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Rosetta: The awakening of a comet chaser


SOMEWHERE IN THE FRIGID BLACKNESS of deep space, a hunter and thief is preparing to be stirred from her slumber. She has spent ten long years chasing down her quarry and now, after a journey of almost seven billion kilometres, she is on the brink of ensnaring her quarry.

When Rosetta set out she was hopeless out-paced by her target, but, after four tours of the inner Solar System (stealing gravitational energy from the planets she encountered along the way) her speed of more than 135,000kph is more than a match for the object in her sights.

But the hunt has been exhausting and, millions of kilometres from home, the Sun has been too weak to sustain her, so, for the last two-and-a-half years she has been hibernating – rationing her reserves for the final pursuit. Now the time has come to for her to awaken and, back on Earth, her handlers at the European Space Agency are waiting for the alarm to go off. 

On Monday, January 20, Rosetta's internal alarm will sound and trigger a process that, if all goes according to plan, will spark up circuits, turn on heaters and trigger instruments – waking the hunter at precisely 10am. 

Assuming she does wake up, Rosetta will then begin a series of manoeuvres that, over the coming months, will see her fall into line behind the comet, catch up and then enter into an orbit around the 5km-wide lump of rock and ice. Once there, she will map the surface of Comet 67P/Churyumov-Gerasimenko and unleash her ‘hound’, Philae.

Philae is armed with a harpoon that it will use to spear the comet and secure itself to the surface – becoming the first spacecraft to make a soft landing on a comet . Once there, the probe will deploy a drill to extract samples to be studied by its panoply of scientific instruments.

But that all lies in the future and, after two-and-a-half years sleeping in the freezer, it will take some time for Rosetta’s instruments fully wake-up and send a message to Earth – so it will be several tense hours before her operators know that the huntress has even survived her hibernation.