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July 20, 1969: One Giant Leap For Mankind (2013) (nasa.gov)
263 points by houseofshards on July 21, 2014 | hide | past | web | favorite | 99 comments

The thing that really shocked me about the Apollo missions was how quickly they jumped from testing the hardware to actual mission to the moon. The _second_ manned launch of Apollo (and _first_ manned launch of the incredible Saturn V rocket) went straight out to the moon and orbited before returning back to Earth! The next missions did a few tests of the lunar lander in space, and the fifth manned mission was Apollo 11 which finally landed. Crazy to think of all the systems, hardware, etc. that just had a couple shakedown flights before the real deal. Incredibly impressive engineering to pull off such a feat without more problems.

There's a nice parallel there to the construction and launch of individual rockets, as described in another story on the homepage[1]. Many rockets are essentially designed to be single-use, so they can't be put through too much stress during testing. Therefore missions are essentially flown with completely new, largely untested rocket hardware.

The work-around is to build two identical copies of the rocket. The first is a test unit which is tested to failure; the second is put through a very brief test to confirm that it appears to behave sufficiently similarly to the first, and then it's put into service.


I recommend Apollo by Cox and Murray, an account of the Apollo program from the perspective of the engineers and managers, written based on hundreds of interviews and archive material. It's fascinating and explains how decisions like this were made in detail.

I second that recommendation. The book can be found for cheap, plus there's even a kindle version if you prefer that format:


They actually could've done it in 4 shake down missions. Apollo 10 was under fuelled for fear the team might attempt to land on the moon before Apollo 11 to achieve the record. They did everything except for the actual moon landing portion of the mission.

Along those lines, the first ever detonation of a nuclear device was 21 days before the bombing of Hiroshima.


Which was only 7 years after the discovery of the phenomenon of nuclear fission.

And was an untested design.

Even more shocking is the fact that today's cell phones have more computing power than the Apollo computers had - talk about optimizing your code! Just think of the code reviews those developers went through.

And, all the work that the Apollo program brought forth with physics, electronics, etc has powered decades of innovation.

Forget cell phones, your keyboard has vastly more power than the Apollo computers.

The power sequencer I worked with recently for an embedded system was a 16Mhz general purpose 8-bit processor with a bunch of 16 bit instructions and 24 bit addressing.

It cost 17 cents; I'm guessing this is a fraction of the cost of a single BIT of the Apollo computers.

I assume you're aware, but for the general audience: Every bit of memory on space shuttles was an individual physical bead stored in a hand-woven wire grid, with memory contents stored as magnetic orientation. This style of storage was the only available at the time, but continued through the 80's for robustness. No power to maintain memory, and practically immune to bit-flips caused by cosmic radiation.


The article states that the price of a single bit varied from $1 to $0.01 USD over the product lifetime. I would assume that NASA paid extra for higher reliability. 17 cents for a single bit is well within the cost range of a single bit, and a reasonable estimate for that time period.

... jesus tap-dancing christ, a whole dollar for a single BIT? Wolfram|Alpha says that a dollar in 1955 would be worth almost $9 today. The memory in my desktop would be worth more than the GDP of all but 10 US states o_0

The Apollo memory, which was rope core memory, was also known at LOL memory, or "little old lady" memory, since it was women, with their quilting, knitting and crocheting skills, who wove it.


"a whole dollar for a single BIT?"

Talk to people who fool around with homemade relay based computers or guys like me who just draw schematics and then visit your typical supplier like digikey or mouser and search for 12 volt coil latching relays, which are basically elecromechanical single bit storage devices (aside from other more "practical" purposes).

You're looking at a good $4 to $7 bucks. Per bit. Non-aerospace rated. Made in China not USA.

This is why core memory was popular, being a lot faster, smaller, and cheaper.

"have more computing power"

Unfortunately that means nothing. That would imply someone with control over an iphone (apple, etc) could do "more" than the apollo, which is obviously not happening.

Real power is what you can transform those computations into. Obviously the Apollo computer was far more powerful because it could transform those calculations into landing on the moon and returning, whereas a comparatively powerless iphone can, by itself without infrastructure, do little more than play Angry Birds.

