Cometary plasma science

Goetz, Charlotte; Gunell, H.; Volwerk, M.; Beth, Arnaud; Eriksson, Anders; Galand, M.; Henri, Pierre; Nilsson, Hans; Wedlund, Cyril Simon; Alho, Markku; Andersson, L.; André, Nicolas; Keyser, Johan De; Deca, Jan; Ge, Yasong; Glaßmeier, K.‐H.; Hajra, Rajkumar; Karlsson, Torgny; Kasahara, Satoshi; Kolmašová, Ivana; LLera, Kristie; Madanian, Hadi; Mann, Ingrid; Mazelle, C.; Odelstad, Elias; Plaschke, Ferdinand; Rubin, Martin; Sánchez‐Cano, Beatriz; Snodgrass, C.; Vigren, Erik

doi:10.1007/s10686-021-09783-z

Cited by 5 publications

(6 citation statements)

References 150 publications

(173 reference statements)

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“…These questions can be addressed by spacecraft missions (Goetz et al. 2021 ), but also simulations (see Sect. 3.3 ) and laboratory measurements (see Sect.…”

Section: Discussionmentioning

confidence: 99%

“…Goetz et al. ( 2021 ) outline open questions and propose mission concepts that would be able to (partially) answer them. By far the most complete mission profile is that of a dedicated multi-spacecraft mission to study a comet’s plasma environment.…”

Section: Discussionmentioning

confidence: 99%

“…To obtain a truly detailed view of the bow shock of a comet one would need a multi-spacecraft mission that accompanies the comet over an extended period of time (Goetz et al. 2021 ). The possibility of learning about cometary bow shocks by conducting laboratory experiments here on Earth is discussed briefly in Sect.…”

Section: Large Scale Structuresmentioning

confidence: 99%

“…Addressing these questions probably requires a multi-point measurement of the diamagnetic cavity, its boundary and upstream plasma conditions (Goetz et al. 2021 ).

Fig.…”

Section: Large Scale Structuresmentioning

confidence: 99%

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The Plasma Environment of Comet 67P/Churyumov-Gerasimenko

et al. 2022

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The environment of a comet is a fascinating and unique laboratory to study plasma processes and the formation of structures such as shocks and discontinuities from electron scales to ion scales and above. The European Space Agency’s Rosetta mission collected data for more than two years, from the rendezvous with comet 67P/Churyumov-Gerasimenko in August 2014 until the final touch-down of the spacecraft end of September 2016. This escort phase spanned a large arc of the comet’s orbit around the Sun, including its perihelion and corresponding to heliocentric distances between 3.8 AU and 1.24 AU. The length of the active mission together with this span in heliocentric and cometocentric distances make the Rosetta data set unique and much richer than sets obtained with previous cometary probes. Here, we review the results from the Rosetta mission that pertain to the plasma environment. We detail all known sources and losses of the plasma and typical processes within it. The findings from in-situ plasma measurements are complemented by remote observations of emissions from the plasma. Overviews of the methods and instruments used in the study are given as well as a short review of the Rosetta mission. The long duration of the Rosetta mission provides the opportunity to better understand how the importance of these processes changes depending on parameters like the outgassing rate and the solar wind conditions. We discuss how the shape and existence of large scale structures depend on these parameters and how the plasma within different regions of the plasma environment can be characterised. We end with a non-exhaustive list of still open questions, as well as suggestions on how to answer them in the future.

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“…These questions can be addressed by spacecraft missions (Goetz et al. 2021 ), but also simulations (see Sect. 3.3 ) and laboratory measurements (see Sect.…”

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Large Scale Structuresmentioning

confidence: 99%

“…Addressing these questions probably requires a multi-point measurement of the diamagnetic cavity, its boundary and upstream plasma conditions (Goetz et al. 2021 ).

Fig.…”

Section: Large Scale Structuresmentioning

confidence: 99%

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The Plasma Environment of Comet 67P/Churyumov-Gerasimenko

et al. 2022

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“…Comet Interceptor will perform the first multi-point sam-pling, but the only instrument common to all three spacecraft is a magnetometer, and it is a fast flyby mission. A plasma-science dedicated rendezvous mission with at least four identical spacecraft measuring the interaction between a comet and the solar wind has been proposed as the next big step forward for this field (Goetz et al 2021). While this concept assumes four small-to-medium sized independent spacecraft, it is also interesting to consider the possibilities presented by advances in technology for very small platforms.…”

Section: Small Satellites and Multi-point Measurementsmentioning

confidence: 99%

Past and Future Comet Missions

Snodgrass¹,

Feaga²,

Jones³

et al. 2022

Preprint

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We review the history of spacecraft encounters with comets, concentrating on those that took place in the recent past, since the publication of the Comets II book. This includes the flyby missions Stardust and Deep Impact, and their respective extended missions, the Rosetta rendezvous mission, and serendipitous encounters. While results from all of these missions can be found throughout this book, this chapter focuses on the questions that motivated each mission, the technologies that were required to answer these questions, and where each mission opened new areas to investigate. There remain a large number of questions that will require future technologies and space missions to answer; we also describe planned next steps and routes forward that may be pursued by missions that have yet to be selected, and eventually lead to cryogenic sample return of nucleus ices for laboratory study.

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Particle-in-cell modelling of comet 67P/Churyumov-Gerasimenko

Gunell¹,

Goetz²

2023

A&A

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Context. Sufficiently far from the Sun, all comets go through a phase of low activity. Rosetta observations at large heliocentric distances of approximately 3 au showed that the plasma at a low-activity comet is affected by both steady state electric fields and low-frequency waves. Aims. Our goal is to provide a model for the electric fields in the inner coma at a low-activity comet and to simulate waves and field structures farther away from the nucleus. Methods. We compare analytical models for the convective, ambipolar, and polarisation electric fields to the results of an electrostatic particle-in-cell simulation of a scaled-down low-activity comet. Results. We find good agreement between the steady state field model and the simulation results close to the nucleus. At larger cometocentric distances, waves dominate the electric field. These waves are interpreted as the scaled-down electrostatic limit of the previously observed singing comet waves. The comet ion density is not spherically symmetric. Conclusions. Low-activity comets can be modelled using electrostatic particle-in-cell simulations of a scaled-down system. Outside the innermost part of the coma (r ≳ 40 km), the plasma is not spherically symmetric and the electric field is dominated by waves.

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Cometary plasma science

Cited by 5 publications

References 150 publications

The Plasma Environment of Comet 67P/Churyumov-Gerasimenko

The Plasma Environment of Comet 67P/Churyumov-Gerasimenko

Past and Future Comet Missions

Particle-in-cell modelling of comet 67P/Churyumov-Gerasimenko

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