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Marlin TC, Cable ML, Vu TH, Maynard-Casely HE, Ugelow M, Anderson C, Hodyss R. Propyne: Determination of Physical Properties and Unit Cell Parameters under Titan-Relevant Conditions. ACS EARTH & SPACE CHEMISTRY 2024; 8:957-964. [PMID: 38774358 PMCID: PMC11103771 DOI: 10.1021/acsearthspacechem.3c00303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 01/22/2024] [Accepted: 01/23/2024] [Indexed: 05/24/2024]
Abstract
With its large size, dense atmosphere, methane-based hydrological-like cycle, and diverse surface features, the Saturnian moon Titan is one of the most unique of the outer Solar System satellites. Study of the photochemically produced molecules in Titan's atmosphere is critical in order to understand the mechanics of the atmosphere and, by extension, the interactions between atmosphere, surface, and subsurface water ocean. One example is propyne vapor, a photochemically produced species in Titan's upper atmosphere expected to condense in Titan's stratosphere at lower altitudes. Propyne may also be a trace species in Titan's stratospheric co-condensed ice clouds detected by the Cassini Composite InfraRed Spectrometer. Bulk structural characterization of propyne ice is currently incomplete and is lacking in published laboratory Raman spectra and X-ray diffraction data. Here, we present a laboratory characterization of propyne ice, including the first published X-ray diffraction and Raman spectroscopy results for propyne ice.
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Affiliation(s)
- Theresa C. Marlin
- NASA
Jet Propulsion Laboratory, California Institute
of Technology, 4800 Oak Grove Drive, Pasadena, California 91109, United States
- Division
of Geological and Planetary Sciences, California
Institute of Technology, 1200 East California Boulevard, Pasadena, California 91125, United States
| | - Morgan L. Cable
- NASA
Jet Propulsion Laboratory, California Institute
of Technology, 4800 Oak Grove Drive, Pasadena, California 91109, United States
| | - Tuan H. Vu
- NASA
Jet Propulsion Laboratory, California Institute
of Technology, 4800 Oak Grove Drive, Pasadena, California 91109, United States
| | - Helen E. Maynard-Casely
- Australian
Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee
DC, New South Wales 2234, Australia
| | - Melissa Ugelow
- NASA
Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, Maryland 20771, United States
| | - Carrie Anderson
- NASA
Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, Maryland 20771, United States
| | - Robert Hodyss
- NASA
Jet Propulsion Laboratory, California Institute
of Technology, 4800 Oak Grove Drive, Pasadena, California 91109, United States
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Nixon CA. The Composition and Chemistry of Titan's Atmosphere. ACS EARTH & SPACE CHEMISTRY 2024; 8:406-456. [PMID: 38533193 PMCID: PMC10961852 DOI: 10.1021/acsearthspacechem.2c00041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 11/02/2023] [Accepted: 02/02/2024] [Indexed: 03/28/2024]
Abstract
In this review I summarize the current state of knowledge about the composition of Titan's atmosphere and our current understanding of the suggested chemistry that leads to that observed composition. I begin with our present knowledge of the atmospheric composition, garnered from a variety of measurements including Cassini-Huygens, the Atacama Large Millimeter/submillimeter Array, and other ground- and space-based telescopes. This review focuses on the typical vertical profiles of gases at low latitudes rather than global and temporal variations. The main body of the review presents a chemical description of how complex molecules are believed to arise from simpler species, considering all known "stable" molecules-those that have been uniquely identified in the neutral atmosphere. The last section of the review is devoted to the gaps in our present knowledge of Titan's chemical composition and how further work may fill those gaps.
