Rosetta, Europe's comet-chasing spacecraft, has woken from its sleep. A signal confirming its alert status was recognized by controllers in Darmstadt, Germany, at 18:17 GMT. Rosetta has spent the past 31 months in hibernation to preserve power as it arced beyond the orbit of Jupiter on a path that should take it to Comet 67P/Churyumov-Gerasimenko in August. Engineers will at the present poise the probe's trajectory and prepare its instruments for the daring encounter.
One of the highlights of the task will be the attempt to put a small robotic lander, Philae, on the exterior of the 4.5km-wide comet. This will happen in November. There were nail-biting moments in the Darmstadt control room as its flight engineers waited for the signal to come through. Three quarters of the way during the hour-long window of occasion, they got what they were waiting for. The signal restricted no spacecraft telemetry, but its mere receipt from 800 million km away confirmed to controllers that Rosetta's automated systems were operating as expected.