At http://phys.org/print347187952.html … the Rosetta saga continues – it has now experienced significant buffeting and difficulties over controls as Rosetta swoops low across comet Churyumov-Gerasimenko, so much so that such close encounters may have to be curtailed in the future. It encountered a dense outflow of gases and dust particles that temporary caused scientists on earth to lose control of the spaceship.
See also the mission web site – and the link http://sci.esa.int/where_is_rosetta/