attention to detail and mountains of paperwork (NASA engineers quipped that no spacecraft could fly until the mass of paper documenting its construction and test equalled that of the flight hardware) became an integral part of the NASA culture. NASA was proceeding on its deliberate, step-by-step development of Project Mercury, and in 1961 was preparing for the first space flight by a U.S. astronaut, not into orbit on an Atlas, just a 15 minute suborbital hop on a version of the reliable Redstone rocket that launched the first U.S. satellite in 1958 when, on April 12, 1961, they were to be sorely disappointed when the Soviet Union launched Yuri Gagarin into orbit on Vostok 1. Not only was the first man in space a Soviet, they had accomplished an orbital mission, which NASA hadn’t planned to attempt until at least the following year.

On May 5, 1961, NASA got back into the game, or at least the minor league, when Alan Shepard was launched on Mercury-Redstone 3. Sure, it was just a 15 minute up and down, but at least an American had been in space, if only briefly, and it was enough to persuade a recently-elected, young U.S. president smarting from being scooped by the Soviets to “take longer strides”. On May 25, less than three weeks after Shepard’s flight, before a joint session of Congress, President Kennedy said, “I believe that this nation should commit itself to achieving the goal, before this decade is out, of landing a man on the Moon and returning him safely to Earth.” Kennedy had asked his vice president, Lyndon Johnson, what goal the U.S. could realistically hope to achieve before the Soviets, and after consulting with the NASA administrator, James Webb, a Texas oil man and lawyer, and no other NASA technical people other than Wernher von Braun, he reported that a manned Moon landing was the only milestone the Soviets, with their heavy boosters and lead in manned space flight, were unlikely to do first. So, to the Moon it was.

The Space Task Group people who were, ultimately going to be charged with accomplishing this goal and had no advance warning until they heard Kennedy’s speech or got urgent telephone calls from colleagues who had also heard the broadcast were, in the words of their leader, Robert Gilruth, who had no more warning than his staff, “aghast”. He and his team had, like von Braun in the 1950s, envisioned a deliberate, step-by-step development of space flight capability: manned orbital flight, then a more capable spacecraft with a larger crew able to maneuver in space, a space station to explore the biomedical issues of long-term space flight and serve as a base to assemble craft bound farther into space, perhaps a reusable shuttle craft to ferry crew and cargo to space without (wastefully and at great cost) throwing away rockets designed as long-range military artillery on every mission,followed by careful reconnaissance of the Moon by both unmanned and manned craft to map its surface, find safe landing zones, and then demonstrate the technologies that would be required to get people there and back safely.

All that was now clearly out the window. If Congress came through with the massive funds it would require, going to the Moon would be a crash project like the Manhattan Project to build the atomic bomb in World War II, or the massive industrial mobilisation to build Liberty Ships or the B-17 and B-29 bombers. The clock was ticking: when Kennedy spoke, there were just 3142 days until December 31, 1969 (yes, I know the decade actually ends at the end of 1970, since there was no year 0 in the Gregorian calendar, but explaining this to clueless Americans is a lost cause), around eight years and seven months. What needed to be done? Everything. How much time was there to do it? Not remotely enough. Well, at least the economy was booming, politicians seemed willing to pay the huge bills for what needed to be done, and there were plenty of twenty-something newly-minted engineering graduates ready and willing to work around the clock without a break to make real what they’d dreamed of since reading science fiction in their youth.

The Apollo Project was simultaneously one of the most epochal and inspiring accomplishments of the human species, far more likely to be remembered a thousand years hence than anything else that happened in the twentieth century, and at the same time a politically-motivated blunder which retarded human expansion into the space frontier. Kennedy’s speech was at the end of May 1961. Perhaps because the Space Task Group was so small, it and NASA were able to react with a speed which is stunning to those accustomed to twenty year development projects for hardware far less complicated than Apollo.

In June and July [1961], detailed specifications for the spacecraft hardware were completed. By the end of July, the Requests for Proposals were on the street.

In August, the first hardware contract was awarded to M.I.T.’s Instrumentation Laboratory for the Apollo guidance system. NASA selected Merritt Island, Florida, as the site for a new spaceport and acquired 125 square miles of land.

In September, NASA selected Michoud, Louisiana, as the production facility for the Saturn rockets, acquired a site for the Manned Spacecraft Center—the Space Task Group grown up—south of Houston, and awarded the contract for the second stage of the Saturn [V] to North American Aviation.

In October, NASA acquired 34 square miles for a Saturn test facility in Mississippi.

In November, the Saturn C-1 was successfully launched with a cluster of eight engines, developing 1.3 million pounds of thrust. The contract for the command and service module was awarded to North American Aviation.

In December, the contract for the first stage of the Saturn [V] was awarded to Boeing and the contract for the third stage was awarded to Douglas Aircraft.

By January of 1962, construction had begun at all of the acquired sites and development was under way at all of the contractors.

