Margaret Hamilton, 1936–2026: the woman who wrote software for the Moon
On 7 October 2026, MIT announced that Margaret Hamilton had died aged 90. She led the team that wrote the onboard flight software for the Apollo missions. She also gave a name to the work she did: software engineering. At the time, many people didn't treat programming as serious engineering. Her career helped change that.
From weather models to air defence
Margaret Elaine Heafield was born in Paoli, Indiana, in 1936. She studied mathematics, with a minor in philosophy, at Earlham College and graduated in 1958. She planned to go on to graduate study in abstract mathematics. Instead, in 1959 she took a job at MIT writing weather-prediction software for the meteorologist Edward Lorenz. In 1961 she moved to MIT Lincoln Laboratory, where she wrote software for SAGE, the US air-defence system. One of her programs searched radar data for enemy aircraft.
Taking charge of Apollo
In 1965, at the MIT Instrumentation Laboratory, she became responsible for the onboard flight software of the Apollo command and lunar modules. To win respect for the work, she started calling it software engineering. She also thought hard about how things could go wrong. Her daughter Lauren once crashed the simulator by selecting program P01 at the wrong moment, and Hamilton flagged the risk. During Apollo 8 in 1968, astronaut Jim Lovell made the same mistake and erased navigation data. Her team worked out how to restore it.
The Apollo 11 alarms
In July 1969, minutes before the first Moon landing, the lunar module computer raised 1201 and 1202 overload alarms. Her priority scheduling dropped the low-priority tasks and kept landing guidance running, so the landing went ahead. That same year, MIT photographed her standing beside printouts of the Apollo source code, stacked as tall as she was. It became one of the best-known images in computing history.
After the Moon
Her division at Draper Laboratory went on to write flight software for Skylab, the first American space station. In 1976 she co-founded Higher Order Software with Saydean Zeldin. In 1986 she founded Hamilton Technologies, which developed the Universal Systems Language. Recognition came slowly but kept growing. NASA gave her its Exceptional Space Act Award in 2003, and in 2016 President Barack Obama awarded her the Presidential Medal of Freedom. Lego made a minifigure of her in 2017. In 2019 Google arranged thousands of mirrors in the Mojave Desert into a giant sunlit portrait of her.
You can follow every stage of her life and work in the Margaret Hamilton: Apollo Software Pioneer timeline.