by Dorothy Piper
Lex Simms is an alien who lives near Leeds, while most of his folks live on Mars. They are amazing creatures but they can't produce the water they need to survive. Preemo, their leader, sends members of his family to Earth in 1965 to breed with humans and have children who will visit Mars and terraform it. As soon as he is twelve, Lex embarks upon his mission, but then a comet messes up his plans.