UPDATE: Rosetta calls home: Signal received from comet-hunting spacecraft

Above: After years of hibernation in deep space, scientists at the European Space Agency were jumping for joy as Rosetta — a probe they plan to land on a comet — finally wakes up. Robin Gill explains.

TORONTO – After 31 months of sleep, the European Space Agency’s (ESA) Rosetta spacecraft is awake and ready to do its science.

Rosetta is en route to the Comet 67P/Churyumov-Gerasimenko where it will study the composition of the comet and its environment.

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Rosetta was put into hibernation on June 8, 2011. Only the computer and heaters were active as it travelled from 660 million km from the sun to 790 million km and back.

READ MORE: European Space Agency sets tentative date for 1st comet landing Nov. 2014

It wasn’t the ESA that established contact with the spacecraft, but rather the other way around: the agency waited patiently for the first signal from Rosetta, which finally communicated at 1:18 p.m. EST. The signal was received by NASA’s Goldstone ground station in California.

“We have our comet-chaser back,” says Alvaro Giménez, ESA’s Director of Science and Robotic Exploration. “With Rosetta, we will take comet exploration to a new level. This incredible mission continues our history of ‘firsts’ at comets, building on the technological and scientific achievements of our first deep space mission Giotto, which returned the first close-up images of a comet nucleus as it flew past Halley in 1986.”

Rosetta is named after a block of stone that allowed archaeologists to decipher ancient Egyptian hieroglyphs. Scientists hope the probe’s findings will help them understand the composition of comets and thereby discover more about the origins and evolution of our solar system.

Many scientists believe that comets are responsible for bringing water to Earth, thereby starting the process of life as we know it. Like asteroids, comets also pose a danger of colliding with Earth.

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“Over the millennia comets have actually affected our evolution,” said Paolo Ferri,head of mission operations at the ESA.

“There are many theories about comets hitting the Earth and causing global catastrophes. So understanding comets is also important to see in the future what could be done to defend the Earth from comets.”

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If all goes well with Rosetta, the spacecraft will meet up with Comet 67/P Churyumov-Gerasimenko over the next few months and in November, will drop its lander Philae onto its icy surface to analyze the comet’s composition.

Rosetta was launched on March 2, 2004. In order to place it in orbit around the comet, it needed to conduct four gravity assist manouvres: three from Earth and one from Mars.

A gravity assist uses the gravity of planets to accelerate a spacecraft.

— with files from The Associated Press