Comets are the primitive building blocks of the Solar System and the likely source of much of Earth’s water, perhaps even delivering to Earth the ingredients that helped life evolve.
By studying the nature of a comet close up with an orbiter and lander, Rosetta will show us more about the role of comets in the evolution of the Solar System.
Rosetta was launched on 2 March 2004, and through a complex series of flybys – three times past Earth and once past Mars – set course to its destination: comet 67P/Churyumov–Gerasimenko. It also flew by and imaged two asteroids, Steins on 5 September 2008 and Lutetia on 10 July 2010.
In July 2011 Rosetta was put into deep-space hibernation for the coldest, most distant leg of the journey as it travelled some 800 million kilometres from the Sun, close to the orbit of Jupiter. The spacecraft was oriented so that its solar wings faced the Sun to receive as much sunlight as possible, and it was placed into a slow spin to maintain stability.
Now, as both the comet and the spacecraft are on the return journey back into the inner Solar System, the Rosetta team is preparing for the spacecraft to wake up.
