Before an astronaut made the mistake on the way to the Moon, a four-year-old had already made it
MIT's Instrumentation Lab had a simulator of the Apollo command module. One day Lauren, the four-year-old daughter of programmer Margaret Hamilton, was playing on it. Somehow she launched P01, a program meant to run only before launch, in the middle of the "flight". The simulator crashed.
Hamilton had joined the lab in 1965 as the project's first programmer; by 1968 she was in charge of the Command and Service Module team. She put a warning in the technical documentation: do not launch P01 in flight. She also proposed a change to the code so it could never happen on a real mission. She was overruled: highly trained astronauts, she was told, would never make that mistake.
In December 1968, Apollo 8 became NASA's first crewed mission to orbit the Moon. In flight, Jim Lovell accidentally launched P01. The navigation data vanished. Hamilton's team was called in, and the changes she had proposed went into the program. MIT's obituary of her, published in October 2026, calls it an early example of "defensive" programming.
Margaret Hamilton died on 30 September 2026, aged 90. She began calling her work "software engineering" to set it apart from other kinds of engineering. The record kept the episode under her daughter's name: "the Lauren error".
Sources
- Liberty J. Margaret Hamilton, computing pioneer who led software development for the Apollo program, dies at 90. MIT News, Department of Aeronautics and Astronautics, 7 October 2026. news.mit.edu/2026/margaret-hamilton-computing-pioneer-dies-1007
- NASA. Apollo 8. Mission page, nasa.gov/mission/apollo-8/ (accessed 22 October 2026).