In Their Own Words: Margaret Hamilton on Her Daughter's Simulation

Margaret Hamilton worked in computer science and software engineering for the Apollo Program and the MIT Instrumentation Lab / Draper.

"My daughter Lauren would often come to work with me at nights and weekends because we were all so dedicated. There wasn't a time when we weren't working. She liked to play astronaut because she saw me playing that way in certain simulations we would run. This was in a hardware simulation because we wanted to try how the software worked with all the other things—the astronaut, the hardware. So I remember one time when Lauren's simulation crashed and I thought, 'Oh my god, how did that happen?'

We checked it out and she had done something the astronaut was never supposed to do. Because, once you lift off prelaunch, you're now on the way. She selected P01 which was the prelaunch program during mid-course flight. So I went back and looked at the listing and sure enough that would be possible. So I brought it to the people, whoever was involved, saying this is amazing, look what happened. I don't know which people at NASA or MIT said, 'Well it's never going to happen because the astronauts are so well trained. It's just not going to happen.' I said but what if it does happen. My whole emphasis was always what if, right?

I wanted somebody to make the error detection recovery code saying, 'Hey, this is not the right time to select P01.' That's what the code would do. They kept saying, you know, it’s not going to happen. So I wrote a program note because that becomes part of the spec so the astronaut knows it's there. They can find it and the program notes said simply do not select one during flight. That's what the note said.

Well, the very next flight, Apollo 8, that's exactly what happened. After that they said, “Yes, Margaret, you can put that change in there.” So it did get in there for the very next mission.