Wakey, wakey. Rosetta, the European probe that was in deep sleep just woke up. It is gearing up for an unprecedented comet rendezvous and landing this year that will cap a 10 year voyage across the solar system.

Rosetta has been asleep for two and a half years. It woke up after cruising nearly 673 million kilometers from the sun. Rosetta took hours to wake up, as it switched on heaters to warm itself after many many cold nights in space.

"We made it!" Andrea Accomazzo, Rosetta's spacecraft operations manager, shouted in exultation in a webcast. "We can definitely see a signal from Rosetta!"

The first signal from Rosetta was received by NASA's Deep Space Network at 1:18 p.m. EST (1818 GMT) and relayed to ESA's Space Operations Center in Darmstadt, Germany, which erupted in cheers and applause as the signal was confirmed.

Rosetta's first message home via Twitter: "Hello, world!"

The signal came after 18 minutes of tense silence as Rosetta's mission team awaited word from the spacecraft.

"We have our comet-chaser back," said Alvaro Gimenez, ESA's Director of Science and Robotic Exploration, in a statement. "With Rosetta, we will take comet exploration to a new level."