Mir is common world for peace in some parts of the world. Russian space program (or better space station) is/was just one of the projects using this word as codename.

I think this is nice change to have codename forged from "foreign" word and to make "native" speakers see there is a lot more in this world beyond english language. Bottom line in some parts of the world when you say mir i assure you this is not associated directly with space stations.