The Apollo Missions Used Guidance Software That Was Literally Woven by Hand

It's hard to imagine how we made some of history's greatest achievements with the technology available at the time. In the 1700s, scientists calculated the movement of comets with pen and paper. Likewise, in the 1960s, the super-advanced computing power NASA had at its disposal was less than you get on a single iPhone these days. Nonetheless, we made those achievements with what we had. And one of the things we had was an unbelievable technology known as core rope memory.

Knitting Projects in Space

The Apollo program of the 1960s and 1970s needed computers and software aboard its spacecraft to complete its missions. If you've ever seen the computers of that era — devices that relied on rows upon rows of paper punch cards, or massive, heavy tape drives — you can see why that wasn't exactly easy. The technology they needed would have to be lightweight enough to avoid weighing down the spacecraft and robust enough to avoid being destroyed by extreme temperatures or power failures. This is why they turned to core rope memory, a form of memory made by hand-weaving wires through tiny magnetic rings.

All computer programs — even today's — are at their most basic a series of ones and zeros, also known as binary. The workers who wove core rope memory encoded ones by passing a wire through a magnetic ring and zeroes by passing the wire around it. Since they literally encoded each one and zero by hand, the manufacturing process was slow, tedious, and prone to error. But in the end, this woven memory is what helped humans finally reach the moon.

Unsung Heroes

NASA engineers would sometimes refer to this memory as "LOL memory," for "little old lady." As Apollo specialist Jack Garman explained for the NASA Johnson Space Center Oral History Project, "What they told us was that these were all little old women that would weave the ropes. I trust it was more mechanized than that. I actually remember going to see it once, and I don't remember — the myth got ahead of the fact, I'm sure."

Regardless of their age, however, the workers responsible for the software that helped the Apollo missions reach the moon were mostly women — as was their leader, the now-legendary computer scientist Margaret Hamilton. Hamilton's contributions to the Apollo software may have saved missions, in fact. It was her idea to program in emergency warnings and error correction in case of a computer malfunction. That came in handy during Apollo 11 — the first flight to land humans on the moon — which might have aborted the landing if Hamilton's programming into a hand-woven bundle of software hadn't saved the day.

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To learn more about the women who helped humans go to space, check out "Hidden Figures: The American Dream and the Untold Story of the Black Women Mathematicians Who Helped Win the Space Race" by Margot Lee Shetterly — the book that inspired the blockbuster movie. We handpick reading recommendations we think you may like. If you choose to make a purchase, Curiosity will get a share of the sale.

Written by Ashley Hamer April 15, 2018

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