The New Horizon spacecraft, which was launched in 2006, has traveled more than 3 billion miles to reach Pluto. But the probe won’t orbit nor land on Pluto. Instead, it will keep flying, heading deeper into the Kuiper Belt, a region that scientists think is filled with hundreds of small, icy objects. The mission will complete what NASA calls the reconnaissance of the classical solar system, and it makes the U.S. the first nation to send a space probe to every planet from Mercury to Pluto.