What Does "Set SCE To AUX" Mean Anyway - Apollo 12's Lightning Strike Explained
It's an often told story about Apollo 12 getting struck by lightning, crippling the command module in flight and John Aaron in mission control figuring out the exact switch to flip to fix the stricken vessel and save the day. It's an understandably popular story, but the details are never quite right, so this is my attempt to explain what exactly went wrong and what problems SCE-to-AUX fixed.
Here's a few of the references I used to understand what happened:
Apollo 12 Flight Journal
history.nasa.gov/afj/ap12fj/0...
Apollo 12 Mission Control
history.nasa.gov/alsj/a12/A12...
Apollo 12 Saturn V Performance
history.nasa.gov/afj/ap12fj/p...
John Aaron Interview for NASA Oral history Project
historycollection.jsc.nasa.go...
Apollo 12 Technical Debrief
www.hq.nasa.gov/alsj/a12/a12-...
Apollo Command Module User Manual - Telecoms Subsystem
apollo.josefsipek.net/ApolloPr...
Analysis of Apollo 12 Lightning Incident
spaceflight.nasa.gov/outreach...
Scott Schneeweis Collection of Apollo Hardware:
www.spaceaholic.com/index.php/...
"where the computer thought it needed to realign the inertial guidance platform really quickly" *Kerbals screaming.avi*
*when I place the probe core upside down*
*pause* Restart from launch pad
Actually its only two Kerbals screaming. Jeb's shit-eating grin only goes away when things start exploding.
Tanall naw, he goes to his grave with that laughter. He’s dead inside, happy for the release of rapid “unplanned” disassembly.
Lol funny
The more I learn about Apollo sub systems, especially the digital/non-chemical reaction stuff, the more impressed I am by 1960s NASA.
I agree. I wonder if today's all digital systems would have been as robust.
It was like just one step more advanced than Steampunk rocket flight, LOL.
It's impressive that even a lightning strike ran into the safety systems and not the critical hardware.
@@PSquared-oo7vq And had such robust programs. Check out "reasonableness test" at 9:57. Managed to cram that into those very few bytes they had, on top of more obvious needs.
@@PSquared-oo7vq quite probably not. If anything modern electronics running at far lower voltages and being nearly exclusively digital rather than analog would simply go poof and be dead. However it would be reasonable to assume that technology to electrically isolate the more sensitive components would be used extensively in the effort to preserve redundancy.
To get to the AUX position, they had to go through the OFF position, so they literally did switch it off and on again.
This is a new level of brilliance
Not if the switch was make before break.
@@NeverTalkToCops1 But if it is an actual three-way switch, it MUST break before make, especially if the centre position is in fact the OFF one (which Scott mentioned), otherwise the centre position would bridge both extremes which is not only weird but arguably also everything BUT off.
@@NeverTalkToCops1 I would assume it would be best to have a "break before make" on a powered system like that. Everything ran directly from high current batteries. The last thing you want to do is to switch from a bad battery to a good one with a temporary short.
Step 1 "Hard reset." Step 2 "Take it offline and turn on the backup. I'll come have a look at it."
"Laughed all the way to orbit" is one of my favourite phrases ever.
I do this every time i smoke pot😜😜
@@pyroglyphics hell yeah, weed
and the russians is helping you bless you
soundns like some happy children story
"Yo pass the aux cord" "You better not crash the rocket"
*rocket man starts playing* or alternatively... *ground control to major tom starts playing*
@@billdewahl7007 Space oddity
@@IrismonoYT Idk how that escaped me. Damnit lol.
*puts fly me to the moon*
Can't, apple decided rockets don't need those anymore.
Mission control: have you tried turning it off and on again?
That's 50% of all engineering problem solving. And Apollo (12) was no exception. The hard part is to know WHAT to restart.
“Repair procedure #1” (AKA “percussive maintenance”)
@@5Andysalive And WHEN it's not a bad idea.
@@donjones4719 Also in most cases no lifes are at stake, just a bit of productivity.
The other one is if you can't fix it bridge it
The test lead at the aircraft company I worked at had a sign over his desk: "You can't trust what you can't test." True in aeronautics and in life!
In the intelligence community, a somewhat similar motto is "Trust. But verify." Originally attributed to the Soviets, but anglicized and used by President Reagan during nuclear arms talks. Later used by a number of intelligence agencies.
@@WoodworkerDon >>> *_"In GOD we trust._** All others we monitor."* 😊😊😊
I once told a fellow programmer that "untested code is broken code".
