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Titan: Exploring an Earthlike World. Second Edition
Abstract
Titan: Exploring an Earthlike World presents the most comprehensive
description in book form of what is currently known about Titan, the
largest satellite of the planet Saturn and arguably the most intriguing
and mysterious world in the Solar System. Because of its resemblance to
our own planet, Titan is often described as a "frozen primitive Earth"
and is therefore of wide interest to scientists and educated laypersons
from a wide range of backgrounds. The book aims to cater to all of these
by using nontechnical language wherever possible, while maintaining a
high standard of scientific rigor.
The book is a fully revised and extensively updated edition of Titan:
The Earthlike Moon, which was published in 1999, before the Cassini and
Huygens missions arrived to orbit Saturn and land on Titan. As
investigators on these missions, the authors use the latest results to
present the most recent revelations and latest surprises about an
exciting new world.
... L'objectif était d'envoyer une sonde interplanétaire (l'orbiteur Cassini) en orbite autour de Saturne avec une trajectoire complexe afin de survoler les différents corps du système saturnien (Saturne, ses anneaux et ses lunes) ainsi que de déposer un module (le module Huygens) à la surface de Titan. Les objectifs initiaux de la mission en ce qui concerne Titan était (Coustenis and Taylor, 2008) : ...
... De plus, des nuages d'éthane ont été détectés au pôle Nord durant l'hiver nord. Les différents nuages de Titan peuvent être classés en 4 catégories (Coustenis and Taylor, 2008) : ...
... 5 shows the effect of the oceanic transport for Earth. Without oceanic transport, sea ice cover rises, yielding a ...
This thesis focuses on the study of the atmospheres of Titan and the early Earth with Global Climate Models (GCM). First, I analysed the thermal structure and the dynamics of Titan's lower troposphere. This analysis allowed a full caracterization of the planetary boundary layer and revealed the existence of a boundary layer circulation which impacts every aspect of Titan's weather (wind patterns, atmospheric waves, dune and cloud formation, exchange of momentum with the surface, and development of the superrotation). Thanks to this study, I proposed a new hypothesis to explain the eastward orientation of Titan's dunes that implies a coupling between tropical storms and the superrotation. This has been validated with mesoscale simulations and provided a general framework to explain Titan's dune formation and features. Then, I participated to the development of a generic GCM, designed to study any kind of atmosphere. I applied it to Titan's paleoclimates, when the atmosphere was depleted of methane. In such a case, the climate should have been different from today, with potentially fundamental geological consequences, in particular for the erosion and the age of the surface. Finally, I applied this GCM to the case of the early Earth using greenhouse gas abundances constrained by mineralogical data. I showed that despite a weaker solar insolation, the Archean Earth's climate may have been temperate. In particular, the Earth may have avoided a full glaciation and remained suitable for the development of life thanks to cloud feedback, even assuming a amount of CO2 just a little larger than today.
... Titan has a unique atmosphere , in that it is dense and consists mainly of N2 (98.4%), as on Earth. CH4 (1.4%), H2 (0.1%) and traces of argon, ethane, acetylene, propane and more complex hydrocarbons and nitriles, as well as condensates and organic aerosols (COUSTENIS & TAYLOR, 2008 ) constitute the rest of the atmosphere . The identification of such atmospheric compo-nents endorse theories suggesting that even though Titan is far out of the habitable zone, it is one of the most likely worlds in our solar system of astrobiological interest (RAULIN, 2008). ...
... The identification of such atmospheric compo-nents endorse theories suggesting that even though Titan is far out of the habitable zone, it is one of the most likely worlds in our solar system of astrobiological interest (RAULIN, 2008). Except for the new atmospheric discoveries such as the organic chemistry in the ionosphere, new components in the neutral atmosphere and the properties of the troposphere, Cassini-Huygens' most surprising discovery was Titan's complex and Earth-like geology (COUSTENIS & TAYLOR, 2008). As far as the surface is concerned, one of the moon's exceptional characteristics is the existence of surface liquid bodies that resemble terrestrial lakes (STOFAN et al., 2007). ...
... Earth-like body (COUSTENIS & TAYLOR, 2008). In addition, many atmospheric aspects such as the climate and the meteorology , as Titan displays a 'methanological' weather cycle of clouds, rainfall and evaporation that parallels the 'hydrological' cycle of the Earth, as well as, its complex morphology, make Titan an extremely important astrobiological place. ...
