The trip to Pluto began in 2006, when New Horizons launched from Cape Canaveral, Fla. The spacecraft's Dec. 6 wake-up call is a big milestone—but not a particularly worrisome one for Alan Stern, the mission's principal investigator. After all, New Horizons has slept through 66 percent of its journey. "I don't think there's any worry in the project about whether the 18th time is different from the first 17," Stern said, speaking to reporters at the 46th annual Division for Planetary Sciences of the American Astronomical Society meeting in Tucson, Ariz. Stern, who calls the Pluto encounter the most exciting planetary reveal since Voyager 2 passed Neptune in 1989, said New Horizons' pre-programmed wakeup sequence begins at 3 p.m. EST (20:00 UTC). By 4:37 p.m., the spacecraft will be out of hibernation. It will transmit a thumbs-up signal back to Earth—a signal that won't reach home until about 9:30 p.m.

Alice Bowman, the New Horizons Mission Operations Manager, said the spacecraft will spend six weeks in a checkout phase. Ground controllers will conduct extensive checks of the probe's memory system. Two 10-gigabyte data recorders—one of which is a backup—will be formatted to hold more than 1,000 images captured during closest approach. Final command sequences will be uploaded, along with the latest Earth-calculated navigation data. "All of this is being done to prepare for the big show, which begins Jan. 15, 2015," Bowman said.

From January to April, instruments aboard New Horizons will scan Pluto as it slowly comes into focus. By May, images of the icy world will be better than those currently available from the Hubble Space Telescope. As New Horizons gets closer to the Pluto system, scientists will look for new moons and rings. They'll see how the solar wind affects the dwarf planet's atmosphere. And a high-resolution telescope will sweep the surface, looking for evidence of cryovolcanoes. Hal Weaver, a New Horizons project scientist, said that while the mission's best results will probably come from observations made around July 14, all of 2015 is game for scientific surprises." I really want to emphasize that we'll have lots of juicy science—historic science—accumulated well before the day of the closest approach," he said.