The Atmosphere of Titan

2021 ◽  
Author(s):  
Athena Coustenis
Keyword(s):  
Solar System ◽  
Thermal Structure ◽  
Trace Gases ◽  
Chemical Compounds ◽  
Strong Interactions ◽  
Origin And Evolution ◽  
Extensive Analysis ◽  
System P ◽  
Surface Liquid ◽  
Main Component

Titan, Saturn’s largest satellite, is one of the most intriguing moons in our Solar System, in particular because of its dense and extended nitrogen-based and organic-laden atmosphere. Other unique features include a methanological cycle similar to the Earth’s hydrological one, surface features similar to terrestrial ones, and a probable under-surface liquid water ocean. Besides the dinitrogen main component, the gaseous content includes methane and hydrogen, which, through photochemistry and photolysis, produce a host of trace gases such as hydrocarbons and nitriles. This very advanced organic chemistry creates layers of orange-brown haze surrounding the satellite. The chemical compounds diffuse downward in the form of aerosols and condensates and are finally deposited on the surface. There is very little oxygen in the atmosphere, mainly in the form of H2O, CO, and CO2. The atmospheric chemical and thermal structure varies significantly with seasons, much like on Earth, albeit on much longer time scales. Extensive analysis of Titan data from ground, Earth-orbiting observatories, and space missions, like those returned by the 13-year operating Cassini-Huygens spacecraft, reveals a complex system with strong interactions among the atmosphere, the surface, and the interior. The processes operating in the atmosphere are informative of what occurs on Earth and give hints as to the origin and evolution of our outer Solar System.

Drifting Through a Planetary System

2018 ◽  
Author(s):  
Karel Schrijver
Keyword(s):  
Seventeenth Century ◽  
Solar System ◽  
Virtual Worlds ◽  
Planetary System ◽  
System P ◽  
History Of ◽  
Or Team ◽  
Water Contents

This chapter describes how the first found exoplanets presented puzzles: they orbited where they should not have formed or where they could not have survived the death of their stars. The Solar System had its own puzzles to add: Mars is smaller than expected, while Venus, Earth, and Mars had more water—at least at one time—than could be understood. This chapter shows how astronomers worked through the combination of these puzzles: now we appreciate that planets can change their orbits, scatter water-bearing asteroids about, steal material from growing planets, or team up with other planets to stabilize their future. The special history of Jupiter and Saturn as a pair bringing both destruction and water to Earth emerged from the study of seventeenth-century resonant clocks, from the water contents of asteroids, and from experiments with supercomputers imposing the laws of physics on virtual worlds.

Exploring the Solar System

2018 ◽  
Author(s):  
Karel Schrijver
Keyword(s):  
Solar System ◽  
Planetary Systems ◽  
Interplanetary Dust ◽  
Terrestrial Planets ◽  
The Moon ◽  
System P ◽  
Asteroids And Comets

In this chapter, the author summarizes the properties of the Solar System, and how these were uncovered. Over centuries, the arrangement and properties of the Solar System were determined. The distinctions between the terrestrial planets, the gas and ice giants, and their various moons are discussed. Whereas humans have walked only on the Moon, probes have visited all the planets and several moons, asteroids, and comets; samples have been returned to Earth only from our moon, a comet, and from interplanetary dust. For Earth and Moon, seismographs probed their interior, whereas for other planets insights come from spacecraft and meteorites. We learned that elements separated between planet cores and mantels because larger bodies in the Solar System were once liquid, and many still are. How water ended up where it is presents a complex puzzle. Will the characteristics of our Solar System hold true for planetary systems in general?

