Search Publications
Observations of Modulation of Ion Flux in the Coma of Comet 67P/Churyumov-Gerasimenko
Altwegg, K.; Nilsson, H.; Goldstein, R. +4 more
On 6-8 June 2015, the Ion and Electron Sensor on board Rosetta observed keV-range water-group pickup ions arriving from the solar direction. Based on magnetic field intensification and variations, the appearance of the ions was likely to have been caused by a coronal mass ejection. During the 3-day period when Rosetta was 200 km from the comet, pe…
Momentum and Pressure Balance of a Comet Ionosphere
Nilsson, H.; Goetz, C.; Richter, I. +3 more
We calculate the momentum flux and pressure of ions measured by the Ion Composition Analyzer (ICA) on the Rosetta mission at comet 67P/Churyumov-Gerasimenko. The total momentum flux stays roughly constant over the mission, but the contributions of different ion populations change depending on heliocentric distance. The magnetic pressure, calculate…
Singing Comet Waves in a Solar Wind Convective Electric Field Frame
Goetz, C.; Taylor, M. G. G. T.; Plaschke, F.
The cometary plasma environment at low gas production rates is dominated by highly compressional, large-amplitude magnetic field waves in the 10-100 mHz range. They are thought to be caused by an ion-Weibel instability due to a cross-field current, which is caused by the cometary ions that are accelerated along the solar wind convective electric f…
Simultaneous Observation of Negatively and Positively Charged Nanograins at Comet 67P/Churyumov-Gerasimenko
Goldstein, R.; Goetz, Charlotte; LLera, K. +1 more
Observations near comet 67P by Rosetta show evidence of charged nanograins. Specifically, the ion and electron sensor (IES) observed negative particles with energy/charge (E/q) consistent with charged nanograins. However, theory predicts that both polarities should be present. On 19 September 2014, IES detected positively and negatively charged pa…
Migrating Scarps as a Significant Driver for Cometary Surface Evolution
Soderblom, J. M.; Davidsson, B.; Oklay, N. +10 more
Rosetta observations of 67P/Churyumov-Gerasimenko (67P) reveal that most changes occur in the fallback-generated smooth terrains, vast deposits of granular material blanketing the comet's northern hemisphere. These changes express themselves both morphologically and spectrally across the nucleus, yet we lack a model that describes their formation …
The Rocky-Like Behavior of Cometary Landslides on 67P/Churyumov-Gerasimenko
Bertaux, Jean-Loup; Da Deppo, Vania; Naletto, Giampiero +36 more
Landslides have been identified on several solar system bodies, and different mechanisms have been proposed to explain their runout length. We analyze images from the Rosetta mission and report the global characterization of such features on comet 67P/Churyumov-Gerasimenko's surface. By assuming the height to runout length as an approximation for …
Extremely Low-Frequency Waves Inside the Diamagnetic Cavity of Comet 67P/Churyumov-Gerasimenko
Gunell, H.; Eriksson, A.; Karlsson, T. +7 more
The European Space Agency/Rosetta mission to comet 67P/Churyumov-Gerasimenko has provided several hundred observations of the cometary diamagnetic cavity induced by the interaction between outgassed cometary particles, cometary ions, and the solar wind magnetic field. Here we present the first electric field measurements of four preperihelion and …
Rosetta measurements of lower hybrid frequency range electric field oscillations in the plasma environment of comet 67P
Nilsson, H.; André, M.; Karlsson, T. +6 more
Electric field measurements from cometary environments are very rare but can provide important information on how plasma waves help fashion the plasma environment. The long dwelling time of the Rosetta spacecraft close to comet 67P/Churyumov-Gerasimenko promises to improve this state. We here present the first electric field measurements from 67P,…
Mass loading at 67P/Churyumov-Gerasimenko: A case study
Behar, E.; Nilsson, H.; Richter, I. +3 more
We study the dynamics of the interaction between the solar wind ions and a partially ionized atmosphere around a comet, at a distance of 2.88 AU from the Sun during a period of low nucleus activity. Comparing particle data and magnetic field data for a case study, we highlight the prime role of the solar wind electric field in the cometary ion dyn…
Spatial distribution of low-energy plasma around comet 67P/CG from Rosetta measurements
Glassmeier, K. -H.; Szego, K.; Nilsson, H. +22 more
We use measurements from the Rosetta plasma consortium Langmuir probe and mutual impedance probe to study the spatial distribution of low-energy plasma in the near-nucleus coma of comet 67P/Churyumov-Gerasimenko. The spatial distribution is highly structured with the highest density in the summer hemisphere and above the region connecting the two …