Thermodynamicsof giant planetary impacts from ab initiosimulations

2021 ◽  
Author(s):  
Razvan Caracas ◽  
Sarah T. Stewart
Keyword(s):  
Stability Field ◽  
The Moon ◽  
Supercritical Regime ◽  
Horizon 2020 ◽  
Research And Innovation ◽  
The Earth ◽  
Magma Oceans ◽  
The Stability ◽  
Dynamics Simulations ◽  
Planetary Impacts

<h3>Impacts are highly energetic phenomena. They abound in the early stages of formation of the solar system, when they actively participated to the formation of large bodies in the protoplanetary disk. Later on, when planetesimals and embryo planets formed, impacts merged smaller bodies into the large planets that we know today. Giant impacts dominated the last phase of the planetary accretion, with some of these impacts leaving traces observable even today (planets tilts, moon, missing mantle, etc). The Earth was not spared, and its most cataclysmic event also contributed to the formation of the Moon.</h3><h3>Here we present the theoretical tools used to explore the thermodynamics of the formation of the protolunar disk and the subsequent condensation of this disk. We show how ab initio-based molecular dynamics simulations contribute to the determination of the stability field of melts, to the equilibrium between melts and vapor and the positioning of the critical points. Together all this information helps building the liquid-vapor stability dome. Next we investigate the supercritical regime, typical of the post-impact state. We take a focused look to the transport properties, the formation of the first atmosphere, and compare the properties of the liquid state typical of magma oceans, to the super-critical state, typical of protolunar disks.</h3><h3>We apply this theoretical approach on pyrolite melts, as best approximants for the bulk silicate Earth. These simulations help us retrace the thermodynamic state of the protolunar disk and infer possible condensation paths for both the Earth and the moon.</h3><h3> </h3><p>RC acknowledges support from the European Research Council under EU Horizon 2020 research and innovation program (grant agreement 681818 – IMPACT) and access to supercomputing facilities via the eDARI gen6368 grants, the PRACE RA4947 grant, and the Uninet2 NN9697K grant. STS was supported by NASA grants NNX15AH54G and 80NSSC18K0828; DOE-NNSA grants DE-NA0003842 and DE-NA0003904.</p>

Low selenocentric orbits stability analysis

2020 ◽  
Author(s):  
Chongrui Du ◽  
O.L. Starinova
Keyword(s):  
Rate Of Change ◽  
The Sun ◽  
Space Systems ◽  
The Moon ◽  
Orbital Structure ◽  
Motion Modeling ◽  
The Earth ◽  
Long Time ◽  
The Stability

The tasks of studying the Moon require long-term functioning space systems. Most of the low selenocentric orbits are known to be unstable, which requires a propellant to maintain the orbital structure. For these orbits, the main disturbing factors are the off-center gravitational field of the Moon and the gravity of the Earth and the Sun. This paper analyzes the stability of low selenocentric orbits according to passive motion modeling and takes into account these main disturbing factors. We put forward a criterion for determining the stability of the orbit and used it to analyze the circular orbit of the Moon at an altitude of 100 kilometers. According to different initial data and different dates, we obtained ranges of the Moon’s orbits with good stability. At the same time, we analyzed the rate of change in the longitude of the ascending node, and found a stable low lunar orbit which can operate for a long time.

Thermal effects on the figure of the Moon

1967 ◽  
Vol 296 (1446) ◽  
pp. 266-269 ◽  
Keyword(s):  
Thermal Effects ◽  
Hydrostatic Equilibrium ◽  
Moment Of Inertia ◽  
The Moon ◽  
Moments Of Inertia ◽  
The Earth ◽  
Principal Moments Of Inertia ◽  
Long Time ◽  
The Stability ◽  
Lunar Rotation

Before discussing its cause, one must be clear in exactly what respect the lunar figure deviates from the equilibrium one. This is necessary because there has been confusion over the question for a long time. It was known early that the Moon’s ellipsoid of inertia is triaxial and that the differences of the principal moments of inertia determined from observations are several times larger than the theoretical values corresponding to hydrostatic equilibrium. The stability of lunar rotation requires that the axis of least moment of inertia point approximately towards the Earth and the laws of Cassini show that it is really so.

