Comet 67P is indeed transmitting some kind of signal which has been confirmed on the ESA's own live streaming site in a post on November 11th, 2014 titled "Hear our comet sing".

   Rosetta’s Plasma Consortium (RPC) has uncovered a mysterious ‘song’ that Comet 67P/Churyumov-Gerasimenko is singing into space. The comet seems to be emitting a ‘song’ in the form of oscillations in the magnetic field in the comet’s environment. It is being sung at 40-50 millihertz, far below human hearing. To make the music audible to the human ear, the frequencies have been increased in this recording:   - ESA Live Stream


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