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Scientific rationale for Uranus and Neptune in situ explorations

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journal contribution
posted on 2018-01-04, 17:15 authored by O. Mousis, D. H. Atkinson, T. Cavalié, L. N. Fletcher, M. J. Amato, S. Aslam, F. Ferri, J-B. Renard, T. Spilker, E. Venkatapathy, P. Wurz, K. Aplin, A. Coustenis, M. Deleuil, M. Dobrijevic, T. Fouchet, T. Guillot, P. Hartogh, T. Hewagama, M. D. Hofstadter, V. Hue, R. Hueso, J-P. Lebreton, E. Lellouch, J. Moses, G. S. Orton, J. C. Pearl, A. Sanchez-Lavega, A. Simon, O. Venot, J. H. Waite, R. K. Achterberg, S. Atreya, F. Billebaud, M. Blanc, F. Borget, B. Brugger, S. Charnoz, T. Chiavassa, V. Cottini, L. d'Hendecourt, G. Danger, T. Encrenaz, N. J. P. Gorius, L. Jorda, B. Marty, R. Moreno, A. Morse, C. Nixon, K. Reh, T. Ronnet, F-X. Schmider, S. Sheridan, C. Sotin, P. Vernazza, G. L. Villanueva
The ice giants Uranus and Neptune are the least understood class of planets in our solar system but the most frequently observed type of exoplanets. Presumed to have a small rocky core, a deep interior comprising ~70% heavy elements surrounded by a more dilute outer envelope of H2 and He, Uranus and Neptune are fundamentally different from the better-explored gas giants Jupiter and Saturn. Because of the lack of dedicated exploration missions, our knowledge of the composition and atmospheric processes of these distant worlds is primarily derived from remote sensing from Earth-based observatories and space telescopes. As a result, Uranus's and Neptune's physical and atmospheric properties remain poorly constrained and their roles in the evolution of the Solar System not well understood. Exploration of an ice giant system is therefore a high-priority science objective as these systems (including the magnetosphere, satellites, rings, atmosphere, and interior) challenge our understanding of planetary formation and evolution. Here we describe the main scientific goals to be addressed by a future in situ exploration of an ice giant. An atmospheric entry probe targeting the 10-bar level, about 5 scale heights beneath the tropopause, would yield insight into two broad themes: i) the formation history of the ice giants and, in a broader extent, that of the Solar System, and ii) the processes at play in planetary atmospheres. The probe would descend under parachute to measure composition, structure, and dynamics, with data returned to Earth using a Carrier Relay Spacecraft as a relay station. In addition, possible mission concepts and partnerships are presented, and a strawman ice-giant probe payload is described. An ice-giant atmospheric probe could represent a significant ESA contribution to a future NASA ice-giant flagship mission.


The work contributed by O.M., B.B. and T.R. was carried out thanks to the support of the A*MIDEX project (no ANR-11-IDEX-0001-02) funded by the “Investissements d’Avenir” French Government program, managed by the French National Research Agency (ANR). We acknowledge support from the “Institut National des Sciences de l’Univers” (INSU), the “Centre National de la Recherche Scientifique” (CNRS) and “Centre National d’Etude Spatiale” (CNES). Parts of this research were carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. D.H.A, M.D.H., G.S.O., K.R. and C.S. were supported by NASA funds to the Jet Propulsion Laboratory, California Institute of Technology. L.N.F was supported by a Royal Society Research Fellowship and European Research Council Grant at the University of Leicester. R.H. and A.S.L. were supported by the Spanish MINECO project AYA2015-65041-P (MINECO/FEDER, UE) and Grupos Gobierno Vasco IT-765-13. P.W. acknowledges support from the Swiss National Science Foundation. J.H.W. acknowledges the support of Southwest Research Institute.



Planetary and Space Science, 2017

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/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Physics and Astronomy


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Planetary and Space Science





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