Such was the urgency with which NASA was responding to Kennedy’s challenge and deadline that all of these decisions and work were done before deciding on how to get to the Moon—the so-called “mission mode”. There were three candidates: direct-ascent, Earth orbit rendezvous (EOR), and lunar orbit rendezvous (LOR). Direct ascent was the simplest, and much like idea of a Moon ship in golden age science fiction. One launch from Earth would send a ship to the Moon which would land there, then take off and return directly to Earth. There would be no need for rendezvous and docking in space (which had never been attempted, and nobody was sure was even possible), and no need for multiple launches per mission, which was seen as an advantage at a time when rockets were only marginally reliable and notorious for long delays from their scheduled launch time. The downside of direct-ascent was that it would require an enormous rocket: planners envisioned a monster called Nova which would have dwarfed the Saturn V eventually used for Apollo and required new manufacturing, test, and launch facilities to accommodate its size. Also, it is impossible to design a ship which is optimised both for landing under rocket power on the Moon and re-entering Earth’s atmosphere at high speed. Still, direct-ascent seemed to involve the least number of technological unknowns. Ever wonder why the Apollo service module had that enormous Service Propulsion System engine? When it was specified, the mission mode had not been chosen, and it was made powerful enough to lift the entire command and service module off the lunar surface and return them to the Earth after a landing in direct-ascent mode.

Earth orbit rendezvous was similar to what Wernher von Braun envisioned in his 1950s popular writings about the conquest of space. Multiple launches would be used to assemble a Moon ship in low Earth orbit, and then, when it was complete, it would fly to the Moon, land, and then return to Earth. Such a plan would not necessarily even require a booster as large as the Saturn V. One might, for example, launch the lunar landing and return vehicle on one Saturn I, the stage which would propel it to the Moon on a second, and finally the crew on a third, who would board the ship only after it was assembled and ready to go. This was attractive in not requiring the development of a giant rocket, but required on-time launches of multiple rockets in quick succession, orbital rendezvous and docking (and in some schemes, refuelling), and still had the problem of designing a craft suitable both for landing on the Moon and returning to Earth.

Lunar orbit rendezvous was originally considered a distant third in the running. A single large rocket (but smaller than Nova) would launch two craft toward the Moon. One ship would be optimised for flight through the Earth’s atmosphere and return to Earth, while the other would be designed solely for landing on the Moon. The Moon lander, operating only in vacuum and the Moon’s weak gravity, need not be streamlined or structurally strong, and could be potentially much lighter than a ship able to both land on the Moon and return to Earth. Finally, once its mission was complete and the landing crew safely back in the Earth return ship, it could be discarded, meaning that all of the hardware needed solely for landing on the Moon need not be taken back to the Earth. This option was attractive, requiring only a single launch and no gargantuan rocket, and allowed optimising the lander for its mission (for example, providing better visibility to its pilots of the landing site), but it not only required rendezvous and docking, but doing it in lunar orbit which, if they failed, would strand the lander crew in orbit around the Moon with no hope of rescue.

After a high-stakes technical struggle, in the latter part of 1962, NASA selected lunar orbit rendezvous as the mission mode, with each landing mission to be launched on a single Saturn V booster, making the decision final with the selection of Grumman as contractor for the Lunar Module in November of that year. Had another mission mode been chosen, it is improbable in the extreme that the landing would have been accomplished in the 1960s.

The Apollo architecture was now in place. All that remained was building machines which had never been imagined before, learning to do things (on-time launches, rendezvous and docking in space, leaving spacecraft and working in the vacuum, precise navigation over distances no human had ever travelled before, and assessing all of the “unknown unknowns” [radiation risks, effects of long-term weightlessness, properties of the lunar surface, ability to land on lunar terrain, possible chemical or biological threats on the Moon, etc.]) and developing plans to cope with them.

This masterful book is the story of how what is possibly the largest collection of geeks and nerds ever assembled and directed at a single goal, funded with the abundant revenue from an economic boom, spurred by a geopolitical competition against the sworn enemy of liberty, took on these daunting challenges and, one by one, overcame them, found a way around, or simply accepted the risk because it was worth it. They learned how to tame giant rocket engines that randomly blew up by setting off bombs inside them. They abandoned the careful step-by-step development of complex rockets in favour of “all-up testing” (stack all of the untested pieces the first time, push the button, and see what happens) because “there wasn’t enough time to do it any other way”. People were working 16–18–20 hours a day, seven days a week. Flight surgeons in Mission Control handed out “go and whoa pills”—amphetamines and barbiturates—to keep the kids on the console awake at work and asleep those few hours they were at home—hey, it was the Sixties!

This is not a tale of heroic astronauts and their exploits. The astronauts, as they have been the first to say, were literally at the “tip of the spear” and would not have been able to complete their missions without the work of almost half a million uncelebrated people who made them possible, not to mention the hundred million or so U.S. taxpayers who footed the bill.