If you're trying to land on the moon, or mars, an iphone is utterly useless and doesn't have even a fraction of the "power" required. It just can't do it. Doesn't have the I/O or the reliability required, not to mention the lack of software.

It is very much an apples and oranges comparison.

> Obviously the Apollo computer was far more powerful because it could transform those calculations into landing on the moon and returning

I'm afraid you aren't looking at how the system went together. The landing process was manual. Remember this was 1969, when there were still elevator operators (though they were by then redundant), steam trains in regular service, etc.

You can read the cockpit transcripts of the landing and compare those to the cockpit transcripts of a modern plane. Armstrong was making burn decisions HIMSELF based on what he saw out the window and what Aldrin was choosing HIMSELF to tell him mattered (Armstrong couldn't see the instruments; Aldrin couldn't see out the window. Astonishing teamwork!)

You can also read the source code for that computer program. Essentially it was a slide rule doing coordinate translation and some instrumentation monitoring. But the fact that they landed with the computer non functional tells you its role in the process.

This is hard to appreciate now when we have computer modulated machinery (stability dynamics in your quadcopter, machine control of your brakes etc) and even materials (both in design, manufacture, and even dynamic control of some beams etc). But back then they couldn't do that kind of thing.

I disagree. I think that if you took that Apollo computer and removed it from the spacecraft, it would have the same amount of computing power . You are correct in pointing out that computing power is not the same as the ability to change the world, but that does not make it meaningless.

Also, you could write the appropriate software and connect the appropriate equipment to the phones I/O port and use an iPhone to land a spacecraft on the moon. It does in fact have the "power" required.

There are both wheeled robots and quadcopter drones that are controlled by phones, you can buy a kit to make them. I don't know whether anyone's done anything particularly impressive with them, but it's certainly possible.

Reminds me of that bit in Iron Sky ...

(not gonna spoil it for those who haven't seen it, it's a totally hilarious film about Nazis on the dark side of the moon, just go watch it)

Is there a github repo of that original code?

The post-hoc analysis of that could burn down the internet for weeks.

I don't know of a github repository, but the source code can be found on the Virtual AGC page. Colossus is the command module program, while Luminary is the Lunar module program.

http://www.ibiblio.org/apollo/Colossus.html http://www.ibiblio.org/apollo/Luminary.html

This is really cool. Here is PLANETARY_INERTIAL_ORIENTATION.agc which contains Apollo command module code for converting between vectors in earth or moon based coordinate systems and a basic reference system: http://www.ibiblio.org/apollo/listings/Comanche055/PLANETARY...

It really looks surprisingly similar to modern assembly code. Well commented too.

Nice. Fun to take a glimpse into the code. Random line:


The Chinese have a very "measured" manned space program. They launch about every three years. They make a lot of progress between launches. I dont know if its finances or careful engineering. They have the advantage of two previous space programs to study. And they arent racing anybody.

This is actually the only compelling argument in favor of the landing being a hoax. Too much progress too fast with a bit too much disregard to astronauts' lives.

>> Too much progress too fast with a bit too much disregard to astronauts' lives.

We live in a much different world today. Back then if someone died (and some did) they were heros, lessons were learned, and we moved on. Today everyone is so afraid, even the military has a low risk tolerance. But remember how WWII was won, on D-day they basically thew bodies at the enemy to achieve a foothold. People did what it took to achieve goals, even at great cost in dollars or lives. It's just not like that today so it seems rather unbelievable.

I just read a book [1] which argues that while the Americans didn't worry too much about getting the most they could out of their manpower on D-Day - because they had several million more troops waiting to go - the British were conscious of their limited manpower and so optimized their landing in a number of ways, such as longer aerial bombing and specialized tanks for breaking through obstacles on the beach.

[1] http://www.amazon.com/Engineers-Victory-Problem-Solvers-Turn...

Interesting to note that with our increased fear, things didn't get much safer. 1.5% of all shuttle launches killed their crews.