Since 2004, investigations, measurements and data analysis by the Cassini-Huygens mission showed that Titan, Saturn's largest satel-lite, presents complex, dynamic and Earth-like geology. Endogenous, as well, as exogenous dynamic processes, have created diverse terrains with extensive ridges and grooves, impact units, caldera-like structures, layered plains and liquid hydrocarbon lakes. Observations by the Cassini Visual Infrared Spectrometer instrument (VIMS) have indicated possible cryovolcanic terrains in the areas called Tui Regio (20°S, 130°W) and Hotei Regio (26°S, 78°W). In addition, Cassini's investigation over another icy moon of Saturn, Enceladus, identified its cryovolcanic activity and partially re-vealed its unique topography indicating several types of surface expressions. We present a comparative study of volcanic analogues from Earth and Enceladus that derive insight on the origin of some of these features. In this work, we focus on the analysis of VIMS data using the Principal Com-ponent Analysis technique in order to identify regions of altered chemical composition on Titan. The analysis of VIMS data suggests that possible cryovolcanic activity formed both the Tui Regio and the Hotei Regio. ΠΕΡΙΛΗΨΗ: Μακροχρόνιες έρευνες, μετρήσεις και αναλύσεις δεδομένων από την αποστολή Cassini-Huygens από το 2004, έδειξαν ότι ο Τιτάνας, ο μεγαλύτερος δορυφόρος του Κρόνου, παρουσιάζει περίπλοκη, δυναμική και παρόμοια με τη Γη γεωλογία. Ενδογενείς, όσο και εξωγενείς δυναμικές διεργασίες, έχουν δημιουργήσει ποικίλα γεωλογικά πεδία με εκτεταμένες ράχες και αύλακες, κρατήρες πρό-σκρουσης, δομές καλδέρας, πεδιάδες με στρωμάτωση καθώς και λίμνες υδρογονανθράκων. Παρατηρήσεις από το Cassini Visual Infrared Mapping Spectrometer (VIMS) όργανο, έχουν δείξει πιθανές κρυοηφαιστειακές εκτάσεις στις περιοχές Tui Regio (20 ° Ν, 130 ° Δ) και Hotei Regio (26°Ν, 78°Δ). Επιπλέον, η έρευνα του Cassini στον παγωμένο δορυφόρο του Κρόνου, Εγκέλαδο, επιβεβαίωσε την κρυοηφαιστει-ακή του δραστηριότητα και αποκάλυψε μερικώς τη μοναδική του τοπογραφία, παρουσιάζοντας ποικίλους τύπους επιφανειακών εμ-φανίσεων. Παρουσιάζουμε μια συγκριτική μελέτη, δείχνοντας ηφαιστειακά ανάλογα της Γης και του Εγκέλαδου, που παρέχουν πληροφορίες για τη δημιουργία κάποιων σχηματισμών. Σε αυτή τη μελέτη, επικεντρωνόμαστε στην ανάλυση δεδομένων VIMS, χρησι-μοποιώντας τη μέθοδο Ανάλυσης Κύριων Συνιστωσών σε περιοχές με διαφορετική χημική σύσταση. Οι αναλύσεις των VIMS δεδομένων των προαναφερθέντων εκτάσεων δείχνουν ότι τόσο η περιοχή Tui Regio όσο και η περιοχή Hotei Regio πιθανά σχηματίστηκαν από κρυοη-φαιστειακή δραστηριότητα. Λέξεις-κλειδιά: Πλανητική Γεωλογία, Παγωμένοι δορυφόροι, Τιτάνας, Εγκέλαδος, κρυοηφαιστειότητα, φασματοσκοπία. * Απεικόνιση των πιθανών ενεργών γεωλογικών περιοχών στους δορυφόρους του Κρόνου Τιτάνα και Εγκέλαδο: Μελέτη για την κρυοηφαιστειότητα µε τη χρήση υπέρυθρων φασµατικών δεδοµένων INTRODUCTION
... For example, Titan (Strobel and Shemansky, 1982) has a 1.45 bar atmosphere consisting of 98.4% N 2 , 1.4% CH 4 , and 0.1-0.2% H 2 (Coustenis and Taylor, 2008). However, the origin of such atmospheres is related to early photolysis of accreted and outgassed NH 3 from subsurface H 2 O-NH 3 oceans, leading to a very different environment compared to Earth's N 2 atmosphere (Coustenis and Taylor, 2008;Mandt et al., 2009Mandt et al., , 2014. ...
... H 2 (Coustenis and Taylor, 2008). However, the origin of such atmospheres is related to early photolysis of accreted and outgassed NH 3 from subsurface H 2 O-NH 3 oceans, leading to a very different environment compared to Earth's N 2 atmosphere (Coustenis and Taylor, 2008;Mandt et al., 2009Mandt et al., , 2014. In this hypothesis paper, we focus on classical rocky terrestrial planets that originated in an inner planetary system; frozen worlds like Titan, Triton, and Pluto are not considered. ...
Since the Archean, N2 has been a major atmospheric constituent in Earth’s atmosphere. Nitrogen is an essential element in the building blocks of life; therefore, the geobiological nitrogen cycle is a fundamental factor in the long-term evolution of both Earth and Earth-like exoplanets. We discuss the development of Earth’s N2 atmosphere since the planet’s formation and its relation with the geobiological cycle. Then we suggest atmospheric evolution scenarios and their possible interaction with life-forms: first for a stagnant-lid anoxic world, second fora tectonically active anoxic world, and third for an oxidized tectonically active world. Furthermore, we discuss a possible demise of present Earth’s biosphere and its effects on the atmosphere. Since life-forms are the most efficient means for recycling deposited nitrogen back into the atmosphere at present, they sustain its surface partial pressure at high levels. Also, the simultaneous presence of significant N2 and O2 is chemically incompatible in an atmosphere over geological timescales. Thus, we argue that an N2-dominated atmosphere in combination with O2 on Earth-like planets within circumstellar habitable zones can be considered as a geo-biosignature. Terrestrial planets with such atmospheres will have an operating tectonic regime connected with an aerobic biosphere, whereas other scenarios in most cases end up with a CO2-dominated atmosphere. We conclude with implications for the search for life on Earth-like exoplanets inside the habitable zones of M to K stars.
... For example, Titan (Strobel and Shemansky, 1982) has a 1.45 bar atmosphere consisting of 98.4 % N2, 1.4 % CH4, and 0.1-0.2 % H2 (Coustenis and Taylor, 2008). However, the origin of such atmospheres is related to early photolysis of accreted and outgassed NH3 from sub-surface H2O-NH3-oceans leading to a very different environment compared to Earth's N2 atmosphere (Coustenis and Taylor, 2008;Mandt et al., 2009;. ...
... % H2 (Coustenis and Taylor, 2008). However, the origin of such atmospheres is related to early photolysis of accreted and outgassed NH3 from sub-surface H2O-NH3-oceans leading to a very different environment compared to Earth's N2 atmosphere (Coustenis and Taylor, 2008;Mandt et al., 2009;. In this hypothesis paper we focus on classical rocky terrestrial planets that originated in an inner planetary system; frozen worlds like Titan, Triton, and Pluto are not considered. ...
Since the Archean, N2 has been a major atmospheric constituent in Earth's atmosphere. Nitrogen is an essential element in the building blocks of life, therefore the geobiological nitrogen cycle is a fundamental factor in the long term evolution of both Earth and Earth-like exoplanets. We discuss the development of the Earth's N2 atmosphere since the planet's formation and its relation with the geobiological cycle. Then we suggest atmospheric evolution scenarios and their possible interaction with life forms: firstly, for a stagnant-lid anoxic world, secondly for a tectonically active anoxic world, and thirdly for an oxidized tectonically active world. Furthermore, we discuss a possible demise of present Earth's biosphere and its effects on the atmosphere. Since life forms are the most efficient means for recycling deposited nitrogen back into the atmosphere nowadays, they sustain its surface partial pressure at high levels. Also, the simultaneous presence of significant N2 and O2 is chemically incompatible in an atmosphere over geological timescales. Thus, we argue that an N2-dominated atmosphere in combination with O2 on Earth-like planets within circumstellar habitable zones can be considered as a geo-biosignature. Terrestrial planets with such atmospheres will have an operating tectonic regime connected with an aerobe biosphere, whereas other scenarios in most cases end up with a CO2-dominated atmosphere. We conclude with implications for the search for life on Earth-like exoplanets inside the habitable zones of M to K-stars.
