Are there any videos, photographs or diagrams of the boulder field that Neil Armstrong rejected as Tranquility Base?
I’m not about to deny the Moon Landings; quite the contrary, I’m fascinated as to just how difficult it was.
Pages 41-47
Okay, I would have shat myself.
I think the suits were pretty absorbent.
The Apollo 10 mission just shoved all the fake Moon rocks out at once and just made a mess of the Apollo 11 landing site … so Michael Collins was much more careful scattering the fake rocks around the Apollo 12 landing site … live and learn …
Cool. The “landing point designator” that Neil used to determine that the big crater (“West Crater”) was in the way was just amarking on his little triangular window, NOT the detailed radar-obtained images shown in that document. (I’m guessing those were produced later, using the radar data).
I am just barely old enough to remember the first moon landing.
When I later watched video from the event, and I was actually old enough to understand it better, it seemed to me that it went pretty smoothly. It was only much later that I found out how bad things actually went. If you listen to the moon landing, you can hear them counting down what seems to be seconds before landing. It’s not. They are counting down the remaining fuel time. The fact that it eerily coincides with the actual landing time shows how close they came to running out of fuel.
You also hear the astronauts asking about a code 1201 and 1202 from the guidance computer. Seems innocent enough until you realize that those codes basically means that the computer ran out of processing time and crashed. Fortunately, instead of the blue screen of death that you get from Windows, the guidance computer’s crash handler basically deleted low-priority tasks until it could complete all of its assigned tasks properly, thereby automatically recovering from the overflow.
I think a lot of the engineers wore brown pants that day as potential camouflage, just in case.
Saying the computer “crashed” is a bit misleading isn’t it? Those codes meant the computer couldn’t process everything being asked of it, but it was designed to prioritize its workload and all the “important” computations were handled.
As I understand it, the computer actually rebooted in order to sort itself out, and the displays froze while it was doing so.
In a modern desktop/laptop computer, if it reboots, it starts over and clears out its memory. The crash handler in the Apollo kept programs in memory and restarted them based on priority (a spiffy whiz-bang feature if you ask me) so the reboot wasn’t quite so catastrophic.
But still, I’d call that a crash. It didn’t just dump the lowest tasks and keep going, although that’s effectively what it ended up with after rebooting.
When first looking through that pdf I couldn’t find the pictures of the landing site mentioned, but staying calm and with steely nerves and grim determination I realised I was looking at the page layout indicated on my browser and not the physical marks on the pdf itself.
Pictures successfully located, Armstrong himself would be proud.
In this custom audio edit I did of the Apollo 11 lunar landing, you can hear the flight controllers and “back room” computer specialists working on the problem throughout the landing. A key person was 24-yr-old Jack Garman, credited with saving the mission.
4MB .mp3: Apollo_11_Landing.mp3 - Google Drive
Rough transcript inc’l background: Apollo 11 lunar landing audio - Flight and Guidance loops
Garman receiving awards for his quick thinking: https://joema.smugmug.com/Aerospace/Jack-Garman-and-Apollo-11/
Awesome, joema (again).
NASA knew Neil was the guy for moments like this, based on the huge brass testicles he demonstrated a couple years previously, when his Gemini craft starting spinning out of control and he got it back to rights.
Joema, that audio is absolutely gripping. Thank you.
Joema, your annotated transcript is fantastic. One thing, though – I couldn’t open the jpeg of Garman’s notes. (Maybe it’s a no-go from my end).
Computers can do that? Did you hear that, Microsoft? 
Works now. 
Now there’s a phrase you don’t often hear!
NO. Its completely misleading to call it crash because “Crash” implies
- probably unknown cause,
- probably corrupted or even code or important cpu/OS features, for example, stack, stack pointer,interrupt table… in corrupted state
- some program has stopped running (not merely blocked from running)
Further the computer program (OS AND tasks) was as DESIGNED and the OS and TASKS ran AS DESIGNED. its not possible call running as designed a crash !
They designed it to report faults. With so limited ROM RAM and CPU power, they did not have sophisticated fault reporting, and in fact the design was done this way knowing that this was a one shot fault reporter !. Instead of having a specified “test it out phase”, eg the first minute, they made it so that that at first the navigation mode of the computer would be interrupted by any detectable fault … Basically, the “test it out” phase was extended until a fault was detected, because detecting faults caused no issue, and it was better to let the crew know there is a fault as soon as possible. But then , once a fault was detected, that was the end of "test it out " phase. They would either abort, or put it into “assume no fault and navigate” phase or both abort and change it to ignore faults.
So the design was that if a fault was detected, it was ok to prevent navigation working…the fault was more important … Simply, It was not a crash. It was designed behaviour.
Also, by design, because it didnt matter how it was done, was that that to turn off the fault reporting so that the navigation task could run, was press two buttons, one to change the mode, and the other to restart the computer’s bootstrap, so that the bootstrap code would start the program in “don’t let faults interfere with navigation” mode. Basically that just means they had a “ignore faults” button. Same thing… it was designed knowing the first fault would interfere with the navigation task, and it was designed that they pressed a button, and it would then run navigation task with no further interference from faults. No departure from designed behaviour, so no crash.
The story of the error alerts is remarkably interesting, although a few things wrong in earlier posts.
The errors were indeed errors where the real time executive found that it had unexpectedly been unable to finish all the tasks. Why it was unable to finish these tasks is a brilliant lesson on configuration and change management.
The basic landing profile that they used had been designed with an abort capability - where they fired the explosive bolts on the lander stage and lit the ascent engine - whilst in flight - and returned to orbit. It was considered a good idea to leave the rendezvous radar running during landing so that it could get a lock on the CSM as soon as possible. Sometime before the real landing, a decision was made not to do this, and to turn the radar off. So the landing configuration included turning the mode switch in the rendezvous radar to Off. But nobody asked what this meant for the computer software. Surely, the radar was off, so that was it - right? No. During the real landing the radar input to the computer was random junk - and the rendezvous control program tried to made sense of it - was unable to converge on an abort profile - and ran past its allocated time slice as it did so. So the run time executive found itself with a violation of the real time guarantees it was supposed to preserve. So the errors went off.
A lot of this computer software was bleeding edge - the actual design of the real time executive was done for Apollo.
The call made was that if the computer wasn’t streaming the errors continuously, things were probably going OK enough not to the a danger. But continuous s going to mean an abort. As well as Jack Garman in the back room, Steve Bales was guido in the trench, and responsible for making the final call of go/no-go. He received the Medal of Freedom along with the three Apollo astronauts for this.
Francis Vaughan, can you suggest a fuller account of this in book or documentary film?