I think it was C.S. Lewis that said something like the following, but I can’t find the actual quote. He supposed that it would be no stretch for other beings to exist in the universe. He also figured that they may live in their own paradise untouched by sin. But then he brings up his mixed feelings about that. While it would be great to live in paradise (and in constant relationship with God), then one would never know the grace and forgiveness and redemption of God.
I wish I could find the quote. I did find another interesting conversation:
Wirt: Do you think there will be widespread travel in space?
Lewis: “I look forward with horror to contact with the other inhabited planets, if there are such. We would only transport to them all of our sin and our acquisitiveness, and establish a new colonialism. I can’t bear to think of it. But if we on earth were to get right with God, of course, all would be changed. Once we find ourselves spiritually awakened, we can go to outer space and take the good things with us. That is quite a different matter.”
In that same article it said that Lewis and Tolkein were discussing space travel and time travel one evening. After much discussion they each agreed to write about one of the topics. They flipped a coin to see who would get which topic, and Lewis got space travel. He ended up writing much about it - Tolkein never got around to his writing about time travel! (Or at least that is what the article said.)
My understanding is that Lewis had to write about being in another space we’ve never been to,never been to, which resulted in the Space Trilogy. Tolkien had to write about a time we’ve never had, which resulted in the LOTR.