She has become our most frequent guest. It's no wonder. The Cassini mission regularly solves old mysteries and uncovers new ones about Saturn, its moons, and its rings. Emily Lakdawalla says the moon is KREEPy. Bill Nye closes out a big week with his commentary. Bruce Betts returns from the not yet launch of Space Shuttle Endeavour and unveils a new What's Up? space trivia contest.