Margaret Hamilton

Margaret Elaine Heafield was born in Paoli, Indiana, to a poet father and, further back, a headmaster grandfather — she credits the pair of them for the philosophy minor she took alongside mathematics. The family moved to Michigan, where she finished high school in 1954. She spent a year at the University of Michigan, then transferred to Earlham College, where her mother had studied and where the head of the mathematics department, Florence Long, pushed her toward abstract mathematics and a professor's life. She graduated in 1958, married that June, taught high school mathematics and French for a short spell in Boston, Indiana, and moved to Massachusetts intending to start graduate work at Brandeis. She never did. In mid-1959 she took a job writing weather-prediction code for Edward Lorenz.

The Lorenz work fed into chaos theory, and she trained her own replacement when she left. From 1961 to 1963 she wrote software at MIT Lincoln Lab for the SAGE air-defense system, where the initiation rite was a program nobody had ever made run, whose author had written all his comments in Greek and Latin. She got it working. It printed its answers in Greek and Latin. In 1965 she joined the MIT Instrumentation Laboratory as the first programmer hired for Apollo there, and rose to direct the Software Engineering Division, responsible for all the onboard flight software in the command and lunar modules and later Skylab. She designed the error detection and recovery scheme and the priority displays. Then she built two companies on the same ideas, in 1976 and 1986.

The story that gets told is that her code saved the landing. The record is messier and better. Three minutes above the surface the guidance computer threw alarms because the rendezvous radar was drawing incorrectly phased power and flooding it with interrupts. Whether the crew had left a switch on is disputed — Robert Wills of the National Museum of Computing rejects that account. Aldrin's call for altitude data was the eighth program on a machine designed for seven. The software shed the low-priority work and kept the landing tasks, which is what she had built it to do. Her priority displays carried a hazard of their own: the switchover ran a step behind the screen, so an astronaut who pressed too fast would get the previous answer. Her fix was to tell them to count to five.

For decades the software was credited to MIT and to NASA rather than to anyone in particular. NASA gave her its Exceptional Space Act Award in 2003, with 37,200 dollars attached, the largest sum it had ever paid an individual. Barack Obama gave her the Presidential Medal of Freedom in 2016. A Lego set of NASA women followed in 2017, her minifigure standing beside a small replica of the photograph of her next to a stack of Apollo listings taller than she is. In 2019 Google aimed the mirrors of the Ivanpah solar plant to draw her portrait in moonlight. The word she made up for a joke is now the name of the job several million people do.

Margaret Hamilton's life against the full span of the corpus — the fading end marks a life still in progress.

• Weather-prediction software for Edward Lorenz other
  Written on an LGP-30 and a PDP-1 — the work fed into chaos theory 1959
• SAGE air-defense software other
  Written at MIT Lincoln Lab for the prototype AN/FSQ-7 1961
• Apollo onboard flight software invention
  Command module, lunar module and later Skylab, with the priority displays she designed 1969
• Higher Order Software company
  Founded with Saydean Zeldin around error prevention, and its USE.IT product 1976
• Hamilton Technologies company
  Built around the Universal Systems Language and the 001 Tool Suite 1986
• Universal Systems Language invention
  Designed to keep errors out of a system rather than test for them afterward 1986

• June 15, 1958 aged 21 Graduates from Earlham in mathematics and marries James Cox Hamilton She taught high school mathematics and French in Boston, Indiana, for a term.
• 1959 aged ~23 Takes a job writing weather software for Edward Lorenz instead of starting graduate school
• 1961 aged ~25 Joins the SAGE project at MIT Lincoln Lab The hazing program she was handed came commented in Greek and Latin. She made it run.
• 1965 aged ~29 Becomes the first programmer hired for Apollo at the MIT Instrumentation Laboratory
• July 20, 1969 aged 32 Her priority displays interrupt the crew three minutes above the lunar surface The computer shed low-priority tasks and kept the ones needed to land.
• 1976 aged ~40 Co-founds Higher Order Software with Saydean Zeldin
• March 1986 aged 49 Founds Hamilton Technologies in Cambridge, Massachusetts
• 2003 aged ~67 Receives NASA's Exceptional Space Act Award, 34 years after the landing The 37,200 dollars attached was the largest NASA had given an individual.
• November 22, 2016 aged 80 Barack Obama awards her the Presidential Medal of Freedom

• Neil Armstrong 1930–2012
  Astronaut who commanded Apollo 11 and became the first person to set foot on the lunar surface. wrote the code his crew flew on
• Buzz Aldrin b. 1930
  Apollo 11 lunar module pilot and second person to walk on the Moon. triggered the alarms she had planned for
• Grace Hopper 1906–1992
  Computer scientist and Navy rear admiral who helped develop early programming languages and computing. the other founder of the profession
• Katherine Johnson 1918–2020
  NASA mathematician whose orbital trajectory calculations supported the Mercury and Apollo crewed flights. did the same arithmetic by other means
• Frances Allen 1932–2020
  Pioneered compiler optimization at IBM and was the first woman to receive the Turing Award. contemporary in compiler research
• Wernher von Braun 1912–1977
  German-American aerospace engineer who led the development of the Saturn V rocket that took humans to the Moon. built the rocket her software steered