Multi-ring basins and planetary evolution

1993 ◽  
pp. 224-231
Keyword(s):  
Planetary Evolution

Global Governance in the “Anthropocene”

2018 ◽  
pp. 466-478
Author(s):  
Frank Biermann
Keyword(s):  
United Nations ◽  
Political Theory ◽  
Global Governance ◽  
Political Systems ◽  
Research Topics ◽  
Planetary Evolution ◽  
Village Level ◽  
International Political Theory ◽  
New Challenges ◽  
The Village

The concept of an Anthropocene is now widely used in a variety of contexts, communities, and connotations. This chapter explores the possible consequences of this paradigmatic turn for the field of International Political Theory (IPT), arguing that the notion of an Anthropocene is likely to change the way we understand political systems both analytically and normatively, from the village level up to the United Nations. This makes the Anthropocene one of the most demanding, and most interesting, research topics for the field of IPT. The chapter first lays out the manifold new challenges for IPT that have been brought about by the concept of the Anthropocene, and then illustrates these challenges with an example: the increasing need of governments to define and agree upon “desirable” futures for planetary evolution.

Coupled models of magma oceans and their primordial atmospheres: volatile speciation, cooling history, and impact of condensables

2021 ◽  
Author(s):  
Tim Lichtenberg ◽  
Robert J. Graham ◽  
Ryan Boukrouche ◽  
Raymond T. Pierrehumbert
Keyword(s):  
Extrasolar Planets ◽  
Initial Distribution ◽  
Magma Ocean ◽  
Coupled Models ◽  
Time Resolved ◽  
Planetary Evolution ◽  
Sensitive Dependence ◽  
History Of ◽  
Magma Oceans ◽  
Rocky Planets

<p>The earliest atmospheres of rocky planets originate from extensive volatile release during magma ocean epochs that occur during assembly of the planet. These establish the initial distribution of the major volatile elements between different chemical reservoirs that subsequently evolve via geological cycles. Current theoretical techniques are limited in exploring the anticipated range of compositional and thermal scenarios of early planetary evolution. However, these are of prime importance to aid astronomical inferences on the environmental context and geological history of extrasolar planets. In order to advance the potential synergies between exoplanet observations and inferrences on the earliest history and climate state of the solar system terrestial planets, I will present a novel numerical framework that links an evolutionary, vertically-resolved model of the planetary silicate mantle with a radiative-convective model of the atmosphere. Numerical simulations using this framework illustrate the sensitive dependence of mantle crystallization and atmosphere build-up on volatile speciation and predict variations in atmospheric spectra with planet composition that may be detectable with future observations of exoplanets. Magma ocean thermal sequences fall into three general classes of primary atmospheric volatile with increasing cooling timescale: CO, N<sub>2</sub>, and O<sub>2</sub> with minimal effect on heat flux, H<sub>2</sub>O, CO<sub>2</sub>, and CH<sub>4</sub> with intermediate influence, and H<sub>2</sub> with several orders of magnitude increase in solidification time and atmosphere vertical stratification. In addition to these time-resolved results, I will present a novel formulation and application of a multi-species moist-adiabat for condensable-rich magma ocean and archean earth analog atmospheres, and outline how the cooling of such atmospheres can lead to exotic climate states that provide testable predictions for terrestrial exoplanets.</p>

Major Transitions in Planetary Evolution

2018 ◽  
Author(s):  
Hikaru Furukawa ◽  
Sara Imari Walker
Keyword(s):  
Major Transitions ◽  
Planetary Evolution

The Early Earth: An Ocean with Volcanoes

2019 ◽  
Author(s):  
David W. Deamer
Keyword(s):  
Graduate Student ◽  
North Pole ◽  
Equal Probability ◽  
Early Earth ◽  
Planetary Evolution ◽  
The North ◽  
Tectonic Processes ◽  
The Earth ◽  
Life On Mars ◽  
Geophysical Processes

