Rosetta, the European Space Agency's comet-chasing spacecraft sent back a signal to mission control on Monday.

The Rosetta hasn't been heard from in 31 months after being placed in hibernation until power needed to be restored, reports Fox News. Rosetta, which is supposed to rendezvous with the 67P/Churyumov-Gerasimenko comet, has been off since 2011.

The scientists at the ESA were nervous as they wouldn't find out the status of the spacecraft until it had completely turned back on and could orient itself in the right direction towards Earth. "There is a possibility that we're not going to hear anything," Paolo Ferri, head of ESA's mission controls, had said. "Two-and-a-half years are a long time."

According to Bloomberg, the Rosetta is supposed to reach the comet in August, where it will attempt to set a probe down and scientists hope to learn more about comets and how they fit into the universe.

Fox News notes Ferri said, "Over the millennia comets have affected our evolution. There are many theories about comets hitting the Earth and causing global catastrophes. So understanding comets is also important to see in the future what could be done to defend the Earth from comets."

The spacecraft will initially simply orbit the comet as it gets closer to the Sun and observe. Then Rosetta's Philae probe will attempt the first landing on a comet with the assistance of two harpoons.

image: Wikimedia Commons