Perhaps of relevance to Hacker News:

Four minutes before the moon landing, the Apollo Guidance Computer began throwing 1202 and 1201 alarms - indicating that it wasn't completing its processing loop in time.

Here's the audio from the flight director and guidance loops, as they troubleshooted the problem in real time, clearing Apollo 11 to land.


Some more information on the 1202 and 1201 alarms: http://www.hq.nasa.gov/alsj/a11/a11.1201-pa.html

tl;dr: Some misconfigured switches meant that rendezvous radar jobs kept being erroneously scheduled, which used up available memory. Whenever there was no more memory available, the alarm would fire and the computer was rebooted. It would immediately restart (resuming from near where they left off) all the high priority jobs (while not restarting the radar jobs), meaning that it could still land safely.

Jack Garman had hand-written down all the trouble codes on a "cheat sheet". He's the one who called "go". I am not even sure if the MIT software team knew what 1201 and 1202 were.

The AGC was one of the first to use priority multitasking. The 1201 and 1201 faults were indication that lower priority tasks were getting yanked.

See "Moon Machines". Seriously.

Display and keypad as I recall.

The problem was actually a deployment problem. The checklist for configuring the computer left a diagnostic mode on that sucked up a lot of CPU.

What would be an example of a lower-priority task in this situation?

A couple of links to the videos you mentioned:


The above is probably one of the most informative 2 minute videos I've ever seen.


"there were no specs, we made it up" "if you screwed up you got a stack of papers that was 2 feet thick" "the overall memory for the Apollo guidance computer was 72 kilobytes"



Clicked into the first one and got a thing about the insulation between the tanks - the 3rd video in the playlist was about them hiring surfboard makers to do the honeycomb insulation between the fuel tanks, since they had more experience working with the materials in the heat conditions.

Just another kind of "the space program was amazing" thing - the sheer diversity of people who got hired on to contribute is continually surprising. An amazing tribute to the pragmatism of NASA under the conditions.

Oops - display and keypad. See above :)

This is definitely the best way to listen to the audio:


this is amazing

And I thought zero-downtime web app deployments were stressful... this really puts stuff into perspective.

It's embarrassing that web apps have has much downtime as they do given the processing power they are given.

It actually makes sense given the economics of the situation: time invested in high availability is a poorer use of resources than, say, adding features for most web sites.

We can make web sites that stay up, always. It's just that it costs a lot more and / or they do less.

Oddly enough Google is throwing an error on that file.... to many people downloading the file recently.


Because there was no text chat then. BBN was contracted to build the first four IMP machines in 1969.

We put someone on the moon before we invented text-chat? Wow.

We put men on the moon before we invented the digital watch.

We put men on the moon before we put wheels on suitcases.


Seeing as the computers were spitting error numbers instead of error messages, I am guessing that wasn't an option at that time with the hardware they had.

I highly recommend the Discovery Channel mini-series "When We Left Earth: The NASA Missions". This mini-series covers the entire breadth of the NASA missions, from Mercury to the International Space Station. This series is available on Netflix: www.netflix.com/WiMovie/70218722

If "When We Left Earth" sparks your interest. I suggest watching "Apollo 13" and "The Right Stuff" next.

Lastly, I'm currently reading the excellent book "Moon Lander: How We Developed the Apollo Lunar Module". This book gives an insiders view of what it took to build the Lunar Module (LM). I particularly appreciate that the book covers a lot of the hard work, arguments, and drama that are often forgotten when we romanticize the past.

You forgot "From the Earth to the Moon", which was an excellent miniseries produced by the same team that did Apollo 13.

Largely based on _A Man on the Moon_ by Andrew Chaikin. Excellent read.

I haven't seen that yet. Thanks for the recommendation!

You might also consider reading the book "Failure is not an option."

It gives an account, from the flight director's perspective, of the space program from Mercury to Apollo 13.

This is one of my favorites. Not only is it riveting, but for anyone building software with others it's a great course in leadership, team building, and testing.

