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Exo-planetary high-temperature hydrocarbons by emission and absorption spectroscopy (e-PYTHEAS project)
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Previous issue date: 2019-06-19e-PYTHEAS is a multidisciplinary project which combines theoretical and experimental work with exoplanet modelling applications. It sits on the frontier between molecular physics, theoretical chemistry and astrophysics. It aims at enhancing our understanding of the radiative properties of hot gaseous media to allow for improved analysis and interpretation of the large mass of data available on the thousands of exoplanets and exoplanetary systems known to date. Our approach is to use theoretical research validated by laboratory experiments and to then inject it into models of the atmospheres of the giant gaseous planets in the solar system and other planetary systems. This will help to analyse data and address essential questions on the formation and evolution of planetary systems, such as retrieved by ESA's M4 space mission ARIEL. Our consortium of 5 French laboratories and associated partners proposes to improve the existing high-temperature spectroscopy data for several molecular species detected in exoplanets. The provision of infrared (IR) laboratory data of methane, acetylene, ethylene and ethane, between 500 and 2500 K will help to refine thermal profiles and provide information on the gaseous composition, the hazes and their temporal variability.
See the project's website: http://e-pytheas.cnrs.f
Habitable conditions in the outer solar system : the space missions that changed our perception of what exists out there
No full textInternational audienceSome of the satellites of the gas giants Jupiter and Saturn, at orbits beyond the snow-line and the traditional “habitable zone”, have been revealed by missions like Galileo, Cassini-Huygens and Juno as unique and extremely interesting bodies with a strong astrobiological potential [1]. Jupiter’s Europa and Ganymede show indications of harboring liquid water oceans under their icy crusts, which, in the case of Europa, may be in direct contact with a silicate mantle floor and kept warm through time by tidally generated heat. Ganymede, the largest satellite in our Solar System, is unique in possessing an induced magnetic field and probably harbours an undersurface liquid water ocean contained between two ice layers. Thanks to the fabulous international cooperation that came behind the Cassini-Huygens mission, Saturn’s system was revealed and Titan [2] and Enceladus [3], were found to possess organic chemistry, unique geological features and internal liquid water oceans. I will describe my personal experience of the Cassini-Huygens mission.The icy satellites provide a conceptual basis within which new theories for understanding habitability can be constructed. In view of the many questions remaining unanswered [4], these bodies will be further investigated in the future by new missions to the giant planets systems. Future space exploration towards the Galilean satellites will be performed by missions such as ESA’s JUpiter Icy moons Explorer (JUICE, [5]) (whose main target is Ganymede and will be launched in April 2023) and NASA’s Europa Clipper mission to launch in 2024. For a return to Titan, NASA has recently selected the Dragonfly mission [6], while other concepts are being studied for these and other icy moons, also around the ice giants.Future in situ measurements will be extremely useful in unveiling these worlds. In the meantime, Juno data and ground-based observations can help complement the space discoveries.I will discuss what we currently know and what we expect to learn about habitable conditions in the outer solar system and how our perception of these worlds has changed, along with the need to better protect their environments [7].References: 1. Coustenis, A., Encrenaz, Th., 2013. Life beyond Earth: the search for habitable worlds in the Universe. CUP. ISBN: 9781107026179. 2. Coustenis, A., 2021. The Atmosphere of Titan. In Read, P. (Ed.), Oxford Research Encyclopedia of Planetary Science.  DOI: 10.1093/acrefore/9780190647926.013.120 3. Lunine, J., Coustenis, A., Mitri, G., et al., 2018. “Future exploration of Enceladus and other Saturnian moons”. In “Enceladus and the Icy Moons of Saturn”. LPI/UA/Space Science Series, P. Schenk, R. Clark, C.J.A. Howett, A. Verbiscer, J.H. Waite Eds., ISBN 9780816537075. 4. Nixon, C. A., et al., 2018. PSS, 155, 50-72. 5. Coustenis, A., Witasse, O., Erd, C., 2021. The JUICE mission: expectations and challenges. Fall issue of The Bridge on space exploration, Sept. 2021, Vol. 51, issue #3, pp. 41-50. https://www.nae.edu/260902/The-JUICE-Mission-Challenges-and-Expectations 6. Barnes, J. et al., The Plan. Sci. J., 4, 18. 7. Fisk, L., Worms, J.-C., Coustenis, A., et al., 2021. Introductory Note to the June 2021 and Update of the COSPAR Policy on Planetary Protection. Space Research Today 211, Aug. 2021, 9-25, https://doi.org/10.1016/j.srt.2021.07.009 and Policy : https://doi.org/10.1016/j.srt.2021.07.010   
