The Code that Took Humans to the Moon. By William Van Zyl (published December, 23, 2022).

The Extravagant Podcast

“Five minutes before landing.”

“Three minutes before landing,” said the leader of the mission. All eyes were fixated on the large black-and-white screen.

“Houston, we have a problem!”

“What! What is the problem?”

“Listen to the alarm. We think it is the onboard computer.”

Margaret Hamilton moved closer to the screen. She had her large, heavy laptop open. Her computer stored over 600,000 lines of code. Behind her was a stack of handwritten computer codes on size A3 paper. The stack was as tall as Hamilton herself. About 1.7 m high.

She ran to the stack. She grabbed volume 17 - right at the top, and opened it on page 95.

“We think it is the radar system,” said the astronaut.

“I have thought about all sorts of interferences. I have programmed the computer to recognise such an error. The software’s priority scheduling would complete high-priority tasks first — like preparing for landing. The code that has been written will ignore lower-priority ones.”

“Margaret, it seems to have settled now. I think your high-priority code kicked in! The alarms went off!”

The ground crew sighed in relief.

“One minute before landing, all engines running.”

“The Eagle has landed!”

The ground crew - at NASA Mission Control Centre - and the 3 famous astronauts jumped for joy. Neil, Buzz and Michael were over the moon.

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Did Margaret Hamilton write the code for the Apollo Moon landing?

The answer is Yes! She is far lesser known as Neil Armstrong - the first man on the Moon. However, she is the woman who helped them to get there. Margaret Hamilton and her team of software engineers at the MIT Instrumentation Laboratory wrote the sprawling code that made the mission possible.

I saw the great picture below of Margaret Hamilton standing next to a 1.7 m high pile of handwritten code on social media. Immediately an article popped into my head. I have written it for you.

Who is Margaret Hamilton? She is an American computer scientist and software engineer. She led the team who developed the software for the Apollo moon missions and the Skylab space station in the 1960s and 70s. Her code helped the 3 men to get to the moon - and back!

How many lines of code did she write for the Apollo?

There are 17 binders in the photo. Assuming the 17 piles (bound volumes) are 5″4′ (1.524 mm) in total (stacked on top of each other), they're all code (not simulation) and applying Mike's measurements, assuming 10 binders are Aurora-like and 7 are Luminary-like yields 14,500 code pages, about 660,000 code lines.

What software was used for the Apollo?

The Apollo Guidance Computer (AGC) was installed on board the Apollo 11 Command Module (CM) and Lunar Module (LM). The computer’s software was written in Assembly Language. It was called Assembler. Assembler is considered a low-level programming language as there are very few “plain language” type words - for example instructions - readily recognised by humans.

The article includes great images and a video that will make the article a compelling read. The introduction had been dramatised.

Read the article as a blog post: https://fivehousepublishing.com/2022/12/22/the-code-that-took-humans-to-the-moon/

Author's website: http://williamvanzyl.com/