Goetz Charlotte, Behar Etienne, Beth Arnaud, Bodewits Dennis, Bromley Steve, Burch Jim, Deca Jan, Divin Andrey, Eriksson Anders I, Feldman Paul D, Galand Marina, Gunell Herbert, Henri Pierre, Heritier Kevin, Jones Geraint H, Mandt Kathleen E, Nilsson Hans, Noonan John W, Odelstad Elias, Parker Joel W, Rubin Martin, Simon Wedlund Cyril, Stephenson Peter, Taylor Matthew G G T, Vigren Erik, Vines Sarah K, Volwerk Martin
ESTEC, European Space Agency, Keplerlaan 1, 2201 AZ Noordwijk, The Netherlands.
Department of Mathematics, Physics and Electrical Engineering, Northumbria University, Newcastle-upon-Tyne, UK.
Space Sci Rev. 2022;218(8):65. doi: 10.1007/s11214-022-00931-1. Epub 2022 Nov 10.
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.
彗星的环境是一个迷人且独特的实验室，可用于研究等离子体过程以及从电子尺度到离子尺度及以上的激波和间断等结构的形成。欧洲航天局的罗塞塔任务收集了两年多的数据，从2014年8月与67P/丘留莫夫－格拉西缅科彗星会合开始，直至2016年9月底航天器最终着陆。这个伴随阶段跨越了彗星绕太阳轨道的一大段弧线，包括其近日点，对应日心距离在3.8天文单位和1.24天文单位之间。活跃任务的时长以及在日心和彗心距离上的跨度，使得罗塞塔数据集独一无二，且比以往彗星探测器获得的数据集丰富得多。在此，我们回顾罗塞塔任务中与等离子体环境相关的结果。我们详细介绍了等离子体所有已知的来源、损失及其内部的典型过程。原位等离子体测量的结果得到了对等离子体发射的遥感观测的补充。文中给出了研究中使用的方法和仪器的概述，以及对罗塞塔任务的简短回顾。罗塞塔任务的长时间持续提供了一个机会，能更好地理解这些过程的重要性如何随诸如出气率和太阳风条件等参数而变化。我们讨论了大规模结构的形状和存在如何取决于这些参数，以及如何表征等离子体环境不同区域内的等离子体。最后，我们列出了一系列尚未解决的问题，并对未来如何解答这些问题提出了建议。
