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Goetz C, Behar E, Beth A, Bodewits D, Bromley S, Burch J, Deca J, Divin A, Eriksson AI, Feldman PD, Galand M, Gunell H, Henri P, Heritier K, Jones GH, Mandt KE, Nilsson H, Noonan JW, Odelstad E, Parker JW, Rubin M, Simon Wedlund C, Stephenson P, Taylor MGGT, Vigren E, Vines SK, Volwerk M. The Plasma Environment of Comet 67P/Churyumov-Gerasimenko. SPACE SCIENCE REVIEWS 2022; 218:65. [PMID: 36397966 PMCID: PMC9649581 DOI: 10.1007/s11214-022-00931-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Accepted: 10/20/2022] [Indexed: 06/04/2023]
Abstract
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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Affiliation(s)
- Charlotte Goetz
- ESTEC, European Space Agency, Keplerlaan 1, 2201 AZ Noordwijk, The Netherlands
- Department of Mathematics, Physics and Electrical Engineering, Northumbria University, Newcastle-upon-Tyne, UK
| | - Etienne Behar
- Swedish Institute of Space Physics, Box 812, 981 28 Kiruna, Sweden
- Lagrange, OCA, UCA, CNRS, Nice, France
| | - Arnaud Beth
- Department of Physics, Umeå University, 901 87 Umeå, Sweden
| | - Dennis Bodewits
- Physics Department, Leach Science Center, Auburn University, Auburn, AL 36832 USA
| | - Steve Bromley
- Physics Department, Leach Science Center, Auburn University, Auburn, AL 36832 USA
| | - Jim Burch
- Southwest Research Institute, P.O. Drawer 28510, San Antonio, TX 78228-0510 USA
| | - Jan Deca
- Laboratory for Atmospheric and Space Physics, University of Colorado Boulder, 3665 Discovery Drive, Boulder, CO 80303 USA
| | - Andrey Divin
- Earth Physics Department, St. Petersburg State University, Ulianovskaya, 1, St Petersburg, 198504 Russia
| | | | - Paul D. Feldman
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 USA
| | - Marina Galand
- Department of Physics, Imperial College London, Prince Consort Road, London, SW7 2AZ UK
| | - Herbert Gunell
- Department of Physics, Umeå University, 901 87 Umeå, Sweden
| | - Pierre Henri
- Lagrange, OCA, UCA, CNRS, Nice, France
- LPC2E, CNRS, Orléans, France
| | - Kevin Heritier
- Department of Physics, Imperial College London, Prince Consort Road, London, SW7 2AZ UK
| | - Geraint H. Jones
- UCL Mullard Space Science Laboratory, Holmbury St. Mary, Dorking, RH5 6NT UK
- The Centre for Planetary Sciences at UCL/Birkbeck, Gower Street, London, WC1E 6BT UK
| | | | - Hans Nilsson
- Swedish Institute of Space Physics, Box 812, 981 28 Kiruna, Sweden
| | - John W. Noonan
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85719 USA
| | - Elias Odelstad
- Swedish Institute of Space Physics, Box 537, SE-751 21 Uppsala, Sweden
| | | | - Martin Rubin
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, 3012 Bern, Switzerland
| | - Cyril Simon Wedlund
- Space Research Institute, Austrian Academy of Sciences, Schmiedlstr. 6, 8042 Graz, Austria
| | - Peter Stephenson
- Department of Physics, Imperial College London, Prince Consort Road, London, SW7 2AZ UK
| | | | - Erik Vigren
- Swedish Institute of Space Physics, Box 537, SE-751 21 Uppsala, Sweden
| | - Sarah K. Vines
- Johns Hopkins Applied Physics Laboratory, Laurel, MD 20723 USA
| | - Martin Volwerk
- Space Research Institute, Austrian Academy of Sciences, Schmiedlstr. 6, 8042 Graz, Austria
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Kivelson MG, Bargatze LF, Khurana KK, Southwood DJ, Walker RJ, Coleman PJ. Magnetic Field Signatures Near Galileo's Closest Approach to Gaspra. Science 1993; 261:331-4. [PMID: 17836843 DOI: 10.1126/science.261.5119.331] [Citation(s) in RCA: 101] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Two large magnetic field rotations were recorded by the spacecraft Galileo 1 minute before and 2 minutes after its closest approach to the asteroid Gaspra. The timing and the geometry of the field changes suggest a connection with Gaspra, and the events can be interpreted as the result of the draping of the solar wind field around a magnetospheric obstacle. Gaspra's surface field is inferred to be within an order of magnitude of Earth's surface field, and its magnetic moment per unit mass is in the range observed for iron meteorites and highly magnetized chondrites. The location of the magnetic signatures suggests that perturbations are carried by waves in the magnetosonic-whistler mode with wavelengths between electron and ion gyro radii.
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