This was not a straight march to victory. Three astronauts died in a launch pad fire the investigation of which revealed shockingly slapdash quality control in the assembly of their spacecraft and NASA’s ignoring the lethal risk of fire in a pure oxygen atmosphere at sea level pressure. The second flight of the Saturn V was a near calamity due to multiple problems, some entirely avoidable (and yet the decision was made to man the next flight of the booster and send the crew to the Moon). Neil Armstrong narrowly escaped death in May 1968 when the Lunar Landing Research Vehicle he was flying ran out of fuel and crashed. And the division of responsibility between the crew in the spacecraft and mission controllers on the ground had to be worked out before it would be tested in flight where getting things right could mean the difference between life and death.

What can we learn from Apollo, fifty years on? Other than standing in awe at what was accomplished given the technology and state of the art of the time, and on a breathtakingly short schedule, little or nothing that is relevant to the development of space in the present and future. Apollo was the product of a set of circumstances which happened to come together at one point in history and are unlikely to ever recur. Although some of those who worked on making it a reality were dreamers and visionaries who saw it as the first step into expanding the human presence beyond the home planet, to those who voted to pay the forbidding bills (at its peak, NASA’s budget, mostly devoted to Apollo, was more than 4% of all Federal spending; in recent years, it has settled at around one half of one percent: a national commitment to space eight times smaller as a fraction of total spending) Apollo was seen as a key battle in the Cold War. Allowing the Soviet Union to continue to achieve milestones in space while the U.S. played catch-up or forfeited the game would reinforce the Soviet message to the developing world that their economic and political system was the wave of the future, leaving decadent capitalism in the dust.

A young, ambitious, forward-looking president, smarting from being scooped once again by Yuri Gagarin’s orbital flight and the humiliation of the débâcle at the Bay of Pigs in Cuba, seized on a bold stroke that would show the world the superiority of the U.S. by deploying its economic, industrial, and research resources toward a highly visible goal. And, after being assassinated two and a half years later, his successor, a space enthusiast who had directed a substantial part of NASA’s spending to his home state and those of his political allies, presented the program as the legacy of the martyred president and vigorously defended it against those who tried to kill it or reduce its priority. The U.S. was in an economic boom which would last through most of the Apollo program until after the first Moon landing, and was the world’s unchallenged economic powerhouse. And finally, the federal budget had not yet been devoured by uncontrollable “entitlement” spending and national debt was modest and manageable: if the national will was there, Apollo was affordable.

This confluence of circumstances was unique to its time and has not been repeated in the half century thereafter, nor is it likely to recur in the foreseeable future. Space enthusiasts who look at Apollo and what it accomplished in such a short time often err in assuming a similar program: government funded, on a massive scale with lavish budgets, focussed on a single goal, and based on special-purpose disposable hardware suited only for its specific mission, is the only way to open the space frontier. They are not only wrong in this assumption, but they are dreaming if they think there is the public support and political will to do anything like Apollo today. In fact, Apollo was not even particularly popular in the 1960s: only at one point in 1965 did public support for funding of human trips to the Moon poll higher than 50% and only around the time of the Apollo 11 landing did 50% of the U.S. population believe Apollo was worth what was being spent on it.

In fact, despite being motivated as a demonstration of the superiority of free people and free markets, Project Apollo was a quintessentially socialist space program. It was funded by money extracted by taxation, its priorities set by politicians, and its operations centrally planned and managed in a top-down fashion of which the Soviet functionaries at Gosplan could only dream. Its goals were set by politics, not economic benefits, science, or building a valuable infrastructure. This was not lost on the Soviets. Here is Soviet Minister of Defence Dmitriy Ustinov speaking at a Central Committee meeting in 1968, quoted by Boris Chertok in volume 4 of Rockets and People.

…the Americans have borrowed our basic method of operation—plan-based management and networked schedules. They have passed us in management and planning methods—they announce a launch preparation schedule in advance and strictly adhere to it. In essence, they have put into effect the principle of democratic centralism—free discussion followed by the strictest discipline during implementation.

This kind of socialist operation works fine in a wartime crash program driven by time pressure, where unlimited funds and manpower are available, and where there is plenty of capital which can be consumed or borrowed to pay for it. But it does not create sustainable enterprises. Once the goal is achieved, the war won (or lost), or it runs out of other people’s money to spend, the whole thing grinds to a halt or stumbles along, continuing to consume resources while accomplishing little. This was the predictable trajectory of Apollo.

Apollo was one of the noblest achievements of the human species and we should celebrate it as a milestone in the human adventure, but trying to repeat it is pure poison to the human destiny in the solar system and beyond.

This book is a superb recounting of the Apollo experience, told mostly about the largely unknown people who confronted the daunting technical problems and, one by one, found solutions which, if not perfect, were good enough to land on the Moon in 1969. Later chapters describe key missions, again concentrating on the problem solving which went on behind the scenes to achieve their goals or, in the case of Apollo 13, get home alive. Looking back on something that happened fifty years ago, especially if you were born afterward, it may be difficult to appreciate just how daunting the idea of flying to the Moon was in May 1961. This book is the story of the people who faced that challenge, pulled it off, and are largely forgotten today.

