In 2014, shortly after Rosetta's arrival at Comet 67P/Churyumov-Gerasimenko, the magnetometer on the Rosetta Plasma Consortium (RPC) suite of instruments, RPC-Mag, detected some surprising oscillations in the plasma surrounding the nucleus, revealing the comet's mysterious “song”.
Now, after two years of monitoring the plasma around the comet, the RPC team present a new song based on data collected during the entire mission, describing the comet's evolution from the point of view of Rosetta's magnetometer.
While the nucleus of Comet 67P/C-G is itself not magnetised, as measured by plasma instruments on both Rosetta and the lander Philae, it is embedded in the interplanetary magnetic field carried throughout the Solar System by the solar wind – a continuous flow of electrically charged particles streaming from the Sun. As the comet pours water vapour and other molecules into space, disturbing the solar wind, interesting phenomena take place in the surrounding plasma.
Analogy between the pile-up of the magnetic field near a comet nucleus and the pile-up of water in front of an obstacle. Image courtesy K-H Glassmeier
The interaction between comets and the solar wind had been studied in the past during the flybys of previous cometary missions, but Rosetta was the ...