Evolution with seasons of the organic content on Titan : from its atmosphere to the surface
No full textInternational audienceSaturn's Earth-like satellite Titan has a thick and dense atmosphere consisting of nitrogen (98.4%), methane (1.6%) and trace gases such as hydrocarbons and nitriles. The condensed organics are deposited on the surface and the atmosphere-surface-interior interactions shape the ground. In particular, Titan's methane cycle, similarly to the Earth's hydrologic cycle, plays an important role in these exchanges by transporting methane at all layers. We analyse spectroscopic data from the Cassini/CIRS instrument in the far-infrared and spectro-imaging data (0.8-5.2 µm) from Cassini/VIMS to study Titan's surface changes consisting of a multivariable geological terrain
Science goals for future exploration of the habitability of the gaseous giant planets' satellites
No full textInternational audienceLarge satellites of the gas giants Jupiter and Saturn, at orbits beyond the snow-line and the traditional "habitability zone", have been revealed as extremely astrobiologically interesting bodies presenting promising conditions for habitability and the development and/or maintenance of life. Jupiter's Europa and Ganymede show indications of harboring liquid water oceans under their icy crusts, which, in the case of Europa, may be in direct contact with a silicate mantle floor and kept warm through time by tidally generated heat. Around Saturn, Titan and Enceladus, were found by the Cassini-Huygens mission to possess active organic chemistries with seasonal variations, unique geological features and possibly internal liquid water oceans, among other. Thus, the icy satellites provide a conceptual basis within which new theories for understanding habitability can be constructed. Measurements from the Voyager and Galileo spacecraft revealed the potential of these satellites in this context. Their hydrospheres may be extremely thick (~600 km for Ganymede and Callisto for instance). The science goals for future exploration of the icy moons are broad and cover a large range of aspects from formation and evolution to habitability. In the case of Titan for example, the science objectives can be summarized as follows. - How do the satellites function as a system? How are the similarities and differences with Earth, and other solar system bodies, a result of the interplay of the geology, hydrology, meteorology, and aeronomy present in the systems? - What is the organic inventory available in the atmosphere and on the surface? How does this inventory differ from known abiotic organic material in meteorites and contribute to our understanding of the origin of life in the Solar System? What is the complexity of Titan's organic chemistry in the atmosphere, within its lakes, on its surface, and in its putative subsurface water ocean? - What is the exchange of energy and material between the Jupiter and Saturn magnetospheres, solar wind and their satellites? What is the source of geysers on Enceladus and Europa? Does complex chemistry occur in the geysers? These goals should be investigated in future missions exploring the icy moons around the giant planets. If the silicate mantles of Europa and Ganymede and the liquid sources of Titan and Enceladus are geologically active as on Earth, giving rise to the equivalent of hydrothermal systems, the simultaneous presence ofwater, geodynamic interactions, chemical energy sources and a diversity of key chemical elements may fulfill the basic conditions for habitability. In addition, Ganymede, the largest satellite in the Solar System presents unique features with its induced magnetic field, which can be connected to the presence of a liquid water undersurface ocean trapped between ice layers, as in the case of Europa, except that in the latter case the ocean is hypothesized to be in contact with the silicate core. Future exploration towards the Galilean satellites include missions such as ESA's JUpiter Icy moons Explorer (JUICE) (whose main target is Ganymede and will be launched in 2022 for arrival in the jovian system in 2030) and NASA's Europa Clipper mission. For a return to Titan, NASA has recently selected the Dragonfly mission and other concepts are being studied. Such endeavours will greatly enhance our understanding of the icy moons, their potential habitability and the formation of the Solar System in genera
