Scientists hope comet-chaser spacecraft wakes up

                        
A comet-chasing space probe is due to wake up from years of hibernation Monday, but scientists are facing an agonizing wait of several hours until the first signal reaches Earth.

Dormant systems on the unmanned Rosetta spacecraft will be switched back on at 11 a.m. (1000 GMT; 5 a.m. EST) in preparation for the final stage of its decade-long mission to rendezvous with comet 67P/Churyumov-Gerasimenko. They had been powered down in 2011 to conserve energy, leaving scientists in the dark about the probe's fate until now.                 

"We don't know the status of the spacecraft," said Paolo Ferri, head of mission operations at the European Space Agency. "There is a possibility that we're not going to hear anything. Two-and-a-half years are a long time. We're talking about sophisticated electronics and mechanics. We've taken all possible precautions for this not to happen but of course we cannot exclude that problems may have happened."                     

Rosetta, named after a block of stone that helped archeologists decipher ancient Egyptian hieroglyphs, will seek to help scientists unlock the composition of comets and thereby understand more about the origins and evolution of our solar system.                          

If all goes as planned, the probe will reach 67P in the coming months and drop a lander onto its icy surface in November.                            

The unprecedented mission is different from NASA's Deep Impact probe that fired a projectile into a comet in 2005 so scientists could study the resulting plume of matter. NASA also managed to land a probe on an asteroid in 2001, but comets are much more volatile places because they constantly release dust and gas that can harm a spacecraft.                            

The European Space Agency will bridge the time between Rosetta's alarm going off and the first signal traveling the 800 million kilometers (500 million miles) back to Earth by holding a social media competition. Space enthusiasts are being asked to compose and perform songs to "wake up Rosetta," with the winning entry being beamed to the spacecraft and witness the landing from ESA's mission control room.               

The agency says the earliest it might receive the probe's all-clear call is about 6.30 p.m. (1730 GMT; 12:30 p.m. EST). If no signal is received by Tuesday scientists will try to manually restart the probe from the ground. 


AP