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Cometary Plasma Science -- A White Paper in response to the Voyage 2050 Call by the European Space Agency

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Pith's one-line read A multi-spacecraft comet rendezvous mission is proposed to resolve open questions in cometary plasma physics that single-spacecraft missions like Rosetta could not answer.

arxiv 1908.00377 v1 pith:2CDF7LKZ submitted 2019-08-01 astro-ph.EP

Charlotte Götz , Herber Gunell , Martin Volwerk , Arnaud Beth , Anders Eriksson , Marina Galand , Pierre Henri , Hans Nilsson
show 22 more authors
Cyril Simon Wedlund Markku Alho Laila Andersson Nicolas Andre Johan De Keyser Jan Deca Yasong Ge Karl-Heinz Gla{ss}meier Rajkumar Hajra Tomas Karlsson Satoshi Kasahara Ivana Kolmasova Kristie LLera Hadi Madanian Ingrid Mann Christian Mazelle Elias Odelstad Ferdinand Plaschke Martin Rubin Beatriz Sanchez-Cano Colin Snodgrass Erik Vigren
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classification astro-ph.EP
keywords cometplasmaprocessessolarstructurescometarycometslarge-scale
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The pith

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The reading

Comets release gas that becomes ionized and forms a plasma around the nucleus. The solar wind flows into this plasma, creating boundaries like a bow shock, a region where solar wind ions disappear, and a magnetic-field-free cavity. Previous missions, Giotto and Rosetta, measured these regions at single points. Rosetta orbited comet 67P for two years and saw these structures form, disappear and reform, but one spacecraft cannot tell whether changes are spatial or temporal.

This white paper, written for ESA's Voyage 2050 planning, reviews these results and lists the open questions: the shape of the bow shock, the mechanism that forms the diamagnetic cavity, the cause of tail disconnections, the role of electrons in carrying magnetic field, and the behavior of dust in the plasma. The authors argue that the only way to answer them is a mission with at least four spacecraft in formation around a comet, so the same boundary can be sampled at multiple points at once. They propose three profiles: a full multi-spacecraft rendezvous, sub-spacecraft added to a nucleus mission, and an artificial comet experiment near Earth.

The paper is not a research result; it is a mission proposal and literature review. Its value depends on ESA selecting such a mission and on the technical assumption that spacecraft can measure low-energy ions despite charging problems that limited Rosetta.

Extended reading notes

Core claim

The paper concludes that 'the multi-point rendezvous mission (A) is needed to answer many of the questions that still remain' (Conclusions, Table 4.1). If correct, a comet rendezvous with a multi-spacecraft formation would be the decisive next step in cometary plasma physics and would yield the first time-resolved 3D measurements of a comet-solar wind interaction.

Load-bearing premise

The proposal assumes that active spacecraft potential control can be made effective in the warm, dense plasma of a comet's inner coma so that low-energy ions and electrons can be measured accurately. Section 2.1.3 states that Rosetta could not measure low-energy ion distribution functions 'due to a very negative spacecraft potential,' and Section 3 acknowledges that keeping spacecraft potential close to zero 'is challenging in a plasma that is warm and dense.' The whole science case for profile A depends on this technical capability, together with the assumption that four spacecraft can be operated in formation around a low-gravity comet.

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Assumptions & free parameters 0 free parameters · 3 assumptions · 0 invented entities

The paper introduces no new physical quantities, particles, or forces. Its central content is a review of existing observations and a mission architecture, so the only load-bearing inputs are domain assumptions about feasibility and scientific priority.

assumptions (3)
  • domain assumption The open questions listed in Section 2 are genuinely unanswered by prior missions and are answerable by in situ multi-point measurements.
    Section 2 frames a set of 'main questions' without a quantitative analysis showing that the proposed measurements will resolve them.
  • domain assumption Active spacecraft potential control can be made effective in the warm, dense cometary plasma, where Rosetta's potential was too negative to measure low-energy ions.
    Section 2.1.3 reports the Rosetta limitation; Section 3 assumes new development will solve it.
  • standard math The curlometer technique, used with Cluster and MMS, yields valid 3D current estimates at comet spatial scales.
    Section 3 invokes it without derivation; it is an established multi-spacecraft analysis method from prior missions.

