Materials Science of the Earth's Deep Interior

MRS Bulletin ◽  
1992 ◽  
Vol 17 (5) ◽  
pp. 30-37 ◽  
Author(s):  
A. Navrotsky ◽  
D.J. Weidner ◽  
R.C. Liebermann ◽  
C.T. Prewitt
Keyword(s):  
Materials Science ◽  
Basic Question ◽  
Material System ◽  
Sound Waves ◽  
Outer Planets ◽  
The Earth ◽  
Deep Interior ◽  
Direct Sampling ◽  
Deep Earth ◽  
Vertical Temperature Distribution

Man has walked on the moon, sent probes to or near the surfaces of Mars and Venus, and dispatched vehicles to fly near comets, asteroids, and the outer planets and their moons. In contrast, a journey to the center of the Earth remains as unattainable and fictional as in Jules Verne's day. We know the interior of our planet from several types of evidence: direct sampling of rock brought to the surface by geologic process from depths no greater than 200 km, remote sensing especially by seismology (the study of natural or anthropogenic sound waves passing through the Earth), inferences from the chemistry of meteorites and from other geochemical arguments, and laboratory and computational simulations of the conditions at depth. The laboratory study of Earth materials at high temperatures and pressures is the subject of this review. In a sense, the basic question of deep earth geophysics is a peculiar sort of inverse problem in materials science; rather than determining the properties of a given material, one seeks to find materials, under constraints of natural elemental abundances, which have properties consistent with seismological and other geophysical observations.What are the “hard facts” about planet Earth as a material system? Its radius and mass are well constrained, as are pressure and density as a function of depth (see Figure 1). Its vertical temperature distribution is less well known, but it is clear that the interior is hot, with temperatures in the mantle reaching perhaps 3000 K and in the core perhaps 6000–7000 K.

scholarly journals Dynamic Equilibria in Statistical and Nonlinear Physics of Uniform Stress Rotating Space Elevators (USRSE)

2019 ◽  
Vol 11 (6) ◽  
pp. 56
Author(s):  
Leonardo Golubovic ◽  
Steven Knudsen
Keyword(s):  
Carbon Nanotubes ◽  
Materials Science ◽  
Dynamic Equilibrium ◽  
Outer Space ◽  
Point Of View ◽  
Uniform Stress ◽  
The Earth ◽  
Equilibrium Configurations ◽  
Space Elevators ◽  
Dynamic Equilibria

The discovery of ultra-strong materials such as carbon nanotubes and diamond nano-thread structures has recently motivated an enhanced interest for the physics of Space Elevators connecting the Earth with outer space. A new concept has recently emerged in space elevator physics: Rotating Space Elevators (RSE) [Golubović, L. & Knudsen, S. (2009). Classical and statistical mechanics of celestial scale spinning strings: Rotating space elevators. Europhysics Letters 86(3), 34001.]. Objects sliding along rotating RSE string (sliding climbers) do not require internal engines or propulsion to be transported from the Earth's surface into outer space. Here we address the physics of a special RSE family, Uniform Stress Rotating Space Elevators (USRSE), characterized by constant tensile stress along the string. From the point of view of materials science, this condition provides the best control of string’s global integrity. We introduce an advanced analytic approach to obtain the dynamic equilibrium configurations of USRSE strings. We use our results to discuss the applications of USRSE for spacecraft launching.

1. What is geophysics?

2018 ◽  
pp. 1-5
Author(s):  
William Lowrie
Keyword(s):  
Magnetic Fields ◽  
Physical Properties ◽  
Complex Behaviour ◽  
Tectonic Plates ◽  
Natural Processes ◽  
Research Fields ◽  
The Earth ◽  
Deep Interior ◽  
Wide Range ◽  
Geophysical Investigations

Geophysics is a field of earth sciences that uses the methods of physics to investigate the complex physical properties of the Earth and the natural processes that have determined and continue to govern its evolution. ‘What is geophysics?’ explains how geophysical investigations cover a wide range of research fields—including planetary gravitational and magnetic fields and seismology—extending from surface changes that can be observed from Earth-orbiting satellites to complex behaviour in the Earth’s deep interior. The timescale of processes occurring in the Earth also has a very broad range, from earthquakes lasting a few seconds to the motions of tectonic plates that take place over tens of millions of years.

scholarly journals Cosmic ray spectra in planetary atmospheres

2008 ◽  
Vol 4 (S257) ◽  
pp. 471-473
Author(s):  
M. Buchvarova ◽  
P. Velinov
Keyword(s):  
Experimental Data ◽  
Solar Cycle ◽  
Cosmic Rays ◽  
Cosmic Ray ◽  
Planetary Atmospheres ◽  
Galactic Cosmic Rays ◽  
Outer Planets ◽  
Practical Possibility ◽  
The Earth ◽  
Theoretical Results

AbstractOur model generalizes the differential D(E) and integral D(>E) spectra of cosmic rays (CR) during the 11-year solar cycle. The empirical model takes into account galactic (GCR) and anomalous cosmic rays (ACR) heliospheric modulation by four coefficients. The calculated integral spectra in the outer planets are on the basis of mean gradients: for GCR – 3%/AU and 7%/AU for anomalous protons. The obtained integral proton spectra are compared with experimental data, the CRÈME96 model for the Earth and theoretical results of 2D stochastic model. The proposed analytical model gives practical possibility for investigation of experimental data from measurements of galactic cosmic rays and their anomalous component.