@@CaptainJellyBS The one I live by is "Believe half of what you see, none of what you hear." which is pretty much a version of "trust but verify".
13:30 To be fair, if the parachutes did fail, they were going to die whether they'd been to the moon or not. May as well go to the moon anyway.
Plunge to your death now or in a week -- your choice. "Or the horse may learn to sing." If it doesn't work now, maybe it'll magically repair itself, given enough time. Procrastinate now!
@@icollectstories5702 You miss the point it is about a chance, not a fact.
@@5Andysalive It's unknown and unknowable until you flip the switch. What do you gain by assuming it does work?
I think you both missed my point. It's the same as Apollo 13's heat shield; it may have been damaged in the explosion, or it may not. The only way to find out is to try it, and there's nothing we can do about it anyway, so we may as well just get on with things, get them to the point where they have to rely on it and then hope for the best, and, in both cases, the astronauts got lucky.
to be fair, it's an explosive. if the electronics are working (and they had backups, just give it full battery voltage), it's not likely to have been zapped with 15 million volts and failed without going off. if it failed, the parachute should be hanging out the side.
Apollo 12: No time for heart attacks
I know, right? - Eh? Nah, there was no time for heart attacks up here. But anyway, back to my story... - And all this at orbital velocity. Funny.
Great mission statement lol
Dave Bowman: “HAL, set SCE to AUX” HAL: “ I’m sorry Dave, but I’m afraid I can’t do that”
*Crew almost dies* Crew: "LOL guys we almost died!" Ground: "Holy shit lmao yeah we thought you were gonna die!" Crew: Ground: Crew: Ground: Everyone: *Drinks heavily*
Yeah pretty much
They were mostly pretty familiar with almost dying. XD The first group of astronauts were USAF combat pilots, that alone was serious business, as the technology was far from as save at it is today. Many of them had combat missions on their records. Some of these were pretty close calls. I think it was Buzz Aldrin, who got part of his wing shot off while doing a bomb run on the deck (as in low-level) over an Korean rail yard. His plane went out of control and he managed to get it back under control just a few feet above the ground. Nursed the plane back to his carrier, but had to eject because it was unfit to land. Check out their biographies on Wikipedia and you find some serious bad-ass aviator stories. :D
to be fair, space travel is still pretty unsafe
I think you mean *smokes heavily*.
....GAY!
Then : Turn SCE to AUX Today: Please don't turn off your rocket while we update your computer...
(text on screen) "the guidance computer is rebooting 'now' to install updates" (crew looks out the window in horror at re-entry plasma enveloping the craft). You want to reboot NOW!? (Kerbals screaming animation) If it's not broken, it doesn't have enough features yet. lol.
BLUE SCREEN......
@@Zarcondeegrissom When it is reentering, you dont need comp, right?
@@alexwang982 right, if it is ballistic, but if not, and has guidance fins, bye bye
@@alexwang982 or if engines are lit, then i dont know what would happen
"We're having cardiac arrests, man." "I ain't got time to have a cardiac arrest."
"Set SCE to AUX" was the name of my high school garage band.
Switch it to that one, dude. I think that one goes to 11. Uh, oh... try some chest compressions.
You are hereby now a fully accredited Space Nerd!
That's awesome. But I'm.surprised you weren't the Steely Eyed Missile Men lol
Well now, no bucks, no Buck Rogers.
I think it was mentioned in one of the "The Martian" videos in reference to "rich Purnell is a steely eyed missile man"
I love this story, and in fact when I went to Huntsville a few years ago I was ecstatic to find the SCE switch in the mock up trainer that they have.
I have proof that you are the oldest comment on this video. It's in the "sort from newest" function
I found that very same switch in that very same mockup. :-) :-)
So ... was it on Aux?
@@jaroslavstava3704 I'm going to the Huntsville Space And Rocket Center tomorrow, I'll check.
@@jaroslavstava3704 probably set to Aux with a note "Alan Bean was here here!"
Its never ceases to amaze me all the redundancies and procedures they had for dealing with such a variation of issues , truly impressive
I believe it was Chaikin who wrote that NASA was afraid to lose an astronaut because a $5 part failed, thus the redundancy.
Very good point, I’m impressed by the redundancy in modern air planes, and I doubt they have what, the rocket has, way back then. So crazy to me!
And the crazy thing is even with all that this is still a story of them flying by the seat of their pants and needing to improvise. No way your planning and contingencies ever cover everything, but they sure do help. Enough things kept working that they had minutes+ to troubleshoot.
