Digital Apollo, Human and Machine in Spaceflight

Post by **FlyingPenguin** » Tue Jan 10, 2012 5:53 pm

It was only available in hardcover when I bought it unfortunately, but now it's in soft cover and Kindle (and BTW, I will ship my hard cover copy to anyone who wants to read it now that I've finished it - just PM me).

Great read for anyone, like me, who was immersed in Apollo and wants to understand exactly what all those controls in the Lunar Lander did (for instance: why was there a horizon ball in the CM and LM if there's not horizon in space, and what drove it?). If you really want to understand how the Apollo computer system worked, how it was the first and basis for all future digital fly-by-wire systems (an actual Apollo computer was used as the auto-pilot for a testbed jet fighter in the 70s), and how it would have been impossible to fly (and especially land) on the moon without a digital computer onboard, then you'll find this fascinating.

The main point the author is trying to make is a discussion of man-computer interfacing, and how it relates today where nearly everything has a computer between you and the actual vehicle you're piloting. But you will learn a LOT about how Apollo flew and landed on the moon, including minute by minute analysis of transcripts of actual moon landings, and the facts behind the infamous computer error codes during the Apollo 11 landing.

It's written for laymen so it won't immerse you in deep math or computer programming.

http://www.amazon.com/Digital-Apollo-Hu ... 673&sr=8-1

normalicy · Post by **normalicy** » Tue Jan 10, 2012 6:18 pm

Oh, this sounds fun. If no-one else grabs it, I'll take your copy.

Post by **FlyingPenguin** » Tue Jan 10, 2012 8:29 pm

It's yours. You're the first one. PM me your mailing address.

Yeah, by the time the book is done you'll feel you could probably sit in the LM simulator and actually fly it. There's a million little things in there that are explained that I always wondered about.

For instance:

What exactly are those degree scales etched into the LM windows? Now I know. They're for eyeballing the landing site under computer control. You run a program on the computer and it gives you a number and you sight out that window and look through the same number on the grid and that's your landing spot. The commander could then re-designate the landing site by moving it a few degrees in any of the four compass points by clicking his stick.

What's is the display that looks like a tiny CRT with two cross hairs? It's a vertical & horizontal speed indicator in feet per second (it's not a CRT, it's just a pair of needles with a back light).

No one ever flew the LM under complete manual control - it would likely not have been possible. The computer actually flew it in a variety of modes including the so-called "manual" mode that all the LM commanders used for landings. In that mode the computer maintains a rate of descent and holds the LM level. The commander can then use the stick to tell the computer to increase the speed in any direction by a foot per second per click of the stick.

Lot's of fascinating stuff in there. Like I knew that the computer used core memory, but I just assumed that the programs were held in volatile memory. Not so, and in hindsight that would have been unreliable in case of a reboot - either manual or automatic. In case of a fault or crash the computer was designed to save all variables and reboot itself. It happened several times during the Apollo 11 landing, but the autopilot never glitched despite the multiple reboots.

Instead all programs were stored in permanent memory. Since there were no ROMS back then, this was also core memory but it was custom woven with all the programs. Because it took a month or more to weave (literally weave - it was done by professional seamstresses) the core memory holding the programs, all the programming for a mission HAD TO be completed 3 months before launch to allow enough time, and each mission had it's own custom programs so no two Apollos flew with the same firmware.

Just amazingly in-depth info. I'll probably buy the book on Kindle just to reference and re-read it later.

normalicy · Post by **normalicy** » Tue Jan 10, 2012 9:39 pm

Jeez, I was already hooked. Now I'm gonna have to put it on the top of my "to read" pile.

Thanks! PM sent.

normalicy · Post by **normalicy** » Thu Dec 20, 2012 7:21 am

Well, it didn't quite make it to the top of my pile, but I haven't had as much time to read as usual this year.

Anyhow, I really enjoyed this book. It did an excellent job of actually helping you understand what they did on the mission. I agree, I almost feel like I could fly the lander by this point. It's funny that my whole life I had assumed that there was much more "manual" control of the rocket/lander than there actually was. Honestly, I kind of wonder why they never did just do a fully automatic mission for the heck of it. It seems that a majority of the issues on the missions were human error. What's funny is this is almost as impressive as the Mars rover landing, and yet they did it 40 years earlier.

normalicy · Post by **normalicy** » Sun Dec 23, 2012 10:52 pm

Oh and to continue the tradition, if anyone is interested in reading it, I'll send it your way.

Post by **FlyingPenguin** » Mon Dec 24, 2012 9:05 am

Having read that book, I can really appreciate how we BARELY had the computer technology to land on the moon. Today the data processing required would be nothing - you could probably fly to the moon using an iPad.

normalicy · Post by **normalicy** » Mon Dec 24, 2012 11:02 pm

I love that they used such outside-the-box methods to make the computer.

GuardianAsher · Post by **GuardianAsher** » Tue Dec 25, 2012 6:16 pm

I was reading an article about the Apollo 13 mission and how it went so wrong, but so right due to the dedication of countless individuals to get our men home. It was fascinating... I have it bookmarked on the work computer, next time I'm there, I'll post it up.

And if no one else claims it, I'd love to read that book

normalicy · Post by **normalicy** » Tue Dec 25, 2012 8:31 pm

PM me your info & I'll send it your way when I'm back in town.

And I'd love to check out the article.

GuardianAsher · Post by **GuardianAsher** » Wed Dec 26, 2012 9:31 pm

Here are the articles I was talking about. The first is an Ars Technica article that shows a behind the scenes look at the restored Mission Control Center.

http://arstechnica.com/science/2012/10/ ... ontroller/

At the end of the article, it gives a link to the one I was originally referring to. A big in-depth look at exactly what caused the whole Apollo 13 mission to go awry, as well as what every one did to make sure those astronauts got back to earth.

http://spectrum.ieee.org/aerospace/spac ... -solution/

It's a long read, split into 3 parts of about 6 pages each, but fascinating. Definitely worth the time.

Normalicy, check your PM later, I'll send you my particulars.

normalicy · Post by **normalicy** » Tue Jan 01, 2013 2:39 am

Just read both articles one fell swoop. Good reading there. Really puts you in the command center.

Post by **FlyingPenguin** » Tue Jan 01, 2013 12:32 pm

Awesome read!

Did you guys read the suggested article on the Ars Technica page:

Apollo Flight Controller 101: Every console explained
Your handy reference to each station in the Apollo Mission Control room.
http://arstechnica.com/science/2012/10/ ... explained/

normalicy · Post by **normalicy** » Tue Jan 01, 2013 1:18 pm

I almost clicked one it, but was too tired to read any more.

Post by **FlyingPenguin** » Tue Jan 01, 2013 1:31 pm

If anyone is interested, I have these three articles in PDF format. I wanted to keep these articles in my e-book collection for future re-reading.

I just spent an hour carefully pasting these articles together in Word - replacing the low res images with the higher res ones where appropriate - and then converting them into PDF format. They look great on my Nexus 7 tablet in either ES File Explorer's PDF viewer, or the Kindle reader app.

If anyone wants them, PM me.