There's George R.R. Martin's "The Way of Cross and Dragon," but I read it so long ago that I wouldn't be able to say whether it was good or not. (I also enjoyed The Sparrow at the time, so obviously past!me is not a reliable gauge of quality!) Oh! A Canticle for Leibowitz is of course a classic, though not in space.

Orson Scott Card wrote setting-changed Space!AU for the Book of Mormon, but that's not quite the same :) (and I wouldn't really recommend it to someone who doesn't know original canon :) )