... Titan is the satellite with the densest atmosphere in the Solar System and has the only nitrogen-rich atmosphere aside from Earth's. Its atmosphere is mainly composed of nitrogen (97%) and methane (2.7AE1%), and lodges trace amounts of a high variety of hydrocarbons such us ethane, diacetylene, methylacetylene, acetylene, and cyanoacetylene (Niemann et al., 2005;Coustenis and Taylor, 2008). The atmosphere is characterized by distributed hazes of aerosol layers and the known Titan orange haze at altitudes of around 500 km (Isra€ el et al., 2005;Coates et al., 2009;Lavvas et al., 2013). ...
... We make use of the atmospheric model reported by Coustenis and Taylor (2008) and an adapted cosmic rays spectra for Saturn's orbit and moderate solar activity (Molina-Cuberos et al., 1999b) in order to calculate the ionization rate by cosmic rays. Solar wind interacts with the cosmic particles in the interplanetary medium and its variations related to the solar activity produce changes in the spectrum of cosmic rays. ...
... Another planetary body which has even more similarities with the Earth (Coustenis and Taylor 2008), but can be considered as a possible Class IV habitat, is Saturn's largest satellite Titan, which is unique in the Solar System due to its extensive nitrogen atmosphere, four times denser at the surface than on our own atmosphere, and host to a rich organic chemistry and some CH 4 . Titan's atmosphere is not in chemical equilibrium. ...
... The second most abundant constituent, methane, is dissociated irreversibly to produce hydrocarbons and nitriles, by combination with nitrogen. Recent Cassini-Huygens discoveries have revolutionized our understanding of the Titan system and its potential for harboring the "ingredients" necessary for life (Coustenis and Taylor 2008). These discoveries reveal that Titan is rich in organics, most probably contains a vast subsurface ocean, and has sufficient energy sources to drive chemical evolution. ...
... Many open questions are still to be answered regarding the atmosphere, geological features, surface composition, lakes and seas, rivers and craters, also including the possibility of pre-biotic evolution in its surface organics, directly linked to the presence of life. A thick icy shell with oceans of water underneath, combined with the presence of hydrocarbons in liquid bodies and the atmosphere, raise the point of using such potential resources available within Saturn's satellite [2]. Even though many data are available from the Cassini/Huygens mission and the potential scientific knowledge return from Dragonfly is expected to be high, both missions have focused on the equatorial region of Titan. ...
Considering its Earth-like characteristics such as the atmosphere (mostly composed of nitrogen and methane) and the presence of oceans, Titan has been considered as one of the most promising bodies for space exploration in the Solar System. Following the Global Exploration Roadmap, the students from the Space Exploration and Development Systems (SEEDS) Specializing Master's program have chosen to focus on deep space exploration and target Titan by developing state-of-the-art technologies. In this regard, this study presents the selection and preliminary design of space probes to be sent to Titan in order to broaden the knowledge of Saturn's satellite and examine the viability of in-situ resource utilization. Depending on the requirements provided for the mission, the concept design includes multiple tools,instruments and systems selected through tradeoff analysis techniques. Concepts of modules have been developed to analyze the available resources, to study the liquid bodies on Titan as well as to collect data about its seismic activity and atmosphere. The outcome of this work presents a configuration of the system, including the required technologies to perform the aforementioned activities, general dimension specifications and physical architecture. This proposed mission to Titan aims to enable exploration with an excellent suite of benefits such as in-situ resource utilization evaluation, an operational experience beyond cislunar space and a confidence-building for future mission scenarios. The data collected could provide more information on the history of the Solar system, raising the question about the possibility of sending humans to Titan.
... The interpretation of INMS measurements (limited to masses up to 100 Daltons) and of Cassini/CAPS data strongly suggests that high molecular weight species (up to several 1000 Daltons) may be present in the ionosphere (Waite et al. 2007, Fig. 7). Models applied to the data have pointed to the presence of complex molecules (see Tables 6.2 and 6.4 in Coustenis & Taylor 2008). The vertical distributions of the trace gases increase with altitude, confirming that these species form in the upper atmosphere and then diffuse downward in the stratosphere. ...
In this paper, we review the scientific aspects of planetary space weather at different regions of our Solar System, performing a comparative planetology analysis that includes a direct reference to the circum-terrestrial case. Through an interdisciplinary analysis of existing results based both on observational data and theoretical models, we review the nature of the interactions between the environment of a Solar System body other than the Earth and the impinging plasma/radiation, and we offer some considerations related to the planning of future space observations. We highlight the importance of such comparative studies for data interpretations in the context of future space missions (e.g. ESA JUICE; ESA/JAXA BEPI COLOMBO). Moreover, we discuss how the study of planetary space weather can provide feedback for better understanding the traditional circum-terrestrial space weather. Finally, a strategy for future global investigations related to this thematic is proposed.
... Recent researches indicate that graphene could be synthesized easily from methane or carbon dioxide through lightning in the absence of oxygen (14,15), meaning that graphene might exist in the early Earth. NASA scientists claimed this year that several macromolecular materials with strong aromatic characteristics have been detected in the atmosphere of the Titan (16), which is considered to be similar to that of the early Earth (17). There is an abundance of evidence that aromatic species, such as graphene and fullerene, from the destruction of hydrogenated amorphous-carbon, are extremely common and abundant in the universe (18)(19)(20)(21). ...
Many signs indicate that the graphene could widely occur on the early Earth.