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Affiliation(s)
- Conor A. Nixon
- Planetary Systems Laboratory, NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, Maryland 20771, United
States
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Mouzay J, Piétri N, Couturier-Tamburelli I, Chiavassa T. UV irradiation of benzene in N2 matrix: A relevant study for titan's chemistry. J Mol Struct 2021. [DOI: 10.1016/j.molstruc.2021.130296] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Teanby NA, Sylvestre M, Sharkey J, Nixon CA, Vinatier S, Irwin PGJ. Seasonal evolution of Titan's stratosphere during the Cassini mission. GEOPHYSICAL RESEARCH LETTERS 2019; 46:3079-3089. [PMID: 33100421 PMCID: PMC7580802 DOI: 10.1029/2018gl081401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Accepted: 02/19/2019] [Indexed: 06/11/2023]
Abstract
Titan's stratosphere exhibits significant seasonal changes, including break-up and formation of polar vortices. Here we present the first analysis of mid-infrared mapping observations from Cassini's Composite InfraRed Spectrometer (CIRS) to cover the entire mission (Ls=293-93°, 2004-2017) - mid-northern winter to northern summer solstice. The north-polar winter vortex persisted well after equinox, starting break-up around Ls∼60°, and fully dissipating by Ls∼90°. Absence of enriched polar air spreading to lower latitudes suggests large-scale circulation changes and photochemistry control chemical evolution during vortex break-up. South-polar vortex formation commenced soon after equinox and by Ls∼60° was more enriched in trace gases than the northern mid-winter vortex and had temperatures ∼20 K colder. This suggests early-winter and mid-winter vortices are dominated by different processes - radiative cooling and subsidence-induced adiabatic heating respectively. By the end of the mission (Ls=93°) south-polar conditions were approaching those observed in the north at Ls=293°, implying seasonal symmetry in Titan's vortices.
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Affiliation(s)
- N A Teanby
- School of Earth Sciences, University of Bristol, Wills Memorial Building, Queens Road, Bristol, BS8 1RJ, UK
| | - M Sylvestre
- School of Earth Sciences, University of Bristol, Wills Memorial Building, Queens Road, Bristol, BS8 1RJ, UK
| | - J Sharkey
- School of Earth Sciences, University of Bristol, Wills Memorial Building, Queens Road, Bristol, BS8 1RJ, UK
| | - C A Nixon
- Planetary Systems Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
| | - S Vinatier
- LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Univ. Paris Diderot, Sorbonne Paris Cité, 5 place Jules Janssen, 92195 Meudon, France
| | - P G J Irwin
- Atmospheric, Oceanic & Planetary Physics, Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford, OX1 3PU. UK
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Coustenis A, Jennings DE, Achterberg RK, Bampasidis G, Nixon CA, Lavvas P, Cottini V, Flasar FM. SEASONAL EVOLUTION OF TITAN'S STRATOSPHERE NEAR THE POLES. THE ASTROPHYSICAL JOURNAL. LETTERS 2018; 854:L30. [PMID: 32373309 PMCID: PMC7199715 DOI: 10.3847/2041-8213/aaadbd] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In this paper we report the monitoring of seasonal evolution near Titan's poles. We find Titan's south pole to exhibit since 2010 a strong temperature decrease and a dramatic enhancement of several trace species such as complex hydrocarbons and nitriles (HC3N and C6H6 in particular) previously only observed at high northern latitudes (Coustenis et al. 2016 and references therein). This results from the seasonal change on Titan going from winter (2002) to summer (2017) in the north and, at the same time, the onset of winter in the south pole. During this transition period atmospheric components with longer chemical lifetimes linger in the north undergoing slow photochemical destruction, while those with shorter lifetimes decrease and reappear in the south. An opposite effect was expected in the north, but not observed with certainty until now. We present here an analysis of high-resolution nadir spectra acquired by Cassini/CIRS at in the past years and describe the temperature and composition variations near Titan's poles. From 2013 until 2016, the northern polar region has shown a temperature increase of 10 K, while the south has shown a more significant decrease (up to 25 K) in a similar period of time. While the south polar region is continuously enhanced since about 2012, the chemical content in the north is finally showing a clear depletion for most molecules only since 2015. This is indicative of a non-symmetrical response to the seasons in Titan's stratosphere that can set constraints on photochemical and GCM models.
