Analysis of the charged particle radiation effect for a CubeSat transiting from Earth to Mars

This paper presents a computational estimation of the total ionizing dose from protons and electrons in the Earth's magnetosphere and interplanetary space for a hypothetical CubeSat transiting from Earth to Mars. An initial hyperbolic escape of the spacecraft from Earth's gravitation is assumed, followed by an elliptical transfer from Earth to Mars under the Sun's gravitation. The rapid traversal of the Earth's radiation belt yields a smaller ionizing dose, whereas high-energy solar protons in the interplanetary space have the greatest effect on the ionizing dose during the transfer between the planets. Variation in the heliocentric distance of the spacecraft is considered in the calculation. Calculation of the shielding distributions with Geant4 and the transport of the ionizing particles across the obtained distributions yields an estimation of the total ionizing dose as a function of position within the spacecraft as well as statistical confidence levels. With a moderate confidence level, this calculation shows that a practical exploration of Mars with a CubeSat is possible in terms of the expected total ionizing dose.     

The atmospheres of the Earth and the terrestrial planets: Their origin and evolution

The stability of the Earth's atmosphere is reviewed, and the importance of the hydrosphere and biosphere in the development of the atmosphere is emphasized. Although the Earth's atmosphere has naturally been investigated in the greatest detail, the atmospheres of other terrestrial planets may have had a simpler developmental history. The atmospheres of the Earth, Venus and Mars are compared, and it is shown that a consistent model of their evolution can be obtained on the basis of degassing from the solid planet.     

Communicating science

In this article we discuss the structure and dynamics of the Earth's plasma environment and how it is influenced by its interaction with the outer atmosphere of the Sun, as revealed by both space-based and ground-based observations over the past thirty years. We begin with a discussion of the basic physical principles involved, and then apply these principles to the solar wind and interplanetary magnetic field (IMF), and their interaction with the Earth's magnetic field. The structure and flow of magnetospheric plasma populations then follows, together with consequent magnetosphere-ionosphere interactions. The initial discussion applies to a steady-state magnetosphere driven by steady reconnection, which we then generalized to the time-dependent case resulting from variations in the direction of the IMF.     

Pressure dependence of melting temperature and shear modulus of hcp-iron

The pressure effects on melting temperature and shear modulus of hcp-iron have been studied based on the semi-empirical approach in the Debye model. The recent well-established pressure-dependent Grüneisen parameter has been applied to derive the analytical expressions of the Debye frequency, the Debye temperature, melting temperature and shear modulus which are of importance to geophysical implications. Numerical calculations have been performed for hcp-iron as functions of pressure up to the pressure of Earth's inner core. Our calculations are compared with those of previous experimental and theoretical data showing the good and reasonable agreements. The present results contribute to the database of high pressure melting, especially Earth's inner core boundary temperature, and could also be used to verify as well as analyze the future high pressure diamond-anvil cell experiments.     

Geomagnetism and the dynamo: where do we stand?

We review recent developments both in the observation of the Earth's magnetic field (from the short, human life timescale, to the long, geological timescale) and in the modelling of its origin (using the numerical or the experimental approach). We attempt a confrontation of these results, coming from very different fields, and show how, when combined, they can yield a better understanding of the Earth's core dynamics. We assume prior knowledge of dynamo theory, but not of geophysics. To cite this article: E. Dormy, J.-L. Le Mouël, C. R. Physique 9 (2008).     

Theoretical prediction of the elastic properties of body-centered cubic Fe-Ni-Mg alloys under extreme conditions

Using density functional theory formulated within the framework of the exact muffin-tin orbital method, we investigate the elastic properties of the body-centered cubic Fe_0.85Ni_0.1Mg_0.05 alloy in the conditions at the Earth's inner core. We demonstrate that in this system, the chemical stabilization effect of Mg is significantly larger than that of Ni. We show that the elastic properties of Fe_0.85Ni_0.1Mg_0.05 are in good agreement with those of the Earth's inner core, as given by seismic observations. We find that the excellent mechanical properties of Fe_0.85Ni_0.1Mg_0.05 are primarily due to Mg.     

