London, Jan 21 (IANS): Rosetta, the comet-chasing space probe launched by the European Space Agency a decade ago, has woken up from a 31-month long hibernation.

The mission operators heard from the distant spacecraft for the first time in 31 months Jan 20, said a press release from the European Space Agency (ESA).

Since its launch in 2004, Rosetta is chasing down a Comet named '67P/Churyumov-Gerasimenko'.

Operating on solar energy, Rosetta was placed into a deep space slumber in June 2011 as it cruised out to a distance of nearly 800 million km from the warmth of the sun - beyond the orbit of jupiter, said the release.

Now, as Rosetta's orbit has brought it back to within 'only' 673 million km from the sun, there is enough solar energy to power the spacecraft fully again.

Still about 9 million-km from the comet, Rosetta's pre-programmed internal 'alarm clock' has woken up the spacecraft.

After warming up its key navigation instruments, Rosetta sent a signal to let mission operators know it had survived the most distant part of its journey.

“We have our comet-chaser back,” Alvaro Giménez, ESA's director of science and robotic exploration, was quoted as saying.

“With Rosetta, we would take comet exploration to a new level,” he added.

Towards the end of May this year, the spacecraft would execute a major manoeuvre to line up for its critical rendezvous with the comet in August.