Margaret Hamilton, Who Led Apollo's Flight Software Team, Dies at 90

Margaret Hamilton, who led the team that wrote the on-board flight software for NASA's Apollo missions, died on September 30 at age 90, MIT News reported on October 7, 2026.

She joined MIT's Instrumentation Lab in 1965 as the first programmer on the Apollo project, according to MIT. By 1968 she was assistant director of the lab's Command and Service Module team, and more than 400 people worked on Apollo software under her.

The alarm that did not abort the landing

MIT's account of the Apollo 11 descent is specific. In July 1969, shortly before the Eagle landed, the guidance computer raised a 1202 alarm. It was overloaded, which MIT says was likely caused by a faulty hardware switch.

Hamilton's team had written priority-driven software that dropped non-essential tasks when the computer ran short of capacity. Houston approved the landing.

The same pattern appears in an earlier episode MIT calls the "Lauren error". Her young daughter accidentally started the P01 program during a simulator flight, which crashed it. Hamilton's proposed fix was overruled. On Apollo 8, in 1968, Jim Lovell launched P01 in flight, and her changes were then adopted. MIT cites it as an early example of defensive programming.

The code is public

The source is readable. The Apollo-11 repository on GitHub, maintained by Chris Garry, holds the Command Module code (Comanche055) and the Lunar Module code (Luminary099) and had 72.5k stars when we read it. It says the code was digitised by the Virtual AGC project and the MIT Museum, with the work performed by Paul Fjeld and arranged by Deborah Douglas of the museum.

Her name is in the files. The contract and approvals table lists "Margaret H. Hamilton" as "Colossus Programming Leader", dated March 28, 1969. The assembly stamps read 10:28 on April 1, 1969 for Comanche055 and 16:27 on July 14, 1969 for Luminary099.

Career before and after Apollo

Hamilton was born in 1936 in Paoli, Indiana, and took a mathematics degree at Earlham College in 1958. In 1959 she took a temporary MIT meteorology post, writing weather-prediction software for Edward N. Lorenz. In 1961 she joined MIT Lincoln Laboratory as a programmer on SAGE, the U.S. air defense system, where MIT says she became interested in software reliability.

She stayed at MIT until the mid-1970s. In 1976 she founded Higher Order Software, built around error prevention and fault tolerance. About a decade later she founded Hamilton Technologies, whose flagship product is the Universal Systems Language, a modelling language for complex software.

Year	Recognition	Source
2003	NASA Exceptional Space Act Award	MIT News
2016	Presidential Medal of Freedom	MIT News
2017	Computer History Museum Fellow Award	MIT News
2022	National Aviation Hall of Fame	MIT News

MIT says she authored more than 130 publications and helped establish software engineering as a discipline. Obama's 2016 citation said she "defined new forms of software engineering and helped launch an industry that would forever change human history."

What colleagues and Hamilton said

Olivier de Weck, MIT's Apollo Program Professor and interim head of Aeronautics and Astronautics, said she "has been an inspiration to generations of computer scientists and engineers." Jerry M. Wohletz, president and chief executive of Draper, the lab that grew out of the Instrumentation Lab, said she "left an indelible mark on Draper".

Hamilton told El País in 2018 that software "eventually and necessarily gained the same respect as any other discipline." Speaking to MIT News in 2009 about the Apollo years, she said: "Looking back, we were the luckiest people in the world."

She is survived by her daughter Lauren Hamilton, son-in-law Richard Selesnick, two grandsons and four great-grandchildren. A memorial service is planned for spring in Cambridge, Massachusetts. For present-day reliability work in widely used code, see our report on curl 8.23.0 and its 22 vulnerabilities and the Python 3.15 benchmarks.