Margaret Hamilton (scientist)

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Margaret Hamilton
Margaret Hamilton 1995.jpg
Margaret Hamilton in 1995.
Born 1936 (age 78–79)
Education Earlham College
Occupation CEO of Hamilton Technologies, Inc.
Computer scientist
Spouse(s) James Cox Hamilton

Margaret Heafield Hamilton (born 1936)[1] is a computer scientist, systems engineer, and business owner. She was Director of the Software Engineering Division of the MIT Instrumentation Laboratory, which developed on-board flight software for the Apollo space program.[2] Hamilton's work prevented an abort of the Apollo 11 moon landing.[3] In 1986, she became the founder and CEO of Hamilton Technologies, Inc. in Cambridge, Massachusetts. The company was developed around the Universal Systems Language based on her paradigm of Development Before the Fact (DBTF) for systems and software design.[4]

Hamilton has published over 130 papers, proceedings, and reports concerned with the 60 projects and 6 major programs in which she has been involved.

Early life[edit]

Margaret Heafield was born to Kenneth Heafield and Ruth Esther Heafield (née Partington).[5] She graduated from Hancock High School in 1954 and earned a B.A. in mathematics with a minor in philosophy from Earlham College in 1958.[6] After graduation, she briefly taught high school math and French while her husband finished earning his undergraduate degree. She moved to Boston, Massachusetts with the intention of doing graduate study in abstract mathematics at Brandeis University, but instead she took a job as a programmer at MIT in 1960 for a professor who did research in meteorology.[1] At that time, computer science and software engineering were not yet disciplines; instead learning was done on the job with hands on experience.[2]

From 1961 to 1963, she worked for Philco-Ford's Sage Project, which used radar to track unknown aircrafts and also programmed for the Air Force Cambridge Research Laboratory.


Hamilton during her time as lead Apollo flight software designer.

Hamilton then joined the Charles Stark Draper Laboratory at MIT, which at the time was working on the Apollo space mission.[7] She became the director and supervisor of software programming[8] in 1965.

At NASA Hamilton was responsible for helping pioneer the Apollo on-board guidance software required to navigate and land on the moon, and its multiple variations used on numerous missions (including the subsequent Skylab).[2] She worked to gain hands-on experience during a time when computer science and software engineering courses or disciplines were non-existent.

In the process, she produced innovations in the fields of system design and software development, enterprise and process modelling, development paradigm, formal systems modelling languages, system-oriented objects for systems modelling and development, automated life-cycle environments, methods for maximizing software reliability and reuse, domain analysis, correctness by built-in language properties, open-architecture techniques for robust systems, full life-cycle automation, quality assurance, seamless integration, error detection and recovery techniques, man/machine interface systems, operating systems, end-to-end testing techniques, and life-cycle management techniques.[2]

She developed concepts of asynchronous software, priority scheduling, and Human-in-the-loop decision capability, which became the foundation for modern, ultra-reliable software design.

Apollo 11[edit]

Margaret Hamilton during the Apollo Program.

Hamilton's work prevented an abort of the Apollo 11 moon landing:[3] Three minutes before the Lunar lander reached the Moon's surface, several computer alarms were triggered. The computer was overloaded with incoming data, because the rendezvous radar system (not necessary for landing) updated an involuntary counter in the computer, which stole cycles from the computer. Due to its robust architecture, the computer was able to keep running; the Apollo onboard flight software was developed using an asynchronous executive so that higher priority jobs (important for landing) could interrupt lower priority jobs. Initially, the fault had been attributed to a faulty checklist and the radar being erroneously activated by the crew, but a 2005 re-analysis concluded that a hardware design error in the rendezvous radar provided the computer with faulty information even while in standby mode.[9]

Due to an error in the checklist manual, the rendezvous radar switch was placed in the wrong position. This caused it to send erroneous signals to the computer. The result was that the computer was being asked to perform all of its normal functions for landing while receiving an extra load of spurious data which used up 15% of its time. The computer (or rather the software in it) was smart enough to recognize that it was being asked to perform more tasks than it should be performing. It then sent out an alarm, which meant to the astronaut, I'm overloaded with more tasks than I should be doing at this time and I'm going to keep only the more important tasks; i.e., the ones needed for landing ... Actually, the computer was programmed to do more than recognize error conditions. A complete set of recovery programs was incorporated into the software. The software's action, in this case, was to eliminate lower priority tasks and re-establish the more important ones ... If the computer hadn't recognized this problem and taken recovery action, I doubt if Apollo 11 would have been the successful moon landing it was.

—Margaret Hamilton, Letter to Datamation, March 1, 1971[10]


In 1977, Hamilton and Saydeen Zeldin founded a company called Higher Order Software that evolved into a product called USE.IT.[11] The software they designed was intended to catch bugs before they happened, a systems design model known as Development Before the Fact (DBTF).