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Pith. "Pith review of Cometary Plasma Science -- A White Paper in response to the Voyage 2050 Call by the European Space Agency." pith.science (2026). https://pith.science/paper/2CDF7LKZ

@misc{pith2026190800377,
  author       = {Pith},
  title        = {Pith review of: Cometary Plasma Science -- A White Paper in response to the Voyage 2050 Call by the European Space Agency},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/2CDF7LKZ}},
  note         = {Machine review of arXiv:1908.00377}
}
read the original abstract

Comets hold the key to the understanding of our solar system, its formation and its evolution, and to the fundamental plasma processes at work both in it and beyond it. A comet nucleus emits gas as it is heated by the sunlight. The gas forms the coma, where it is ionised, becomes a plasma and eventually interacts with the solar wind. Besides these neutral and ionised gases, the coma also contains dust grains, released from the comet nucleus. As a cometary atmosphere develops when the comet travels through the solar system, large-scale structures, such as the plasma boundaries, develop and disappear, while at planets such large-scale structures are only accessible in their fully grown, quasi-steady state. In situ measurements at comets enable us to learn both how such large-scale structures are formed or reformed and how small-scale processes in the plasma affect the formation and properties of these large scale structures. Furthermore, a comet goes through a wide range of parameter regimes during its life cycle, where either collisional processes, involving neutrals and charged particles, or collisionless processes are at play, and might even compete in complicated transitional regimes. Thus a comet presents a unique opportunity to study this parameter space, from an asteroid-like to a Mars- and Venus-like interaction. Fast flybys of comets have made many new discoveries, setting the stage for a multi-spacecraft mission to accompany a comet on its journey through the solar system. This white paper reviews the present-day knowledge of cometary plasmas, discusses the many questions that remain unanswered, and outlines a multi-spacecraft ESA mission to accompany a comet that will answer these questions by combining both multi-spacecraft observations and a rendezvous mission, and at the same time advance our understanding of fundamental plasma physics and its role in planetary systems.

Figures

Figures reproduced from arXiv: 1908.00377 by the authors.

Figure 1.1
Figure 1.1. A sketch of the cometary plasma environment in the plane containing the magnetic field and the solar wind flow. The three panels show different stages, left: weak activity, middle: intermediate activity, right: high activity. Boundaries and regions are labelled: bow wave (BW), solar wind ion cavity (SC), and diamagnetic cavity (MC). Adapted from Götz (2019). At a comet there are two plasma types: (1) the light solar… view at source ↗
Figure 1.2
Figure 1.2. Energy spectrogram of the solar wind ions summed over all viewing directions and integrated over 1 hour for the entire Rosetta comet phase. One can see clearly that the spacecraft was located in a solar wind ion free region during the months around comet 67P perihelion (August 2015), when the gas production rate was highest. Adapted from Nilsson et al. (2017). A multitude of upstream wave phenomena have been observe… view at source ↗
Figure 1.3
Figure 1.3. Magnetic field observations of cavities at 1P (measured by Giotto’s magnetometer) and 67P (measured by the magnetometer onboard Rosetta). In regards to the formation mechanism of the diamagnetic cavity at the artificial comet, two models have been presented: Haerendel et al. (1986) showed that the dynamic pressure of the expanding ion cloud is sufficient to stave off the magnetic field, whereas Valenzuela et al. (19… view at source ↗
Figures from the paper (4 more)
Figure 1.4
Figure 1.4. Figure 1.4: Photograph of Comet Morehouse, (Rahe and Donn, 1969). Comets can have more than one tail. In addition to the most clearly visible dust tail there is an ion or plasma tail. While the dust grains in the dust tail are pushed away from the Sun by the photon pressure, the…
Figure 1.5
Figure 1.5. Figure 1.5: Solar wind charge-exchange interactions at comet 67P (Simon Wedlund et al., 2019b). Solar wind ion interaction with the neutral coma In a charge exchange reaction, one or several elec￾trons are semi-resonantly transferred between a neutral particle (atom or molecule)…
Figure 1.6
Figure 1.6. Figure 1.6: ENA emissions from the subso￾lar magnetopause of Earth (Fuselier et al., 2010). No ENA instrument has been flown to a comet yet. Ekenbäck et al. (2008) conducted MHD simulations of a comet and found that remote observations at large dis￾tances should be feasible. A c…
Figure 1.7
Figure 1.7. Figure 1.7: Dust acoustic waves (Heinrich et al., 2009). Large dust grains break up into smaller fragments due to electric forces, stemming from the electric charge of the grain (Hilchenbach et al., 2017). Thus, not only does the size dis￾tribution influence the grain charge as …