Here, we report a new theory that graphene might be an embryo of protocell
membrane, and found several evidences. Firstly, the graphene oxide and
phospholipid-graphene oxide composite would curl into capsules in strongly
acidic saturated solution of Pb(NO3)2 at low temperature, providing a
protective space for biochemical reactions. Secondly, L-animi acids exhibit
higher reactivity than D-animi acids for graphene oxides in favor of the
formation of left-handed proteins. Thirdly, monolayer graphene with nanopores
prepared by unfocused 84Kr25+ has high selectivity for permeation of the
monovalent metal ions (Rb+ > K+ > Cs+ > Na+ > Li+), but does not allow Cl-
through, which could be attributed to the ion exchange of oxygen-containing
groups on the rim of nanopores. It is similar to K+ channels, which would cause
efflux of some ions from capsule of graphene oxides with the decrease of pH in
the primitive ocean, creating a suitable inner condition for the origin of
life. Consequently, the strongly acidic, high salinity and strong radiation as
well as temperature changes in the early Earth, regarded as negative factors,
would be indispensable for the origin of protocell. In short, graphene bred
life, but digested gradually by the evolution.
... Such a toxic ocean may also lay beneath the frozen landscape of Titan. Though Titan is the only icy satellite with a relatively thick atmosphere which is about 1.2 times as massive of the atmosphere of Earth (Coustenis and Taylor, 2008) (Fig. 5), environmental conditions are exceedingly challenging to life on Titan as well (Fig. 4). In addition, the radiation from the Sun is only 1% of that received on the surface of the Earth (Borucki et al., 1984), indicating very minor material circulation on the surface, although the material difference may play significant role in circulation. ...
Habitable Trinity is a newly proposed concept of a habitable environment. This concept indicates that the coexistence of an atmosphere (consisting largely of C and N), an ocean (H and O), and a landmass (supplier of nutrients) accompanying continuous material circulation between these three components driven by the Sun is one of the minimum requirements for life to emerge and evolve. Life body is consisting of C, O, H, N and other various nutrients, therefore the presence of water only is not sufficient condition. Habitable Trinity environment must be maintained to supply necessary components for life body. Habitable Trinity concept is also able to be applied to other planets and moons such as Mars, Europa, Titan, and even exoplanets as useful index in the quest for life-containing planetary bodies.
... Saturn's largest moon-the second largest moon in the solar system-is Titan. With an atmosphere of nitrogen four times denser at the surface than sea level air density on Earth, Titan is a unique body in the solar system (Coustenis and Taylor 2008). And yet, paradoxically, it may represent the most common type of body in the cosmos with a stable surface "volatile cycle" (Lunine 2009). ...
Titan is Saturn's Mercury-sized moon with the densest atmosphere-save
that of Venus-of any solid body in the solar system. The presence of
large amounts of liquid and solid hydrocarbons, discovered by the
Cassini-Huygens mission, implies a cycling between vapor, liquid and
possibly solid states akin to the hydrological cycle on the Earth. A
number of interesting sites for chemistry may be identified on Titan,
despite the cold temperatures, including zone of recent impacts, areas
of enhanced geothermal activity, the polar lakes and seas, and basins
where acetylene may have collected and is polymerizing over time,
releasing stored chemical energy as heat.
... The Cassini orbiter has since been continuously monitoring the saturnian system, an important aspect of which is the environments of the saturnian satellites, including Enceladus, a moon ejecting large quantities of water vapor into space (e.g., Dougherty et al., 2006; Porco et al., 2006). Titan, the largest kronian moon, is organic-rich in the atmosphere through the combination of nitrogen and methane (Coustenis and Taylor, 2008; Vuitton et al., 2009; Waite et al., 2010), with precipitation and lakes of ethane and methane forming on the surface (Stofan et al., 2007, Turtle et al., 2011). Organic components were also measured in Enceladus' plumes (Waite et al., 2006). ...
Abstract In this paper, we provide a detailed review of Ganymede's characteristics that are germane to any consideration of its planetary protection requirements. Ganymede is the largest moon in our solar system and is the subject of one of the main science objectives of the JUICE mission to the jovian system. We explore the probability of the occurrence of potentially habitable zones within Ganymede at present, including those both within the deep liquid ocean and those in shallow liquid reservoirs. We consider the possible exchange processes between the surface and any putative habitats to set some constraints on the planetary protection approach for this moon. As a conclusion, the "remote" versus "significant" chance of contamination will be discussed, according to our current understanding of this giant icy moon. Based on the different estimates we investigate here, it appears extremely unlikely that material would be exchanged downward through the upper icy layer of Ganymede and, thus, bring material into the ocean over timescales consistent with the survival of microorganisms. Key Words: Planetary science-Planetary protection-Ice. Astrobiology 13, 991-1004.
... In this work as an object of investigation was chosen the van der Waals CH 4 AN 2 complex, the interest to which was raised by studies of low-temperature nitrogen-methane atmosphere of Titan [43] [44] [45] [46] [47] [48] [49] [50] (the satellite of Saturn). At present, this complex is not very well investigated. ...
The static first hyperpolarizability of the van der Waals CH(4) N(2) complex was calculated. The calculations were carried out in the approximation of the rigid interacting molecules for a broad range of intermolecular separations (R = 6-40 a(0) ) and for six configurations at CCSD(T) level of theory using the correlation consistent aug-cc-pVTZ basis set with the basis set superposition error correction. It was shown that the long-range classical approximation, including the terms up to R(-6) , is in a good agreement with ab initio calculations for R > 11 a(0) . It was found out that for the family of most stable configurations of the complex, the first hyperpolarizability invariants practically do not change (the changes are less than 0.1%). Under forming the stable van der Waals CH(4) N(2) complex, the intensity and degree of depolarization of the hyper-Rayleigh scattering are noticeable decreased (by ∼10%) to be compared with the free CH(4) and N(2) molecules. © 2012 Wiley Periodicals, Inc.
... In this work as an object of investigation was chosen the van der Waals CH 4 AN 2 complex, the interest to which was raised by studies of low-temperature nitrogen-methane atmos- phere of Titan [43][44][45][46][47][48][49][50] (the satellite of Saturn). At present, this complex is not very well investigated. ...