First Iteration Design of the Flotant Concept

2021 ◽  
Author(s):  
Jordi Serret ◽  
Bernardo Kahn ◽  
Bruce Cavanagh ◽  
Patricia Lorente ◽  
Remy Pascal ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Open Source ◽  
Elastic Behaviour ◽  
International Electrotechnical Commission ◽  
Floating Platform ◽  
Horizon 2020 ◽  
Research And Innovation ◽  
Seakeeping Performance ◽  
Floating System ◽  
The Stability

Abstract This paper presents the first iteration design of the Flotant concept developed within the framework of a Cooperation Research Project funded by the European Union’s Horizon 2020 research and innovation programme. The Flotant concept is a hybrid concrete-plastic barge-type floating offshore substructure holding a 12MW wind turbine with the singularity of getting floatability by using plastic foam material fitted within the floater substructure. The INS12MW generic wind turbine, an upscaling exercise based on the DTU10MW reference wind turbine, is presented and simulated using open-source certified aeroelastic code. The floating platform and the mooring system are designed for two different sites, West of Barra and South East of Gran Canaria island. The principal dimensions are presented along with the hydrostatic and hydrodynamic properties of the floating system. A relevant subset of design load cases derived from International Electrotechnical Commission and Det Norske Veritas standards was simulated using an open-source aeroelastic code (NREL FAST) to check the coupled aero-hydro-elastic behaviour of the floating system and to generate the required load-matrix for the structural assessment of the different components. The evaluation of the design includes the seakeeping performance, the stability of the floating platform and the global performance analysis for the abovementioned sites. It demonstrates the technology developed within the Flotant project is feasible even in rough conditions like the ones in the West of Barra site.

Identification of Kelvin-Helmholtz vortices at the Earth’s magnetosphere

2021 ◽  
Author(s):  
Adriana Settino ◽  
Denise Perrone ◽  
Yuri V. Khotyaintsev ◽  
Daniel B. Graham ◽  
Oreste Pezzi ◽  
...  
Keyword(s):  
Spatial Behavior ◽  
Space Plasmas ◽  
Helmholtz Instability ◽  
Horizon 2020 ◽  
Multi Scale ◽  
Research And Innovation ◽  
Nonlinear Phase ◽  
The Earth ◽  
Total Current Density ◽  
Clear Identification

<p>Kelvin-Helmholtz instability is a widespread phenomenon in space plasmas, such as at the planetary magnetospheres. During its nonlinear phase, the generation of Kelvin-Helmholtz vortices takes place. The identification of such coherent structures is not straightforward in observational data contrary to numerical simulations where both temporal evolution and spatial behavior can be observed. Recently, a comparison between a hybrid Vlasov-Maxwell simulation and Magnetospheric Multi-Scale satellites observation of a Kelvin-Helmholtz event has shown the presence of kinetic features that can uniquely characterize the boundaries of Kelvin-Helmholtz vortices.  Indeed, a strong total current density has been observed in correspondence of the edges of each vortex associated with a weakly distorted distribution function from the equilibrium distribution; while the opposite occurs inside the vortex region. Moreover, a new tool has been proposed to distinguish the different phases of the Kelvin-Helmholtz instability and to identify the trajectory of the spacecraft across the vortex itself. Such a tool takes into consideration the mixing degree between the magnetospheric-like and magnetosheath-like particles population in the Earth environment. The clear identification of a vortex in <em>in situ</em> data is an important achievement since it can provide a better understanding of the role that Kelvin-Helmholtz instability plays in weakly collisional space plasmas in the contest of energy dissipation.</p><p>This work has received funding from the European Unions Horizon 2020 research and innovation programme under grant agreement no. 776262 (AIDA,).</p>

scholarly journals Fossil Subduction Recorded By Quartz From The Coesite Stability Field

2020 ◽  
Author(s):  
Matteo Alvaro ◽  
Mattia L. Mazzucchelli ◽  
Ross J. Angel ◽  
Mara Murri ◽  
Nicola Campomenosi ◽  
...  
Keyword(s):  
Elastic Anisotropy ◽  
Mantle Xenoliths ◽  
Stability Field ◽  
X Ray Diffraction ◽  
Perfect Agreement ◽  
Research And Innovation ◽  
Eclogite Xenolith ◽  
The Stability ◽  
Field Geology

<p>Investigation of mantle xenoliths can provide information on the architecture and evolution of subcontinental lithospheric mantle through time. These reconstructions rely also on correct estimates of the pressures and temperatures (P-T) experienced by these rocks over time. Unlike chemical geothermobarometers, elastic geobarometry does not rely on chemical equilibrium between minerals, so it has the potential to provide information on over-stepping of reaction boundaries and to identify other examples of non-equilibrium behaviour in rocks. Here we introduce a method that exploits the elastic anisotropy of minerals to determine the unique P and T of equilibration from a measurements of single-crystal mineral inclusions trapped in a crystalline host from an eclogite xenolith [1]. We apply it to perfectly preserved quartz inclusions in garnet from eclogite xenoliths in kimberlites. We show that the elastic strains of inclusions calculated from in-house Raman spectroscopy measurements of the inclusions are in perfect agreement with those determined from in-situ X-ray diffraction measurements performed both in-house and at the synchrotron. Calculations based on these measured strains demonstrate that quartz trapped in garnet can be preserved even when the rock passes into the stability field of coesite (high pressure and temperature polymorph of quartz). This supports a metamorphic origin for these xenoliths that provides constraints on mechanisms of craton accretion from a subducted crustal protolith. Furthermore, we show that some key inclusion minerals do not always indicate the P and T attained during subduction and metamorphism.</p><p> </p><p>This project has received funding from the European Research Council under the H2020 research and innovation programme (N. 714936 TRUE DEPTHS to M. Alvaro)</p><p> </p><p>[1] M Alvaro, ML Mazzucchelli, RJ Angel, M Murri, N Campomenosi, M Scambelluri, F Nestola, A Korsakov, AA Tomilenko, F Marone, M Morana (2020) Fossil subduction recorded by quartz from the coesite stability field, Geology, 48, 24-28</p>

