What is "moonwind"

Moonwind is a 1986 science fiction novel by English author Louise Lawrence about two teenagers winning a trip to the moon. One of them, Gareth, a rebellious Welsh child, falls in love with an alien, Bethkahn, after the two meet on a couple of brief encounters. In the final pages of the book Gareth walks out onto the moon to his death, just before shouting "I am here, Bethkahn"