What Does "Set SCE To AUX" Mean Anyway - Apollo 12's Lightning Strike Explained 

"where the computer thought it needed to realign the inertial guidance platform really quickly" *Kerbals screaming.avi*

To get to the AUX position, they had to go through the OFF position, so they literally did switch it off and on again.

"Laughed all the way to orbit" is one of my favourite phrases ever.

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!

The more I learn about Apollo sub systems, especially the digital/non-chemical reaction stuff, the more impressed I am by 1960s NASA.

Mission control: have you tried turning it off and on again?

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.

Then : Turn SCE to AUX Today: Please don't turn off your rocket while we update your computer...

"Yo pass the aux cord" "You better not crash the rocket"

Apollo 12: No time for heart attacks

*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*

"Set SCE to AUX" was the name of my high school garage band.

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.

Lightning striking the Saturn V is one of the coolest images in history.

"We're having cardiac arrests, man." "I ain't got time to have a cardiac arrest."

Its never ceases to amaze me all the redundancies and procedures they had for dealing with such a variation of issues , truly impressive

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.

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.

It's amazing they didn't call an abort. Big stainless steel balls.

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.

Gotta get me one of those SCE to AUX light switch covers!

That anecdote about the parachutes is what I found most chilling in this entire video!

: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.

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!

After going through all that, Alan Bean went and broke the video camera, on the moon.

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.

I vote for more stories in this format! It was really amazing to learn all these details, and very well put! Cheers.

Wonder if my dad’s company, Control Switch Corp., made that one. They made a lot of the switches in the CM and LM.

I love telling this story so much I call my home wifi network "SCE to Aux" so people will ask me what it means.

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.

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.

I really want to go to sleep but this guy really has so many awesome videos and I can’t stop watching them

Love the "steely eyed missle man" reference!

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.

That guy that said that will never be forgotten in the space industry. Prevented a mission abort because of a cool headed response.

I love these historical videos. All the sound recordings and photos of the equipment you're talking about really add to the story.

John Aaron is my hero. I've seen many interviews he's done. He is one smart and humble man.

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.

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 :)

The engineering of the Apollo missions is nothing less than absolute genious.

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. 🙂🇦🇺

A very concise, (non-ambiguous) dissertation on what happened in the first hours of Apollo 12. Great job, Scott!

Finally, I found the perfect SCE to AUX video. Thank you. 😍

"Stand by, 12, while we call Dell Technical Support."

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!

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).

Arguably the finest moment of quick thinking in the whole history of spaceflight.

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.

I'd heard of this, but never heard an in-depth explanation of what all it encompassed. Thanks again!

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!

Thanks Scott - one of my favourite Apollo stories.

One of my favorite moments in exploration history.

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 RU-vid!!! 😀 👍

I love the commitment to being a subject matter expert in the systems you are responsible for.

FINALLY SOMEONE MADE THE SHIRT! SET SCE TO AUX!!! Love it

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!

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.

and 50 years later we are still impressed by knowledge, engineering and technology of all those involved in Apollo program. Just unreal.

I love histories that i "know" being told in depth by someone that knows what its talking about.

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..

And these kind of stories is why I follow this channel. Thank you, Scott.

Your videos always contain fantastic graphics. Thanks for all of your research and hard work.

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.

Thank you for researching this, was extremely interesting.

Awesome job by the entire Apollo 12 team - amazing how low tech their high tech seems - and very interesting video (as usual) Scott.

Great history lesson. Your delivery and attitude make it come to life.

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.

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.

Hey Scott... I love these type of reviews. Being an operational engineer myself of sorts, it's awesome review and analysis. Thank you brother!

I'm happy it's this one, and not the other "greatest hit" of Mission Control: "Flight, GC. Lock the doors."

Well told and well explained! Thank you for an interesting science history lesson!

I mean if the parachutes are dead there is literally no point in aborting and -lithobreaking- landing early.

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.

Thanks, Scott. Excellent subject to discuss. Very interesting and enjoyable to watch and learn.

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?

Love the Sandia shirt! Greetings from New Mexico

You! Are! Fantastic! This is the way, kind, art & style to explain our technical history, I can listen to for millenia.

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.

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 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!

Very good episode. The technical diagrams and drawings are much appreciated.

As usual Scott, fantastic job explaining and very informative video!

I just love that the automatic subtitling says “oh it’s got manly here” 😆 Where’s the lie though?

Where the starship models from?

thank you for your very wonderful story telling. your reverence and respect for the achievements and the people involved is obvious.

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.

Pete Conrad: "Try FCE to AUXILIARY. What the hell is that?" It's at about this point that I'd be getting concerned.

Everyday a schoolday with Scott 😊

I am somewhat well informed about space stuff but I never realized how much went wrong on this launch. Amazing. Thanks for the info!

Thanks, Scott. Just now saw your post. Always refreshing.

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.

"SCE to AUX" EverydayAstronaut should use that for his next album

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. 😊

Love your work Scott! Thanks. I’m also in total awe of this guys!

The parachute test anecdote reminds me of the Columbia disaster flight assessment. The flight risk assessors decided not to tell the Columbia crew about the potentially catastrophic heat shield damage, since there was no way to fix it if it were damaged anyway.

Weird. Somehow I thought you'd already done an SCE to AUX video.

Yet another really really interesting and informative story brilliantly told, thanks Scott

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.