An artist’s impression of Rosetta and its Philae lander approaching the target comet.

Rosetta’s 11-year expedition began in March 2004, with an Ariane 5 launch from Kourou in French Guiana, and the spacecraft was then sent towards the outer Solar System. The long journey includes three gravity assists at Earth (2004, 2007, 2009), one at Mars (2007), and two asteroid encounters: (2867) Steins (2008) and (21) Lutetia (2010).

Rosetta will reach Comet 67P/Churyumov-Gerasimenko in 2014, and will be the first mission ever to orbit a comet’s nucleus and to deliver a lander, called Philae, on its surface.