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Works this paper leans on

20 extracted references · 12 canonical work pages

  1. [5]

    doi:10.1093/mnras/stx2725. Deca, J. et al. Electron and Ion Dynamics of the Solar Wind Interaction with a Weakly Outgassing 22 Cometary Plasma Science Comet. Physical Review Letters , 118:205101, May

    work page doi:10.1093/mnras/stx2725

  2. [6]

    doi:10.1103/PhysRevLett.118.205101. Deca, J. et al. Building a weakly outgassing comet from a generalized Ohm’s law. Physical Review Let- ters, 2019. in press. Delva, M. et al. Upstream proton cyclotron waves at venus near solar maximum. J. Geophys. Res. (Space Physics), 120(1):344–354, 1 2015. ISSN 2169-9402. doi:10.1002/2014JA020318. Dennerl, K. Charge ...

    doi:10.1103/physrevlett.118.205101 2019

  3. [11]

    Lisse, C.M

    doi:10.1051/0004-6361/201732353. Lisse, C.M. et al. Discovery of X-ray and Extreme Ultraviolet Emission from Comet C/Hyakutake 1996 B2. Science, 274:205–209, Oct. 1996. doi:10.1126/science.274.5285.205. Luehr, H., Kloecker, N. and Acuña, M.H. The dia- magnetic effect during AMPTE’s tail releases - Ini- tial results. Advances in Space Research , 8:11–14,

    doi:10.1051/0004-6361/201732353 1996

  4. [12]

    Lundin, R

    doi:10.1016/0273-1177(88)90336-5. Lundin, R. et al. Solar wind-induced atmospheric erosion atMars: First results from ASPERA-3 on Mars express. Science, 305:1933–1936, 2004. doi:10.1126/science.1101860. Madanian, H. et al. Plasma Environment around Comet 67P/Churyumov-Gerasimenko at Perihelion: Model Comparison with Rosetta Data. AJ, 153:30, Jan. 2017. do...

    work page arXiv 1933

  5. [16]

    Noonan, J.W

    doi:10.1051/0004-6361/201833199. Noonan, J.W. et al. Ultraviolet Observations of Coronal Mass Ejection Impact on Comet 67P /Churyumov-Gerasimenko by Rosetta Alice. AJ, 156:16, July 2018. doi:10.3847/1538-3881/aac432. Odelstad, E. et al. Ion velocity and electron tem- perature inside and around the diamagnetic cav- ity of comet 67P. Journal of Geophysical ...

    work page doi:10.1051/0004-6361/201833199 2018

  6. [18]

    Vigren, E

    doi:10.3847/1538-3881/aa6006. Vigren, E. and Galand, M. Predictions of Ion Produc- tion Rates and Ion Number Densities within the Diamagnetic Cavity of Comet 67P/Churyumov- Gerasimenko at Perihelion. ApJ, 772:33, July 2013. doi:10.1088/0004-637X/772/1/33. Vigren, E. et al. On the Possibility of Signifi- cant Electron Depletion due to Nanograin Charg- ing i...

    doi:10.3847/1538-3881/aa6006 2013

  7. [19]

    Vigren, E

    doi:10.1088/0004-637X/798/2/130. Vigren, E. et al. Effective ion speeds at 200-250 km from comet 67P/Churyumov-Gerasimenko near perihelion. Monthly Notices of the Royal Astronomical Society , 469:S142–S148, July 2017. doi:10.1093/mnras/stx1472. Vourlidas, A. et al. First direct observation of the interaction between a comet and a coro- nal mass ejection le...

    work page doi:10.1088/0004-637x/798/2/130 2017

  8. [1987]

    Cravens, T.E

    doi:10.1016/0273-1177(87)90212-2. Cravens, T.E. Galactic cosmic rays and cell-hit frequencies outside the magnetosphere. Ad- vances in Space Research , 9(10):293–298, Jan 1989. doi:10.1016/0273-1177(89)90452-3. Cravens, T.E. Comet Hyakutake x-ray source: Charge transfer of solar wind heavy ions. Geophys. Res. Lett. , 24:105–108, 1997. doi:10.1029/96GL0378...

    doi:10.1016/0273-1177(87)90212-2 1989

Show all 20 references
  1. [1988]

    doi:10.1029/JA093iA07p07527. Gan, L. and Cravens, T.E. Electron energetics in the inner coma of Comet Halley. Journal of Geophysical Research , 95:6285–6303, May 1990. doi:10.1029/JA095iA05p06285. Gilet, N. et al. Electrostatic Potential Radiated by a Pulsating Charge in a T w...

