Hal Laning: The Man You Didn’t Know Saved Apollo 11

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This video has a lot to it. If you’re like me and take things in better when you read, check out my companion blog post over on Discover.

  1. Leggo MuhEggo

    BASIC was developed in 1965

  2. James Frangione

    A terrific episode, Amy! I love your work! Thank you for doing what you do.

  3. Mike Bugal

    I would say “few” have heard of Hal. Those of us with a long experience with the Space Program have definitely heard of him.

  4. Psyclotron xx

    God Amy, you’re great! This was a really good story!

  5. Rob Babcock

    It’s amazing how much there still is to discover about those early programs and the extraordinary people that made them work. Thanks, Amy!

  6. Chris J

    This is one of your best Amy!

  7. Ian Durr

    Thanks Amy! Love your channel and your brain!

  8. StringerNews1

    One enabling technology that made the soft reboot w/o losing state possible was a from of NVRAM called magnetic core.
    I keep seeing people saying that “Apollo was analog” trying to explain how the technology survived passage through the Van Allen Belt, and that of course is nonsense. The Apollo spacecraft used cutting-edge digital technology. Neither analog _or_ digital circuits in Apollo used Very Large Scale Integration IC chips, mainly because they had been yet to be developed in the 1960s. DRAM was brand new when we landed on the moon, too late to be used in the computers developed years before then. Not that engineers would have rushed to a new and unproven technology for the sake of newness. So ironically the “slow” magnetic core enabled the LM computer to reboot quickly to its last state.

  9. Zhu Bajie

    You got a bunch of guys about to turn blue. We’re breathing again.-Charlie Duke

  10. brocktechnology

    I’ve heard these innovations attributed to Margaret Hamilton as well, but I can smell the research on your stuff.

  11. sei shin

    Please interview Don Pettit about his famous video.

  12. LaPabst

    Great to see you back on YT!! Question, during the Apollo 13 accident, Gene Kranz was only doing flight direction for an hour or so. I’m sure he assumed emergency duties. Who was the ‘night shift’ guy that took over as flight director. I have listened to as much of the audio as I can find, there is no mention of his name. He was very capable and calm.

  13. Ver64

    I made the request 3 years ago to explain and elaborate about the 1201 and 1202 alarm….and now I got it ….worth waiting..thanks. And thumbs up 👍🏻👍🏻👍🏻

  14. Papepo Mamemo

    I wouldn’t leave Hal alone in the spaceship.

  15. Jason Ludlum

    Great video, Amy! Will you be offering signed copies of both books later on? I’ve asked this on many occasions on social media but can’t get a response.

  16. Stewart Johnson

    Fabulous video. Great presentation. You are terrific.

  17. Helium Road

    Automatic thumbs up for using the term “centiseconds”

  18. Troubled Sole

    Thank you. Always informative and interesting.

  19. Craig Corson

    There were tens of thousands of unsung heroes of the Apollo program, the people who designed, built, and tested everything that was needed to get the astronauts there and back again. I’m proud to say that my Dad was one of them; he worked on the guidance system.

  20. Francois Lacombe

    Hello Amy. May I suggest taking a look at the proposed NASA mission to Halley’s comet in 1986, how far along it got and why it was cancelled?

  21. Bill Dunne

    Great Amy well done.Another great video Bill

  22. P

    You can bet that if Hal Laning’s computing components had design flaws serious enough to fail catastrophically (abort mission, lose vehicle, kill crew) then the world would know his name.

  23. cn 250

    I’m not getting notifications when you upload.

  24. Frank Harr

    I love it when analog and digital can work together.
    That is a piece of insanely good fortune. HAL! Is he the guy the computer was named after?

  25. killernat1234

    At 3:58 I paused the video and went to go do something, when I was finished I played the video again and I thought I had lots of bits on my screen, turns out it was just stars

  26. TheCimbrianBull

    How fast would Pete be able to program a computer? 🖥️🐱🐈

  27. Tony Elsom

    Yup, that was touch an’ go..imagine getting “11 updates pending, android is rebooting “..thank god for old computers…I still have my 1982 zx “speccy”…not much difference

  28. Solar Eclipse Timer

    This is a great video! Love it! I have followed the NASA space program since I was a child and watched in amazement as Walter Cronkite narrated the 1st Moon walk! I live next to Marshall Space Fight Center now, which has a tremendous Apollo history and I have met great people from MSFC and the US Space and Rocket Center. In July, under the name of my eclipse timing app, Solar Eclipse Timer, I am sponsoring a table at the US Space and Rocket Center to celebrate the 50th Anniversary of the Apollo 11 Launch and Landing.