Lightning striking the Saturn V is one of the coolest images in history.
My brother had a Saturn Vue. It was crap.
@@135tvyeah2 Hope it wasn't the 4 cylinder, those were hopeless.
Except that it doesn't have any image of the Saturn actually being hit by the lightning, only the launch tower at the pad.
2nd coolest image: Any normal launch photo of the Saturn V.
But there is video of the strike. It was captured with one of the tracking video cameras on the ground.
That phrase saved Apollo 12, but there’s a darker one needed once for the STS-51-F mission, after one of the SSMEs shutdown: “Limits to inhibit.” The commander moved a switch to tell the Orbiter “Don’t shutdown any other engines no matter what!” STS-51-F was the only abort-to-orbit mission. A second shutdown would’ve likely been a loss-of-vehicle and LOC event.
Not necessarily, there were certain abort scenarios they could've done. Probably would've been hair raising but they could've still saved it.
I was camping in Maine when STS-51-F passed overhead not long after sunset. It was noticeably bigger and brighter and moving faster than any other time I'd seen a shuttle pass overhead before or since. Obviously losing the engine during launch had put it into a much lower orbit than intended.
@@Gaozetagar Not really. Contingency aborts were not a thing at the time of STS-51-F. If they didn't have energy for TAL they'd be dead, since they didn't have any way of safely abandoning the vehicle in flight.
@@delayed_control actually they did. They just never tested or implemented it. The first test flight originally was supposed to be a test of the return to base abort but saner minds prevailed.
AFAIK they could abort any time after booster separation, whereby they would land either at the launch site or at one of three sites across the Atlantic. The second engine failure would be critical only in the first minute or two after booster separation. Beyond that a single engine would be sufficient to land at one of the sites across the Atlantic.
Coming from a ramshackle IT background, I love these deep dives into the troubleshooting and impromptu engineering during spaceflight anomalies. You always get us the best details! Thanks, Scott.
Yeah I've had my share of overnight stays in the server room "setting SCE to AUX" lol
Because of how that switch is set up they definitely got a free reboot out of "set SCE to AUX"
Gotta get me one of those SCE to AUX light switch covers!
It is really amazing to listen to the entire audio of the launch with all the systems audio feeds. There is so much communicating going on. Mission control, being all cool and collected, instructing the astronaut's procedures to deal with all the alarms going off. Then you had the systems guys trying to figure out the telemetry. They are all pretty much talking at once, but they got it all sorted out.
:00 Lightning strikes Apollo 12. :45 Flight Director asks EECOM, "How's it looking, EECOM?" [No Response] "EECOM, What do you see?" :49 EECOM (Aaron) says, "Flight, try SCE to Aux" :59 CAPCOM radios crew, "Apollo 12, Houston, try SCE to Auxillary, over." 1:09 EECOM, "We got it back, Flight. It looks good."
Hey Scott, I love your videos. I was fortunate enough to sit at his EECOM console in old mission control some years ago on an individual tour. My daughter took a photo and John was kind enough to sign it, including "set SCE to Aux". Pretty amazing. Al Bean sure also saved that day! I also live near Udvar-Hazy and when family or friends visit I give tours, maybe 14 times now and I always stop at the instrumentation ring and tell this story. Pretty amazing fast thinking. I wish I could have met Pete as a fellow aviator and motorcyclist, I think we would have got along great. He sure had a wonderful sense of humor. Craig
Be sure pause and read the text pages. I’m allows impressed with the depth of knowledge that the crews had of the systems.
I vote for more stories in this format! It was really amazing to learn all these details, and very well put! Cheers.
They are everywhere, he found this story too, they are all well documented! the non metric calculation!
I had heard it was struck but had no idea of this gripping story. What blows my mind is the sheer amount of failsafes and procedures which, combined with a LOT of experience and instinct, are able to overcome seemingly impossible challenges.
That's why they take MONTHS of training to memorize all this!
That anecdote about the parachutes is what I found most chilling in this entire video!
It's amazing they didn't call an abort. Big stainless steel balls.
Clanking all the way to the moon!!!
Deana Rupe and all the way back home!
When you’re so committed that going forward is the safest option.
@@wallymcguire2033 yeah when the candle is lit and working :P
So you're saying they got it wrong and John Aaron was a steely BALLED missile man?
I remember this scene in From Earth to the Moon episode 7 where Dave Foley plays Alan Bean. Literally flight control, the other 2 astronauts have no immediate recollection on what SCE is... Fortunately Alan Bean remember it. As for the all weather joke, this is the first Apollo flight by all Navy crew.
