I read this book in the mid to late 80's. All I remember is that there are humans living on a space station (or possibly on the Moon) above an Earth that was devastated by some disaster. It is forbidden for anyone to go to Earth. A young boy steals a shuttle and goes to Earth and meets a young girl for some adventures. I recall that there was a pet involved, but I don't remember if it came with the boy from the space station or if it belonged to the girl.
I recall the book as being rather light fare and not hard sci-fi or heavy drama. I likely read it around 1986 when I was 13 or 14.