Late Accretion and the Origin of Water on Terrestrial Planets in the Solar System

2021 ◽  
Author(s):  
Cédric Gillmann ◽  
Gregor Golabek ◽  
Sean Raymond ◽  
Paul Tackley ◽  
Maria Schonbachler ◽  
...  
Keyword(s):  
Solar System ◽  
Long Term Evolution ◽  
Terrestrial Planets ◽  
Evolutionary Pathway ◽  
Giant Impact ◽  
The Earth ◽  
Term Evolution ◽  
Surface Liquid ◽  
Venus Atmosphere

<p>Terrestrial planets in the Solar system generally lack surface liquid water. Earth is at odd with this observation and with the idea of the giant Moon-forming impact that should have vaporized any pre-existing water, leaving behind a dry Earth. Given the evidence available, this means that either water was brought back later or the giant impact could not vaporize all the water.</p><p>We have looked at Venus for answers. Indeed, it is an example of an active planet that may have followed a radically different evolutionary pathway despite the similar mechanisms at work and probably comparable initial conditions. However, due to the lack of present-day plate tectonics, volatile recycling, and any surface liquid oceans, the evolution of Venus has likely been more straightforward than that of the Earth, making it easier to understand and model over its long term evolution.</p><p>Here, we investigate the long-term evolution of Venus using self-consistent numerical models of global thermochemical mantle convection coupled with both an atmospheric evolution model and a late accretion N-body delivery model. We test implications of wet and dry late accretion compositions, using present-day Venus atmosphere measurements. Atmospheric losses are only able to remove a limited amount of water over the history of the planet. We show that late accretion of wet material exceeds this sink. CO<sub>2</sub> and N<sub>2</sub> contributions serve as additional constraints.</p><p>Water-rich asteroids colliding with Venus and releasing their water as vapor cannot explain the composition of Venus atmosphere as we measure it today. It means that the asteroidal material that came to Venus, and thus to Earth, after the giant impact must have been dry (enstatite chondrites), therefore preventing the replenishment of the Earth in water. Because water can obviously be found on our planet today, it means that the water we are now enjoying on Earth has been there since its formation, likely buried deep in the Earth so it could survive the giant impact. This in turn suggests that suggests that planets likely formed with their near-full budget in water, and slowly lost it with time.</p>

scholarly journals Remotely distinguishing and mapping endogenic water on the Moon

2017 ◽  
Vol 375 (2094) ◽  
pp. 20150391 ◽  
Author(s):  
Rachel L. Klima ◽  
Noah E. Petro
Keyword(s):  
Solar Wind ◽  
Spatial Distribution ◽  
Solar System ◽  
The Moon ◽  
Testing Hypotheses ◽  
Origin And Evolution ◽  
Lunar Interior ◽  
Geological Features ◽  
Insight Into

Water and/or hydroxyl detected remotely on the lunar surface originates from several sources: (i) comets and other exogenous debris; (ii) solar-wind implantation; (iii) the lunar interior. While each of these sources is interesting in its own right, distinguishing among them is critical for testing hypotheses for the origin and evolution of the Moon and our Solar System. Existing spacecraft observations are not of high enough spectral resolution to uniquely characterize the bonding energies of the hydroxyl molecules that have been detected. Nevertheless, the spatial distribution and associations of H, OH − or H 2 O with specific lunar lithologies provide some insight into the origin of lunar hydrous materials. The global distribution of OH − /H 2 O as detected using infrared spectroscopic measurements from orbit is here examined, with particular focus on regional geological features that exhibit OH − /H 2 O absorption band strengths that differ from their immediate surroundings. This article is part of the themed issue ‘The origin, history and role of water in the evolution of the inner Solar System’.