The deep interior of Venus, Mars, and the Earth: A brief review and the need for planetary surface-based measurements

2011 ◽  
Vol 59 (10) ◽  
pp. 1048-1061 ◽  
Author(s):  
Antoine Mocquet ◽  
Pascal Rosenblatt ◽  
Véronique Dehant ◽  
Olivier Verhoeven
Keyword(s):  
Planetary Surface ◽  
The Earth ◽  
Deep Interior

The ionosphere as a whispering gallery

1962 ◽  
Vol 265 (1323) ◽  
pp. 554-569 ◽  
Keyword(s):  
Electron Density ◽  
Spherical Surface ◽  
Low Frequency ◽  
Electron Density Profile ◽  
Whispering Gallery Modes ◽  
Radio Waves ◽  
Sound Waves ◽  
Whispering Gallery ◽  
The Earth ◽  
Reflexion Coefficient

The propagation of radio waves of very low frequency to great distances is conveniently treated by regarding the space between the earth and the ionosphere as a wave-guide. Several authors have found that the least attenuated modes are profoundly affected by the earth’s curvature. This effect is investigated for several models of the ionosphere. It is found, in particular, that for frequencies greater than about 30 kc/s some modes are possible for which the energy is concentrated in a region near the base of the ionosphere, and the field strength near the ground is small. It is useful to think of such modes as being composed of waves repeatedly reflected at the inside spherical surface of the ionosphere, the rays being chords of this sphere. By analogy with sound waves these modes are called ‘whispering gallery modes’. The theory uses wave admittance and reflexion coefficient variables because these satisfy differential equations which are convenient for integration using a digital computer. The curvature of the earth is allowed for by using the method of the modified refractive index, but the earth’s magnetic field is neglected. Formulae for the m ode condition and the excitation of the various modes by a transmitter are given and discussed. A new way of dealing with an ionosphere having a continuous electron density profile is presented. The results of some numerical calculations are given both for a sharply bounded homogeneous ionosphere and for an exponential profile of electron density.

scholarly journals Astromimetics

2018 ◽  
Vol 5 ◽  
pp. 184954351879434 ◽  
Author(s):  
Vuk Uskoković ◽  
Victoria M Wu
Keyword(s):  
Materials Science ◽  
Fine Particles ◽  
Great Majority ◽  
Point Of View ◽  
Iron Core ◽  
Colloidal Form ◽  
The Earth ◽  
Celestial Bodies ◽  
Intended Use

Composite, multifunctional fine particles are likely to be at the frontier of materials science in the foreseeable future. Here we present a submicron composite particle that mimics the stratified structure of the Earth by having a zero-valent iron core, a silicate/silicide mantle, and a thin carbonaceous crust resembling the biosphere and its biotic deposits. Particles were formulated in a stable colloidal form and made to interact with various types of healthy and cancer cells in vitro. A selective anticancer activity was observed, promising from the point of view of the intended use of the particles for tumor targeting across the blood–brain barrier. As an extension of the idea underlying the fabrication of a particle mimicking the planet Earth, we propose a new field of mimetics within materials science: astromimetics. The astromimetic approach in the context of materials science consists of the design of particles after the structure of celestial bodies. With Earth being the most chemically diverse and fertile out of all the astral bodies known, it is anticipated that the great majority of astromimetic material models will fall in the domain of geo-inspired ones.

Ultralow frequency waves in the magnetotails of the Earth and the outer planets

1992 ◽  
Vol 12 (8) ◽  
pp. 57-63 ◽  
Author(s):  
Krishan K. Khurana ◽  
Sheng Hsien Chen ◽  
C. Max Hammond ◽  
Margaret G. Kivelson
Keyword(s):  
Ultralow Frequency ◽  
Outer Planets ◽  
The Earth ◽  
Ultralow Frequency Waves

scholarly journals In situ Investigations from Spinels under high pressure and high Temperatures

2014 ◽  
Vol 70 (a1) ◽  
pp. C398-C398
Author(s):  
Michael Wehber ◽  
Frank Schilling ◽  
Christian Lathe ◽  
Hans Mueller
Keyword(s):  
High Pressure ◽  
Volume Change ◽  
X Ray Diffraction ◽  
Ambient Temperatures ◽  
The Earth ◽  
Deep Interior ◽  
State Apparatus ◽  
Temperature And Pressure ◽  
Murnaghan Equation

Spinels seem to be important constituents of the deep interior of the Earth while transition with spinel or pseudospinel structure strongly influence the dynamic of the mantle. On the other hand, spinels are widely used as artificial material. The spinels Magnetite, Franklinite, and Gahnite are investigated at the Hamburger Synchrotron Laboratory (HASYLAB) at Hamburg. The experiments were carried out using the high pressure multi anvil devices MAX80 (F2.1 Beamline) and MAX200x (W2 Beamline). The MAX80 is a single state apparatus located at a bending magnet, MAX200x is a double state system located at a wiggler. Energy-dispersive X-ray diffraction in combination with Rietveld refinement [1, 2] was used to determine the pressure and temperature induced volume change. Isothermal experiments were performed up to 15 GPa at ambient temperature. The temperature and pressure dependent volume change were derived from compression experiments using MAX80 apparatus up to 5 GPa at temperatures of 298, 500, 700, 900 and 1100 K. Bulk moduli at ambient temperatures using a Birch-Murnaghan equation of state result in KT=184(7) GPa with K'=4.5(2) for Magnetite, KT =178(6) with K'=4.6(4) for Franklinite, and KT =204(9) with K'=4.9(6) for Gahnite.

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