Some more recommendations: the book "Apollo" by Charles Murray and Catherine Bly Cox is really excellent as an overview of everything that it took to get to the moon, as is the HBO mini-series "From The Earth to the Moon"

Surprised I'm the first to mention For All Mankind as another great Apollo documentary. It was nominated for an academy award and is really well polished. Brian Eno did an amazing score of ambient music for it too. Don't go in expecting a factual run down of the Apollo era, in fact there's no narration at all and just great clips and bits of actual film from the training, launches, missions, etc. Criterion Collection has a great release of it that's worth a purchase if you're at all interested in space or the Apollo missions.

"The Right Stuff" is so repeat-watchable. I watch it two or three times a year, never gets boring. Sadly "When we left Earth" isn't available on UK Netflix :(

One of my first vivid memories was watching Apollo 14 or Apollo 15 on my folks old black and white telly. I was four at the time and went to school completely obsessed with the Saturn V rocket and the idea of space travel.

As I've grown older and come to appreciate the limitations of the technology of the day, I am even more in awe of the challenges the Apollo programme had to overcome to get two humans to land on the moon, and the mortal danger these individuals lived in from takeoff to landing.

I wonder if we've plateaued in our ability and willpower to put humans into space and to break new barriers in space travel. I wonder if governments could ever stomach the 1960's attitude of "throwing caution to the wind" to send humans to Mars or beyond.

> I wonder if governments could ever stomach the 1960's attitude of "throwing caution to the wind" to send humans to Mars or beyond.

I would honestly hope not because there's no point in doing it wrong, especially not now when any failure is a huge setback and successes are treated as expected.

We will put people on Mars, we will have space stations and people living on the moons of Jupiter. This won't happen quickly and I do understand that at some point we have to put people in danger but there's no reason to do it as recklessly as we did in the 60's.

Hell we're doing just fine as it is. Right now there are six people living in space. There are companies starting right now to supply them, to get minerals from asteroids, to take people to Mars. It's happening now and it's just not as heroic as it was in the 60's, which to my mind just shows that we're doing it right.

The Right Stuff is an entertaining movie, but beware that it plays fast and loose with a lot of facts, and also does a great disservice in its depiction of the beloved and respected Gus Grissom, who was killed in the Apollo 1 fire and was most definitely not the cave man/coward in the movie.

I've really got to speak to the incredible soundtrack that "When we left Earth" has.


Probably my favourite scene and if I'm honest though I am not even an American, watching the stars and stripes through the condensation ice and the big red U S A crawling by makes me feel a bit patriotic.

See also "Moon Machines".

This is an excellent series. There's an entire episode about the LEM computer which goes into detail about things like the famous alarm codes, hand-wiring core memory, and interviews with the developers.

Thanks, here's another suggestion: "In the Shadow of the Moon"

The ISS programme is a joint project among five participating space agencies: NASA, Roskosmos, JAXA, ESA, and CSA. It's not a NASA mission.

"When we left Earth" - just started watching this. Great !! Thank you for recommending this, good sir.

And remarkably, the Apollo Guidance Computer (AGC) operated at just 0.043 Mhz (43 KHz) and had just 64 Kilobytes of memory. There is more computing power in modern toasters and by comparison the smartphones we all carry around today are supercomputers!

And the complete listing of the AGC can actually be downloaded as a PDF here :


And for the Lunar Lander here:


It is fascinating to go through it!

I know we marvel at the pace of technology lately but it blows my mind that humankind went from:

0. Bicycles in the early/mid 19th century (depending on your definition)

1. to motorized cars 50ish years later

2. to actually flying at the turn of the 20th century

3. to transporting humans into space and then on the moon just 66 years later

I'd argue we haven't made such large, significant technology leaps in such a short span (just over 100 years) since then. Not sure we ever will (hopefully with energy).

>I'd argue we haven't made such large, significant technology leaps in such a short span

In 1999 I used a card catalog at my rural library to get an encyclopedia from 1989.

Just today I used my cell phone to call my friend who is quite literally halfway around the world and had a real time video chat with her. This happened in 14 years.

> ... and had a real time video chat with her

I'm not sure that's a particularly inspiring example of technology progress.

In 1999 video conferencing over the Internet was already a reality, though it was very low quality. I know we tried it in work around that time. Skype launched in 2003 and basically solved that problem.