DUST-BORNE TRACE GASES AND ODORANTS The analysis of dust-borne trace gases requires their i-solation from the dust particles. Procedures for the isolation and characterization of trace gases and odorants in the dust from pig houses are given by SCHAEFER et al. (29), HAMMOND et al.(30) and TRAVIS and ELLIOTT (31). Alcoholic solvents were found to be effective for the extraction of volatile fatty ac­ ids and phenols from the dust of hen (32) and pig houses (33), (34). Today, gas chromatography is usually used for the sepa­ ration and identification of the trace gases. Table IV gives a literature review of compounds identified in the dust of pig houses. There are only very few reports on investigations on the dust from hen houses (32). Most of the odours coming from livestock production units are associated with the biological degradation of the animal wastes (35), the feed and the body odour of the animals (1). Volatile fatty acids and phenolic compounds were found to con­ tribute mostly to the strong, typical odour of animal houses by the help of sensory evaluations parallel to the chemical analysis (29),(30). Table V gives quantitative values of volatile fatty acids and phenolic/indolic compounds found in the aerosol phase and in settled dust of piggeries, respectively. The results from the aerosol phase coincide, particularly as far as acetic acid is concerned. For the investigations of the settled dust the coefficients of variation (CV) and the relative values (%) characterizing the percentage of the single compounds as part of the total amount are quoted. The values are corrected with the dry matter content of the dust. Main components are acetic acid and p-cresol, respectively. Table VI compares results from air, dust and slurry in­ vestigations on VFA and phenolic/indolic compounds in piggeries. Relative values are used. When comparing the results derived from investigations on dust, air or slurry it is necessary to use relative values because of the different dimensions, for experience shows that in spite of large quantitative differ­ ences between two samples within the group of carboxylic acids and within the group of phenolic/indolic compounds the propor­ tions of the components remain rather stable (36). In the group of VFA acetic acid is the main component in air, dust, and slurry followed by propionic and butyric acid. The other three acids amount to less than 25%. In the group of phenols/ indoles p-cresol is the main component in the four cited in­ vestigations. However, it seems that straw bedding can reduce the p-cresol content; in this case phenol is the main compo­ nent , i nstead (37 ). 4. EMISSION OF DUST-BORNE VFA AND PHENOLS/INDOLES FROM PIGGERIES The investigations of dust from piggeries show that both VFA and phenols/indoles are present in a considerable amount. However, compared to the air-borne emissions calculated on the base of the results of LOGTENBERG and STORK (38) less than the tenth part (1/10) of phenols/indoles and about the hundredth part (1/100) of VFA are emitted by the dust, only. Table VII compares the dust-borne and air-borne emissions of VFA and

1986 ◽  
pp. 337-337
Keyword(s):  
Fatty Acids ◽  
Acetic Acid ◽  
Volatile Fatty Acids ◽  
Trace Gases ◽  
Matter Content ◽  
Biological Degradation ◽  
Indolic Compounds ◽  
Settled Dust ◽  
Main Components ◽  
Main Component

The Next Space Patrons

2017 ◽  
Author(s):  
Alexander MacDonald
Keyword(s):  
Solar System ◽  
Political History ◽  
Space Exploration ◽  
Development Program ◽  
The Political ◽  
Early American ◽  
Long Run ◽  
Space Race ◽  
System P ◽  
History Of

Mankind will not remain forever confined to the Earth. In pursuit of light and space it will, timidly at first, probe the limits of the atmosphere and later extend its control to the entire solar system. —Konstantin Tsiolkovsky, Letter to B. N. Vorobyev, 1911 What do we learn from this long-run perspective on American space exploration? How does it change our understanding of the history of spaceflight? How does it change our understanding of the present? This book has provided an economic perspective on two centuries of history, with examinations of early American observatories, the rocket development program of Robert Goddard, and the political history of the space race. Although the subjects covered have been wide-ranging, together they present a new view of American space history, one that challenges the dominant narrative of space exploration as an inherently governmental activity. From them a new narrative emerges, that of the Long Space Age, a narrative that in the ...

