Comet 67P/Churyumov-Gerasimenko
Comet 67P/Churyumov-Gerasimenko was discovered in September 1969 by two Ukrainian astronomers at the Alma Ata astrophysical institute : Klim Ivanovich Churyumov and Svetlana Ivanova Gerasimenko.
This was a lucky chance, since the discovery plates had in fact been taken for the purpose of following comet 32P/Comas-Solà.
67P/Churyumov-Gerasimenko is a short pertiod comet which passes at perihelion about every 6,6 years, and whose nucleus is roughly 2 x 2 x 3 km in size.
A close encounter with Jupiter in February 1959 induced a large change in the cometary orbit, such that its perihelion distance (smallest heliocentric distance) faisant varier sa distance au périhélie (plus courte distance au Soleil) changed from 2,74 to 1,28 ua.
In view of the nature of its orbit, comet 67P is a member of the Jupiter family, since its aphelion (farthest point f rom the Sun) remains in the neighbourhood of the orbit of Jupiter.
Takin from the Agenda astronomique 2014, Institut de mécanique céleste et de calcul des éphémérides de l’Observatoire de Paris, EDP sciences, p. 124
Rosetta’s target
The Rosetta probe will arrive at comet Churyumov-Gerasimenko (67P) at the beginning of August 2014.
Comets eject considerable quantities of granular material (meteoroids) which remains in the vicinity of the cometary nucleus. In order to minimize the risk of an impact with the probe, it is essential to find the distribution of this material.
The adjoining figure shows the cometary nucleus (red star) in the centre of the dust cloud ejected by the comet. The largest particles (several centimetres in size) are shown in yellow and blue, while the millimetre size particles are in white. The Rosetta probes is shown as a red triange.
As can be seen in this 3-d view, the probe does not enter the meteoritic swarm of the comet. However, it will have to do this sooner or later, in order to deposit the lander Philae.
Taken from the Agenda astronomique 2014, Institut de mécanique céleste et de calcul des éphémérides de l’Observatoire de Paris, EDP sciences, p. 110