Day to Day
<iframe src="http://www.npr.org/player/embed/4724753/4724754" width="100%" height="290" frameborder="0" scrolling="no" title="NPR embedded audio player">
A U.S. space probe called Deep Impact may collide with a comet this Sunday — on purpose. Alex Chadwick talks to Ira Flatow, host of NPR's Talk of the Nation Science Friday, about what scientists hope to gain from this unique mission.
NPR thanks our sponsors
Become an NPR sponsor