Apollo 11 People / Intrigue


Guiding space missions before modern computers:
Saving the day with software

NASA’s nine trips to the Moon in the 1960s and ’70s would not have been possible without guidance computers

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Getting a spacecraft to the Moon and back required a complex series of maneuvers, precise navigation, and perfect timing

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While Apollo 11’s lunar module was approaching the Moon’s surface on July 20, 1969, a computer alarm sounded

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The guidance computer on board was receiving an overload of information, so it started shedding less-important tasks. Luckily, a key piece of software made that happen.

At the time, computers and software were still in their infancy, and very few people knew how to write or build computer programs

There was no teaching and little previous experience in computer science. Anyone in this field was a pioneer.

Which makes the remarkable achievements of one woman, Margaret Hamilton, even more astonishing

Hamilton was among those who pioneered the field of software engineering. She walked away from a Ph.D. program in mathematics to work on the NASA project.

Hamilton’s Apollo work was exemplary and ensured that no serious software bugs were ever found during any of the missions. But it wasn’t easy.

Instead of silicon chips, computers in the 1960s stored information on small donut-shaped cores threaded together with wires to make “ropes

Threading the ropes was complicated, and if any mistake was made, correcting it was a tedious process. Hamilton, known as the “Rope Mother”, spent hours checking and noting down explanations of each step of the programs.

“There was no second chance. We all knew that,” said Hamilton

Her software was so excellent, it was adapted for reuse in Skylab and the Space Shuttle

For her contribution to the American space program, Hamilton was awarded a Presidential Medal of Freedom by President Barack Obama in 2016