Next year is going to be an exciting one in space exploration. On Dec. 6, NASA’s New Horizons spacecraft woke up from hibernation more than 2.9 billion miles away from Earth. That puts it just over 162 million miles from Pluto, the focus of its mission – the very last planet in our solar system to be visited by a spacecraft.

New Horizons left Earth nearly nine years ago, and the craft has spent almost two-thirds of that time in one of 18 hibernation periods designed to keep its systems operational. But even though wake-ups have become routine, this one was special: It’s the last time the spacecraft needs to wake up before it gets to Pluto.

And what will it find there? It’s unknown, and that’s the most exciting part. The mission’s principal investigator, Alan Stern of the Southwest Research Institute, has said that New Horizons will radicalize our knowledge of Pluto in the way that Mariner 4’s flyby in 1965 changed our view of Mars.

For reference: Many people assumed that Mars was lush and full of water and life before that flyby, and were surprised to see the cold, red planet we now know well.

Pluto may have lost its full-fledged planetary status in recent years, but it has just as many secrets to reveal to NASA as the rest of the solar system’s bodies.

The real excitement will start on Jan. 15, when New Horizons gets close enough to Pluto to start taking measurements. By mid-May, the spacecraft should send home the best images we’ve ever had of the dwarf planet. To date, the best we have comes from the Hubble – and even that powerful telescope shows Pluto as a blurred splotch.

By July, the spacecraft will make its closest approach, coming within just a few thousand miles of the dwarf planet and its moons.