Well, I was thinking of Christian themes rather than specifically Catholic ones. I haven’t got a list in my head of Catholic science fiction writers.
Arthur C. Clarke is interested in many of the big questions of life, and those are the things he talks about. I am actually not sure of his religious affiliation, but in several books he has Christian characters who put forth fairly well understood Christian responses to the situation at hand. I recall in one of the RAMA books one of the characters, a Roman Catholic, is being sent to investigate the alien ship and has questions about what that could mean for his faith.
C.S. Lewis was of course a very orthodox Anglican, and much as his Narnia books for children are a kind of Christian allegory, so are his science fiction books for adults.
Madeline L’Engle was also an Anglican - and her understanding of the nature of humanity, it’s essential goodness, redemption and sacrifice, all reflect that closely. Those are the main themes of her books. So to I think does her vision of family life which is quite compelling. One of her children’s books, Many Waters, is set around the Great Flood of Noah - it’s quite a fantastic treatment but explores the themes of the story in an interesting way.
(As an aside, her autobiographical story of her marriage is one of the best books there is, IMO, on Christian marriage and what it should be and can mean.)
I think you are missing much that is important in literature given you understanding of science fiction. Science fiction and fantasy do tend to put things into alternate worlds, or the future, but always as a way of serving the authors desire to describe something that he thinks is true about the world, humanity, or God. If the person is a Christian, what is depicted will reflect that, sometimes very effectively and powerfully.
It seems to me you would have to reject many other Christian, and even Catholic, classic works. The Divine Comedy, Pilgrim’s Progress… neither of which takes place in the “real” world.