I'm new to Lisp, having started SICP last month, but I can answer some. The space probes are probably just a standard serial port (RS-232 style UART), with som

I'm new to Lisp, having started SICP last month, but I can answer some. The space probes are probably just a standard serial port (RS-232 style UART), with some radio protocol that has good error correction/stability. In amateur radio, FT-8 is a slow, reliable, long distance serial protocol often used for hobbyist DX (long distance goal) communication. So likely, yes, they have a minimal shell or REPL-style debugger, where they can at least query variables, and change the machine state. Most aerospace devices use single-user Real Time Operating Systems, which have guaranteed timing on programs running, but to a technician end-user, the feeling is similar to an old Unix system, with similar tool names. You can deploy via compilation, with SBCL, or LLVM, etc. But I've mostly seen Lisp (well, I'm looking at Schemes, specifically) extending a compiled app. It's been pretty trivial connecting Racket to my compiled C functions, and I'll try Guile later, and for me it's mostly been a rapid-development tool to work with my WIP C library.