Deep-space hibernation before comet rendezvous

An artist’s impression of Rosetta waking from deep-space hibernation to rendezvous with Comet 67P/Churyumov-Gerasimenko in 2014.

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).

After the third Earth-gravity assist and a large deep-space manoeuvre, the spacecraft will go into hibernation (July 2011 – January 2014). During this period, Rosetta will record its maximum distances from the Sun (about 800 million kilometres) and Earth (about 1 thousand million kilometres). The spacecraft will be reactivated prior to the comet-rendezvous manoeuvre, during which the thrusters will fire for several hours to slow the relative drift rate between the spacecraft and comet to about 25 m/s.