UK & World News
Rosetta: Comet-Chasing Craft's Wake-Up Call
A snoozing spacecraft set the ambitious target of landing on a comet at nearly 25,000mph is being woken from hibernation.
Scientists at the European Space Agency (ESA) sounded Rosetta's internal alarm clock to reboot the mission after two-and-a-half years of deep space slumber.
Once its systems warm up, Rosetta is due to beam a signal back to Earth before it begins to home in on a frozen rock known as 67P/Churyumov-Gerasimenko.
It is due to shoot harpoons into the 2.5-mile dirtball before its Philae lander docks on the surface - a move that has never been attempted before.
ESA project scientist Matt Taylor likened the mission to that of the action film Armageddon, in which Bruce Willis lands on an asteroid to save the world from destruction.
"We're not just landing on the Moon, we're dealing with something dynamic, which is kicking off tonnes of dust and gas every minute," he told the Sunday Telegraph.
Because Rosetta, which has been sleeping to save power, is so far from Earth, it will take 45 minutes for its signal to reach scientists at mission control.
They expect to see a blip on computer monitors between 1730 and 1830 GMT, indicating the spacecraft is up and running again.
Dr Dan Andrews, a planetary scientist at the Open University in Milton Keynes, said: "We're waiting to hear Rosetta is alive and healthy.
"This wake-up call kicks off a chain of events, during which the spacecraft heats itself up, points itself towards the Sun and gets itself ready.
"Remember, this mission is 10 years old - it's a bit of a stroppy teenager and it's going to take a while to wake up."
If all goes to plan, Rosetta will arrive at Churyumov-Gerasimenko in August before descending to the comet several months later.
Dr Andrews described the spacecraft's lander as an "awesome" piece of engineering and said it is equipped with a range of tools similar to those geologists would use on Earth.
The Philae probe and its orbiter will study the plume of gas and water vapour that will boil off and trail behind as the comet nears the Sun.
If the chemical signature of hydrogen matches that found in water on Earth, it will strongly suggest comets filled the oceans when they smashed into the planet billions of years ago.
Around half of the experiments on board involve British scientists, while the craft itself was designed and built by engineers at Astrium UK.
Ralph Cordey, head of science at the company, said: "It's interesting enough ... to actually design, build and launch a spacecraft, but to then see it travel around the solar system for 10 years to get to where it is now is just something else."
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