BigFire I've been watching through From Earth to The Moon for the first time and watched that episode last night. Ironic to see this episode show up today.
Best episode for me it was.
GO NAVY!!!
I just watched that one a couple of days ago. Kinda of cool how this popped up for me today.
The best EP for me was the LEM development one. Those poor guys lost years off their life building those things.
Wow Scott, I just posted a talk by one of the IBM who worked the Saturn V Inertia Unit and mentioned the Apollo 12 lightning strike! You did a superb job of explaining all of this - as you always do!
BTW - when I met John Aaron the first thing he asked me (rather loudly (intimidation test?)) was why was I (a guy from the Marshall Space Flight Center (a rather young engineer I was then)) crashing his meeting (a Space Station Freedom robotics systems meeting). I told him I was representing the Element Integration Office (a MSFC division of Level II) and he just said, "OK" with a grin. I was happily accepted then.
Scott is a really good speaker, I can happily just watch him talk about subjects. It all sounds so natural even the most in depth parts
@@satyris410 He definitely produces great vidoes and is fun and informative to listen too.
I have heard stories about John Aaron for years, With each new one, I find him even more amazing. He had a character in the Apollo 13 movie.
“You can’t run a vacuum cleaner on 12 amps John!”
I love telling this story so much I call my home wifi network "SCE to Aux" so people will ask me what it means.
Ha. LOLOL. Hmmm . . . gives me an idea. I think I'll change mine to "Go_for_TLI".
John Aaron is my hero. I've seen many interviews he's done. He is one smart and humble man.
Backups to backups (via multiplexing) are so important. And that includes the human element. Astronauts and ground controllers being able to troubleshoot issues on the fly, and countermand crazy data inputs makes the "Man In The Loop" concept so good.
Wonder if my dad’s company, Control Switch Corp., made that one. They made a lot of the switches in the CM and LM.
You might have noticed it’s not a question.
I really want to go to sleep but this guy really has so many awesome videos and I can’t stop watching them
As a teenager in the early 90s I spent 14 hours sitting next to John Aaron (EECOM) on a flight from Sydney to LA. He introduced himself "Hi I'm John Aaron and I taught Neil Armstrong to land on the moon." We pretty much spent the whole flight discussing Apollo. 🙂🇦🇺
Love the "steely eyed missle man" reference!
After going through all that, Alan Bean went and broke the video camera, on the moon.
...and was knocked silly by one on splashdown. Guess that's why he became a painter.
@Too Sense Wirth and of the 3 special ordered black and gold 1969 Chevrolet Corvettes (nicknamed the Astrovettes) that the Apollo 12 crew had, its only Alan Bean's that has survived destruction.
I love these historical videos. All the sound recordings and photos of the equipment you're talking about really add to the story.
A very concise, (non-ambiguous) dissertation on what happened in the first hours of Apollo 12. Great job, Scott!
The engineering of the Apollo missions is nothing less than absolute genious.
That last bit about going around the moon anyway makes perfect sense to me.. Not only from an adventurers point of view but also a military one.. get the mission done.. I mean if I had to die anyway.. go around the moon.. anyway.. thanks for the stories Scott.. I remember that launch.. But I didn't know the whole story behind the strikes.. I managed to watch every launch from Allen's to the end of Apollo .. Even the moon landing and this one.. (I was in the corps at the time) You always have to good poop on the behind the scene action and the after action reports.. Thanks for your share as always... Carry on and be safe..
Absolutely. No other decision makes any sense at all - bringing them back early wouldn't have saved them had the damage been real and would have wasted the mission were it false.
I watched the series 'From The Earth To The Moon', and that incident really stuck in my mind. A HUGE hat tip to you, Scott, for digging out the transcripts, technical data and schematics and editing in CM & Mission Control audio and presenting this is such an AWESOME episode!!! This is clearly one of the ⭐️⭐️⭐️⭐️⭐️ BEST Space Exploration videos out there! You ROCK, my Friend!!! In my book, Scott Manley IS the Steely-Eyed Missile Man of KZhead!!! 😀 👍
I don't usually comment on your videos, but lately I've been watching them all. Fantastic research and detailed information made me quite a fan. One of these days, a video on the "fly safe" reference. Thanks again and keep'em coming. Great job and fly safe(ly).
Awesome video Scott! I love hearing the stories from the Mercury/Gemini/Apollo/Shuttle issues. It really shows the ingenuity of our men and women in the space program.
