Astounding Ion Propulsion Nearly Has Dawn to Ceres

NASA's unique Dawn spacecraft has already traveled more than three billion miles since its 2007 launch, and has made some serious changes in course after visiting a mysterious protoplanet, known as Vesta. And yet, it's still far from being out of fuel. How can this be? In a new video from NASA, experts at the Jet Propulsion Laboratory explain the wonders of ion propulsion.