  29. Ponce de Leon

    That’s nothing. Ever see BSOD while working on a term paper?

  30. The Jolly Troll

    Even though Armstrong had nerves of steel, the pucker factor must have been off the charts.

  31. Michael King

    Great presentation as usual especially your explanation of the event. Just on a side note my uncle was one of the engineers that worked on the guidance systems for the Apollo program. 👍

  32. ironwarmonger

    I am an Electrical Engineer, and the various forms of Assemble is the languages I am best at programming in. But my Focus was in Microprocessor Design, so that might be the reason.
    I am fascinated by the development of a priority orientated Task Manager (which it what the Executive was).

  33. Art Ellis

    A great video. What I mean by that is that it’s about computer science and I almost understood it on the first viewing. This is high praise indeed, Ms. Teitel.

  34. Ryan Ehlis

    LMAO! NASA IS A FRAUD! no one went to the moon.

  35. Lance Salyers

    Really well done, Amy. Incredibly informative.

  36. guitarman

    A great clip Amy. very informative. I’ll have to watch it a few times to fully get the fine points. Nice to see you back. I hope you never run out of topics of discussion. This one is really fun.

  37. kab kab

    Good work Amy. 50 anniversary coming up soon. I remember viewing the first walk back then. Thanks for the GREAT STORY and memories.

  38. John Mann

    The Apollo Guidance Computer Application needs to be updated. Start With The Download?

  39. Recon Ty

    Very informative video.
    I always assumed that the computers used were slow and clunky compared to what we have now. I guess they were just small and lacked sufficient memory.
    Pretty cool when you think about it.

  40. CaribSurfKing1

    If only my Android OS did the same for Critical User Input/UI on older devices instead of all the background checking so I could actually use it i.e. the opposite of the Apollo 11 computer!

  41. Greg Doolittle

    Another very interesting and informative video. You’re awesome!!

  42. CloudLicker

    Finally, someone from my generation who knows who Hal Laning was and recognizes his brilliance.

  43. Trace Dominguez

    You’re the best and I miss seeing your face every month!! 💕

  44. Edward Cabaniss

    A concise and accurate explanation of a complex issue even for today’s computer geeks. Well done, Amy!!! Another example of why you’re the best!

  45. matttelz

    More kerbal music please! Great vid! 👍

  46. Josh Davidson

    Excellent video Amy! Welcome back!

  47. HO LAM YIU

    Extremely detailed look into the 1201/1202 alarms, most other sources only touch on this by saying “there was a alarm”… Not disappointed with your comeback!

  48. Eric Anderson

    You want Mario to jump AND kick a turtle at the same time? ALARM! ALARM!

  49. Bruce Rowney

    HI Amy, off topic but just wondering have you any of your amazing insights into to Apollo 10 and the “possibly lost but maybe not” Snoopy? Imagine I had to hear about it from Scott Manley. Love having you back.

  50. mlnlme1

    I’m just here to comment on the Kerbal Space Program music

  51. Harry Callahan

    I am an Electrical Engineer and you did a very good job in this explanation.

  52. Dingo Prod

    can you tell us why the LEM was shaped like that, with those geometric panels and bits and blobs everywhere. Why not a simpler shape? thank youu ;-)

  53. Griever

    Glad to see this channel with fresh content ☺

  54. melkins551

    Don’t leave us again please. I love your documentary videos !!!

  55. Antti Peltonen

    I thought I knew all about the 1201 and 1202 alarms already, but you managed to bring new info to me as well. Fantastic, keep up the good work.

  56. John-Del

    Barely 5 years later, a $600 Hewlett Packard or Texas Instruments hand held scientific calculator would have far more computing power than the Apollo AGC. Not built for the rigors of a space launch or radiation certainly, but still..

  57. networkdeath1

    Solve the 1201 alarm HAL.
    I can do that Neil

  58. Tom Gates

    Regarding hero’s of the Apollo missions, who was the person that decided rolls of duct tape should be included on NASA space flights, and when did it start? Lots of great work by the Apollo 13 ground controllers, but – what if there was no duct tape. 😳

  59. Wright Flyer

    I remember Apollo 11 well because in 1969 I was a radio operator at MacDill AFB in Tampa so I tuned all NASA frequencies on my Collins Scope radio system, using a dummy antenna so as not to interfere with NASA transmissions. I turned on the B&W TV with no volume and turned off all the station lights. Wow, the only illumination came from the TV and the multi-colored lights on my console and the only sound came from NASA. It was truly a day to remember! But I never heard of Hal Laning–until now. Thank You! Wright Flyer, USAF (1968-1972).