So in the next 11 years the main development was in wireless networking, which was basically a refinement of military datalinks which had been in service at least since the AN/ARR-39 of 1956.

So in the next 11 years the main development was in wireless networking, which was basically a refinement of military datalinks which had been in service at least since the AN/ARR-39 of 1956.

You might as well write the whole lot off as a glorified telegram, if that's the stance you're going to take.

Well the internet is essentially just a really fast mail horse so there haven't been any improvements in communication for thousands of years!

Well, by that argument the space program was just a refinement of the Montgolfier balloon of 1783; both involve flying, after all.

In reality, quantitative parameters - cost, performance, reliability, usability - matter more than 'the first X'.

I was sort of attempting to string together related milestones (transportation). It would be better to compare card catalogs to wikipedia (and the printing press before).

Or video communications (FaceTime/Skype) with the telegraph and telephone. The development of telephone goes back as far as the bike/car so I'd posit that communications technology grew at about the same pace.

> I'd argue we haven't made such large, significant technology leaps in such a short span (...)

I can talk to and see someone in Japan (and she can see me too!) with the cellphone in my pocket.

I can find my position anywhere in the globe, down to an accuracy of 10 m, with a $ 100 gadget. It can also give me directions in realtime.

I can type something on Google and find more information about it than I could ever read/watch.

When I was a kid, just 20 years ago, those things weren't available neither affordable. I only had available to me payphones, maps and encyclopedias, inventions from the XVIII, XVI and I centuries, respectively. Now think about that.

Digital electronic computers were developed in the early 1940s. In the early 1970s we had microprocessors, and in the late 70s/early 80s we had affordable personal microcomputers.

There's no single, landmark event in the history of digital computing that compares to the moon landing, and of course the development of computing owns a lot to space exploration research. Still, to the extent that such comparisons make sense at all, the advent of cheap, ubiquitous microcomputers has had far more impact on humanity's welfare and culture than the landing on the moon.

Right. This is due to about 10% inspiration and 90% petroleum. We are 100W machines with 10kW energy footprints. You can do a lot of work with that.

The internet and mobile computing has been an equivalently momentous innovation but it's impact has generally been more indirect and immediate. Future historians will be able to look back and see the impact, but while immersed in it and at some midpoint along the phase change it's much less obvious and noticeable.

Leaps of mankind in this particular field:

1) first satellite - USSR;

2) first man in space - USSR;

3) first man-made object to impact Moon - USSR;

4) first man-made object to land Moon - USSR;


5) Best scale model imitation of the US space shuttle.

6) first failed Mars probe (and second, and third, and fourth, and fifth...)

It's possible to commemorate LANDING A MAN ON THE MOON, on its anniversary, without it necessarily having to be a political dick-waving contest you know.

But since you brought it up, it does make you wonder how the US so completely outleaped the USSR to the moon, given how far ahead the USSR was in space development. The USSR wasn't even second to putting a man on the moon, no one has done it since Apollo.

> Best scale model imitation of the US space shuttle.

Scale model? It was about the same size, though internally very different (it's thought that they used the shape to save on doing some of their own re-entry validation).


It's really kind of ridiculous how similar it looked versus how different it was; the big thing on the Buran stack is a rocket, not a tank, for instance, and the boosters are kerosene.

> But since you brought it up, it does make you wonder how the US so completely outleaped the USSR to the moon, given how far ahead the USSR was in space development.

Well, first, the USSR wasn't that far ahead, perhaps a few years. But its moon programme was inadequately funded (and not funded at all until 1963 or so), not terribly focussed (there were designs based on Proton/Zond for flybys, tested unmanned shortly before Apollo 10, based on the N1, a giant kerosene rocket, on the UR-700, an ultimately undeveloped giant Proton, and so on), and subject to political interference, both from the government, and between the design bureaus.

It also wasn't pursued as the ultimate goal in the same way the US one was; at the time the USSR was also working on the Almaz (later Salyut) space stations, an automated sample return system, a greater focus on interplanetary probes (albeit without much success except for the Venus stuff) and other bits and pieces.

