The Real Story Behind the Apollo 11 Computer Error | WSJ

As a developer, I can't imagine the type of stress when you are put in a spot to debug code live, and the outcome of that directly impacts people's lives.

Software engineering interviews: 60s: - Can you code? - No -...Good you're hired! 2019: - Do you know Javascript, C/C++, C#, HTML, CSS, NodeJS, .NET, Angular, JQuery and React? - Yes - We'll get back to you!

Just prior to the Apollo 11 launch the simulation team realized that they had never simulated approach to landing computer failures in training. Accordingly, they ran a few simulated failures with the ground control team and the back up crew. One of the failures they ran was a 1201/1202 alarm. During the simulation the ground crew mistakenly called for an abort. The simulation team explained that an abort was not required under those conditions. The ground controllers then went through all the possible error codes and noted what should be done for each code. They had that handwritten set of notes available to them during the Apollo 11 approach. When the problem occurred for real during the landing of Apollo 11 it was news to the flight crew, because the backup crew was used in the simulation. The ground controllers, however, had seen it before. If you listen carefully to the ground control loop during the actual landing of Apollo 11 you will hear one of the controllers say “that’s just like what we had”. He was referring to the alarms they had previously seen in the simulation. They knew exactly what to do: allow the crew land. The 1201/1202 alarm was caused by the computer being overloaded by the rendesvous radar which was not required for a landing. But Buzz Aldrin, who had a PhD and orbital mechanics and rendezvous, thought it would be best to leave the rendezvous radar on in case they had to abort. He reasoned that the computer would have a head start for the abort rendezvous with the command module. The checklist, however, specifically required the rendezvous radar to be off during landing to prevent this exact situation from occurring. In the documentary movie “In the Shadow of the Moon” Buzz Aldrin admits to this mistake.

From never have written a single line of code ever and interviewing for insurance jobs at 23 in 1966 to going ahead and programming the computers of Apollo 11 in just 3yrs at 26 in 1969, man this guy is a genius.

I'm amazed they hired someone who didnt code. The good old days where employers would teach you up, instead of treating you like a disposable item.

He politely didn't mention the "human error" was Buzz Aldrin. Aldrin later admitted leaving the tracking radar on. He was scared they may not be able to find Mike Collins after they left the moon, so at the last minute, he decided to leave the radar unit on, instead of follow procedure. He didn't know the computer didn't have the capacity to track the moon and Collins at the same time. Amazing that Aldrin did this... If they had aborted the mission because of the alarms, you would have to speculate that Aldrin would have never flown again. Come to think about it, he didn't.

I was always impressed by Armstrong at that critical moment being so calm. People playing him in movies usually do a poor job because they want to make him hyper and near panic for dramtic effect. I never understood that because we had actual recordings of exactly how he was. Calm as steel.

This guy is like a cross between Matt Damon and Philip Seymour Hoffman

Was bummed he didn't get the insurance job, strolled into the MIT instrumentation lab and was cold hired with no experience. I want that America back.

I received a 1202 error yesterday... after taking a closer look, I realized that I was 2 min late for lunch :)

As a programmer from 74 to 04, watching him pour over the program listing brings back great memories. A great job for this 23yr old back then.

I had an uncle who without a high school diploma or college degree designed electronic circuits that stymied engineers so much he was hired to design communication and inertial guidance circuits for Mercury, Gemini, and Apollo missions, and also on the SR-71. He was very good, but died from a heart attack about age 55.

One correction: Buzz has publicly admitted that he left the rendevous radar ON while the landing was taking place. That was in direct opposition to procedure. Buzz said that he wanted the rendevous radar ON in case they had to abort the landing. The computer was thus receiving TWO radar inputs, not just the landing radar. THAT is why it went into an error state.

Today, if you want to initiate an emergency call, you have to wait for the Ad to finish.

This does not mentions Margaret Hamilton who was the one who came up with the idea of asynchronously running the code despite of the error. She came up with that concept for fail safe which to this day is used in programming.

Android: has like 300 MB of free space Play Store: error 1202, not enough memory

Meanwhile, I'm complaining at work about my horrific python code running too slowly when I have a million times more memory and some absurd amount more processing power to work with. Major kudos to Mr. Eyles for his amazing programming accomplishment and contribution to advancement of humankind.

I had the honor of meeting Mr. Eyles several times in the nineties. Very nice guy. It was only after meeting him a few times that someone told me he "worked on Apollo". He never brought it up. He's got a book out called "Sunburst and Luminary: An Apollo Memoir".

the real story requires mention of margaret hamilton, this guy's boss, who inspired the code that gave mission controllers the confidence to continue the landing.

State of art 36k memory on the Comp doing the most complex effort of that time! Thankx for the info. It's both humbling and imbues appreciation for all the hard work people did back than- laying the foundation stones, and then, the stepping stones for others to improve things later. Our lander just crashed on the moon 12 days ago with TB in memory and multifold of advances.