Precise positions of Triton in 2010–2014 based on Gaia-DR2

2021 ◽  
Author(s):  
Huiyan Zhang ◽  
Yong Yu ◽  
Dan Yan ◽  
Kai Tang ◽  
Rongchuan Qiao
Keyword(s):  
Solar System ◽  
Physical Properties ◽  
Orbital Evolution ◽  
Astronomical Observatory ◽  
Standard Errors ◽  
Origin And Evolution ◽  
Important Target ◽  
Long Time ◽  
Gaia Dr2

Abstract With unique orbital and physical characteristics, Triton is a very important target since it may contain information of the origin and evolution of the solar system. Besides space explorations, ground-based observations over long time also play key role on research of Triton. High-precision positions of Triton obtained from ground telescopes are of great significance for studying its orbital evolution and inverting the physical properties of Neptune. As a long-term observational target, Triton has been observed by the 1.56 m telescope of Shanghai Astronomical Observatory since 1996. In this paper, based on our AAPPDI software and with Gaia DR2 as the reference catalogue, 604 positions of Triton during 2010-2014 are calculated, with standard errors of $19mas-88mas$. A comparison between our results and the ephemeris (DE431+nep096) is also given.

Earth: Imprint of Life

1999 ◽  
Author(s):  
Yuk L. Yung ◽  
William B. DeMore
Keyword(s):  
Solar System ◽  
Hydrological Cycle ◽  
Biogeochemical Cycles ◽  
Terrestrial Environment ◽  
Orbital Parameters ◽  
Planetary Scale ◽  
System P ◽  
Global Biogeochemical Cycles ◽  
The Last Glacial Maximum ◽  
Remote Past

Earth is the largest of the four terrestrial planets, three of which have substantial atmospheres. The astronomical and orbital parameters are summarized in table 9.1. Our planet has an obliquity of 23.5°, giving rise to well-known seasonal variations in solar insolation. The orbital elements are slightly perturbed by other planets in the solar system (primarily Jupiter), with time scales from 20 to 100 kyr, and these changes are believed to cause the advance and retreat of ice sheets. The last glacial maximum (LGM) occurred 18 kyr ago, at which time the planet was colder by several degrees centigrade on average. At present Earth is in an interglacial warm period. The origin of Earth may not be very different from that of the other terrestrial bodies. However, three properties may be unique to this planet. One is the formation of the Moon, probably via collision between Earth and a Mars-sized body. Second is the release of a huge amount of water from the interior (see discussion in section 8.5). Third, Earth is endowed with a large magnetic field that protects it from direct impact by the solar wind. Seventy percent of Earth's surface is covered by oceans, which have a mean depth of 3 km. There is so much water that Arthur C. Clarke proposed that "Ocean" might be a better name for our planet than "Earth." The enormous body of water became the cradle of life as early as 3.85 Gyr ago. The present terrestrial environment is the end-product of billions of years of evolution driven by the hydrological cycle and global biogeochemical cycles, in addition to the slower forces of geodynamics and geochemistry. The massive hydrological cycle and the biogeochemical cycles that operate on Earth are absent from other planets in the solar system. Mars in the remote past might have had a milder climate with liquid water on the surface, but the planet dried up a few eons ago. There is to date no observational evidence for the hypothetical oceans (composed of liquid hydrocarbons) on Titan. Life on a planetary scale equivalent to the terrestrial biosphere does not exist elsewhere in the solar system.

scholarly journals The Motions of Uranus' Satellites: Theory and Application

1979 ◽  
Vol 81 ◽  
pp. 177-180
Author(s):  
Richard Greenberg
Keyword(s):  
Solar System ◽  
Physical Properties ◽  
Celestial Mechanics ◽  
Dynamical Theory ◽  
System Study ◽  
Broad Application ◽  
Origin And Evolution ◽  
Structure And Dynamics ◽  
Principal Source ◽  
Planets And Satellites

As spacecraft and sophisticated ground-based observations measure physical properties of many planets and satellites, dynamical theory and astrometry remain a principal source of such knowledge of the Uranian system. Study of the motions of Uranus' satellites thus has broad application to planetary studies as well as to celestial mechanics. Moreover, the structure and dynamics of the system provide important cosmogonical constraints; any theory of solar system origin and evolution must account for the formation within it of analogous systems of regular satellites.

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