On hydrodynamic instability of the ozone layer

We show that instability may be arisen when the large-scale waves propagate in the ozone layer of Earth's atmosphere. The instability criterion suitable both for the acoustic waves and for the Rossby waves is found. Moreover, the possibility of the spatially located dissipative Rossby vortical structures formation in this layer is established.     

Modified KdV equation for magnetized Rossby waves in a zonal flow of the ionospheric E-layer

Nonlinear interaction of magnetized Rossby waves with sheared zonal flow in the Earth's ionospheric E-layer is investigated. It is shown that in case of weak nonlinearity 2D Charney vorticity equation can be reduced to the one-dimensional modified KdV equation.     

Study of the Impact of Relativistic Double Star Systems on the Earth’s Electric Field

Russian Physics Journal - Dependences of the effective amplitudes of the Earth's electric field (EEF) components spectrally localized at double rotation frequencies of relativistic double...     

Study of the turbulence and inner waves in the stratosphere based on the observations of stellar scintillations from space: A model of scintillation spectra

Abstract

Stellar scintillations observed from space through the atmosphere show that density inhomogeneities in the stratosphere are stretched along the Earth's surface. This is true for vertical scales above dozens of metres. The observations reveal the existence of locally isotropic small-scale structure with fluctuation sizes up to fractions of a metre. The subject of this paper is to find out how the rotation of inhomogeneities with respect to the passing ray affects scintillations. Another subject of this study is chromatic aberration in the atmosphere which distorts the scintillation spectra. Numerical modelling within the weak-fluctuation approximation showed that the characteristic value of the anisotropy parameter is equal to the square root of the Earth's radius divided by the atmospheric scale. After the anisotropy exceeds this value, the growth of scintillation variance quickly becomes saturated. Chromatic aberration suppresses the high-frequency branch of the scintillation spectrum. However, information on the structure of isotropic fluctuations with scales up to the Fresnel radius is retained in scintillation spectra for oblique occultations. The model of composing blocks is suggested to develop the approximation for a three-dimensional fluctuation spectrum in the stratosphere. Parameters of these blocks can be determined from the set of measured scintillation spectra.     

Environmental magnetism and climate change

A major and pressing problem is to understand how, and how fast, the Earth's climate has changed in the past, with and without human influences on the global carbon cycle. Magnetic, remanence-acquiring, minerals, mostly iron oxides and sulphides, occur ubiquitously in sediments. They can act as sensitive recorders of past climates, because as climate has varied (from glacial to interglacial, for example), the mineralogy, magnetic domain state, composition and source of these minerals has varied. Here, the magnetic properties of windblown dust and interbedded soil layers of the Chinese Loess Plateau are used to calculate rainfall for the last million years, identifying the waxing and waning of the Southeast Asian summer monsoon. Comparison of our magnetic rainfall record on land with environmental records from the deep-sea shows that summer monsoon intensity is linked with growth and decay of continental-sized ice sheets, in turn reflecting changes in the Earth's orbit around the Sun.     

Neutron-antineutron oscillation of ultracold neutrons in storage vessels

If neutron-antineutron oscillations exist in nature, UC neutrons, confined in a storage box, may develop a tiny component of antineutrons that eventually annihilate inside the confining walls. The annihilation rate for this process is evaluated taking into account the effect due to the Earth's gravitational field. The result is employed to discuss how UC neutron experiments would compare with experiments with neutron beams.     