Both the 1989 first edition and 2004 paperback revised edition are out of print and available only at absurd collectors’ prices. The Kindle edition, which is based upon the 2004 edition with small revisions to adapt to digital reader devices is available at a reasonable price, as is an unabridged audio book, which is a reading of the 2004 edition. You’d think there would have been a paperback reprint of this valuable book in time for the fiftieth anniversary of the landing of Apollo 11 (and the thirtieth anniversary of its original publication), but there wasn’t.

Project Apollo is such a huge, sprawling subject that no book can possibly cover every aspect of it. For those who wish to delve deeper, here is a reading list of excellent sources. I have read all of these books and recommend every one. For those I have reviewed, I link to my review; for others, I link to a source where you can obtain the book.

If you wish to commemorate the landing of Apollo 11 in a moving ceremony with friends, consider hosting an Evoloterra celebration.

Murray, Charles and Catherine Bly Cox. Apollo. Burkittsville, MD: South Mountain Books, [1989, 2004] 2010. ISBN 978-0-9760008-0-8.

Here is the Apollo 11 walk on the Moon, restored, as you may never have seen it before.  A funny sequence, which I remember from when I heard it as it happened, occurs at 20:34 into the video.

Next we have a discussion for a presentation made in 1989 by those involved in planning the Apollo missions.

Part 3 of this panel does not seem to be available.  Here is part 4.

Another panel discussion of 1989 involved people from Mission Control discussing how the Apollo missions were flown.

Here is an extraordinarily candid interview with famously private Neil Armstrong about his career and the unique circumstances which made Apollo possible.  The interview was recorded in 2011, a year before Armstrong’s death.

This is a one hour interview with Buzz Aldrin recorded at the Science Museum in London three years ago.

Here is a one hour conversation with Apollo 11 Command Module Pilot Michael Collins recorded in April 2019 at the National Press Club.  The interviewer, former CBS News reader Marvin Kalb, is stunningly ignorant, talking repeatedly about the “dark side of the Moon” and believing that the International Space Station is a “Russian space station” where U.S. astronauts “only visit”.

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Author: John Walker

Founder of Ratburger.org, Autodesk, Inc., and Marinchip Systems. Author of The Hacker's Diet. Creator of www.fourmilab.ch.

47 thoughts on “Saturday Night Science: Apollo 11 at 50 I: Apollo

  1. Ha – thanks!  This will be way better than staring at the original and battling nausea, or pulling weeds.  And the universe will make a little more sense.

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  2. The NASA Scientific Visualization Studio has prepared an animation which shows all of the six Apollo landing sites on the Moon with the Moon displaying the phases and librations (apparent “nodding” of the Moon due to its orbital eccentricity and inclination) between the landings.

    [video width="640" height="360" mp4="https://www.ratburger.org/wp-content/uploads/2019/07/apollo_sites_360p30.mp4"][/video]

    This video is as supplied by NASA in MPEG-4 format.  Due to the Balkanisation of video formats by various vendors, it will not play in all browsers.  To view the video in higher resolutions, and for full details on what you’re seeing, visit the NASA “Apollo Landing Sites with Moon Phases” Web page.

    Due to performance limitations of the Apollo hardware, landing sites were restricted to a band centred around the lunar equator.  The times of landings were chosen to be relatively soon after lunar sunrise so that shadows would make terrain and potential obstacles easier to see during the landing phase.

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  3. Today’s Apollo historical document goes way back to the origins of the Apollo spacecraft.  A person identified only as “Ben” found, among his grandfather’s papers, a collection of drawings dated July and August of 1961 which North American Aviation prepared to support their bid to develop the Apollo command and service modules.  All of the original drawings have been scanned and are available on a new Apollo Preliminary Drawings Web site.  These scans are huge and not necessarily well-processed to extract detail; they may be viewed best in an image processing program such as Gimp, which lets you zoom, pan, and adjust contrast and brightness.  Here is my re-processed version of one of the more interesting drawings.

    (Click for a larger image.)  The command module has the shape and size close to what would actually be built years later, but this appears to be a design for a direct ascent or Earth orbit rendezvous mission mode where the entire command and service module (CSM) would land on the Moon and then return directly to Earth.  The CSM is stacked on top of what is called a “lunar landing module”, but this is not a separate spacecraft but rather a propulsion stage used to land the CSM on the lunar surface.  It is equipped with the same J-2 engine that would be used in the second and third stages of the Saturn V.  This is an odd choice for a lander: the J-2 uses liquid hydrogen and oxygen propellants, and the tanks would have to be very carefully insulated to keep these cryogenic fluids liquid on the several day coast to the Moon.  Further, the J-2 could not be throttled, which is essential for a lander.  Perhaps the addition of throttling capability to this engine (as was envisioned for the J-2X for the now-cancelled Constellation program) was proposed as part of the Apollo development project.

    There are what appear to be two rockets mounted on the bottom of the service module, but this drawing does not describe them.  They may provide propulsion for the return to Earth, leaving the lunar landing module on the Moon.  Another drawing of the service module shows what appear to be 19 solid rocket motors in a cluster with the ability to eject them.  I don’t know whether these were part of a “lunar crasher” concept under consideration at the time (used to slow to near approach speed, then jettisoned before landing), or for the Earth return burn.