Apollo 12 will always be my favorite Apollo. They were apparently so concerned that Pete Conrad would drop an f-bomb during lunar broadcasts that they brought in a psychiatrist to try to hypnotize away his swearing problem :)
Scott I am a long term fan of your videos! I did not have clue about this situation during Apollo mission. Amazing, very well told story. Thanks for bringing space tech a little closer to us ;-) All the best!
I'd heard of this, but never heard an in-depth explanation of what all it encompassed. Thanks again!
Thanks Scott - one of my favourite Apollo stories.
Arguably the finest moment of quick thinking in the whole history of spaceflight.
Quite possibly, yes. There are a few other contenders: Neil Armstrong's last-second eject from the LLRV Neil again, stopping the Gemini 8 tumble Jack Garman declaring Go on the 1202's on Apollo 11 Don Eyles Abort Switch override hack on Apollo 14 Any number of actions taken during Apollo 13, arguably the greatest rescue in history.
@@1944GPW Marvelous list.
@@1944GPW 'Neil again, stopping the Gemini 8 tumble' I read in a book (Andrew Chaikin?) where Armstrong described it as a "non-trivial situation", I loved the description. Buzz Aldrin bridging a broken breaker switch for the ascent engine with a metal-barreled pen is another one.
Don't want to fill up the comment section with just thanks you, but really, thanks so much for this. I knew of this story, and it's one of my favourites. The details of the complexity of the engineering behind it really fills out the story. To think that John Aaron was just 26 years old when this took place! What an engineer to troubleshoot this anamoly without ever knowing it would be of any use. That is the true soul of engineering. He made sure that he understood his subsystem throroughly. I know he also played a part in Apollo 13, developing some procedures to bring the craft back home. Genuine legend!
Great reporting. You don't get carried away in the lore but you do report it for it's historic value and you report loads of information. For space history you're the best.
As a Computer Science student, I would say that the sign of garbled data is in itself a form of data. Glad that he saved the mission!
Garbled data is just data from a sensor that isn't supposed to be a sensor.
This is a great video Scott. Thank you for creating a video about the man that Gene Kranz, in his book "Failure is not an Option", wrote, that "To this day John remains the most respected engineer ever to work in mission control". One thing I disagree with, however, is that the astronauts could have diagnosed and fixed the telemetry issue themselves, with their lives at stake. The decision to abort rested on one man, flight director Gerry Griffin and he had less than 2 minutes to make that decision. Talk about pressure. Keep in mind that the job of all the controllers was to monitor all the hundreds of systems that they dealt with. They weren't control panel experts and they were essentially impotent in this situation. Aside from John, none of them knew what to do, especially with so much on the line. Not only did John recognize what the garbled telemetry meant, but he was also familiar enough with the control panel, that he didn't have to resort to trial and error. The SCE switch was not even meant to restore telemetry. It was John's natural curiosity to trace how it could be used this way a year earlier with nothing on the line. When the telemetry was restored virtually everyone connected with NASA wondered, what the hell just happened? What happened was that John bailed NASA out singlehandedly and he became a legend on the spot. Google defines steely-eyed missile man as " An astronaut or engineer who quickly devises an ingenious solution to a tough problem while under extreme pressure". 50 years later I am still awed by this story and John Aaron is my all-time hero.
As important as John's heroics was to NASA, consider what would have happened if this situation arose during Apollo 11 and whether they might have to abort man's first moon landing. Not only would it be a huge black eye to NASA, but it would also mean countless questions about whether they rushed the Apollo program to meet President Kennedy's deadline. So as we know, Apollo 11 changed the course of American history. There wasn't much less riding on Apollo 12. If it had been aborted it would be a major embarrassment to the USA around the world.
From the Earth to the Moon touched on this when telling the story of Apollo 12. this is why I noticed this in my feed, I remember that line fairly well. thank you for expanding on the history of that.
Your videos always contain fantastic graphics. Thanks for all of your research and hard work.
Finally, I found the perfect SCE to AUX video. Thank you. 😍
That guy that said that will never be forgotten in the space industry. Prevented a mission abort because of a cool headed response.
Pete Conrad? yes, absolutely. If you listen to the onboard audio they were indeed on their way to figure out the problem by tracing it to the voltage dip. Pete Conrad certainly wasn't prepared to just abort the mission. Which would have been well within his rights btw. So as Scott mentiones, the outcome of this situation without the sce to aux call is definitely not clear. Pete Conrad kept cool, made quick decisions and saved the mission as much as Aaron did. It was a bit like Gemini 6 where Wally Schirra made the decision NOt to aboard, but to wait it out. Had the rocket moved even inches before the engine shut down, he would HAVE to pull the escape. No discussion. The computer said it had moved. The clock said it had moved. Wallys butt said it hadn't moved. So he waited. Had he aborted they wouldn't have launched days later again to a successful mission. That's what these people did.
