  We study the dynamics of the interaction between the solar wind ions and a
partially ionized atmosphere around a comet, at a distance of 2.88 AU from the
sun during a period of low nucleus activity. Comparing particle data and mag-
netic field data for a case study, we highlight the prime role of the solar
wind electric field in the cometary ion dynamics. Cometary ion and solar wind
proton flow directions evolve in a correlated manner, as expected from the
theory of mass loading. We find that the main component of the acceler- ated
cometary ion flow direction is along the anti-sunward direction, and not along
the convective electric field direc- tion. This is interpreted as the effect of
an anti-sunward polarisation electric field adding up to the solar wind con-
vective electric field.
