Nov 12, 2014 11:28 AM
Cosmic 1st: European spacecraft lands on comet
The Associated Press
DARMSTADT, Germany (AP) Hundreds of millions of miles from Earth, a European spacecraft made history Wednesday by successfully landing on the icy, dusty surface of a speeding comet an audacious first designed to answer big questions about the universe.
The landing on comet 67P/Churyumov-Gerasimenko required immense precision, as even the slightest error could have thrown the spacecraft far off course and imperiled the mission. In the end, the touchdown of the Philae lander appeared to be almost perfectly on target, said Paolo Ferri, head of mission operations for the European Space Agency.
"Everyone cried," he told reporters at mission control in Darmstadt, Germany.
Scientists at the agency first had to sweat through a tense seven-hour countdown 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 (66,000 kph).
During the lander's descent, scientists were powerless to do anything but watch, because its vast distance from Earth 500 million kilometers (311 million miles) made it impossible to send instructions in real time.
Finally, at 1603 GMT (11:03 a.m. EST), the agency received a signal that the washing machine-sized lander had touched down on the comet's icy surface.
While further checks were needed to ascertain the 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.
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 mission will also give researchers the opportunity to test the theory that comets brought organic matter and water to Earth billions of years ago, said Klim Churyumov, one of the two astronomers who discovered the comet in 1969.
Rosetta and Philae will accompany the comet as it races past the sun and becomes increasingly active in the rising temperatures. Between them, they will use 21 different instruments to collect data that scientists hope will help explain the origins and evolution of celestial bodies, and maybe even life on Earth.
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, using solar panels to eke out an extra hour of operations each day.
Although Philae made a gentle landing and seems to be stable, two harpoons that were meant to anchor it to the comet appeared not to have fired, he said. One thing scientists are keen to avoid is having the lander drift off into space in the comet's low-gravity environment.
Ferri said communications with the lander needed to be stabilized, as there were intermittent connection problems after the touchdown. In the meantime, all the data that Philae collects is safely being stored for later transmission, he said.
Wednesday's landing capped a 6.4 billion-kilometer (4 billion-mile) journey that began a decade ago. Rosetta, which was launched in 2004, had to slingshot three times around Earth and once around Mars before it could work up enough speed to chase down the comet, which it reached in August. Rosetta and the comet have been traveling in tandem ever since.
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Geir Moulson in Berlin contributed to this report.