The properties of the singing comet waves in the 67P/Churyumov-Gerasimenko plasma environment as observed by the Rosetta mission
Résumé
While previous cometary missions were only limited to flybys, the groundbreaking ESA/Rosetta mission escorted comet 67P for two years. This enabled for the first time to make in situ measurements of the evolution of a comet's plasma environment. On one hand, low time resolution electron densities are calculated using the plasma frequency extracted from the mutual impedance spectra measured by the RPC-Mutual Impedance Probe (MIP). On the other hand, high time resolution fluctuations of spacecraft potential and ion current are measured by the RPC-Langmuir Probe (LAP). Thus, we perform a MIP-LAP cross-calibration using a spacecraft charging model to retrieve high time resolution electron density fluctuations throughout the entire mission (whenever both the required MIP and LAP operations and data allow). This new dataset will be available to the scientific community on the ESA/PSA around Summer 2019, however it is already available for specific cases of interest. Here, we make use of these data, together with RPC-MAG magnetic field measurements, to investigate in detail the properties of the low-frequency so-called "singing comet" waves observed in the plasma environment of 67P, making use of a change in the wave activity before and during a cometary brightness outburst on February 19, 2016.