    1990 doi

  2. [1995]

    Coates, A.J

    doi:10.1016/0273-1177(94)00125-K. Coates, A.J. and Jones, G.H. Plasma envi- ronment of Jupiter family comets. Plane- tary Space Science , 57:1175–1191, Aug. 2009. doi:10.1016/j.pss.2009.04.009. Cravens, T.E. The Physics of the Cometary Contact Surface. In Battrick, B., Rolfe, ...

    2009 doi

  3. [1998]

    doi:10.1007/978- 94-011-5252-5_13

    ISBN 978-94-011-5252-5. doi:10.1007/978- 94-011-5252-5_13. Johnstone, A.D. et al. Observations of the solar wind and cometary ions during the encounter between Giotto and comet Grigg-Skjellerup. Astronomy & Astrophysics, 273, June 1993. Jones, G.H., Balogh, A. and Horbury , T....

    doi

  4. [2004]

    doi:10.1016/j.nimb.2004.01.208. 27 Cometary Plasma Science 5 Supporters Charlotte Götz⋆ T echnische Universität Braunschweig, Germany Herbert Gunell⋆ Royal Belgian Institute for Space Aeronomy , Bel- gium and Umeå University , Sweden Martin Volwerk⋆ Institut für Weltraumforsch...

    2004 doi

  5. [2009]

    Meier, P ., Glassmeier, K.H

    doi:10.1007/s11214-009-9499-4. Meier, P ., Glassmeier, K.H. and Motschmann, U. Modified ion-Weibel instability as a possible source of wave activity at Comet 67P/Churyumov-Gerasimenko. Annales Geophys- icae, 34(9):691–707, 2016. doi:10.5194/angeo-34- 691-2016. Mendis, D.A. and ...

    doi

  6. [2010]

    Breuillard, H

    doi:10.1017/S1743921310001675. Breuillard, H. et al. The properties of the singing comet waves in the 67P/Churyumov–Gerasimenko plasma envi- ronment as observed by the Rosetta mission. Astronomy & Astrophysics, 2019. doi:10.1051/0004- 6361/201834876. Broiles, T.W. et al. Stati...

    2019 doi

  7. [2011]

    doi:10.1029/2011JA017038

    ISSN 0148-0227. doi:10.1029/2011JA017038. Nemeth, Z. et al. Charged particle signatures of the diamagnetic cavity of comet 67P/Churyumov- Gerasimenko. Monthly Notices of the Royal Astronomical Society , 462:S415–S421, Nov . 2016. doi:10.1093/mnras/stw3028. Neubauer, F.M. Giott...

    doi

  8. [2012]

    Sauer, K

    doi:10.1029/2011JA017300. Sauer, K. and Baumgaertel, K. Magnetic cavity for- mation at comet Halley and at the AMPTE Li re- lease. In Rolfe, E.J. et al, editors, Diversity and Sim- ilarity of Comets , volume 278, pages 113–118, Sept. 1987. Scarf, F. Plasma wave observations at...

    doi

  9. [2015]

    Nilsson, H

    doi:10.1126/science.aaa0571. Nilsson, H. et al. Evolution of the ion environ- ment of comet 67P during the rosetta mission as seen by RPC-ICA. Monthly Notices of the Royal As- tronomical Society , 469(Suppl_2):S252–S261, 2017. doi:10.1093/mnras/stx1491. Nilsson, H. et al. Size...

    doi

  10. [2016]

    Ekenbäck, A

    doi:10.1093/mnras/stw2112. Ekenbäck, A. et al. Energetic neutral atom imaging of comets. Geophys. Res. Lett., 35:L05103, Mar. 2008. doi:10.1029/2007GL032955. Engelhardt, I. et al. Plasma regions, charged dust and field-aligned currents near Enceladus. Plan- etary and Space Scie...

    2008 doi

  11. [2017]

    Auster, H.U

    doi:10.1093/mnras/stx868. Auster, H.U. et al. The nonmagnetic nucleus of comet 67P/Churyumov-Gerasimenko. Science, 349(1): 015102, July 2015. doi:10.1126/science.aaa5102. Bale, S.D. et al. Quasi-perpendicular shock structure and processes. Space Science Re- views, 118(1):161–2...

    2015 doi

  12. [2018]

    Solar System Ices

    doi:10.1093/mnras/sty2166. Hall, B.E.S. et al. Annual variations in the mar- tian bow shock location as observed by the Mars Express mission. J. Geophys. Res. (Space Physics), 121(11), 11 2016. ISSN 2169-9402. doi:10.1002/2016JA023316. Hansen, K.C. et al. Evolution of water pr...

    2016

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