You mean 1991 Elite Plus? The whole series has been reverse-engineered to death and back. Maybe you mean some other game?
Anyway, for those old titles I don't think not having source is that much of a problem. I participated in two reimplementations of 1994 XCOM : UFO2000 and OpenXcom, helped the 1oom project (first Master of Orion) and I don't think having original source would have helped much.
No, I'm doing the original 1987 PC Elite. The later one was written by Chris Sawyer. I asked him recently and he also has no idea about Andy who wrote the prior version (both for Realtime). [both versions I assume were written in 100% ASM] Surprisingly Gemini seems to be pretty good at writing 8088 CGA assembler, especially in Deep Think mode. It one-shot an entire filled poly renderer and 3D engine.
I worked with some of the original XCOM guys after a bunch of them left Microprose to set up on their own. I wrote a lot of the graphics engine for this, which was really a direct descendent of XCOM:
https://www.youtube.com/watch?v=9UOYps_3eM0