Comet 67P/Churyumov-Gerasimenko is a large dirty snowball that orbits the Sun once every 6.6 years.
During this time, it commutes between the orbits of Jupiter and the Earth. However, little is known about it, despite its regular visits to the inner Solar System.
Most of the time, its faint image is drowned in a sea of stars, making observations with Earth-based telescopes extremely difficult.
However, during its short-lived excursions to the inner Solar System, the warmth of the Sun causes ices on its surface to evaporate and jets of gas to blast dust grains into the surrounding space.
Unfortunately, although this enveloping ‘coma’ of dust and gas increases 67P/Churyumov-Gerasimenko’s brightness, it also completely hides the comet’s nucleus.
Rosetta's task is to rendezvous with the comet while it still lingers in the cold regions of the Solar System and shows no surface activity.
After releasing a lander onto the dormant nucleus, the orbiter will chase Comet Churyumov-Gerasimenko as it charges headlong towards the inner Solar System at speeds of over to 100 000 kilometres per hour.
Over an entire year, as it approaches the Sun, Rosetta will orbit the comet, mapping its surface and studying changes in its activity.
As its ices evaporate, instruments on board the orbiter will study the dust and gas particles which surround the comet and trail behind it as streaming tails, as well as their interaction with the solar wind.
|Diameter of nucleus (km)||4|
|Orbital period (years)||6.6|
|Minimum distance from Sun (million km)||186|
|Maximum distance from Sun (million km)||857|
|Orbital inclination (degrees)||7.1|
|Year of discovery||1969|
|Discoverers||K. Churyumov, University of Kiev, Ukraine|
|S. Gerasimenko, Institute of Astrophysics, Dushanbe, Tajikistan|
Last update: 14 November 2013