Her Code Got Humans on the Moon—And Invented Software Itself

Margaret Hamilton was a 24-year-old programmer at MIT when the Apollo program pulled her into work that helped define modern software. The article links her lab work to the Apollo command module computer, the lunar landing, and the later idea of software engineering.

Reading notes

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• Hamilton was unusual as a working mother and a woman in technical work in the 1960s, but she stayed in the lab and led programming work for Apollo.
• At MIT, she and her colleagues helped invent core ideas in computer programming while writing code for the first portable computer.
• The original Apollo engineering requirements did not even mention software, and software was not included in the schedule or budget at first.
• By 1965, Hamilton was responsible for the onboard flight software on the Apollo computers.
• Apollo programming involved punch cards, overnight batch processing on a Honeywell mainframe, and simulation before flight.
• The Apollo computers used copper wire memory made by Raytheon workers, with permanent and temporary memory built into the hardware.
• The article says software was what let the United States win the race to the moon, and that the Apollo work helped create a large software industry.
• During Apollo 11, the computer produced error messages because it was overloaded with unnecessary calculations, but the software’s priority handling let the landing continue.
• Hamilton had pushed for error-checking code after a simulator incident, but NASA rejected it and instead asked for a documentation note.
• A similar mistake happened during Apollo 8 when Jim Lovell selected P01 in flight and erased navigation data.
• Hamilton and the MIT coders fixed the problem by uploading new navigational data, allowing the astronauts to come home.
• After NASA, Hamilton founded and led software companies, including Hamilton Technologies near MIT.