Sat, Jan 25, 2014 - Page 9 News List

Rosetta the comet-chasing spacecraft wakes up

After its three-year slumber, the probe is ready to chase down a comet and place a robot on its surface

By Stuart Clark in Darmstadt and Ian Sample  /  The Guardian, LONDON

Now that Rosetta has woken up, mission controllers can beam the probe a series of commands to ensure that subsystems and 21 scientific instruments aboard the spacecraft and Philae are in working order. Once they are happy that Rosetta has emerged from hibernation in good health, they can fire the spacecraft’s thrusters to close the gap of 9 million kilometers that separate machine and comet.

The mission ahead promises a spectacular demonstration of relative motion that could only be improved by the accompaniment of The Blue Danube.

The comet is traveling at 60,000 kilometers per hour relative to the sun, but Rosetta will close up from behind at walking pace. Alas, in space, no one can hear Strauss.

“It’s like driving on the M25 when the traffic is moving,” Taylor said. “You are shooting along, but the car overtaking will come past you ever so slowly.”

Rosetta is expected to send back its first images of the comet in May when it is still 2 million kilometers behind. At the end of May, mission controllers will send up commands for a major maneuver that will line Rosetta up for a rendezvous with the comet in August.

Once Rosetta has reached the comet, the probe will begin to scan the surface for a suitable place to drop its lander.

On Nov. 11, mission controllers aim to give the spacecraft the all clear to drop off the 100kg lander.

The lander is expected to take one or two hours to reach the comet, another move that will play out at walking pace as the comet, Rosetta and Philae all hurtle towards the sun at around 16km per second. Rosetta must get into an orbit that minimizes any sideways movement for the lander relative to the comet, so it does not tumble or slide when it lands.

If Philae touches down safely, it will beam back a panorama of its extraordinary environment, along with high resolution images of the face of the comet.

Though Philae is expected to die when its electronics overheat from use, the lander may hold fast to the comet and ride it around the sun for three laps before enough material breaks off to dislodge its harpoon.

“We will face many challenges this year as we explore the unknown territory of comet 67P/Churyumov-Gerasimenko, and I’m sure there will be plenty of surprises, but today we are just extremely happy to be back on speaking terms with our spacecraft,” Taylor said.

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