  60. Conrad In Hawaii

    Amy… for you to explain, in detail, the causes and effects of the 1201 and 1202 alarms, which I have been reading about, but not fully understanding, since July 1969, and have those explanations crystal clear to me, a retired commercial pilot with a working, but not technical, knowledge of the flight director/autopilots I operated “back in the day”, as well as my sooo-modern laptop, is a miracle of epic proportion. The people I have known in my life who have made the most lasting impressions on me have been the wonderful teachers I have had. One of them, my first flight instructor, is still a close friend, fifty years later. You are on this exclusive list of mine, and you have a wonderful talent for REALLY teaching, which is all too rare.
    If this country ever institutes a roll of “Living National Treasures”, as Japan has done for decades, you would be at the top of my list as a nominee.
    Me ke aloha mai Hawai’i, Amy… 🌴😊🇺🇸

  61. DerHeimatlose1

    I’m very confused you didn’t even mention Margaret Hamilton’s name ?!?

  62. UtopiaV1

    “It all came down to a man no-one’s ever heard of…” Well, presumably Hal’s friends, family and co-workers had heard of him. Heck, they even named the supercomputer from 2001: A Space Odyssey after him!

  63. Hector DeAnda

    I love this! I didn’t realize so much detailed and interesting information about this could be found. Thank you for your hard work presenting it to us!

  64. Paul Slater

    I’ve just finished Gene Kranz’s book, Failure is not an option… He reports the same thing from a different angle… apparently the SimSup tried to throw a spanner in the works on the last sim before the flight of Apollo 11… everyone was expecting an easy ‘milk run’ simulation to build morale and settle everyone down for the impending launch. Instead, the sim team found an obscure computer error to throw in during the lunar descent – during the sim (with the white team and the backup crew) , the controllers called an abort based solely on this error code- a no no as the done thing was to abort only based on 2 separate data sources… the single error code which led to the abort? The 1202 alarm… it was so obscure that the controllers went away and read up on it… good job really – their new familiarity with the 1202 alarm allowed them to keep giving the ‘go’ as they came in…

  65. Rick Boatright

    I’ll join the horde happy to see you back. As always, not just a deep dive, but an interesting choice of topic ordering, your usual incredible word choice, and precision diction that results in that rare combination of clarity and accuracy.
    Thank you for sharing with us.

  66. setil77

    Amy, please more vintage space here on free YouTube thx!

  67. Donner Pass Whiskey

    Interesting that what you are describing a inertial navigation system combined with a optical instrument to track stars for reference and a computer to control the two is how the “Astral Inertial Navigation” system worked on the SR-71 aircraft.

  68. Wing Lem

    Let’s hear it for those important men and women whose self discipline and passion help lead the way for Apollo and further space exploration when we needed it and laid the foundation for the future of space flight.

  69. Space Pixel

    As a hobbyist programmer, everything you said makes perfect sense. Amazing explanation!

  70. Neil Bonner

    Been listening to ’13 minutes to the moon’ a BBC podcast. In episode 2 they talks about the 1202 alarms.

  71. Epat

    is that a music from VAB/Spaceplane Hangar from Kerbal Space Program?

  72. Richard Mattingly

    Moon landing conspirators are rarely that knowledgeable about the tech. they criticize since it’s easier to claim that only 60s computing power was little more than an abacus with wires and not much else. Indeed the submarine SINS systems set of gyroscopes/accelerometers at the time were the forerunners of what a Smartphone uses in a far more micro sized form today without you being aware that they’re there. The design/priority programming the lander/command modules carried were quite astonishing considering that the closet things that civilians knew of was an adding machine or a cash register in 1969.

  73. Calbeck

    Love your amazing work! You are CRIMINALLY undersubscribed.

  74. Zags Theklown

    Can you do something on Margaret Heafield ? And the other unsung ladies of Apollo.