If they'd been willing to take the risk, they could probably have had the first manned flyby; there were a number of Zond missions, using a modified Soyuz, unmanned, in the couple of years before Apollo 10. It would have been _extremely_ risky, though; most of the Zond missions were at least partial failures.

shrug History is written by the winners, and the USSR lost the Cold War. All of these will be swept away.

BTW, there are more USSR achievements:

5) First spacewalk

6) First woman in space

Not to forget:

0) first animals in space: US fruit flies.

Also the Russians made most of the advances on habitable space stations. Most important achievement for the long term exploration of space IMO. I think it's a shame that many of the achievements will be lost to history for political reasons but I guess it doesn't really matter who did what. The cold war in itself was probably a good thing in that regard.

In a little over 60 years we went from rickety wood planes that could barely fly a few meters to walking on the surface of the moon.

My grandfather lived through that era. he grew up before planes, mass cars and electrifcation. And died after the moon landing, PCs and TVs. Didnt make it to smartphones.

We mighty app developers are following in their legacy. God bless.

I hope you're kidding.

I'm waiting for the 'Let's build a Moonbase' Kickstarter.

Growing up in the early 70's (1970's, that is) I got a small book as birthday present: 'Let's go to the moon'. It was about a bunch of racoons that build a lunar rocket, and a sly fox named Reynard up to no good. Wonderfully illustrated with racoons drawing up plans, wearing goggles, and welding away. Does anyone else remember this masterpiece?

NASA is currently "live" streaming the mission:


>> NASA is currently "live" streaming the mission:

Like an old man telling a story about the good old days. Because, you know, it was the greatest thing NASA ever did and it was 45 years ago.

Good luck Mr Gorsky

I'd like to see some refutation of the claims in this film (and not by the guy - physicist as I recall - in the film who just hand-waves say "well we know they went there and it can't possibly have been a hoax"): https://www.youtube.com/watch?v=yo5w0pm24ic

Why bother? People who believe that one of the most documented events in human history, in which 100s of thousands of people took part, was a hoax are not going to be convinced by refutation of the supposed "evidence" they bring forth.

Because if you watch that film and believe Apollo went to the moon, the only conclusion is that light has different properties on the moon compared to Earth.

I'd like to know what could explain, for example, their shadows lengthening significantly when they move a small distance as shown in the NASA footage better than "the astronauts were close to a large artificial light source" as they claim in the film that physics implies.

I don't know the answer to that. But this is just another in a long line of theories about the shadows in the photos and videos from the lunar surface, all of which are based on ignorance of how photographs work and how three-dimensional space translates into two dimensional images. Every claim of the conspiracy theorists gets proven wrong and then they come up with something else. Sometimes, things they offer as proof that the landing was a fake are actually proof that they're real! They say that it was obviously a set because that hill is in the background of two photos that were supposedly taken miles apart. Well, that's because the "hill" is a mountain bigger than any mountain on Earth, and if you analyse the parallax effect on that mountain in the two images it is consistent with the distance between the two photos.

The point is that googling just about any claim from the conspiracy theorists will return results debunking those claims by experts in photography or other relevant fields, and if it doesn't, that's only because the claim is something new enough that the sisyphean debunkers, who undoubtedly have better things to do with their time given that they actually know what they're talking about, haven't gotten around to it yet.

You can point to some trivia or artifact of photography that you don't understand and cling to that as proof of the hoax, whereas I can point to rocks that came from the moon, or to the fact that ham radio operators were able to pick up the tv transmission from the moon by pointing their receivers at the moon, or the fact that some of the missions placed mirrors on the moon that various third parties have bounced light off of. My evidence beats your "evidence."

If you genuinely want an expert's take on these matters, this is a good place to go: http://www.badastronomy.com/bad/tv/foxapollo.html

Specifically w.r.t. photos: http://www.iangoddard.com/moon01.htm

There's also a book: http://www.amazon.com/Bad-Astronomy-Misconceptions-Revealed-...

That's a long video. I believe in hearing people out even when they sound preposterous, but I'm not going to look through a 2 hour video.

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