BERLIN — Waking up after almost three years of hibernation, a comet-chasing spacecraft sent its first signal back to Earth on Monday, prompting cheers from scientists who hope to use it to drop the first space lander onto a comet.
The European Space Agency received the all-clear message from its Rosetta spacecraft at 1:18 p.m. EST — a message that had to travel about 500 million miles.
Dormant systems on the spacecraft were switched back on in preparation for the final stage of its decadelong mission to rendezvous with the comet named 67P/Churyumov-Gerasimenko. Systems had been powered down in 2011 to conserve energy, leaving scientists in the dark about the probe's fate until now.
Scientists at the space agency's mission control room in Darmstadt, Germany, will now take control of Rosetta again, a procedure slowed by the 45 minutes it takes a signal to travel to or from the spacecraft, said Andrea Accomazzo, the spacecraft's operations manager.
The wake-up call is one of the final milestones for Rosetta before it makes its rendezvous with comet 67P in the summer. The probe will fly a series of maneuvers to observe the comet — a lump of rock and ice about 2 ½ miles in diameter — before dropping a lander onto its icy surface in November. The lander will dig up samples and analyze them with its instruments.
Scientists hope the mission will help them understand the composition of comets and thereby discover more about the origins and evolution of our solar system.