Space probe "Rosetta" operated between 2014 and 2016 around comet 67P/Churyumov-Gerasimenko, collecting data on the comet’s dust, gas and plasma environment, its surface characteristics and its interior structure. As part of the analysis of some 76 000 high-resolution images captured with its OSIRIS camera, scientists have been looking for surface changes. In particular, they were interested in comparing the period of the comet’s closest approach to the Sun – known as perihelion – with that after this most active phase, to better understand the processes that drive surface evolution. Loose debris is seen all over the comet, but sometimes boulders have been caught in the act of being ejected into space, or rolling across the surface. Mission concluded on 30th september 2016, with the programmed crash of the orbiter upon the extraterrestrial object. Source: ESA