The static first hyperpolarizability of the van der Waals CH4 - N 2 complex was calculated. The calculations were carried out in the approximation of the rigid interacting molecules for a broad range of intermolecular separations (R = 6–40 a0) and for six configurations at the CCSD(T) level of theory using the correlation consistent aug-cc-pVTZ basis set with the basis set superposition error correction. It was shown that the long-range classical approximation, including the terms up to R^-6 , is in a good agreement with ab initio calculations for R > 11 a0 . It was found out that for the family of most stable configurations of the complex, the first hyperpolarizability invariants practically do not change (the changes are less than 0.1%). Under forming the stable van der Waals CH4 - N2 complex, the intensity and degree of depolarization of the hyper-Rayleigh scattering are noticeable decreased (by ~10%) to be compared with the free CH4 and N2 molecules.
... Moreover, ethylene dimer is of particular interest for astrophysical applications. These complexes may exist in the atmospheres of giant planets (Jupiter, [4,5] Saturn, [6] Neptune, and Uranus [7] ) and Saturn's satellite Titan, [8][9][10][11][12] and contribute to the IR absorption spectra of their atmospheres. ...
The interaction potential energy and the interaction-induced dipole moment surfaces of the van der Waals C(2)H(4)-C(2)H(4) complex has been calculated for a broad range of intermolecular separations and configurations in the approximation of rigid interacting molecules. The calculations have been carried out using high-level ab initio theory with the aug-cc-pVTZ basis set and within the framework of the analytical description of long-range interactions between ethylene molecules. Binding energy for the most stable configuration of the C(2)H(4)-C(2)H(4) complex was calculated at the CCSD(T)/CBS level of theory. The harmonic fundamental vibrational frequencies for this complex were calculated at the MP2 level of theory.
Nitric oxide is a potential biomarker in the N 2 -O 2 atmospheres of terrestrial exoplanets, which can be detected by space missions, including the planned launch of the Russian Spektr-UF observatory. From observations of the Earth's thermosphere in the polar regions, it is known that important sources of formation of this molecule are the precipitation of high-energy electrons into the planet's atmosphere, as well as the non-thermal processes accompanying them. In this paper the non-thermal processes of nitrogen oxide formation in the polar regions of the Earth's upper atmosphere are investigated, as well as the atmospheres of exoplanets located in the potential habitability zone of active stars. For this purpose, a numerical kinetic Monte Carlo model of the interaction of high-energy electrons with atmospheric gas has been developed; a kinetic Monte Carlo model of the interaction of suprathermal N( 4 S) atoms formed as a result of dissociation of N 2 molecules by electron impact with the surrounding gas; as well as a model of odd nitrogen chemistry with taking into account the molecular and turbulent diffusion. According to the results of calculations, it is confirmed that the process of dissociation of N 2 by an electron impact during the interaction of the stellar wind with the atmosphere of the planet is an important source of suprathermal N atoms, which contribute to a significant increase in the non-thermal formation of NO in the N 2 -O 2 atmospheres of terrestrial planets (both locally, in the case of a planet's own magnetic field, and throughout the planet's surface, in the case of its absence). Because the column concentration of NO during flares becomes larger, therefore the chances of detecting of nitric oxide biomarker in the atmospheres of the terrestrial-type exoplanets located in the potential habitability zone of active stars are also become larger.
The term biosphere designates the “zone of life” on Earth. Outside this sphere, everything becomes “alien.” In this view of things, which I take to be canonical in the modern West, terrestrial life and biosphere overlap more or less neatly. Yet this idea of an almost perfect convergence is not the only view possible. This study presents two anthropological cases which demonstrate, a contrario, that the modern tendency to envisage the biosphere as “our home environment” or as “our familiar world” is in many ways a historical accident. Other ecumenical possibilities (by which I refer to the ancient Greek notion of the “inhabited world,” the oikumene) are by no means unthinkable. Examining the ecumenical originality of two communities that at first sight seem unrelated – Chachi indigenous people in Ecuador and scientists involved in the search for extraterrestrial life – will allow us to cast new light on the metaphysical underpinnings of the modern biosphere concept.
Habitable Trinity is a new concept for a habitable environment proposed by Dohm and Maruyama (2015). This concept indicates that the coexistence of an atmosphere, an ocean, and a landmass, accompanied by a continuous circulation of material among these three components driven by the Sun, is one of the minimum requirements for life to emerge and evolve. Because a life body consists of carbon (mainly from the atmosphere), oxygen (mainly from an ocean), hydrogen (mainly from an ocean), nitrogen (mainly from the atmosphere), and various nutrients (supplied from a landmass), the presence of water alone is not a sufficient condition. The Habitable Trinity concept can also be applied to other planets such as Mars, Europa, and Titan, and even exoplanets, as a useful index in the quest for life-containing planetary bodies.
In order to evaluate the dipole moment, the finite-field method [see Eq. (2. 3. 2)] described by Cohen and Roothaan in (J Chem Phys 43(10):S34–S39, 1) is often employed.
The methods for computation of molecular polarizability are implemented now in many well-known modern quantum chemical codes. Some of their features will be discussed in the next Section.
In this introduction to planetary geology, we review the major geologic processes affecting the solid bodies of the solar system, namely volcanism, tectonism, impact cratering, and erosion. We illustrate the interplay of these processes in different worlds, briefly reviewing how they affect the surfaces of the Earth's Moon,
Mercury, Venus and Mars, then focusing on two very different worlds: Jupiter's moon Io, the most volcanically active object in the solar system, and Saturn's moon Titan, where the interaction between a dense atmosphere and the surface make for remarkably earth-like landscapes despite the great differences in surface temperature and composition.
This book deals with the Origin of Life on Earth and planets, which is currently a very “hot” topic dealt with at several international meetings, conferences and workshops by various societies and groups. The current volume is number 22 of the “Cellular Origin, Life in Extreme Habitats and Astrobiology” series (COLE) published by Springer. The contributors review new data in this field, following current studies from gene and molecular to macro levels. The extremophiles – microorganisms living at the edge of Life under very severe conditions (from our anthropocentric view point) - may point out possibilities of existing Life forms on other planets and satellites.