Estimation of electron fluxes in the Earth's geostationary orbit with Tikhonov regularization during a magnetically quiet period

Electron energy fluxes in the Earth's outer radiation belt are estimated using an inverse theory of the Tikhonov regularization based upon observations in geostationary orbits. Particle Detector (PD) experiment aboard a geostationary satellite GEO-KOMPSAT-2A (GK2A) at a geographic longitude of 128.2°E provided observations of electrons within a 150–2,400 keV energy range with an unprecedented energy resolution of ΔE/E in the range of 5–25%. Instrument response functions, calculated with Monte-Carlo simulations, are deconvoluted with electron observations. Using regularization parameters determined from Generalized Cross Validation (GCV), the Tikhonov method was applied to observations made during a geomagnetically quiet period. This Tikhonov regularization method, now possible for observations in the Earth's radiation belt for the first time, allows direct inference of electron fluxes without resorting to predetermined functional forms. Comparisons of our results with those from conventional methods indicate differences among the results as large as ∼200%.     

Phase equilibria of multicomponent mineral systems at high pressures and high temperatures

Abstract

The substance of the Earth's upper mantle was essentially differentiated in the course of deep-seated magmatic processes. It is for the most part formed by peridotitic as well as pyroxenitic and eclogitic The most deep-seated ones pertain to the garnet-peridotitic facies. Liquidus phase relations between the minerals of primary garnet lherzolite (compositional estimations are given in Refs. 1–3) account for the regularities of the formation, evolution, crystallization of multicomponent silicate magmatic melts and petrogenesis of garnet-peridotitic mantle rocks.     

Small-angle scattering and diffraction

The direct measurement of magnetic fields by magnetometers, originally made of the Earth's magnetic field, has been now extended to solar planets by numerous satellite missions. Magnetic effects have been observed in the solar neighborhood and even near some comets, such as the Giotto mission to comet Halley. However, observations of magnetic fields in cosmic objects require remote sensing methods.     

National school on neutron and x-ray scattering

Human habitation is dependent on the chemical and physical processes that shape Earth's surface environment and control the transport, cycling, and chemical form of elements. The challenges facing society concerning water, energy, climate change, and health require a molecular-scale understanding of these processes. It is not surprising therefore that synchrotron radiation (SR) techniques have become essential research tools for the molecular environmental science (MES) and low-temperature geochemistry (LTG) communities as they address critical needs for society.     

Spectroscopy of low and intermediate Z elements at extreme conditions: in situ studies of Earth materials at pressure and temperature via X-ray Raman scattering

ABSTRACT

X-ray Raman scattering spectroscopy is an emerging method in the study of low and intermediate Z elements' core-electron excitations at extreme conditions in order to reveal information on local structure and electronic state of matter in situ. We discuss the capabilities of this method to address questions in Earth materials' science and demonstrate its sensitivity to detect changes in the oxidation state, electronic structure, coordination, and spin state. Examples are presented for the study of the oxygen K-, silicon L- and iron M-edges. We assess the application of both temperature and pressure in such investigations exploiting diamond anvil cells in combination with resistive or laser heating which is required to achieve realistic conditions of the Earth's crust, mantle, and core.     

Roles of positively charged dust in the formation of ion-acoustic subsonic solitary waves in electron-ion-positively charged dust plasmas

The electron-ion-positively charged dust plasma system containing Boltzmann distributed electron species, cold inertial ion species, and stationary positively charged dust (pcd) species are considered. The roles of pcd species in the formation of ion-acoustic (IA) subsonic solitary waves (SWs) are investigated by the pseudo-potential approach, which is valid for arbitrary amplitude time-independent subsonic SWs, as well as by the reductive perturbation method, which is valid for the time-dependent small amplitude subsonic SWs. It is observed that the presence of the pcd species reduces the phase speed of the IA waves, and consequently supports the IA subsonic SWs with the positive wave potential in such electron-ion-pcd plasmas. This is due to the reduction of the space charge electric field by the presence of the pcd species. The applications of the work in space environments (viz. Earth's mesosphere, cometary tails, Jupiter's magnetosphere, etc.), where pcd species have been detected, are briefly discussed.