    Without the accompanying descriptive material, there is a lot of head scratching details in these drawings.  For example, the command module is shown with a launch escape tower, but another drawing of the command module shows provisions for ejection seats.  Still another drawing shows the Apollo comand module descending under a parawing—while such a landing system was under consideration for Gemini, I’ve never heard it mentioned in conjunction with Apollo.  Maybe the ejection seats were in case of failure of the parawing.

    Here is a Scott Manley video discussing these drawings.  I don’t necessarily agree with Scott’s interpretation of some of these drawings, but there are a lot of curious details that different people will puzzle out in various ways.

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  4. Today, the 50th anniversary of the launch of Apollo 11, the document from the past is the cover of Aviation Week & Space Technology dated July 28, 1969.  Note that magazine cover dates are “pull dates”, and the magazine usually goes on sale at the pull date of the previous issue, which would have been July 21, the day after the Moon landing.  When they went to print, the only image available for the cover was a photo of a TV screen showing the converted video transmitted from the Moon.  (Information about the Moonwalk video and how it was restored ten years ago is in comment #15.)

    Aviation Week & Space Technology cover, 1969-07-28

    As a professional publication, Aviation Week bore the lofty cover price of US$1.  The July 15–28, 2019 issue of the magazine, which reprinted this cover in full, has a cover price of US$14.95.  In 1969, a copy of the New York Times went for a dime, and a Big Mac was fifty cents.  On the other hand, half a megabyte of computer memory would set you back US$823,500 in 1969 dollars, or around US$5.7 million of today’s phoneybucks.

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  5. Apollo 11 launched to the Moon 50 years ago at this moment: 1969-07-16 at 13:32 UTC. Here is a gorgeous 500 frame per second slow motion film of the liftoff, with commentary.

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  6. The Apollo Guidance Computer (AGC) was one of the most remarkable and unappreciated technological achievements of the Apollo program.  Just 10 weeks after Kennedy’s commitment to a Moon landing, NASA made a sole-source contract award to MIT to develop the guidance computer, software, and navigation instrumentation.  The computer had to be able to support autonomous navigation and control of the spacecraft from launch to the Moon and back.  Early in the development stage, MIT decided to use the brand-new technology of integrated circuits (IC), weighing the technology risk as offset by reduction in parts count, number of interconnections, and mass and volume savings.  The entire computer was built from a single type of IC, a three-input NOR gate developed by Fairchild Semiconductor.  In the mid-1960s, when the Apollo Guidance Computers were being assembled, they accounted for a substantial fraction of all of the integrated circuits manufactured in the world.

    The computer had 2048 16-bit words (4 kilobytes) of read-write magnetic core memory and 36,864 words (72 Kb) of read-only core rope memory.  The software for the computer was “woven” into the rope memory by threading wires through magnetic cores one way for a zero and the other for a one.  Both types of memory had a cycle time of 11.72 microseconds.  A substantial part of the computer’s circuitry was devoted to digital and analogue interfaces to hardware in the spacecraft: it was connected to the inertial measurement unit (gyroscope and accelerometers) and an optical alignment telescope which was used to align the measurement unit via star sightings.  Each lunar landing mission carried two identical guidance computers, one in the command module and one in the lunar module, running the same software.  There was strong pressure to simplify the lunar module computer to save weight, but MIT insisted they be identical in the interest of redundancy.  This proved essential when Apollo 13 lost the use of the command module computer and had to use the one in the lunar module to perform the critical maneuvers to get back to Earth.

    Here is a half hour presentation by MIT from 1965 about the development of the guidance computer.

    In 1976, Jamie Loocke, a former NASA engineer who worked on the lunar module, bought two tons of NASA hardware being disposed of as surplus.  Included in the lot was the AGC from the lunar module on which he’d worked.  Starting in late 2018, a group of engineers embarked on a project to restore the AGC and get it running prior to the 50th anniversary of the first lunar landing.  The following YouTube play list chronicles the effort, with its many ups and downs.

    (You may find it more convenient to view the play list directly from YouTube.)

    Of course, somebody has built an AGC simulator, including a complete copy of the Colossus 249 flight software from Apollo 9, that you can run in your browser.

    An excellent history of the AGC is Journey to the Moon: The History of the Apollo Guidance Computer by Eldon C. Hall.

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  7. This is the television transmission sent by Apollo 11 on 1969-07-17 at 23:31 UTC, around halfway to the Moon.  It includes colour imagery of the gibbous Earth.  The spacecraft was around 209,215 km from the Earth at the time.  (The time of the transmission is given incorrectly on the YouTube page; it was sloppily transcribed and off by 12 hours.)

    Here is an image from Earth and Moon Viewer which approximates the view from the spacecraft.

    Earth from Apollo 11, 1969-07-17

    Here is a detailed timeline of Apollo 11, including the television transmissions.

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  8. Tangentially related to the subject of the OP, America: From Apollo to WOKE & BROKE in 50 Years. It made me sad.

    Society grows great when old men plant trees whose shade they know they shall never sit in.