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Affiliation(s)
- A Coustenis
- Laboratoire d'Etudes Spatiales et d'Instrumentation en Astrophysique (LESIA), Observatoire de Paris, CNRS, UPMC Univ. Paris 06, Univ. Paris-Diderot, 5, place Jules Janssen, 92195 Meudon Cedex, France
| | - D E Jennings
- Planetary Systems Laboratory, Goddard Space Flight Center, Greenbelt, MD 20771, USA
| | - R K Achterberg
- Planetary Systems Laboratory, Goddard Space Flight Center, Greenbelt, MD 20771, USA
- Department of Astronomy, University of Maryland, College Park, MD 20742, USA
| | - G Bampasidis
- Faculty of Physics, National and Kapodistrian University of Athens, Panepistimioupolis, 15783 Zographos, Athens, Greece
| | - C A Nixon
- Planetary Systems Laboratory, Goddard Space Flight Center, Greenbelt, MD 20771, USA
| | - P Lavvas
- GSMA, Reims Champagne-Ardenne, 51687 Reims, France
| | - V Cottini
- Planetary Systems Laboratory, Goddard Space Flight Center, Greenbelt, MD 20771, USA
- Department of Astronomy, University of Maryland, College Park, MD 20742, USA
| | - F M Flasar
- Planetary Systems Laboratory, Goddard Space Flight Center, Greenbelt, MD 20771, USA
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The formation and evolution of Titan's winter polar vortex. Nat Commun 2017; 8:1586. [PMID: 29162820 PMCID: PMC5698511 DOI: 10.1038/s41467-017-01839-z] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Accepted: 10/18/2017] [Indexed: 11/09/2022] Open
Abstract
Saturn’s largest moon Titan has a substantial nitrogen-methane atmosphere, with strong seasonal effects, including formation of winter polar vortices. Following Titan’s 2009 northern spring equinox, peak solar heating moved to the northern hemisphere, initiating south-polar subsidence and winter polar vortex formation. Throughout 2010–2011, strengthening subsidence produced a mesospheric hot-spot and caused extreme enrichment of photochemically produced trace gases. However, in 2012 unexpected and rapid mesospheric cooling was observed. Here we show extreme trace gas enrichment within the polar vortex dramatically increases mesospheric long-wave radiative cooling efficiency, causing unusually cold temperatures 2–6 years post-equinox. The long time-frame to reach a stable vortex configuration results from the high infrared opacity of Titan’s trace gases and the relatively long atmospheric radiative time constant. Winter polar hot-spots have been observed on other planets, but detection of post-equinox cooling is so far unique to Titan. The polar hot-spot appeared in Titan after equinox in 2010 suddenly cooled in early 2012, which wasn’t predicted by models. Here the authors use observations to show that the increase in trace gases during the hot-spot resulted in radiative cooling feedback.
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Cordiner MA, Palmer MY, Nixon CA, Irwin PGJ, Teanby NA, Charnley SB, Mumma MJ, Kisiel Z, Serigano J, Kuan YJ, Chuang YL, Wang KS. ETHYL CYANIDE ON TITAN: SPECTROSCOPIC DETECTION AND MAPPING USING ALMA. ACTA ACUST UNITED AC 2015. [DOI: 10.1088/2041-8205/800/1/l14] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Cordiner MA, Nixon CA, Teanby NA, Irwin PGJ, Serigano J, Charnley SB, Milam SN, Mumma MJ, Lis DC, Villanueva G, Paganini L, Kuan YJ, Remijan AJ. ALMA MEASUREMENTS OF THE HNC AND HC
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N DISTRIBUTIONS IN TITAN'S ATMOSPHERE. ACTA ACUST UNITED AC 2014. [DOI: 10.1088/2041-8205/795/2/l30] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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HCN ice in Titan’s high-altitude southern polar cloud. Nature 2014; 514:65-7. [DOI: 10.1038/nature13789] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Accepted: 08/06/2014] [Indexed: 11/08/2022]
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