The CL-SPICE library I used, that wraps the SPICE C library through CFFI, doesn't cover the type of SPICE kernel that I wanted to use for the Comms module. I could try and add it, but it could be more involved than what I expected and put the thing on hold.

So I used the FORTRAN SDK for SPICE, since I had used it before, and it's reasonably small and easy. The alternative coud be using the C SDK, but I went with FORTRAN since I already had most of the code from a previous project.