The television personality and science advocate was officially there for an Earth Day event, but he took the opportunity to talk to the president about space exploration, and specifically, a mission still in its infancy at NASA's Jet Propulsion Laboratory in La Cañada Flintridge that desperately needed funds.

NASA's Europa Clipper will take off on a long journey to Jupiter's moon Europa. The icy moon could potentially host alien life — and there's only one way to find out.