After a number of flybys at short-period comets, the detailed properties of the gas and dust emission from a comet nucleus remain still obscure: we do not know whether the most abundant molecules and the dust are emitted as a uniform mixture, or with different (position dependent) relative abundances, nor whether the production is about uniform over the surface, or restricted to discrete areas. This ignorance follows from the lack of experimental data: e.g., complete nucleus shape and spin state of any comet nucleus has not yet been determined, no near nucleus coma observation has ever been conducted over a time longer than a fraction of the rotation period, nor at successive positions over the orbit. The ESA Rosetta Mission to the short-period comet 67P will soon fill this gap, but to interpret the most significant observations (i.e. images and in-situ samplings of the innermost part of the coma) requires the use of the whole set of inhomogeneous time-dependent dusty gas vacuum outflow modeling techniques. It is hoped, on the basis of the past pioneering works done by Kitamura, Rodionov-Zakharov-Crifo (RZC in short), and the “Swiss-Taiwanese-German” group (STG in short), that it will be possible to answer the questions mentioned above by trial-and-error fits to the observations, playing with the nucleus surface gas and dust flux maps as unknowns.

Image credit: M. Fulle