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  9. On 1969-07-19 Apollo 11 flew behind the Moon and fired its Service Propulsion System (SPS) engine to enter lunar orbit.  An hour and twenty minutes later (18:45 UTC) a television transmission began from the spacecraft.  This broadcast concentrated on views of the Moon from orbit.  At this point Apollo 11 was in an elliptical orbit around the Moon.  An hour after the conclusion of this broadcast a second firing of the SPS would circularise the orbit into that from which descent to the surface would begin the next day.

    Early Apollo landing missions (Apollo 11 and 12) placed the docked command/service and lunar modules into a near-circular orbit about 60 nautical miles (111 km) above the Moon.  The lunar module would then separate, perform a burn to lower its periapsis to around 9 nautical miles (17 km) and then, at closest approach, begin the powered descent to the surface.  Starting with Apollo 14, the service module would make this descent orbit insertion burn with the lunar module attached with the lunar module needing only to perform the powered descent.  This conserved fuel in the lunar module, which allowed accommodating its growing weight as increasingly ambitious missions carried more gear to the lunar surface.

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  10. Today is the fiftieth anniversary of the Apollo 11 landing on the Moon.  The lunar module Eagle touched down on the surface of Mare Tranquillitatis (the Sea of Tranquillity) at 20:17:39 UTC on 1969-07-20.  The first step on the Moon by Neil Armstrong, reckoned in Universal Time, did not occur until 02:56:15 the next day, 1969-07-21, but is usually described as occurring on July 20th as it was still that day in U.S. time zones.

    Today’s historical document is a 1966 MIT Science Reporter film, Landing on the Moon, showing the lunar module in the process of development  and featuring Thomas J. Kelly, head of the lunar module project at Grumman.  Kelly’s 2001 book, Moon Lander, is an excellent insider’s view of the ups and downs of its development process.

    One of the interesting details is that at the time the film was made the mission plan envisioned only one astronaut of the landing crew venturing out on the surface of the Moon.  The other would stay on board the lunar module to monitor systems and stay in communication with mission control.  (This would also have saved weight, since there would only need to have been one life support backpack for the astronaut who walked on the surface.)  This was, of course, completely insane and was changed well before the landing missions approached.  Time on the lunar surface is so precious that going all the way to the Moon and then throwing away half of the potential time that can be used in setting up experiments, collecting samples, etc. would be folly.  NASA had complete telemetry of everything in the lunar module, so there’s nothing an astronaut in the cabin could see that mission control couldn’t.

    In the film we see a little-known device built at the NASA Langley Research Center to study vertical rocket landing on the Moon.  A lander with hydrogen peroxide monopropellant thrusters was suspended from an overhead gantry crane which takes up 5/6 of the simulator’s weight, making it behave as it would under lunar gravity.

    Later, a free-flying Lunar Landing Research Vehicle (LLRV) was developed for astronaut training which used a vertically-mounted jet engine to simulate lunar gravity.  On May 6, 1968, Neil Armstrong lost control of an LLRV when it ran out of attitude control fuel due to high winds.  Armstrong ejected at an altitude of 200 feet (61 metres) and landed only four seconds after his parachute opened, missing the fireball of the LLRV crash.

    The finicky and dangerous LLRV was eventually replaced by an improved Lunar Landing Training Vehicle (LLTV).  All of the Apollo lunar landing crews trained in the LLTV and none had to eject from the device.  However, on 1971-01-29 test pilot Stuart Present, who was testing modifications to the vehicle’s computer system, had to eject from LLTV #3, which was destroyed.  Present, like Armstrong, escaped without injury.

    It’s rare to see depictions of a Moon landing which give a sense of the workload of the astronauts in the lunar module.  Here is a simulation of the Apollo 11 descent in the Orbiter lunar module simulation add-on with a gate-faithful emulation of the Apollo Guidance Computer running actual flight software in the control loop.  I start the video at the point the faithful simulation of Apollo 11 begins, including program alarms due to computer overload.  It you back up to the beginning, you’ll see how it was supposed to go.

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  11. After landing on the Moon and walking on its surface, accomplishing the first half of President Kennedy’s challenge, “landing a man on the Moon”, it was time to get started on the second part, “returning him safely to the Earth”, which would begin with the lunar module Eagle’s ascent stage lifting off from the Moon and entering lunar orbit to rendezvous with mother ship Columbia.  Many, including astronaut Michael Collins in Columbia, thought this was the riskiest part of the endeavour.  At earlier phases of the mission, even in the final approach to landing, there was always a “Plan B” if something went wrong: there was a big “Abort” button on Armstrong’s control panel which, with a single press, would call the whole thing off.  But getting back from the lunar surface relied on the ascent stage’s single engine, the ascent propulsion system (APS).  There was no back-up to this engine: if it failed to fire or cut out before lunar orbit had been achieved, the astronauts would be stranded on the Moon or crash into its surface.