  75. The Stuport

    I was listening to the “Mission To Mars” theme when your “alert” popped up in my mail box…..Very Celestial….Hard to believe this coming July will be The 50th Anniversary of The Apollo 11 Moon Landing!! I still remember watching this as a young boy late at night with my Family and especially my Dad , who at the time was a Lt. Col. in the Air force and had gone to Flight School with his friend Gus Grissom so no doubt this was bitter/sweet for him. As always Amy your video’s are literally OUT OF THIS WORLD…..Us FANS are so lucky for this channel. Cheers From Ohio…Home to Neil Armstrong

  76. Fred Hoffman

    what just drops my jaw is all those computers used fragile core memory ..i am amazed the technology our grandparents help make ..it may had been crude but it worked and led the way for our cushy life we have with our PC’S today ..btw i wuv tha hair :) call me :)

  77. Malcolm Bacchus

    Basic and BASIC shouldn’t be confused but BASIC wasn’t designed in the 1970s as you state 3:30 minutes in, it was created in 1964.

  78. Jeff Alvich

    What a great vid! My dad was one of the many engineers, unknown, unrecognized, but created an incredible program that challenged and excelled the conventional thinking…lessons of which, are still be relearned today by the new engineers who have forgotten history.

  79. pfcwar5150

    Love the Apollo program… America at its finest

  80. orangelion03

    Fascinating!! Thank you for highlighting one of the thousands of individuals who made significant contributions to our space program. Keep these coming =)

  81. Andrew Ongais

    Thank you, Ms. Amy.
    You have a gift for explaining complicated stuff.

  82. mucholocodawg

    While Dr Laning wrote the executive for the guidance computer; it was Margaret Hamilton design was the key to how the system resiliency and error recoverability saved the day.

  83. Aaron John

    So many unsung heroes that allowed NASA to achieve what it did. It just shows that the reason you never heard of them is that they focused on achieving the mission.

  84. Craig Gilbreath

    LOVE these “behind the scenes” peeks into space history! Thanks Amy!

  85. oil9vinergar

    wasn’t a checklist error, it was a design flaw. the two 800 hz power supplies that fed the Rendezvous RADAR ATCA and the CDU were not phased locked causing the ATCA not to respond to polls from the CDU which the CDU then reported to PNGS via an external interrupt. this error happened 12,000 time a second and occasionally there weren’t enough Vector Accumulators and/or Core Sets to handle the interrupt causing 1201, no VAC, 1202, no CORESETS alarms. Since the priority tasks still had their VACs and CORESETs, the executive could flush out and restart the priority tasks: a warm reboot…. preemptive cpu scheduling….

  86. Anthony Phillips

    In the documentary ‘In the Shadow of the Moon’, Buzz Aldrin said that the rendezvous radar program shouldn’t have been running during landing but he decided to run it anyway it case of a landing abort to expedite rendezvous with the Command Module. Thus he almost caused the very thing he was concerned about so it was an ‘anomaly’ of human origin.

  87. MattypusPlatypus

    Hal ‘Moon’ Lan(d)ing
    I’ll be quiet now…

  88. NorthernChev

    I have seen many in-depth explanation videos of this Apollo nav computer numerous times through the years. THIS one blows them ALL away. Best explanation yet. Great job.

  89. Mohammad Usman

    Hal Laning is a Steely Eyed Missile Man

  90. badkarma52

    Me, “man, I didn’t know i left KSP running.”

  91. Rouverius

    Apollo Crew: Houston, we have a problem.
    Hal Laning: Have you tried turning it off and on again?

  92. Marlo Gonzales

    Good job explaining the concept of preemptive multitasking! I had no idea they implemented it this long ago.

  93. Splendid Mendax

    Really admire this woman. Do you have any idea folks how hard she must work? How dedicated to educating all of us she must be? I hope her income grows and that she gets the attention of a degrasse Tyson. Watch more than once .

  94. Goettschwan

    So “HAL” was responsible for the automation of the spaceship and maybe knew more about the missions’ target than the crew? :)

  95. carabela125

    “Open the Command Module door Hal.”
    “I’m afraid I can’t do that Dave.”

  96. Aviator Steve

    Always interesting and informative, so glad to have you back 😀

  97. pawley media consultants llc

    One of the better 1201 / 1202 Alarm explanations I’ve heard. The Graphics were very helpful :)

  98. M T

    Hi I’m clippy, I see you’re having a guidance problem, can I help?

  99. Francois Lacombe

    Hal, a good name for someone engineering computers.

  100. Rory Thomson

    Apollo guidance computer has encountered an unexpected problem and had to close.
    Would you like to send an error report?

Comments are closed.