In eight sections and fifty chapters, the seventy-five authors cover subjects such as chemical evolution, the function of geophysics in Life’s origin, the first steps of cellular evolution, Panspermia (the theory claiming that the source of Life is not from Earth but from Outer Space), possibility of extraterrestrial Life (Astrobiology), and the history of origin of Life on Earth and beyond.
This up-to-date book complements volume 6 (Origin Genesis, Evolution and Diversity of Life (2004) in the COLE series (ISBN: 978-1-4020-1813-8) published by Kluwer Academic Publishers.
Professor D. Deamer ends his Introduction with these words: Future progress in understanding the origin of life will involve simulations of prebiotic conditions that take this complexity into account. Some of the chapters in this book focus on specific aspects of the chemical and physical processes that would be involved in life's origins, while others incorporate increments in complexity such as mineral surfaces and compartments. In a sense, each chapter represents a piece of a puzzle, and readers who take the time to read all the chapters may see unexpected patterns emerge that will give clues to solving the puzzle.
The primary audience for this book are general biologists, geologists, geneticists, astrobiologists and astrophysicists, and advance undergraduate and graduate students, researchers and teachers in those fields.
The ability to observe and identify the presence of trace gases within an environment is a paramount capability needed to advance earth and planetary atmospheric research. Detection of trace levels of gases is also of interest in defense, industrial, security, medical, and environmental health applications. Current scientific objectives largely focus on identifying the presence of specific gases and isotopologues found in planetary atmospheres within our solar system. The presence and relative amounts of these gases allows scientists to deduce history of the planetary atmosphere and the likelihood that life has or could exist there. One challenge is accurately acquiring the data needed to make reliable conclusions when some of the target gas molecules are present in trace quantities of 10 parts per billion (ppb) or less. Laser gas spectrometers are effective ways of collecting in situ gas measurements, but their precision is directly proportional to the path length of the optical system. The Scanning Laser Infrared Molecular Spectrometer (SLIMS) is a novel solution that achieves very long effective path lengths, which yield ppb and sub-ppb measurements of trace gases. It can also accommodate multiple laser channels covering a wide range of wavelengths resulting in detection of more chemicals of interest. The mechanical design of the mirror cell allows for the large effective path length within a small footprint. The same design provides a robust structure which lends itself to being immune to some of the alignment challenges that similar cells face. The continued forward progress of the SLIMS project will rely on optimizing the optical paths and optical alignment geometries. Missions referred to in this document are for planning and discussion purposes only. Historical Background: A key focus in the modern scientific community is to discover and understand the history and evolution of planetary atmospheres within our solar system. One of the most effective ways to do this is to look at the makeup of the gases in an atmosphere. By identifying the presence and relative amounts of key gases, logical speculation can be made about how the atmosphere has changed over time. This includes historical chemical records about the presence of water and chemical isotope ratios providing evidence of carbon based signatures of life. Two targets of particular interest are the planet Venus and Saturn's moon, Titan. Both of these bodies contain dense atmospheres thicker than that of Earth; and each has unique characteristics that make them prime scientific targets.
Collision-induced spectra are the spectra of complexes of two or more atoms or molecules in a “fly-by” collisional encounter. Collision-induced absorption (CIA) has been observed in many dense gases and gas mixtures, in most cases at infrared frequencies in the form of quasi continua, and also in liquids and solids. CIA spectra of several binary complexes have been computed using modern quantum chemical methods, combined with molecular scattering theory, which couples the collisional complex to the radiation field as usual in other spectroscopic work. Binary collisional systems, such as H2 interacting with another H2 molecule, or with a helium or hydrogen atom, are first candidates for such computational work, owing to their small number of electrons and the astrophysical interest in such systems. The computed CIA spectra are found to be in close agreement with existing laboratory measurements of such spectra. Laboratory measurements exist at a limited selection of temperatures around 300 K and lower, but theory currently also provides CIA data for temperatures up to 9000 K and for higher frequencies (well into the visible), on a dense grid of temperatures and frequencies. For such calculations, detailed potential energy surfaces (PES) of the supermolecular complexes, along with the induced dipole surfaces (IDS), are needed so that the rotovibrational matrix elements of PES and IDS may be computed for the molecules involved, which may be highly rotovibrationally excited. Modern astronomical research needs opacity tables for analyses of the atmospheres of “cool” objects, such as cool white dwarfs, solar and extrasolar planets and their big moons, cool main sequence stars, and “first” stars, which are briefly described in a concluding section.
Titan, Saturn's satellite, is one of the most interesting planetary
bodies in the Planetary Geology domain. Spectro-imaging and radar
measurements by the Cassini-Huygens, joint ESA/NASA mission, suggest
that it may be geologically active and could support tectonic processes.
In particular, Titan possesses a complex and dynamic geology as
witnessed by its varied surface morphology resulting from aeolian,
fluvial, and possibly tectonic and endogenous cryovolcanic processes.
The Synthetic Aperture Radar (SAR) instrument, on board Cassini
spacecraft, indicates the possibility for morphotectonic features on
Titan's surface such as mountains, ridges, faults and canyons [1; 2; 3;
4]. Additionally, cryovolcanic structures like calderas, domes, flows
and radial faults [3] are surficial indications of volcanotectonic
activities. The mechanisms that formed these morphotectonic structures
are still unclear since ensuing processes, such as erosion may have
modified or partially obscured them. Due to the limitations of the
Cassini-Huygens in the acquisition of in situ measurements or samples
relevant to geotectonic processes and the lack of high spatial
resolution imaging, we do not have precise enough data of the morphology
and topography of Titan. However, we suggest that contractional
tectonism followed by atmospheric modifications has resulted in the
observed morphotectonic features. To test the possibility of
morphotectonics on Titan, we provide in this work a comparative study
between Cassini observations of the satellite versus terrestrial
tectonic systems and infer suggestions for possible formation
mechanisms. [1] Solomonidou et al., (2011) Planetary and Space
Science, submitted. [2] Lopes, R.M.C. et al., (2010) Icarus 205,
540-558. [3] Soderblom L.A. et al., (2009) Icarus 204, 610-618. [4]
Collins, G.C. et al., (2009) Planetary Tectonics, Cambridge University
Press.
