Sleepy space probe New Horizons awakens for close-up with Pluto

Three billion miles away from Earth, in an unchartered slice of our solar system, a small space probe is shaking off its deep sleep and getting ready to become the first spacecraft to visit Pluto and its moons.

It's the "beginning of the mission's primary objective: the exploration of Pluto and its many moons in 2015," said Alan Stern, New Horizons principal investigator from Southwest Research Institute, Boulder, Colorado, in a NASA news release.

NASA's New Horizons spacecraft was launched on January 19, 2006. It's down to the final 162 million miles of its journey and will arrive July 14, 2015. New Horizons has had 18 hibernation periods totaling 1,873 days to save wear and tear on its components. This was its last nap.

Mission operators at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, say a preprogrammed command ordered the spacecraft to switch from hibernation to "active" at 9:53 p.m. (EST) December 6.

"This is a big deal. It means the start of our pre-encounter operations," said Glen Fountain, New Horizons project manager at APL.

The mission managers will spend several weeks checking out the spacecraft and testing computer commands to guide New Horizons through the rest of its flight.

The probe is 27 inches (0.7 meters) tall, 83 inches (2.1 meters) long and 108 inches (2.7 meters) wide. It weighed 1,054 pounds (478 kilograms) at launch.

New Horizons is packed with cameras and other instruments, and it should start sending back glimpses of Pluto on January 15. By mid-May, we should get "better than Hubble" photos. Until now, the best image we've had of Pluto is a pixilated photo from the Hubble Space Telescope. We'll also see Pluto's five moons: Charon, Nix, Hydra, Kerberos and Styx.

New Horizons was launched before the big debate started over whether it's a planet. For the scientists on the New Horizons team, Pluto is very much a planet -- just a new kind of planet.

"New Horizons is on a journey to a new class of planets we've never seen, in a place we've never been before," says New Horizons Project Scientist Hal Weaver of APL. "For decades, we thought Pluto was this odd little body on the planetary outskirts; now we know it's really a gateway to an entire region of new worlds in the Kuiper Belt, and New Horizons is going to provide the first close-up look at them."