In 1986, she became the founder and CEO of Hamilton Technologies, Inc. in Cambridge, Massachusetts. The company was developed around the Universal Systems Language based on her paradigm of Development Before The Fact for systems and software design.[12]


Official photo for NASA, 1989.

Hamilton is credited for coining the term “software engineering”.[13] In this field she pioneered the concepts of asynchronous software, priority scheduling, end-to-end testing, and human-in-the-loop decision capability, such as priority displays which then became the foundation for ultra reliable software design.[14]

Personal life[edit]

She met her husband James Cox Hamilton while at Earlham College. They married in the late 1950s after Heafield earned her bachelor's degree. They had a daughter together named Lauren.[15] The couple subsequently divorced.[15]


  • 2003, NASA Exceptional Space Act Award for scientific and technical contributions. The award included $37,200, the largest amount awarded to any individual in NASA's history.[3][14][16]


  • M. Hamilton, S. Zeldin (1976) "Higher order software—A methodology for defining software" IEEE Transactions on Software Engineering, vol. SE-2, no. 1, Mar. 1976.
  • M. Hamilton (1994), “Inside Development Before the Fact,” cover story, Special Editorial Supplement, 8ES-24ES. Electronic Design, Apr. 1994.
  • M. Hamilton (1994), "001: A Full Life Cycle Systems Engineering and Software Development Environment," cover story, Special Editorial Supplement, 22ES-30ES. Electronic Design, Jun. 1994.
  • M. Hamilton, Hackler, W. R.. (2004), Deeply Integrated Guidance Navigation Unit (DI-GNU) Common Software Architecture Principles (revised dec-29-04), DAAAE30-02-D-1020 and DAAB07-98-D-H502/0180, Picatinny Arsenal, NJ, 2003-2004.
  • M. Hamilton and W. R. Hackler (2007), “Universal Systems Language for Preventative Systems Engineering,” Proc. 5th Ann. Conf. Systems Eng. Res. (CSER), Stevens Institute of Technology, Mar. 2007, paper #36.
  • M. Hamilton and W. R. Hackler (2007), “A Formal Universal Systems Semantics for SysML, !7th Annual International Symposium, INCOSE 2007, San Diego, CA, Jun. 2007.
  • M. Hamilton and W. R. Hackler (2008), "Universal Systems Language: Lessons Learned from Apollo", IEEE Computer, Dec. 2008.


  1. ^ a b Tiffany K. Wayne (2011). American Women of Science Since 1900. ABC-CLIO. pp. 480–1. ISBN 978-1-59884-158-9. 
  2. ^ a b c d NASA Office of Logic Design "About Margaret Hamilton" (Last Revised: February 03, 2010)
  3. ^ a b c Michael Braukus NASA News "NASA Honors Apollo Engineer" (Sept. 3, 2003)
  4. ^ M. Hamilton, W.R. Hackler (December 2008). "Universal Systems Language: Lessons Learned from Apollo". IEEE Computer. doi:10.1109/MC.2008.541. 
  5. ^ "Ruth Esther Heafield". Wujek-Calcaterra & Sons. Retrieved December 15, 2014. 
  6. ^ a b c "2009 Outstanding Alumni and Distinguished Service Awards". Earlham College. Retrieved December 15, 2014. 
  7. ^ Huber, Hartmut G. M. (August 1987). Higher Order Software - Evaluation and Critique. Washington, D.C. Retrieved 23 December 2014. 
  8. ^ "Margaret Hamilton". Cambridge Women's Heritage Project. Retrieved 23 December 2014. 
  9. ^ Eyles, Don (February 6, 2004). "Tales from the Lunar Module Guidance Computer". 27th annual Guidance and Control Conference. Breckenridge, CO: American Astronautical Society. Retrieved June 13, 2013. 
  10. ^ Hamilton, Margaret H. (March 1, 1971). "Computer Got Loaded". Datamation (Letter) (Cahners Publishing Company). ISSN 0011-6963. 
  11. ^ Rowena Barrett (1 June 2004). Management, Labour Process and Software Development: Reality Bites. Routledge. p. 42. ISBN 978-1-134-36117-5. 
  12. ^ M. Hamilton, W.R. Hackler (December 2008). "Universal Systems Language: Lessons Learned from Apollo". IEEE Computer. doi:10.1109/MC.2008.541. 
  13. ^ Rayl, A.J.S. (October 16, 2008). "NASA Engineers and Scientists-Transforming Dreams Into Reality". NASA. Retrieved December 27, 2014. 
  14. ^ a b NASA Press Release "NASA Honors Apollo Engineer" (September 03, 2003)
  15. ^ a b Stickgold, Emma (August 31, 2014). "James Cox Hamilton, at 77; lawyer was quiet warrior for First Amendment". Boston Globe. Retrieved December 15, 2014. 
  16. ^ NASA Administrator Sean O'Keefe has commented saying “The concepts she and her team created became the building blocks for modern software engineering. It's an honor to recognize Ms. Hamilton for her extraordinary contributions to NASA.”.