L'atmosphere de Titan a partir des observations infrarouges de Voyager
No full textSIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : T 82384 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc
Search for habitable conditions in the outer solar system
No full textInternational audienceThe large satellites of the gas giants Jupiter and Saturn, at orbits beyond the snow-line and the traditional habitability zone, have been revealed as extremely astrobiologically interesting bodies by missions like Galileo, Cassini-Huygens and Juno. They present promising conditions for habitability and the emergence and/or maintenance of life [1]. Jupiters Europa and Ganymede show indications of harboring liquid water oceans under their icy crusts, which, in the case of Europa, may be in direct contact with a silicate mantle floor and kept warm through time by tidally generated heat. Saturns Titan [2] and Enceladus [3], were found to possess organic chemistry, unique geological features and internal liquid water oceans. These bodies will be further investigated in the future with missions such as ESAs JUpiter Icy moons Explorer (JUICE, whose main target is Ganymede) and NASAs Europa Clipper mission. For a return to Titan, NASA has recently selected the Dragonfly mission and other concepts are being studied. I will discuss what we currently know and what we expect to learn about habitable conditions in the outer solar system and how our perception of these worlds has changed, along with the need to better protect their environments [4]. References: Coustenis, A., Encrenaz, Th., 2013. Life beyond Earth: the search for habitable worlds in the Universe. CUP. ISBN: 9781107026179. Coustenis, A., 2021. The Atmosphere of Titan. In Read, P. (Ed.), Oxford Research Encyclopedia of Planetary Science. DOI: 10.1093/acrefore/9780190647926.013.120 Lunine, J., Coustenis, A., Mitri, G., et al., 2018. Future exploration of Enceladus and other Saturnian moons. In Enceladus and the Icy Moons of Saturn. LPI/UA/Space Science Series, P. Schenk, R. Clark, C.J.A. Howett, A. Verbiscer, J.H. Waite Eds., ISBN 9780816537075. Fisk, L., Worms, J.-C., Coustenis, A., et al., 2021. Update of the COSPAR Policy on Planetary Protection. Space Research Today, Elsevier, 08/2021
Comparative study of the diachronic evolution of the geological and volcanological environments of the earth with the saturnian satellites Titan and Enceladus.
Full text linkThis thesis presents on the study of the environment of Titan and Enceladus, Saturn’s satellites observed by the Cassini-Huygens mission. Various aspects of the geology of Titan are presented focusing on the characteristics of the surface geological features and processes,the internal structure and the correlation with the atmosphere. The morphotectonic features are presented on the basis of terrestrial models. Moreover, Titan areas probably correlated with the interior are tested against a geophysical model of tidal distortion and found to conform with localisation and internal dynamics. We then study the surface albedo and composition of specific Titan areas (Hotei Regio, Tui Regio, Sotra Patera) –determined by the PCA method- based on data from Cassini/VIMS (0.4–5 μm) on which a radiative transfer code is applied with the most updated spectroscopic parameters. Monitoring of these areas showed surface albedo changes in the course of 1-3.5 yrs, implying dynamic exogenic-endogenic processes that affect the surface and compatible with cryovolcanism in the case of Sotra Patera. Processes that form the surface of Enceladus are also discussed. In addition, the analogies with the Earth's surface and possible internal processes on the icy satellites are being explored. The astrobiological implications of this work are discussed within the framework of the quest for habitable environments in our outer Solar system. These studies are related to the preparation of future space missions to the systems of Jupiter and Saturn and payload capability. Finally, public awareness and perspectives of this research are discussed
Space exploration of habitable worlds in the outer solar system
