The impressive jets of dust that comets emit into space during their journey around the Sun are not driven solely by the sublimation of frozen water. In some cases further processes augment the outbreaks. Possible scenarios include the release of pressurized gas stored below the surface or the conversion of one kind of frozen water into an energetically more favourable one. These are the findings of a study headed by scientists of the Max Planck Institute for Solar System Research who examined a dust jet from Rosetta’s comet 67P/Chruyumov-Gerasimenko that occurred last year.