    The APS engine was small (just 3500 pounds-force [15.6 kilonewton] thrust), pressure-fed (which allowed it to dispense with complex and failure-prone turbopumps), fixed-thrust (avoiding the complexity of a throttle mechanism), and employed hypergolic propellants which ignited spontaneously on contact (no need for an ignition system).  It was about as simple as a liquid fuel rocket engine could be, and it was based upon the design of an engine used on the Agena upper stage, which had proved highly reliable.  The APS also incorporated a substantial degree of internal redundancy, so that no single failure of a component such as a valve or actuator would cause the engine to fail.  But still, there was only one, and because it used corrosive propellants and had an ablatively-cooled thrust chamber and nozzle, it could not be test-fired prior to being used on the Moon.  Here are details of the ascent engine [PDF].

    At Mission Elapsed Time (MET) 112:56:28, as the moonwalkers were performing their post-EVA activities, Aldrin made this call to Mission Control:

    Houston, Tranquility. Do you have a way of showing the configuration of the engine arm circuit breaker? Over. (Pause) The reason I’m asking is because the end of it appears to be broken off. I think we can push it back in again. I’m not sure we could pull it out if we pushed it in, though. Over.

    This is the circuit breaker that enables the Ascent Propulsion System engine.  Apparently, while maneuvering around in the cramped cabin of the lunar module, Aldrin (it couldn’t have been Armstrong, since the switch was on Buzz’s side of the cabin) bumped the unprotected handle of the switch and broke it off.  Fortunately, Aldrin discovered that the tip of a felt-tipped pen would fit into the hole and allow the breaker to be turned on.  This worked when needed before the launch from the Moon.  Whew!   (On Apollo 12 and subsequent missions, guards were installed over the breakers on this panel to avoid a recurrence.)

    Here is the liftoff from the Moon and flight into lunar orbit, as recorded by a 16 mm movie camera in the lunar module looking out Aldrin’s window.  The camera was set to expose six frames per second.  It is presented here at that rate, synchronised with communications between the lunar module and Houston.

    The liftoff from the Moon was at 17:54:00 UTC on 1969-07-21.  Unlike landing on the Moon, which is a complex process involving both astronauts controlling and monitoring the computer and flying the lander, return to orbit is basically a one-button-push affair.  The entire maneuver is pre-programmed and flown hands-off.  After achieving lunar orbit, Eagle began a sequence of carefully scripted maneuvers to catch up, match orbits, and approach Columbia.  Here is a NASA documentary describing how lunar orbit rendezvous is accomplished, complete with a hep cat jazz soundtrack.

    As the lunar module approached the command/service module, another 16 mm movie camera in that spacecraft filmed the lunar module’s approach to station keeping and re-orientation for docking.

    This was also filmed at 6 frames per second, but is shown here at 24 frames per second, or four times actual speed.  At the very end of the film you can see the Earth behind the lunar module; this was the first “everyone elsie” captured on movie film: every human being other than Michael Collins is in these frames.  The lunar module docked with the command module at 21:35:00 UTC on July 21.  After the astronauts transferred back to the command module, the lunar module ascent stage was jettisoned at 23:41:31.

    And the descent stage?  Why, it’s still on the Moon!  Here is a photo of the Apollo 11 landing site captured in March 2012 by Lunar Reconnaissance Orbiter.  You can see the descent stage of Eagle, the television camera, the scientific instruments deployed on the surface, and the astronauts’ footprints.  Click the image to enlarge.

    Apollo 11 landing site from Lunar Reconnaissance Orbiter, LROC M175124932R

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  12. On July 22nd, 1969, at 04:55:42 UTC, Apollo 11 ignited its Service Propulsion System engine behind the Moon to break out of lunar orbit and begin the coast back to Earth.  The engine burned for 2 minutes and 31 seconds and performed as expected.  Later that day, at 20:01:57 UTC, a  midcourse correction burn of ten seconds was performed to fine-tune the angle at which the spacecraft would hit the Earth’s atmosphere for re-entry.  The flight plan [PDF] provided for three midcourse correction opportunities during the trans-Earth coast phase, but only the first was required.

    Here is a television transmission from Apollo 11 at Mission Elapsed Time of 155:36:00.  This is actually early on the morning of July 23 in UTC, but as most people in the U.S. saw it on the 22nd, I’ll call it close enough for this narrative.

    The broadcast begins with a funny sequence in which Mission Control, looking at the fuzzy television image on their big screen, confuses the Moon for the Earth.  Then it moves inside the command module, where Buzz Aldrin and Michael Collins demonstrate the food they’ve been eating on the voyage and Buzz does a science experiment with a tin of ham spread.

    This is a 1966 documentary from MIT Science Reporter, “Food for Space Travelers”, about the development of food for space flight.

    In-flight entertainment options aboard Apollo spacecraft were limited.  Each astronaut was equipped with a Sony TC-50 tape recorder (kind of a Walkman, ten years before its time, but also able to record and intended for verbal logging during the mission).  Here is a Techmoan episode about the TC-50, resurrecting (more or less) a fifty year old example still in the original box.

    Individual “mix tapes” for each astronaut were prepared by Mickey Kapp, son of the founder of Kapp Records.  Here is the story of the tapes and the music they contained from a December 2018 article in Vanity Fair.

