Rosetta spacecraft phones home

An image of the Rosetta spacecraft Keystone

After almost three years of hibernation, the comet-chasing space probe Rosetta has woken up and sent a message to its creators at the European Space Agency, some 800 million kilometres (500 million miles) away.

“Hello World” was the message received by scientists shortly after 7 p.m. Swiss time (1800 GMT) on Monday.

“It was a little bit late, about half an hour or so, but if you sleep for 2 ½ years that’s understandable,” said Peter Wurz, a co-investigator on the Rosetta mission for the University of Bern.

“It was really cold, and the spacecraft had to wake up,” he told swissinfo.ch. “It’s like us. When it’s cold we take a little while to open our eyes.”

Rosetta, which was put into conservation mode in 2011, is on the way to a rendez-vous with the comet 67P/Churyumov-Gerasimenko. The two are expected to meet up in the coming months.

Rosetta will spend some time observing the comet, which measures about 4 kilometres in diameter, before dropping a lander to collect and analyse samples in November.

The scientists hope to better understand the composition of comets and the origins of our solar system.