The motion of a lunar orbiter

1966 ◽  
Vol 25 ◽  
pp. 373
Author(s):  
Y. Kozai
Keyword(s):  
Degrees Of Freedom ◽  
Dimensional Space ◽  
Artificial Satellite ◽  
Equations Of Motion ◽  
Triaxial Ellipsoid ◽  
The Moon ◽  
Secular Motion ◽  
The Earth ◽  
Close Satellite ◽  
The Mean

The motion of an artificial satellite around the Moon is much more complicated than that around the Earth, since the shape of the Moon is a triaxial ellipsoid and the effect of the Earth on the motion is very important even for a very close satellite.The differential equations of motion of the satellite are written in canonical form of three degrees of freedom with time depending Hamiltonian. By eliminating short-periodic terms depending on the mean longitude of the satellite and by assuming that the Earth is moving on the lunar equator, however, the equations are reduced to those of two degrees of freedom with an energy integral.Since the mean motion of the Earth around the Moon is more rapid than the secular motion of the argument of pericentre of the satellite by a factor of one order, the terms depending on the longitude of the Earth can be eliminated, and the degree of freedom is reduced to one.Then the motion can be discussed by drawing equi-energy curves in two-dimensional space. According to these figures satellites with high inclination have large possibilities of falling down to the lunar surface even if the initial eccentricities are very small.The principal properties of the motion are not changed even if plausible values ofJ3andJ4of the Moon are included.This paper has been published in Publ. astr. Soc.Japan15, 301, 1963.

Formation of Lunar Craters and Bright Rays as a Result of Meteorite Impacts

1962 ◽  
Vol 14 ◽  
pp. 415-418
Author(s):  
K. P. Stanyukovich ◽  
V. A. Bronshten
Keyword(s):  
Explosive Charge ◽  
The Moon ◽  
Meteorite Impacts ◽  
The Earth ◽  
Lunar Craters ◽  
The Impact

The phenomena accompanying the impact of large meteorites on the surface of the Moon or of the Earth can be examined on the basis of the theory of explosive phenomena if we assume that, instead of an exploding meteorite moving inside the rock, we have an explosive charge (equivalent in energy), situated at a certain distance under the surface.

The Origin of the Moon

1962 ◽  
Vol 14 ◽  
pp. 149-155 ◽  
Author(s):  
E. L. Ruskol
Keyword(s):  
Chemical Composition ◽  
Solar System ◽  
The Moon ◽  
The Earth ◽  
The Difference ◽  
Origin Of The Moon

The difference between average densities of the Moon and Earth was interpreted in the preceding report by Professor H. Urey as indicating a difference in their chemical composition. Therefore, Urey assumes the Moon's formation to have taken place far away from the Earth, under conditions differing substantially from the conditions of Earth's formation. In such a case, the Earth should have captured the Moon. As is admitted by Professor Urey himself, such a capture is a very improbable event. In addition, an assumption that the “lunar” dimensions were representative of protoplanetary bodies in the entire solar system encounters great difficulties.

The Origin of the Moon and its Relationship to the Origin of the Solar System

1962 ◽  
Vol 14 ◽  
pp. 133-148 ◽  
Author(s):  
Harold C. Urey
Keyword(s):  
Solar System ◽  
The Moon ◽  
The Past ◽  
The Earth ◽  
Short Period ◽  
Origin Of The Moon

During the last 10 years, the writer has presented evidence indicating that the Moon was captured by the Earth and that the large collisions with its surface occurred within a surprisingly short period of time. These observations have been a continuous preoccupation during the past years and some explanation that seemed physically possible and reasonably probable has been sought.

Probable Structure and Nature of the Formations on the Reverse Side of the Moon According to Photometric Measurements of Lunar Photographs

1962 ◽  
Vol 14 ◽  
pp. 39-44
Author(s):  
A. V. Markov
Keyword(s):  
The Moon ◽  
Probable Structure ◽  
The Earth ◽  
Interplanetary Station ◽  
Photometric Measurements ◽  
Automatic Interplanetary Station

Notwithstanding the fact that a number of defects and distortions, introduced in transmission of the images of the latter to the Earth, mar the negatives of the reverse side of the Moon, indirectly obtained on 7 October 1959 by the automatic interplanetary station (AIS), it was possible to use the photometric measurements of the secondary (terrestrial) positives of the reverse side of the Moon in the experiment of the first comparison of the characteristics of the surfaces of the visible and invisible hemispheres of the Moon.

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