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  13. It’s wonderful to have all these historical resources available. In a sense, it’s a richer experience today, fifty years later, than it was at the time since back in 1969 we were limited to what the networks wanted to show us and you had to be there when they chose to show it. The only parts missing are the excitement of the moment and the uncertainty of how it would turn out.

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  14. Wayne Hale, former Shuttle flight director and program manager, is reporting that Chris Kraft, “flight” in the early days of NASA manned spaceflight, and director of flight operations for Apollo, has died.

    Kraft’s 2001 book, Flight: My Life in Mission Control, is out of print.  Used copies are available, but pricey.

    The entire Mission Control movie is available for free on YouTube.  It contains extensive coverage of Kraft’s career and interviews with him.

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  15. July 23, 1969 was the final day of Apollo 11’s trans-Earth coast.  As this was the third Apollo mission to return from the Moon and there were no anomalies with the spacecraft, everything proceeded according to the flight plan, which budgeted a generous ten hours of sleep and rest time.  At 177:32 Mission Elapsed Time (22:45 UTC, 1969-07-23) the crew made a television broadcast in which they reflected upon the mission and what it meant.

    As the Earth loomed ever larger in the windows, their thoughts turned to the means and techniques they would use to shed all the kinetic energy of falling from the Moon to the Earth and splash safely into the ocean.  Here is a 1966 MIT Science Reporter film on “Returning from the Moon”.

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  16. July 24, 1969 was Apollo 11’s return to Earth day.  At 16:21:12 UTC the command module separated from the service module, and at 16:44:06 it encountered the Earth’s atmosphere at the start of the entry corridor.  Here is a 1968 NASA documentary which describes the “double dip” re-entry trajectory which reduces heating on the spacecraft and allows accurate targeting of the splashdown location.

    The 16 mm movie camera on board the command module captured this film of the view out the window during re-entry.  The audio is from the NASA public affairs commentary, synchronised to the film.

    After splashdown at 16:50:35 UTC, the astronauts were picked up by a Navy helicopter and transferred to the aircraft carrier Hornet, where they entered the biological quarantine trailer and were later greeted by President Nixon.  This is a Navy training film discovered in 2013 which shows the recovery of the astronauts, arrival at the carrier, and recovery of the command module by the ship’s crane.

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  17. After the splashdown of Apollo 11 and recovery of the crew and command module by the aircraft carrier Hornet, attention turned to the lunar surface samples collected by the astronauts.  On July 25, 1969, the two sample return containers, sealed in lunar vacuum, were removed from the command module and flown on separate planes to Johnston Island and Hickam Air Force Base in Hawaii, and then onward to the Lunar Receiving Laboratory in Houston.

    Here is a NASA film about the processing of the lunar samples from Apollo 11.

    Then, of course, there’s the paperwork to fill out.  Here is the customs declaration filed by the astronauts upon their arrival in Hawaii.

    Apollo 11 Customs Declaration, 1969-07-24

    Upon arriving back in Houston, Buzz Aldrin filed the following travel voucher to recover his out of pocket expenses for the trip.

    Buzz Aldrin: Lunar travel voucher 1/2

    Buzz Aldrin: Lunar travel voucher 2/2

    In the run-up to the 50th anniversary of the Apollo 11 Moon landing, former Mythbuster Adam Savage organised “Project Egress”, in which a distributed team of “makers” fabricated a replica of the very complex command module hatch.  All of the independently-developed components were assembled into the hatch on 2019-07-18 at the National Air and Space Museum.  Here is a video of the event by Fran Blanche, who made one of the latches for the project from walnut wood.

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  18. When they arrived at the aircraft carrier Hornet after splashing down in the Pacific on July 24th, 1969, the Apollo 11 astronauts entered the mobile quarantine facility (MQF), a converted Airstream trailer with living and sleeping quarters and a decontamination airlock though which meals could be passed.  They were joined by a NASA medical doctor who would examine the crew and provide any care required and an engineer charged with powering down and safing  the command module, which was attached to the trailer via a flexible tunnel to provide access from the trailer.  The engineer was also charged with removing the lunar sample containers, data tapes, and film from the command module and packaging it for decontamination and processing after being passed out the airlock.  The MQF was maintained at a lower air pressure than ambient so any leakage would be from the outside to inside, and had filters to remove any contamination by lunar material in the air it vented.

    The crew and their two companions would remain in the MQF until it arrived at the Lunar Receiving Laboratory (LRL) in Houston on July 28th, having been delivered to Pearl Harbor on the Hornet and then flown on a C-141 cargo plane to Ellington Air Force Base near Houston and transferred by road to the LRL.

    Here is a tweet from Buzz Aldrin showing the crew inside the MQF.

    The Apollo 11 crew, physician, and engineer would remain in quarantine at the more spacious facilities of the LRL until August 10th, 1969.

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  19. Notwithstanding this tweet from somebody who was there, I think this picture dates from July 28, 1969 or later.  The Apollo 11 crew did not arrive at the Lunar Receiving Laboratory in Houston (where this photo was taken) until 10:00 UTC on that date.

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