Following our recent study devoted to measurements of intensities of pure rotation lines of methane, room temperature far infrared spectra of methane diluted in nitrogen at five total pressures between 100 and 800 hPa have been recorded at the AILES beamline of the SOLEIL synchrotron. One hundred and five N2 broadening coefficients of methane pure rotation lines have been measured in the 83–261 cm−1 spectral range using multi-spectrum non-linear least squares fitting of Voigt profiles. Pressure-induced line shifts were not needed to fit the spectra to the noise level and line mixing effects were neglected. One hundred and seventy-six self broadening coefficients have also been measured in the 59–288 cm−1 spectral range using the pure methane spectra recorded in our previous work. The measured N2 broadening coefficients were compared to semi-classical calculations.
The surface of Titan has been revealed globally, if incompletely, by Cassini observations at infrared and radar wavelengths as well as locally by the instruments on the Huygens probe. Extended dune fields, lakes, mountainous terrain, dendritic erosion patterns and erosional remnants indicate dynamic surface processes. Valleys, small-scale gullies and rounded cobbles such as those observed at the Huygens landing site require erosion by energetic flow of a liquid. There is strong evidence that liquid hydrocarbons are ponded on the surface in high-latitude lakes, predominantly, but not exclusively, at high northern latitudes. A variety of features including extensive flows and caldera-like constructs are interpreted to be cryovolcanic in origin. Chains and isolated blocks of rugged terrain rising from smoother areas are best described as mountains and might be related to tectonic processes. Finally, impact craters are observed but their small numbers indicate that the crater retention age is very young overall. In general, Titan exhibits a geologically active surface indicating significant endogenic and exogenic processes, with diverse geophysical and atmospheric processes reminiscent of those on Earth.
The combination of limb and disk views of Titan's haze acquired by the Cassini Imaging Science Subsystem from 2004 to the present reveals a variety of structures which evolve over many time scales. Titan's haze structure was significantly reduced in Voyager times relative to what ISS observed early in the mission. This feature may be an indication of long-term secular change rather than seasonal change. Images in the 890-nm methane absorption band reveal a polar structure which is offset from the rotational pole (Roman et al., Icarus 203, 242-249, 2009). Here we compile observations of haze structure at many wavelengths from the near-UV to the near-IR including three methane bands. We describe few-km-scale structure in the vertical haze profiles and albedo changes as a function of latitude with time sampling of several months. Multiple haze layers at or above 510 km altitude are seen at most latitudes. Preliminary evidence suggests the altitudes of the outer visible layers are decreasing with time. The region poleward of the polar vortex boundary near latitude 55 degrees is quite complex. These and future observations will constrain aerosol microphysical models and reveal detail on how seasonal change takes place. Our radiative transfer models make use of a multi-scatter code with spherical shell symmetry. This work was performed by the Jet Propulsion Lab, California Institute of Technology
A high-resolution vertical profile of Titan's winds was inferred from ground-based radiotelescopes, which recorded the Doppler Wind Experiment measurements of the carrier frequency during the Huygens mission (Bird et al., 2005). It indicates the existence of a wind shear layer with surprisingly low wind speed nearing zero, at altitudes between 60 and 100km. We call this phenomenon the ‘zonal wind collapse’. Titan's stratosphere is also characterized by an atmospheric superrotation. To identify the physical cause of the zonal wind collapse on Titan, we employ a Planetary General Circulation Model (PGCM) to simulate Titan's general circulation and vertical profiles of the zonal wind under different scenarios of angular velocities. The results show that both the zonal wind collapse and superrotation are closely associated with the magnitude of angular velocity and occur in the slowly rotating regime. This result may be a general phenomenon applicable beyond Titan. In addition, the Community Atmosphere Model version 2 (CAM2) was used to simulate the Earth's atmosphere under different rotation periods for two different physical parameterizations. The zonal wind collapse also observed on Earth is reproduced mainly for a dry atmosphere in the case of rotation periods between 5–50 days and is related to a positive meridional temperature gradient. Besides, a moist process does not only suppress the zonal wind collapse, but also may have an impact on the strength of the superrotation.
The current interest of astrobiology in Saturn’s satellite Titan, which is the second largest satellite of the solar system,
is mainly due to the Cassini-Huygens Mission, an ESA-NASA collaboration that in 2004 dropped a probe through the thick atmosphere
of Titan and in 2005 discovered plumes of water ice and dust emanating form the tiny moon Enceladus.
Our understanding of Titan, Saturn's largest satellite, has recently been consid-erably enhanced, thanks to the Cassini-Huygens mission. Since the Saturn Orbit Injection in July 2004, the probe has been harvesting new insights of the Kronian system. In par-ticular, this mission orchestrated a climax on January 14, 2005 with the descent of the Huygens probe into Titan's thick atmosphere. The orbiter and the lander have provided us with picturesque views of extraterrestrial landscapes, new in composition but reassuringly Earth-like in shape. Thus, Saturn's largest satellite displays chains of mountains, fields of dark and damp dunes, lakes and possibly geologic activity. As on Earth, landscapes on Titan are eroded and modeled by some alien hydrology: dendritic systems, hydrocarbon lakes, and methane clouds imply periods of heavy rainfalls, even though rain was never observed directly. Titan's surface also proved to be geologically active – today or in the recent past – given the small number of impact craters listed to date, as well as a few possible cryovolcanic features. We attempt hereafter a synthesis of the most significant results of the Cassini-Huygens endeavor, with emphasis on the surface.
