NASA's unprecedented mission to Pluto has now begun counting down the final year of its almost decade-long, three-billion-mile journey.
The New Horizons Pluto-Kuiper Belt Mission launched an unmanned spacecraft to Pluto in January 2006. This week, mission engineers tested its systems, nudged the small spacecraft into a better trajectory, and announced that it is on track to fly by Pluto one year from now, with the closest approach expected in mid-July 2015.
Pluto is the only planet in our solar system that has never been explored by a space probe, NASA points out. The mission to Pluto and its moon Charon -- sometimes considered a twin planet -- will explore the mysterious, icy worlds at the edge of our solar system and help scientists learn more about the origin and evolution of our distant planetary neighbors.
Pluto is part of the Kuiper Belt, the outer ring of the solar system containing countless chunks of space ice of varying sizes.
In February 2007 the New Horizons spacecraft used Jupiter to slingshot it with a gravitational boost toward Pluto, cutting three years off the trip. Like any good tourist, New Horizons sent back photos from interesting locations, including dramatic pictures of a volcanic eruption on one of Jupiter's moons and the stunning montage image below of Jupiter and its moon Io.