A long time ago, I read and enjoyed Ron Garret's story of using Lisp at the Jet Propulsion Laboratory. Now, he retells the story in a Google Talk that is well worth watching. Part of the story explains how they were able to debug a problem when the DS1 spacecraft was a 10 or 45 (it's not clear from the video) light minutes round trip away because the Lisp image that was running the program had a REPL.
Another story involved the Galileo magnetometer that was controlled by a Forth program. One of the bytes on the computer running Forth went bad so the engineers had to modify the program to avoid using the bad byte. The problem was that the program was originally developed using an Apple II Forth environment and the Apple II systems had long since been decommissioned. They solved this problem by recreating the entire Apple II Forth environment in Lisp.
If you enjoy hearing Lisp stories or stories about space flight and exploration then you should invest 70 minutes and watch the video.