Guests: Alan Stern, David Grinspoon

NASA’s New Horizons spaceship launched in 2006 to visit tiny Pluto at edge of our solar system, the longest journey ever attempted. The plutonium-powered spacecraft traveled three billion miles over nine years, zooming by Pluto in 2015, and was the fastest probe ever built.  The spacecraft gathered data and took pictures of the icy planet and its moons. It’s still flying and sending back information from the frigid Kuiper Belt. New Horizons mission leader, ALAN STERN, and astrobiologist, DAVID GRINSPOON, join Marty to talk about the mission, the close calls that nearly sidelined the 26-year-long project, and what we’re learning about the Pluto system. Their new book is, Chasing New Horizons: Inside the Epic First Mission to Pluto.