When you think about it, Lisp is perfect for their use cases. Pushing patches live without rebooting and easy modification of a running system image while running.

What use cases?

There were a lot of Lisp systems for Space Shuttles which were not needing such a feature.

Examples:

'Automating Planning and Scheduling of Shuttle Payload Operation'

http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.96....

'The objective of EMPRESS (expert mission planning and replanning scheduling system) is to support the planning and scheduling required to prepare science and application payloads for flight aboard the US Space Shuttle. EMPRESS was designed and implemented in Zetalisp on a 3600 series Symbolics LISP machine. Initially, EMPRESS was built as a concept demonstration system.'

https://ieeexplore.ieee.org/document/17369

'NASA used Symbolics' high-definition technology to analyze HDTV video images of the Discovery launch in real-time. This high-definition system enabled NASA engineers to get an instant replay of critical launch systems.'

ftp://ftp.ai.sri.com/pub/mailing-lists/slug/900531/msg00199.html

'An Intelligent Training System for Flight Controllers Space Shuttle'

http://www.aaai.org/Papers/IAAI/1989/IAAI89-021.pdf

and so on...

https://news.ycombinator.com/item?id=19952974

Remote Agent was a part of the Deep Space 1 space mission...