Some Funny Things Happened on the Way to the Moon (2002) | Hacker News Reader

Some Funny Things Happened on the Way to the Moon (2002)

fermatslibrary.com

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For anyone else looking for a flat PDF http://www.eng.buffalo.edu/~psingla/Teaching/CelestialMechan...

What in the heck is the reader on that page called? Couldn't zoom, fonts looked terrible, very slow...

https://github.com/coolwanglu/pdf2htmlEX

Site works great on my Nexus 5X. Works almost as well as a regular PDF opened in a native app.

It absolutely murders ligatures (fl, fi, etc)

Thank you. The site is pretty unusable on my iPhone.

Something that just struck me. There is absolutely no mention of Margaret Hamilton in this article. Didn't she lead the team that wrote the Apollo software?

Her name is the very first one in the original documentation: https://github.com/chrislgarry/Apollo-11

Sort of. Only right at the end: https://news.ycombinator.com/item?id=12993945

Well, maybe she didn't lead the team during the whole process, but she certainly wrote code for it. You'd think she'd be mentioned, especially in the part about the AGC alarms that went off during Apollo 11's landing sequence.

If I recall correctly, over the course of the program some 300-400 people wrote code for the AGC, so it's not surprising that not everybody gets mentioned. Don Eyles (who saved Apollo 14) has an MIT org chart from the time of Apollo 11 on his website: http://www.doneyles.com/LM/ORG/index.html That only includes people at MIT that worked on it -- there were also many at Raytheon, AC Electronics, and various other contractors (like Adams Associates) that we don't know the names of.

The code that kept Apollo 11 going was Hal Laning's, and he's mentioned a lot in the article.

> who saved Apollo 14

For reference, I presume you're referring to how the LM computer was monkey-patched to ignore an abort signal from a faulty switch? [1]

[1] https://en.wikipedia.org/wiki/Apollo_14#Lunar_descent

Yep, that's right -- Don was the guy who came up with that procedure.

I suspect that's the same Eyles with (i'm guessing) Peter Adler who wrote the ignition system.

I don't find apollo source particularly enlightening, but i love the title and comments - BURN BABY BURN [1]

Noli se tangere - don't touch me.

Honi soit qui mal y pense - May he be shamed who thinks badly of it.

[1] https://github.com/chrislgarry/Apollo-11/blob/master/Luminar...

Indeed! He has a fun anecdote on his website [1] about the throttle control routines, which he was responsible for. His account of it is worth reading, but long story short: The ICD for the descent engine specified that its throttle response time was 0.3 seconds, and so that's what the simulator hardware implemented. Don discovered, through testing, that he only needed to code in 0.2 seconds to get a clean throttle control, and so he opted to not give it any more compensation than needed.

At some point, though, the throttle response time for the descent engine was improved from 0.3 seconds to 0.075 seconds, but the ICD was not updated. So at least Apollo 10-13* all flew with 0.2 seconds of compensation. As it turns outs, the throttle was just barely stable with this much, and if Don had implemented the specified 0.3 second compensation it wouldn't have worked.

Apollo 15-17 (and likely Apollo 14) all had this issue corrected. You can see the difference in the constant THROTLAG comparing the Apollo 13 [2] and Apollo 15-17 [3] lunar module source.

* We haven't yet found a copy of the Apollo 9 or Apollo 14 flight software, so I can't definitively say that either had the error. We do have Apollo 5 source, but THROTLAG, the constant in question, does not have the same name there, and I'm not sure what the equivalent value is.

[1] http://www.doneyles.com/LM/Tales.html (towards the bottom)

[2] https://github.com/virtualagc/virtualagc/blob/master/Luminar...

[3] https://github.com/virtualagc/virtualagc/blob/master/Luminar...

>I still remember the  rst time I told my wife that I was in chargeof “Apollo Software.” She exh orted me: “ Please don’t tell any ofour friends!”I suppose real men do “Hardware” just as real men don’t eatquiche.It was an attitude that prevailed a long time in many organiza-tions. Salaries fo r computer programmers did not keep up with thesalaries of engineers.Engineers did engineering.The programming(or coding)was more menial work and should be left to others.

It's funny how much this attitude has changed so much over the years. Now engineering is seen as menial work and the programmers are the real men and rockstars.

It may have changed in the Silicon Valley/tech startup bubble but definitely not in the rest of the world. Engineers still receive far more prestige than IT workers (which is what programmers are largely seen as, technicians) and in most countries, it's as prestigious a career path as being a doctor, lawyer, or professor.

The vast majority of companies that work with physical things, like silicon designers/fabricators, auto makers, manufacturers of capital equipment like machining tools and lab equipment, energy companies, agricultural machine suppliers, hardware conglomerates like GE and Samsung, and on and on, still view (for the most part) software as the red headed stepchild, a necessary evil because their hardware has gotten so complex.

It may just be my own hang-ups, but in the company of unequivocal members of the "professional" class I definitely get the sense that as a software developer I sit somewhere above blue-collar, but barely, and that largely due to salary rather than the work I do.

