Comets are icy bodies remnants of the earliest moments of the solar
system formation and that are now studied in details by space missions.
The most recent spacecraft, Rosetta, has ended its studies in September
2016 after having landed Philae for the first time on the surface of a
cometary nucleus and followed 67P on its orbit for more than two Earth
years. The on-board scientific instruments have demonstrated the
sporadic behavior of the cometary activity as a function of its orbital
properties. Cameras have unveiled an irregular surface prone to erosion
and deposition of dust, with few spots of ice detected on its surface.
Dust particles detectors have shown that two types of solid particles
are ejected by the nucleus, one being dense and compact grains and the
other being very fluffy irregular dust particles. No specific structures
inside the cometary nucleus were detected by instruments sounding inside
the nucleus, and the very low density of the cometary material (0.5
g.cm-3) remains difficult to explain. Gaseous particles ejected by the
comet contain a high fraction of O2 and complex carbonaceous molecules
like glycine, an amino acid that was first detected in situ by Rosetta.
We will review the results from the whole Rosetta/Philae mission and
describe in details what we have learned about these objects.
Local contact: V. Lebouteiller