Same for the BOOSTER officer that made the call "Engine limits to inhibit" during the launch of Challenger STS-51F, Jenny M. Howard
Yup, no one will forget ol' wossisname.
@@lorenzopappatico that was a sad era when managers took the safety for granted. This was different, safety was not compromised.
@@5Andysalive John Aaron was the one.
Awesome job by the entire Apollo 12 team - amazing how low tech their high tech seems - and very interesting video (as usual) Scott.
and 50 years later we are still impressed by knowledge, engineering and technology of all those involved in Apollo program. Just unreal.
Wow amazing details thank you Scott ! It's so cool how this guy thought about what to do by observing a previous failure of the Not A team. It shows that failure is a great what to learn how to do stuff. Gotta mention SpaceX. That book Liftoff was such a fun read.
"Stand by, 12, while we call Dell Technical Support."
"your call is very important to us ..."
This problem is velly velly bad my friend!
"We have message your computer has virus … "
The Dell of today would try and sell them a warranty package first.
"Have you installed any third party software on your Apollo Guidance Computer, such as Microsoft Office? If so, that is very likely the problem."
Hey Scott... I love these type of reviews. Being an operational engineer myself of sorts, it's awesome review and analysis. Thank you brother!
And these kind of stories is why I follow this channel. Thank you, Scott.
Love the phrase "reasonableness test" at 9:57. The computers had that back then, yet didn't for the Mars probe that crashed? One you did a vid on, that relied on the out-of-norm-expected input of one sensor even though different sensors for altitude, speed, etc, were in agreement, differing greatly from it? Gotta give it up for the elegant programming in those "simple" flight computers.
Not sure the mars probe would have been saved by a reasonableness test. It's like asking faulty programming to correct itself. My understanding is that It's more of a redundancy to correct for faulty readings or misbehaving computer.
Don Jones sometimes people don't care about the results of their work.
Reasonableness tests work when translating analog values, as analog by definition being "fuzzy", their values can vary into non-useful areas as part of routine operation, where "routine" also includes these systems combining input from multiple other analog sources; stack up enough random variation, and you can get some non-reasonable values by chance alone, and you want to be able to skip over those. Digital to digital translations, however, by definition, do _not_ stack up any random variation. If you put in a reasonableness test in those, when they trigger, they are _much_ more likely to throw out _correct,_ though unexpected values than ignore a routine fuzziness, possibly allowing a disturbance develop into a catastrophe. Instead of reasonableness tests, digital data can have digital verification -- error detection/correction codes, like parity, checksums, and the like. This ensures the values are known to be correct, even if unexpected. In fact, it's because of error detection/correction codes that systems have moved away from analog to digital over the decades; all analog data is converted to digital as close to the source as possible, so nothing has to _guess_ if it's working or not. Doubt makes a lousy foundation for modern massively complex computer systems.
you're telling me they care more about human lives than a probe? nooo....
Bear Mro *facepalm*
FINALLY SOMEONE MADE THE SHIRT! SET SCE TO AUX!!! Love it
Got one. Bought it five years ago. It attracts comment from time to time...
Great history lesson. Your delivery and attitude make it come to life.
I love the commitment to being a subject matter expert in the systems you are responsible for.
One of my favorite moments in exploration history.
Thank you for researching this, was extremely interesting.
Thanks, Scott. Excellent subject to discuss. Very interesting and enjoyable to watch and learn.
Thanks, Scott. Just now saw your post. Always refreshing.
I first learned about programming and minicomputer hardware in the late 1960's, and I KNOW what sort of gear and code those systems had. I sort of doubt anyone raised from the 1980's and on has ANY idea of what those systems were like. DEC PDP-8 computers functioned with a 4K core memory stack, and accepted an additional extended memory 4K stack, for data only (not code). Yes, 4K was what you had available for ALL of your programs. It's always very impressive to me what these NASA systems were able to do with that. By and large *everything* was written in machine language, and you had to write your own interrupt handling routines, etc. Handling and interpreting data out of those systems in real time during a crisis must have been nerve wracking!
