these other big political thorny problems, there's lots of folks already working on it. i could add my voice, but i would have very little to contribute. whereas, if you look at the areas where society isn't worried, where we've shrugged it off, those are the areas where you might actually make a difference. so it's important, whether it's inventing technology for people that no one else seems to care enough about to invent technology for, or threats from rare but potentially very significant things like new epidemics or bioterror, it's in those area that is you can really add value by paying some attention, by focusing on it and a little bit being a gadfly and bothering people and saying, hey, pay attention. >> nathan myhrvold, pleasure to have you on. >> thank you. next on "gps," we'll stay extraterrestrial but this story may have a happy ending. why science is excited about a moon many millions of miles away. i'll explain when we come back.