Next month's wake-up call was pre-programmed into New Horizons' on-board computer in August, commanding it come out of hibernation December 6.

Work on the Earth is well under way to prepare the spacecraft for a six-month encounter with Pluto that begins January next year, NASA said in statement.

"New Horizons is healthy and cruising quietly through deep space - nearly three billion miles from home but its rest is nearly over," says Alice Bowman, New Horizons mission operations manager at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland.

"It is time for New Horizons to wake up, get to work, and start making history," Bowman added.

Since its launch in January 2006, New Horizons has spent 1,873 days in hibernation about two-thirds of its flight time "spread over 18 separate hibernation periods from mid-2007 to late 2014 that ranged from 36 days to 202 days long".

In hibernation mode much of the spacecraft is underpowered; the onboard flight computer monitors system health and broadcasts a weekly beacon-status tone back to Earth.

"The final hibernation wake up December 6 signifies the end of an historic cruise across the entirety of our planetary system," added New Horizons principal investigator Alan Stern from Southwest Research Institute.

"We are almost on Pluto's doorstep!" Stern added.

Distant observations of the Pluto system begin January 15 and will continue until late July 2015; closest approach to Pluto is July 14.

The USD 700 million (Rs.4,329.85 crore) mission should help lift the veil on Pluto, which has remained largely mysterious since its 1930 discovery because it is so small, dim and distant, Space.com reported.

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