Planetary meteorologists seek to understand the origin and evolution of the family of planets that orbit the Sun, to investigate the stability of their atmospheres and to compare the surface environment and climate with the Earth. The radiative, dynamical and chemical processes in Earth's atmosphere all have analogues on the other planets: by studying all of them, we learn more than by studying the Earth as an isolated example. Space missions to the planets are now sufficiently numerous and sophisticated, and computer models sufficiently versatile, to make such studies meaningful. This article reviews the current state of knowledge. Copyright © 2010 Royal Meteorological Society
Life on Earth is ubiquitous. Most of the organisms that we know thrive in normal environments that we consider to be ambient
habitats. Extremophiles are among the microorganisms living on the edge of life under severe conditions. In recent years microorganisms
have been discovered living in extreme environments, such as very high temperature (up to 115°C), and also at very low temperature
(∼ minus 20°C). In addition, they can also withstand a variety of stresses, amongst them we mention both ends of the pH range;
very strong acidity vs. high alkalinity; saturated salt solutions and high hydrostatic pressure. Astrobiology considers the
possibility that extraterrestrial civilizations may be present in some exoplanets in the large suite that has been discovered
so far. The instruments of research are radio telescopes. Astrobiology also raises the possibility of life elsewhere in the
Solar System. (The most promising examples are Mars, Europa, and possibly Titan and Enceladus). We suggest that if microbial
communities can thrive under extreme conditions on Earth, they could also emerge on extraterrestrial environments.
The atmospheres/exospheres of icy satellites greatly vary from one to the next in terms of density, composition, structure
or steadiness. Titan is the only icy satellite with a dense atmosphere comparable in many ways to that of the Earth’s atmosphere.
Titan’s atmosphere prevents the surface from direct interaction with the plasma environment, but gives rise to Earth-like
exchanges of energy, matter and momentum. The atmospheres of other satellites are tenuous. Enceladus’ atmosphere manifests
itself in a large water vapor plume emanating from surface cracks near the south pole. Io’s SO2 atmosphere originates from volcanoes. Europa’s tenuous O2 atmosphere is produced by intense radiation bombardment. This chapter reviews the characteristics of the atmospheres of Titan,
Enceladus, Io and Europa based on observations.
KeywordsAtmospheres-Exospheres-Icy satellites-Titan-Io-Enceladus-Europa
Much of our knowledge of planetary surface composition is derived from remote sensing over the ultraviolet through infrared
wavelength ranges. Telescopic observations and, in the past few decades, spacecraft mission observations have led to the discovery
of many surface materials, from rock-forming minerals to water ice to exotic volatiles and organic compounds. Identifying
surface materials and mapping their distributions allows us to constrain interior processes such as cryovolcanism and aqueous
geochemistry.
The recent progress in understanding of icy satellite surface composition has been aided by the evolving capabilities of spacecraft
missions, advances in detector technology, and laboratory studies of candidate surface compounds. Pioneers 10 and 11, Voyagers
I and II, Galileo, Cassini and the New Horizons mission have all made significant contributions. Dalton (Space Sci. Rev.,
2010, this issue) summarizes the major constituents found or inferred to exist on the surfaces of the icy satellites (cf. Table1
from Dalton, Space Sci. Rev., 2010, this issue), and the spectral coverage and resolution of many of the spacecraft instruments that have revolutionized our
understanding (cf. Table2 from Dalton, Space Sci. Rev., 2010, this issue). While much has been gained from these missions, telescopic observations also continue to provide important
constraints on surface compositions, especially for those bodies that have not yet been visited by spacecraft, such as Kuiper
Belt Objects (KBOs), trans-Neptunian Objects (TNOs), Centaurs, the classical planet Pluto and its moon, Charon.
In this chapter, we will discuss the major satellites of the outer solar system, the materials believed to make up their surfaces,
and the history of some of these discoveries. Formation scenarios and subsequent evolution will be described, with particular
attention to the processes that drive surface chemistry and exchange with interiors. Major similarities and differences between
the satellites are discussed, with an eye toward elucidating processes operating throughout the outer solar system. Finally
we discuss the outermost satellites and other bodies, and summarize knowledge of their composition. Much of this review is
likely to change in the near future with ongoing and planned outer planet missions, adding to the sense of excitement and
discovery associated with our exploration of our planetary neighborhood.
KeywordsComposition-Icy satellites-Infrared spectroscopy
The interaction-induced dipole moment surface of the van der Waals CH(4)-N(2) complex has been calculated for a broad range of intermolecular separations R and configurations in the approximation of the rigid interacting molecules at the MP2 and CCSD(T) levels of theory using the correlation-consistent aug-cc-pVTZ basis set with the basis set superposition error correction. The simple model to account for the exchange effects in the range of small overlap of the electron shells of interacting molecules and the induction and dispersion interactions for large R has been suggested. This model allows describing the dipole moment of van der Waals complexes in analytical form both for large R, where induction and dispersion have the key role, and for smaller R including whole ranges of their potential wells, where the exchange effects are important. The proposed model was tested on a number of configurations of the CH(4)-N(2) complex and was applied for the analytical description of the dipole moment surface for the family of the most stable configurations of the CH(4)-N(2) complex.
Earth is the only known inhabited planet in the universe to date. However,
advancements in the fields of astrobiology and observational astronomy, and the
discovery of large varieties of extremophiles with extraordinary capablities to
thrive the in the harshest environments on Earth, have led to speculation that
life may be thriving on many of the extraterrestrial bodies in the universe.
Coupled with the growing number of exoplanets detected over the past decade,
the search for the possibility of life on other planets and satellites within
the solar system and beyond has become a passion as well as a challenge for
scientists in a variety of fields. This paper examines such possibility of
finding life, in the light of findings of the numerous space probes and
theoretical research undertaken in this field over the past few decades.
The evolution of matter in the cosmos includes the production of elements which, over time, produces carbon and other heavy elements needed to form planets and life. The overall physics of the process and the environments in stars where carbon, nitrogen, and oxygen are formed are generally fairly well understood. It is carbon's particular properties of chemical bonding along with its high abundance that make it especially suited as the foundation for life. Over 120 organic molecules are found in interstellar space, and organic phases - some with slight enrichment of one ``chiral-enantiomeric'' form over the other - are known in meteorites. Delivery of this material to the Earth during formation of the planets was aided by the early presence of Jupiter, whose gravity ensured mixing of materially radially throughout the solar system. In the outer solar system, organic-rich worlds are present and chemistry is evolving there today - Titan is a particularly promising example in this regard. For life as we know it, liquid water is required (though forms of non-Earth life might exist in other liquids), and hence the inferred liquid water environments in Jupiter's moon Europa and Saturn's moon Enceladus are of keen interest along with environments on and within Titan that contain aqueous and non-aqueous liquids.
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