Malcolm Walter was talking about the Pilbara region of Western Australia where some of the oldest known biosignatures of ancient life, in the form of extensive fossilized stromatolites, are preserved. The first potential stromatolite was discovered by graduate student John Dunlop, who was studying barite deposits at the North Pole Dome. Roger Buick went on to investigate the biogenicity of the stromatolites for his PhD (Buick, 1985) and Dunlop, Buick, and Walter published their results (Walter et al., 1980). In a prescient paper, Walter and Des Marais (1993) proposed that the ancient stromatolite fossils could guide the search for life on Mars. I have walked with Malcolm Walter through the Dresser formation where the fossils were found. It is humbling to realize that if time passed at a thousand years per second, it would take 41 days to go back in time to the first signs of life on our planet. In any description of events that occurred some 4 billion years ago, certain assumptions must be made. I will try to make assumptions explicit throughout this book, beginning here with the geochemical and geophysical conditions prevailing on the early Earth and Mars. I am including Mars not as an afterthought but because both planets had liquid water 4 billion years ago. Most of our understanding of planetary evolution comes from observations of our own planet, but it is now clear that the Earth and Mars were undergoing similar geophysical processes during the first billion years of the solar system’s existence, with an equal probability that life could begin on either planet. In a sense, the surface of Mars is a geological fossil that has preserved evidence of what was happening there at the same time that life began on the Earth. For instance, Martian volcanoes offer direct, observable evidence that volcanism was occurring nearly 4 billion years ago; making it plausible that similar volcanism was common on Earth even though the evidence has been completely erased by geological and tectonic processes.

scholarly journals A virtual tour of the Galilean Satellites

2010 ◽  
Vol 6 (S269) ◽  
pp. 254-268
Author(s):  
Paul Schenk
Keyword(s):  
Volcanic Eruptions ◽  
Impact Craters ◽  
Subsurface Water ◽  
Galilean Satellites ◽  
Virtual Tour ◽  
Planetary Evolution ◽  
The Earth ◽  
Planetary Bodies ◽  
Tidal Heating ◽  
Common Understanding

Galileo's imagination was quick to comprehend the importance of the 4 starry objects he observed near Jupiter in January 1610, not only for himself as a scientist but for our common understanding of the place of the Earth and our species in the cosmos. Even he, however, could not have imagined what those four objects would actually look like once humans got their first good look. Some 369 years the fast traveling Voyager 1 and 2 spacecraft provided that first good look during 1979, followed by an even closer look from the Galileo Orbiter beginning in 1996 through 2001. The following mosaics represent some of the best of those views. They include views of impact craters young and ancient, icy terrains that have been intensely faulted, eroded or disrupted, mountains towering 10 or more kilometers high, and volcanic eruptions hotter than those on Earth. Each of the four Galilean satellites is geologically distinct, betraying very diverse global histories and evolutions. Images and other observations of these 4 objects revealed the importance of tidal heating and subsurface water oceans in planetary evolution, but mapping is very incomplete. New missions to explore these planetary bodies are being planned and the images and observations of the missions that went before will lay the groundwork for these new explorations as we begin the 5th Galilean century.

scholarly journals The role of biology in planetary evolution: cyanobacterial primary production in low-oxygen Proterozoic oceans

2015 ◽  
Vol 18 (2) ◽  
pp. 325-340 ◽  
Author(s):  
Trinity L. Hamilton ◽  
Donald A. Bryant ◽  
Jennifer L. Macalady
Keyword(s):  
Primary Production ◽  
Low Oxygen ◽  
Planetary Evolution

scholarly journals Modeling climate diversity, tidal dynamics and the fate of volatiles on TRAPPIST-1 planets

2018 ◽  
Vol 612 ◽  
pp. A86 ◽  
Author(s):  
Martin Turbet ◽  
Emeline Bolmont ◽  
Jeremy Leconte ◽  
François Forget ◽  
Franck Selsis ◽  
...  
Keyword(s):  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Planetary Science ◽  
Water Ice ◽  
Planetary Evolution ◽  
Ice Surface ◽  
Surface Condensation ◽  
Synchronous Rotation ◽  
Ice Shell

