Margaret Hamilton : The woman scientist behind the Apollo 11 moon landing

July 20th, 2016 marked the 47th anniversary of the Apollo 11 Lunar Landing, and the day that Neil Armstrong became the first man to walk on the moon. But did you know that Margaret Hamilton, director of software engineering for the project, saved the mission from near disaster? DiscovHER takes a look at this remarkable woman who worked behind the scenes on one of man’s most incredible feats.

Margaret Hamilton studied Mathematics at Earlham College, earning her B.A. in 1958. After a brief stint as a high school math and French teacher, she accepted an interim position at MIT in 1960. Her plan was to work until her husband earned his undergraduate degree, then enroll in a graduate program at Brandeis University for abstract mathematics. However, she excelled in her position, working on the SAGE Project, where she wrote software to search for “unfriendly” aircrafts during the Cold War, and her plans of returning to a graduate program disappeared.

Because of how well she did on the SAGE Project, she was recommended for the role of lead programmer on Apollo, to develop the software for landing the spacecraft. Programming in the 1960s was extremely tedious work, consisting of punching holes in cards to execute orders. However, the code would often include telling the computer to advance a certain number of cards – and if an extra card was added, or a card was taken out of the program due to changes, the computer would no longer end up on the right card, causing errors. Hamilton was aware of these difficulties and worked rigorously to test codes in order to avoid such problems.

Once the programs were created, they were run through a mainframe computer to simulate the Apollo lander and then sent to a team of seamstresses nicknamed the “Little Old Ladies” who would manually sew the code into magnetic rings. A wire threaded through the core was a 1, and a wire going around the core was a 0.

Hamilton’s dedication to rigorous testing was essential to the success of the Apollo landing, particularly the priority scheduling she developed. On July 20th, 1969, unexpected error messages began to pop up on the guidance computer, nearly cancelling the entire mission. The computer was being overloaded by incorrect calculations and was being asked to execute too many processes at once. However, due to Hamilton’s code, it was able to go through all the processes and prioritize which actions were the most important (landing the module), and it focused specifically on that. Without this foresight and attention to detail, the mission would have been aborted.

After her work for the Apollo 11 mission, Hamilton went on to found Higher Order Software, focused on developing error prevention strategies and Hamilton Technologies, Inc. She has received various awards, including the Augusta Ada Lovelace Award, by the Association for Women in Computing, in 1986 and the NASA Exceptional Space Act Award for scientific and technical contributions in 2003.

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