I think this might be a misunderstanding, the claim just shows up in a single CIA report about contemporary Soviet computer technology. Elsewhere[0] we read,

> Two new specific software languages known as "PROL-2" (used by the on-board computers) and "DIPOL" (used by ground computers using vehicle testing) [...] were developed for Buran

So I guess the what the CIA report refers to as Prolog is PROL-2. But is this really a Prolog variant? That seems like an unlikely choice of language for a real-time system.

Later, both of these languages developed into DRAKON [1], and looking at the Wikipedia page that language doesn't appear very Prolog-like, at least not superficially.

On the other hand, here[2] is a reddit comment that claims that is was indeed a Prolog variant, but it doesn't cite the source.

[0] https://books.google.com/books?id=qSwNBwAAQBAJ&pg=PT6&lpg=PT...

[1] https://en.wikipedia.org/wiki/DRAKON

[2] http://www.reddit.com/r/programming/comments/ujx7m/what_soft...

After my post I read up more and, like you, am now skeptical. I wonder if it's a case of someone mistaking PROL to be an abbreviation of prolog?

My old German university's web server was written in prolog, so it's not completeley inconceivable for a spacecraft, but I'd like to see more evidence.

Yes, that is my guess too. On the other hand, I would be _extremely_ interested to see a real-time Prolog dialect used to control real-life space shuttles, that's totally my aesthetic. :) But I can't understand Russian, which makes it difficult to research.