A Journey of 4 Billion Miles Ends (with video)

Comet could provide key cosmic answers

EUROPEAN SPACE AGENCY/Courtesy<br>The Philae lander of the European Space Agency’s Rosetta mission took this self-portrait of the spacecraft on Oct. 7 at a distance of 10 miles from comet 67P/Churyumov–Gerasimenko.  The image, taken with Philae’s CIVA camera, captures the side of the Rosetta spacecraft and one of Rosetta’s 46-foot-long solar wings, with the comet in the background. Two images with different exposure times were combined to bring out the faint details in this very high contrast situation. The comet’s active “neck” region is clearly visible, with streams of dust and gas extending away from the surface.

EUROPEAN SPACE AGENCY/Courtesy<br>The Philae lander of the European Space Agency’s Rosetta mission took this self-portrait of the spacecraft on Oct. 7 at a distance of 10 miles from comet 67P/Churyumov–Gerasimenko.  The image, taken with Philae’s CIVA camera, captures the side of the Rosetta spacecraft and one of Rosetta’s 46-foot-long solar wings, with the comet in the background. Two images with different exposure times were combined to bring out the faint details in this very high contrast situation. The comet’s active “neck” region is clearly visible, with streams of dust and gas extending away from the surface.

DARMSTADT, Germany (AP) - Landing with a bounce after traveling 4 billion miles, a European spacecraft made history Wednesday by successfully reaching the icy, dusty surface of a speeding comet - a cosmic first designed to answer big questions about the universe.

The landing by the washing machine-sized crafter after a decade-long journey required immense precision, as even the slightest error could have resulted in stellar calamity.

Indications were that the spacecraft touched down almost perfectly, save for an unplanned bounce, said Stephan Ulamec, head of the lander operation.

"Today we didn't just land once. We maybe even landed twice," he said with a chuckle.

Ulamec said thrusters that were meant to push the lander, called Philae, onto the surface, and harpoons that would have anchored it to the comet failed to deploy properly. Initial data from the spacecraft indicated that it lifted off again, turned and then came to rest.

Scientists were still trying to fully understand what happened and whether those failures would affect the lander's ability to remain on the comet, called 67P/Churyumov-Gerasimenko. But so far, most of the instruments were working fine and sending back data as hoped, Ulamec said.

"Tomorrow morning we should know a lot more," he said.

The landing team at mission control in Darmstadt had to sweat through a tense seven-hour wait that began when Philae dropped from the agency's Rosetta space probe as both it and the comet hurtled through space at 41,000 mph.

During the lander's descent, scientists were powerless to do anything but watch, because its vast distance from Earth - more than 300 million miles - made it impossible to send instructions in real time.

Finally, at 16:03 GMT (11:03 a.m. EST), the agency received a signal that the lander had touched down.

While it may take a while to determine the exact state of the 220-pound (100-kilogram) lander, the fact that it was resting on the surface of the comet was already a huge success - the highlight of Rosetta's decade-long mission to study comets and learn more about the origins of these celestial bodies.

The head of the European Space Agency underlined Europe's pride in having achieved a unique first ahead of its U.S. counterpart, NASA.

Scientists have likened the trillion or so comets in our solar system to time capsules that are virtually unchanged since the earliest moments of the universe.

"By studying one in enormous detail, we can hope to unlock the puzzle of all of the others," said Mark McCaughrean, a senior scientific adviser to the mission.

The insight gleaned will give researchers the opportunity to test the theory that comets brought organic matter and water to Earth billions of years ago, giving them a key role in the evolution of life on our planet, said Klim Churyumov, one of the two astronomers who discovered the comet in 1969.

Rosetta and Philae will accompany the 2½-mile wide comet as it races past the sun and becomes increasingly active in the rising temperatures. Between them, they will use 21 different instruments to take 3D images, analyze the comet's chemical composition and electrical properties, and even probe its internal structure with low-frequency radio signals.

Mission manager Paolo Ferri said there was no time to celebrate, because the lander had only enough battery power to operate for up to 64 hours. After that it will have to recharge.

Mobile users click here for ESA video illustrating Rosetta mission