TRAPPIST-1 planets are invaluable for the study of comparative planetary science outside our solar system and possibly habitability. Both transit timing variations (TTV) of the planets and the compact, resonant architecture of the system suggest that TRAPPIST-1 planets could be endowed with various volatiles today. First, we derived from N-body simulations possible planetary evolution scenarios, and show that all the planets are likely in synchronous rotation. We then used a versatile 3D global climate model (GCM) to explore the possible climates of cool planets around cool stars, with a focus on the TRAPPIST-1 system. We investigated the conditions required for cool planets to prevent possible volatile species to be lost permanently by surface condensation, irreversible burying or photochemical destruction. We also explored the resilience of the same volatiles (when in condensed phase) to a runaway greenhouse process. We find that background atmospheres made of N2, CO, or O2are rather resistant to atmospheric collapse. However, even if TRAPPIST-1 planets were able to sustain a thick background atmosphere by surviving early X/EUV radiation and stellar wind atmospheric erosion, it is difficult for them to accumulate significant greenhouse gases like CO2, CH4, or NH3. CO2can easily condense on the permanent nightside, forming CO2ice glaciers that would flow toward the substellar region. A complete CO2ice surface cover is theoretically possible on TRAPPIST-1g and h only, but CO2ices should be gravitationally unstable and get buried beneath the water ice shell in geologically short timescales. Given TRAPPIST-1 planets large EUV irradiation (at least ~103 × Titan’s flux), CH4and NH3are photodissociated rapidly and are thus hard to accumulate in the atmosphere. Photochemical hazes could then sedimentate and form a surface layer of tholins that would progressively thicken over the age of the TRAPPIST-1 system. Regarding habitability, we confirm that few bars of CO2would suffice to warm the surface of TRAPPIST-1f and g above the melting point of water. We also show that TRAPPIST-1e is a remarkable candidate for surface habitability. If the planet is today synchronous and abundant in water, then it should very likely sustain surface liquid water at least in the substellar region, whatever the atmosphere considered.

Geological Characteristics of the Moon

2020 ◽  
Author(s):  
Long Xiao ◽  
James W. Head
Keyword(s):  
The Moon ◽  
Planetary Evolution ◽  
Geological Characteristics ◽  
Lunar Interior ◽  
Geological Processes ◽  
Sequence Of Events ◽  
Geological Features ◽  
History Of ◽  
Lunar Evolution ◽  
Human Exploration

The geological characteristics of the Moon provide the fundamental data that permit the study of the geological processes that have formed and modified the crust, that record the state and evolution of the lunar interior, and that identify the external processes that have been important in lunar evolution. Careful documentation of the stratigraphic relationships among these features can then be used to reconstruct the sequence of events and the geological history of the Moon. These results can then be placed in the context of the geological evolution of the terrestrial planets, including Earth. The Moon’s global topography and internal structures include landforms and features that comprise the geological characteristics of its surface. The Moon is dominated by the ancient cratered highlands and the relatively younger flat and smooth volcanic maria. Unlike the current geological characteristics of Earth, the major geological features of the Moon (impact craters and basins, lava flows and related features, and tectonic scarps and ridges) all formed predominantly in the first half of the solar system’s history. In contrast to the plate-tectonic dominated Earth, the Moon is composed of a single global lithospheric plate (a one-plate planet) that has preserved the record of planetary geological features from the earliest phases of planetary evolution. Exciting fundamental outstanding questions form the basis for the future international robotic and human exploration of the Moon.

The Solar System of Forking Paths: Bifurcations in Planetary Evolution and the Search for Life-Bearing Planets in Our Galaxy

Astrobiology ◽  
2016 ◽  
Vol 16 (7) ◽  
pp. 551-559 ◽  
Author(s):  
A. Lenardic ◽  
J.W. Crowley ◽  
A.M. Jellinek ◽  
M. Weller
Keyword(s):  
Solar System ◽  
Planetary Evolution
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