It was brought to life to chase comets but has been asleep for 31 months, drifting beyond the orbit of Jupiter. Yesterday (Jan. 20), the European spacecraft Rosetta successfully turned itself on. The craft had been powered down to save energy, but is now closer to the sun and the comet that it was designed to approach and land on later this year, Comet 67P/Churyumov-Gerasimenko. After turning itself it called home to signal that all was well. It also tweeted, "Hello, world!"