Sci Fi for girls

I have a friend who loves _Podkayne of Mars_. I do not share her enthusiasm, but _The Ship Who Sang_ was the only other science fiction novel with female heroine that I could think of for that age group. Any other suggestions? (C.S. Lewis? Ursula LeGuin? I don't count the Pern books.)

If not, would one of you please write a science fiction novel with female heroine aimed at a teenage audience?