You are absolutely correct! I worked with an IBM 1620 in the 70s and one had to write very efficient programs in Fortran for it on punched paper tape as the memory was (I think) about 25K.
The first PLC I learned to programme on only had 4K Ram and 8 bit analogue channels, When a customer wanted extra functionality on the plant they had to buy a 16K ram pack it cost £350.
Well told and well explained! Thank you for an interesting science history lesson!
Glad you got the background to Aaron's ability to get into the minutia of the problem. No one at KSC wanted to explain to Aaron what exactly had happened to cause the low voltage, and it took someone like Kraft to intervene and ensure the information was passed on. It was that NA engineer who told Aaron 'you know, if you just switch the SCE to aux, you'd be right.' He remembered that comment in the heat of battle many months later. Aaron was smart, but more importantly he was curious and hard working. This is all covered in that brilliant book Apollo: Race to the Moon.
As usual Scott, fantastic job explaining and very informative video!
Interesting. The current Boeing SCE (Spacecraft Control Electronics) also works at 28V and is responsible for telemetry (and most everything else). On some spacecraft there are three (one is aux or reserve).
I'm not an Avionics expert but all the avionics stuff I've seen has run at 28V.
@@AndrewBlucher We've had several voltages from 28V to 200V, but 28V is the most common.
Yeah, the CM was in the ONC (I think on 3rd shift) at the time of the bus drop that caused the first SCE problem noted, definitely not the A-team. The story about the parachutes may be stretched over time. No doubt someone did question the potential consequences of the lightning strike on the pyro circuits but there was nothing that could have been done if they had been damaged (it would have been far more dangerous to charge the PICs and still probably not learn anything from it than to just wait until the time comes). Besides, there were three separate circuits with 3 separate PICs and two out of three chutes were OK and even only one may be survivable.
Very good episode. The technical diagrams and drawings are much appreciated.
Andrew Chaikin's book, "Man on the Moon" served as the reference for the Tom Hanks mini-series "From the Earth to the Moon." In the book, Chaikin describes the discussions around the pyrotechnics for the re-entry parachutes. Ground controllers determined that the only way to know anything would be for an EVA to visually inspect the pyrotechnics. This was a procedure that the crew was neither equipped nor prepared for. Eventually they decided that if the parachutes didn't deploy, the crew would be just as dead now as they would be in 11 days. The concern about the pyros was not even discussed with the crew. They were not told of the concerns until after they returned.
Love the Sandia shirt! Greetings from New Mexico
I love histories that i "know" being told in depth by someone that knows what its talking about.
thank you for your very wonderful story telling. your reverence and respect for the achievements and the people involved is obvious.
Great assessment of the Apollo 12 launch sequence. Was fortunate to have Mr Aaron on a flight years ago and get to shake his hand. This event was well before my time, but still find it to be one of the most fascinating things to research. I did wear a “keep calm and try SCE to aux” shirt in Aruba and I just got confused looks at the Bugaloe lol. Ty for the video, just found your channel and will I’m looking fwd to watching the others.
Reminiscent of Chesley Sullenberger. Exactly the right person in the right job at the right time, someone who knows the system inside out and can work out what the options are for the best chance of success. It is just a shame those people in positions of political power don't realise that the more you know about a subject, and the harder you work, the better decisions you make.
Well, you see, the decisions politicians care about are whatever ones give them money and power. So they don't care much about this stuff.
@@KuK137 U didn't fix sh!t coz it's just about ALL politicians these days that only care about themselves!
@@moth.monster Besides money and power, always have somebody to blame.
@@KuK137 still thinking the same way buddy?
Where the starship models from?
As someone who went through the usual US Army Basic training of the early 1980's, one of the training requirements was to demonstrate the ability to deploy a Claymore mine. The equipment used was a simulator, but part of that was that the hand detonator for the mine had a 'test' mode that if everything was connected correctly, you would put the detonator into 'Test' mode, squeeze the detonator as if you were igniting the mine, and a light would flash on the detonator indicating that everything was configured correctly, and you would loudly report "I see the light" to the evaluator, who would then advise you to move the detonator out of 'test' and detonate the mine. In this mode you were expected to have ducked down behind your berm on the off chance that you were in the back blast for one or more of the mines attached to the detonator, and detonate the mine. (simulated, no explosion.) As I never deployed a live Claymore mine, I have no idea if the live equipment functioned the same way, but it was impressed upon us that it would. The reason I relate this is that since this mine was (I seem to recall) widely deployed during Vietnam, it seems to me that the testing of the primer and detonation system could have been performed in a similar way on the Apollo Command Module. The likely issue with this was that it would add complexity, and since Primers are somewhat temperamental in any case, much less after they have been through a launch, and are now in free fall, and in an environment that they are not necessarily well tested in on top of their being temperamental, there is some risk to doing anything like the test the Claymore would go through. I'm not at all sure that there weren't a few missteps in that procedure during Vietnam that may have provided some discouragement to doing the testing as well, most likely a situation where the soldier knew that they didn't have the detonator in test mode when the 'test' the setup, to someone's displeasure.On the other hand, the 'test' function of the detonator may have been added post Vietnam. I mean I was in basic fully 2 decades after we left.