I'd imagine it's a bit different for the (giving a very generous estimate) 1% of developers who do work that is all of: challenging, difficult, and important, on a regular basis, but that's not me, or the overwhelming majority of people making pretty damn good money writing software.

For the artsy-intelligentsia folks all the people who do technical stuff (no matter if HW,SW, civil engineering) are just "engineers", i.e. people who have never heard about Stendhal or Vermeer. On top of that my ex-mother-in-law, an accomplished theater actress, used to call us non-actors as "civilians", so there's also that.

I for myself don't care one bit how my work is seen by others(I'm a programmer) as long as it's reasonably well paid (meaning I can pay rent, food + some other stuff) and it's not that physically demanding.

FWIW, when we hang out with my wife's colleagues (she's a neurosurgeon), almost everyone assumes that my job is more demanding and interesting. When we hang out with my colleagues, its exactly the opposite. Grass is always greener.

Most of that prestige comes from the mandatory education required to enter the profession. Whereas there is no minimum qualification to become a software developer. (I know some employers have their own minimums but there is nothing for the field as a whole.)

Well, speaking of software… I assume LaTeX-to-HTML is the reason this formatting is so horrendously screwed up? It’s even mirrored in your copy-pasted text (“the  rst time”, “ She exh orted me:” “any ofour friends”, etc). I tried Safari and Chrome and got the same result, and had to read the PDF instead.

At least it made "fi" into a ligature. I don't know what we would do without that.

I apologize for the errors, I'm on iOS and it's difficult to check the output of copy & paste.

A treasure trove of great anecdotes.

Just one example:

A few weeks before the launch, the Navigator Command Module Pilot, Jim Lovell, spent a few hours practicing on the earth-horizon sextant simulator at MIT. He consistently identified the “horizon” about 20 miles above the real horizon. Great! Jim Lovell could be calibrated and his bias number loaded in the flight computer.

In the same vein as this article, I am always deeply moved watching Dr. William Widnall's lecture on Apollo's guidance, navigation, and control:

https://www.youtube.com/watch?v=4Vf6Y98ZjwQ

> I have at my fingertips several orders of magnitude more computing power than the Apollo Guidance Computer which was carried onboard the Apollo spacecraft. And this marvel of modern technology sits on my desk at home...

Yeah, but one has to admit, the Apollo Guidance Computer had way more gravitas any other computer since or before!

Today I learned APOLLO := America's Program for Orbital and Lunar Landing Operations. So the Greek god thing was a nice intersect?

Naming things that have nice properties like this are often designed. Very unlikely that it just happened that way.

Probably a backronym.

It has always bothered me that they named the moon missions after the god of the sun.

It has always bothered me that we insist on calling our space farers "astronauts" when they don't go anywhere near the Sun or stars, vs the entirely accurate "cosmonaut".

Well, the same is true of astronomy. One could spend their entire life looking through a telescope at only planets, and still be considered an astronomer.

Given the number and scope of misnomers in astronomy, astronaut seems downright sensical. Those dark patches on the moon? They're bone dry, but we call them seas. Those beautiful planetary nebulae? They're the tombs of dead stars; any planets there are coincidental. Those small, mountain sized rocks floating in space? We say call them starlike.

If it helps, I think of an astronaut as someone who sails among the stars, rather than to the stars. In that sense, it's just as accurate as cosmonaut. But, given that every living thing on Earth can rightfully be called an astronaut or cosmonaut, neither term is very precise. It is more precise to identify a person as human than to identify him as a cosmonaut, since cosmonaut can also refer to monkeys, rabbits, dogs, insects... :)

Well it's the political origin of the term that is bothersome. The Russians came up with the perfectly sensible and accurate term 'cosmonaut' and the USA refused to use it.

I'm really curious if it's usage was political. I did find this forum post[0], but it didn't really shed any light on the question. It does, however, suggest that the term was chosen in ignorance of it already existing in fiction for (at least) decades by the time the space race had started. So, if the forum post is to be believed (I couldn't find the cited first source), a defense suggesting it was already in the lexicon couldn't be supported since the selectors of the term themselves admit their ignorance of the term previously being used.

Cosmonaut, I believe, more literally translates to "spacenaut", which sounds terrible, because of the Russian word for space, which, like our cosmos, is derived from the word kosmos. The English term cosmonaut is not through the greek kosmos and nautis, but just an Anglicization of the Russian word.

[0] - http://www.collectspace.com/ubb/Forum34/HTML/000108.html

Whereas in British English, they're just "spacemen"!

Also the god of truth/order/reason, projectile weapons (bow & arrow), and colonies...

These are always backronyms.

Just like it was a coincidence how the Uniting and Strengthening America by Providing Appropriate Tools Required to Intercept and Obstruct Terrorism Act conveniently shortened to USA PATRIOT Act.

This is great, the article starts out discussing TeX and then proceeds to screw up every instance of `fi` and `fl` by replacing it with terrible ligatures.

This is not the original format. This PDF is formatted much better. http://www.eng.buffalo.edu/~psingla/Teaching/CelestialMechan...

Great article, but it should probably be marked 2002.

I love reading old stories about how the final frontier was (and is) being won.

It's generally understood that Fermat's Library deals with very old papers.

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