No full textInternational audienceIn looking for habitable conditions in the outer solar system recent research focuses on the natural satellites ra-ther than the planets themselves. Indeed, the habitable zone as traditionally defined may be larger than originally conceived. The outer solar system satellites provide a conceptual basis within which new theories for understanding habitability can be constructed. Measurements from the ground but also by the Voyager, Galileo and the Cassini spacecrafts revealed the potential of these satellites in this context, and our understanding of habitability in the solar system and beyond can be greatly enhanced by investigating several of these bodies together [1]. Their environ-ments seem to satisfy many of the “classical” criteria for habitability (liquid water, energy sources to sustain metab-olism and chemical compounds that can be used as nutrients over a period of time long enough to allow the devel-opment of life). Indeed, several of the moons show promising conditions for habitability and the development and/or mainte-nance of life. The strong gravitational pull caused by the giant planets may produce enough energy to sufficiently heat the cores of orbiting icy moons. Europa and Ganymede may be hiding, under their icy crust, putative undersur-face liquid water oceans [2] which, in the case of Europa [3], may be in direct contact with a silicate mantle floor and kept warm by tidally generated heat [4]. Titan and Enceladus, Saturn’s satellites, were found by the Cassini-Huygens mission to possess active organic chemistries with seasonal variations, unique geological features and possibly internal liquid water oceans. Titan’s rigid crust and the probable existence of a subsurface ocean create an analogy with terrestrial-type plate tectonics, at least surficial [5], while Enceladus’ plumes find an analogue in geysers. As revealed by Cassini the liquid hydrocar-bon lakes [6] distributed mainly at polar latitudes on Titan are ideal isolated environments to look for biomarkers. Currently, for Titan and Enceladus, geophysical models try to explain the possible existence of an oceanic layer that decouples the mantle from the icy crust. Titan has further been suggested to be a possible cryovolcanic world due to the presence of local complex volcanic-like geomorphology and the indications of surface albedo changes with time [7,8]. Such dynamic activity that would most probably include tidal heating, possible internal convection, and ice tectonics, is believed to be a pre-requisite of a habitable planetary body as it allows the recycling of minerals and potential nutrients and provides localized energy sources. In one of our geophysical studies [4], we have showed that tidal forces are a constant and significant source of internal deformation on Titan and the interior liquid water ocean can be relatively warm for reasonable amounts of ammonia concentrations, thus completing the set of parameters needed for a truly habitable planetary body. If the silicate mantles of Europa and Ganymede and the liquid sources of Titan and Enceladus are geologically active as on Earth, giving rise to the equivalent of hydrothermal systems, the simultaneous presence of water, geo-dynamic interactions, chemical energy sources and a diversity of key chemical elements may fulfill the basic condi-tions for habitability. Such habitability indications from bodies at distances of 10 AU, are essential discoveries brought to us by space exploration and which have recently revolutionized our perception of habitability in the solar system. In the solar system’s neighborhood, such potential habitats can only be investigated with appropriate de-signed space missions, like those proposed for Titan and Eneladus (TSSM and others) and JUICE (JUpiter ICy moon Explorer) for Ganymede and Europa [9]. JUICE is an ESA mission to Jupiter and its icy moons, recently se-lected to launch in 2022. Other future mission concepts are being studied for exploring the moons around Saturn. References: [1] Coustenis, A., Encrenaz, Th., in “Life Beyond Earth : the search for habitable worlds in the Universe”, Cam-bridge Univ. Press, 2013. [2] Grasset, O., et al.: Astrobiology 13, 991-1004, 2013. [3] Patterson, G.W., et al.: AGU P41F-09, 2011. [4] Sohl, F., et al.: JGR 119, 1013-1036, 2014. [5] Solomonidou, A., et al.: PSS 77, 104-117, 2013. [6] Stofan, E.R., et al.: Nature 445, 61-64, 2007. [7] Solomonidou, A., et al.: JGR 119, 1729-1747, 2014.. [8] Solo-monidou, A., et al: Icarus in press, doi:10.1016/j.icarus.2015.05.003.. [9] Grasset, O., et al.: PSS, 78, 1-21, 2013
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