The spacecraft launched by the National Aeronautics and Space Administration (NASA) in January 2006 to study Pluto up close is now awake to prepare for the key parts of its mission.

After travelling 3 billion miles from Earth for almost nine years, the New Horizons robotic probe awoke from hibernation on Dec. 6, after a preset program alarmed and roused it from electronic slumber at 3 p.m. EST.

The control team on Earth, however, received confirmation that the spacecraft was already in active mode after 9:30 p.m. owing to New Horizons' distance from Earth. Radio signals from the craft travel at the speed of light but because the probe is so far away, the signals take four hours and 25 minutes to reach Earth.

"This is a watershed event that signals the end of New Horizons crossing of a vast ocean of space to the very frontier of our solar system, and the beginning of the mission's primary objective: the exploration of Pluto and its many moons in 2015," said New Horizons principal investigator Alan Stern.

New Horizons spent most of the past nine years in hibernation mode in order to conserve power, reduce operational costs and reduce the wear and tear of the electronics it has onboard, but it will now remain awake to make the necessary preparations ahead of Jan. 15, when it is set to start making long-range observations of Pluto.

The spacecraft is still about 162 million miles away from the dwarf planet but as it gets nearer Pluto, its observations are expected to improve. By May 2015, the spacecraft will send images of Pluto, which will be sharper than the best photos taken by NASA's Hubble Space Telescope.

Pluto was still considered a planet when the spacecraft was launched in 2006. Later that same year, however, the International Astronomical Union (IAU) reclassified Pluto as a dwarf planet.

New Horizons will take photos of Pluto and its moons, but while the dwarf planet is known to have five moons, close range observations of New Horizons may reveal that it has more moons and even icy rings.

New Horizons will get nearest Pluto on July 15. During this month, the space probe may also possibly catch sight of clouds and ice volcanoes that scientists think exist in Pluto. After Pluto, the spacecraft may also proceed to study another icy object in the Kuiper belt.