In 1994 JPL started working on the Remote Agent (RA), an autonomous spacecraft control system. RA was written entirely in Common Lisp despite unrelenting political pressure to move to C++. At one point an attempt was made to port one part of the system (the planner) to C++. This attempt had to be abandoned after a year. Based on this experience I think it's safe to say that if not for Lisp the Remote Agent would have failed.
We used four different Common Lisps in the course of the Remote Agent project: MCL, Allegro, Harlequin, and CLisp. These ran in various combinations on three different operating systems: MacOS, SunOS, and vxWorks. Harlequin was the Lisp that eventually flew on the spacecraft. Most of the ground development was done in MCL and Allegro. (CLisp was also ported to vxWorks, and probably would have been the flight Lisp but for the fact that it lacked threads.) We moved code effortlessly back and forth among these systems.
The Remote Agent software, running on a custom port of Harlequin Common Lisp, flew aboard Deep Space 1 (DS1), the first mission of NASA's New Millennium program. Remote Agent controlled DS1 for two days in May of 1999. During that time we were able to debug and fix a race condition that had not shown up during ground testing. (Debugging a program running on a $100M piece of hardware that is 100 million miles away is an interesting experience. Having a read-eval-print loop running on the spacecraft proved invaluable in finding and fixing the problem. The story of the Remote Agent bug is an interesting one in and of itself.)
The Remote Agent was subsequently named "NASA Software of the Year".