"Rosetta launched in 2004 and will arrive at comet 67P/Churyumov-Gerasimenko on 6 August. It will be the first mission in history to rendezvous with a comet, escort it as it orbits the Sun, and deploy a lander to its surface. Rosetta is an ESA mission with contributions from its member states and NASA. Rosetta's Philae lander is provided by a consortium led by DLR, MPS, CNES and ASI."
http://rosetta.esa.int/
http://rosetta.esa.int/
Here is a video that shows Rosetta's journey from 2004 to present