Europe's Rosetta spacecraft set off on a collision course Thursday with the comet it orbited for two years, mission control said, nearing the end of an audacious quest to unravel the Solar System's mysteries.

"Next stop #67P!" the European Space Agency tweeted, confirming that the command for Rosetta to exit Comet 67P/Churyumov-Gerasimenko's orbit, and head for its surface, was delivered as planned.