Space engineers report that they have now received a signal from the Rosetta spacecraft, which has been sleeping for more than two years. Launched from the Guiana Space Centre in French Guiana in March, 2004, Rosetta is on a 10-year mission to Comet 67P/Churyumov-Gerasimenko. The spacecraft was placed in a hibernation mode in June, 2011. The wake-up procedure began at 4 a.m. CST (10:00 UTC) this morning with four alarm clocks on board Rosetta set to go off, triggering a series of changes aboard the spacecraft that would result in its antenna pointing toward Earth and sending a signal our way. That signal has now been received. The video below, made in advance of the event, shows what happened when Rosetta woke up.

Rosetta is currently over 500 million miles (800 million kilometers) away.

Rosetta will study Comet 67P/Churyumov-Gerasimenko – called “67P” for short, by astronomers – up close as it enters the inner solar system. If all goes well, it will be the first spacecraft to orbit a comet’s nucleus and the first lander to do a controlled touchdown on the surface of a comet. The comet is just a few kilometers across.

Space engineers believe Rosetta’s navigation camera could glimpse the comet from a distance of 100,000 kilometers by March, 2014. After course correction in May, the probe will be set to rendezvous with 67P/Churyumov-Gerasimenko in August, enter an orbit around the comet and accompany it as it heads towards the sun over the following months.

Why is this craft named Rosetta? The idea is that comets provide a window back in time to the formation of the solar system, just as the Rosetta Stone let us look back in time on Earth.

Comet 67P/Churyumov-Gerasimenko, here we come!

Follow the Rosetta mission at @ESA_Rosetta on Twitter.

Bottom line: Rosetta spacecraft is awake!