@article{3069976,
    title = "Scientific rationale for Saturn's in situ exploration",
    author = "Mousis, O. and Fletcher, L.N. and Lebreton, J.-P. and Wurz, P. and Cavalié, T. and Coustenis, A. and Courtin, R. and Gautier, D. and Helled, R. and Irwin, P.G.J. and Morse, A.D. and Nettelmann, N. and Marty, B. and Rousselot, P. and Venot, O. and Atkinson, D.H. and Waite, J.H. and Reh, K.R. and Simon, A.A. and Atreya, S. and André, N. and Blanc, M. and Daglis, I.A. and Fischer, G. and Geppert, W.D. and Guillot, T. and Hedman, M.M. and Hueso, R. and Lellouch, E. and Lunine, J.I. and Murray, C.D. and O'Donoghue, J. and Rengel, M. and Sánchez-Lavega, A. and Schmider, F.-X. and Spiga, A. and Spilker, T. and Petit, J.-M. and Tiscareno, M.S. and Ali-Dib, M. and Altwegg, K. and Bolton, S.J. and Bouquet, A. and Briois, C. and Fouchet, T. and Guerlet, S. and Kostiuk, T. and Lebleu, D. and Moreno, R. and Orton, G.S. and Poncy, J.",
    journal = "Planetary and Space Science",
    year = "2014",
    volume = "104",
    number = "PA",
    pages = "29-47",
    publisher = "Elsevier Ireland Ltd",
    issn = "0032-0633",
    doi = "10.1016/j.pss.2014.09.014",
    keywords = "Atmospheric chemistry;  Atmospheric composition;  Atmospheric pressure;  Extrasolar planets;  Inert gases;  Isotopes;  Probes;  Remote sensing;  Reservoirs (water);  Troposphere, Entry probes;  Giant planet formation;  In-situ measurement;  Isotopic composition;  Solar system formation, Interplanetary flight",
    abstract = "Remote sensing observations meet some limitations when used to study the bulk atmospheric composition of the giant planets of our solar system. A remarkable example of the superiority of in situ probe measurements is illustrated by the exploration of Jupiter, where key measurements such as the determination of the noble gases' abundances and the precise measurement of the helium mixing ratio have only been made available through in situ measurements by the Galileo probe. This paper describes the main scientific goals to be addressed by the future in situ exploration of Saturn placing the Galileo probe exploration of Jupiter in a broader context and before the future probe exploration of the more remote ice giants. In situ exploration of Saturn's atmosphere addresses two broad themes that are discussed throughout this paper: first, the formation history of our solar system and second, the processes at play in planetary atmospheres. In this context, we detail the reasons why measurements of Saturn's bulk elemental and isotopic composition would place important constraints on the volatile reservoirs in the protosolar nebula. We also show that the in situ measurement of CO (or any other disequilibrium species that is depleted by reaction with water) in Saturn's upper troposphere may help constraining its bulk O/H ratio. We compare predictions of Jupiter and Saturn's bulk compositions from different formation scenarios, and highlight the key measurements required to distinguish competing theories to shed light on giant planet formation as a common process in planetary systems with potential applications to most extrasolar systems. In situ measurements of Saturn's stratospheric and tropospheric dynamics, chemistry and cloud-forming processes will provide access to phenomena unreachable to remote sensing studies. Different mission architectures are envisaged, which would benefit from strong international collaborations, all based on an entry probe that would descend through Saturn's stratosphere and troposphere under parachute down to a minimum of 10 bar of atmospheric pressure. We finally discuss the science payload required on a Saturn probe to match the measurement requirements. © 2014 Elsevier Ltd."
}