This is an excellent summary in almost every way, and I thank you for telling it so well. I was a teen when this happened, but I later had the incredible good fortune of working at the Johnson Space Center on both the Shuttle and ISS, during which time I got to know many of the principals in this story. John Aaron himself told me the story of the flight and the background on why he knew about the SCE, and Gene Kranz told me John was "the smartest man in the control center". I also briefly met Pete Conrad and he left me with the sense that they would not likely have solved this in time. Remember the expectation was a significant failure during ascent would automatically result in an abort if it could not be resolve within 20 seconds. Obviously they extended that time in this case, but in my view that was only because John had a plan to get to a solution. They did not want people thrashing in the dark.
I love this story, Al Bean knew where the switch was, the other 2 didn’t. I have seen that video,The crew laughed all the way into orbit. This is a Great video.The computer was basically I have read an IBM 360 I believe, a powerful computer at that time! A giant calculator now!
From my understanding most early rocket computers were application specific. Basically each sub-system was built for one specific task unlike a desktop computer that's built for general purpose computing. That's also why an old computer was enough to get Apollo to the moon, it had been configured for a couple very specific task and nothing more. It is possible that it was a modified IBM 360, probably with a few features tweaked or removed entirely. I've also heard that rocket computers have to use larger circuitry and have extra fortifications to protect them from the extreme vibrations and radiation of space though some older computers are a bit closer to those specs than more modern ones. I seem to remember something about a SuperCray being used and something about them figuring out an early form of hyper-threading to improve performance but I couldn't find any info on it with a quick search (and unlike most of what I mentioned in this comment the SuperCray thing is an ancient memory).
That’s because the switch was on a panel that could only be reached by Al Bean. It was his job to know every switch on his panels.
where do i get that t-shirt? also could you do a video on the space shuttle safety systems, specifically what happened when something went wrong on the pad?
I was going to ask why he got an SNL shirt. Need to get him an LLNL shirt...
CTXSLPR SNL has several rocket programs, maybe he’s has some connection there...
Hello there
Thank you for this very informative video, I enjoy watching all your videos, you explain the problems and solutions so clearly to me. Keep up the great work, thank you. 😊
Yet another really really interesting and informative story brilliantly told, thanks Scott
This is a great video! I have written a (German language) book about the Lunar Landings and so I knew most of this stuff - but not all! I do think that the story about proceeding with the mission although not being sure about the condition of the parachute system is true. After all it makes total sense! I for one would "rather" die after having been on the moon ...
I just love that the automatic subtitling says “oh it’s got manly here” 😆 Where’s the lie though?
Love your work Scott! Thanks. I’m also in total awe of this guys!
There should be an "SCE to Aux" button for humans, during critical moments of miscommunication. Also, what I liked about the schematic at 12:20 was that it was a "Simplified" version: hahaha. Thank you Scott for a brilliant presentation.
Apollo Operations Handbook, 15 April 1969. Page 2.8-20: "The only external control for the SCE (Signal Conditioning Equipment) is the 3-position SCE switch on MDC-3." - Full explanation of switch function on page. (sorry, just to clear up the SCE acronym doubts - BC.). Great video. Fascinating space engineering tech history. See: apollo.josefsipek.net/ApolloProjectOnline/Documents/SMA2A-03-BLOCK%20II%20Volume%201%2019691015/aoh-v1-2-08-telecoms.pdf & thanks, Joe.
Not only does the "We die either way, so let's go to the moon first" make perfect sense for the chute pyrotechnics, but: If there was a problem that was immediate and transient (e.g. built up static from the strike), taking time to go to the moon might have allowed the problem to self-heal before they had to use the chutes.
That really isn’t a thing.
You! Are! Fantastic! This is the way, kind, art & style to explain our technical history, I can listen to for millenia.
Fascinating! I have a background in electronics - from that era actually, so I was right there along with you in your story.