Planetology

In this paper, aimed at the general public, we give an overview of the theory and phenomenology of shooting stars, whose association to comets was first proposed and demonstrated by Giovanni Virginio Schiaparelli, the Milanese astronomer of Mars fame. Since his popular treatise on shooting stars, despite its age, in our opinion is still the best introduction to the subject, we base our treatment on Schiaparelli's booklet.

Author demonstrates the application of the distribution transformation introduced by the Dutch astronomer Jacobus C. Kapteyn in 1903. In this paper, the log grain size is replaced by log settling velocity (beta units). This transformation reduced the negative skewness and shows that this deviation of normality does not need to exist, if we are using log settlinge rate as independent variable. Gerald Middleton has redefined the log settling rate logarithm  and calls it PSI (analogy to Krumbein's PSI). I have discussed this subject with W. C. Krumbein, he is mentioning this approach in his book on statistical models in geology (page 108): W. C. KRUMBEIN & Franklin A. GRAYBILL, 1965, An Introduction to Statistical Models in Geology; McGraw-Hill, 475 pages.

The surprisingly low S/Si ratio of Asteroid 433 Eros measured by the NEAR Shoemaker spacecraft probably reflects a surface depletion rather than a bulk property of the asteroid. The sulfur X-ray signal originates at a depth < 10 μm in the regolith. The most efficient process for vaporizing minerals at the heliocentric distance of Eros are sputtering by solar wind ions and hypervelocity impacts. These are the same processes that account for the changes in optical properties of asteroids attributed to “space weathering” of lunar surface materials, although the relative importance of sputtering and impacts need not be the same for the Moon and asteroids. Troilite, FeS, which is the most important sulfide mineral in meteorites, and presumably on S-type asteroids like Eros, can be vaporized by much less energy than other major minerals, and will therefore be preferentially lost. Within 10^6 years either process can remove sulfide from the top 10–100 μm of regolith. Sulfur will be lost into space and some sulfur will migrate to deeper regolith layers. We also consider other possible mechanisms of surficial sulfur depletion, such as mineral segregation in the regolith and perhaps even incipient melting. Although we consider solar wind sputtering the most likely cause of the sulfur depletion on Eros, we cannot entirely rule out other processes as causes of the sulfur deficiency. Laboratory simulations of the relevant processes can address some of the open questions. Simulations will have to be carried out in such a way that potential sulfur loss processes as well as resurfacing can be studied simultaneously, requiring a large and complex environmental chamber.

Following current evidence, it is widely accepted that many asteroids would be ‘gravitational aggregates’, i.e. bodies lacking internal cohesion. They could mainly originate from the catastrophic disruption of some parent body, through the gravitational re-accumulation of the resulting fragments. The same events produced the dynamical families that we observe. In this work we address the problem of the origin of shapes of gravitational aggregates, that could contain signatures of their origin. We use a N-body code to simulate the collapse of a cloud of fragments, with a variety of initial velocity distributions and total angular momentum. The fragments are treated as inelastic spheres, that rapidly accumulate to form rotating aggregates. The resulting shapes and rotational properties are compared with theoretical predictions. The results show that only a precise category of shapes (flattened spheroids) are created via this mechanism. This may provide interesting constraints on the evolution of asteroid shapes, in particular for those with one or more satellites.

The present contribution is devoted to some aspects of history and evolution of the early Solar system. The origin of the Sun, Earth, other planets and its satellites has long been a matter of great concern for people. Over the past few decades astronomers and cosmologists have considerably advanced in the perception of the structure, history, and evolution of the Solar System. However, one can hardly speak about a proper narrative here; we more often work with hypotheses. The present paper is structured as follows. First, it outlines the history of formation of the Solar system in the first hundred million years of its existence, when the most considerable changes took place. Then while describing certain formative processes we show the opportunities to define them in terms of evolutionary laws and rules. Of course, this paper presents only a few such laws and rules. We suppose that the present study will be of interest to a reader in two ways. First, there are quite a few consistent and brief surveys of the Solar System history accounting for the latest achievements in astrophysics and cosmology. Meanwhile, they are very important and productive for theorizing part of Big History. Second, the discussion employing the general evolutionary laws and rules allows defining some common features in the formation of the Solar system and especially of its planetary system which are characteristic for every level and stage of Big History. This brings us to the idea of the integrity of Big History not only in historical and systemic terms but also with respect to its integrity in detecting general laws, patterns and mechanisms.

The paper concerning Tunguska meteorite (1908).
This paper describes results of 30 years of author's research concerning Tunguska impact (1908). The mechanism of Tunguska blast is determined as quick destruction of four main fragments of the comet in dense atmosphere. The structure of comet is determined, its substance and final size of each fragment. Detailed explanation of thermal damages due to explosion is described. More accurate coordinates of regions are obtained on the area of Tunguska site, where the most heavy sediments or fragments are possible to discover (meteorites). Quasi three-dimensional mathematical modeling of the impact was produced with the help of PIC-method (particle-in-cell method). It was shown that Tunguska-size comets are able to penetrate considerable deep into dense atmosphere due to decrease of drag effect. This decrease is explained by forward-directed jet from cavern of ice body, which located at the region of stagnation point. The author describes some stones which he found at the bottom of Khushmo River's shoal during 1988 expedition into the region of the Tunguska impact (1908). The idea is declared that main incoming of space substance to the Earth is provided by comets. Also the author declare that interstellar substance of Tunguska comet not considerably differ from terrestrial substance. This is explanation why scientists was not able to find substance of Tunguska comet during 100 years. The author suggests new vision of mechanism of initiation of life on planets after Tunguska similar impacts. This mechanism takes into consideration not only incoming cosmic organic substance but also information, which is connected to this substance. Mathematical metrics of atom of hydrogen is deduced which may be used for pattern recognition algorithm. In accordance to author's opinion, similar algorithm can promote evolution (transformation) of inert organic substance into living substance. There is additional information for emergency organizations for training of people against comets and asteroids danger, its mechanical, thermal and electromagnetic influence. (in Russian).

Spectrum analysis of Jupiter|s great red spot area\ rotation\ longitude\ and latitude\ for the period 0852
0856\ has been performed[
The methods of maximum entropy\ power spectrum "Blackman
Tukey approach#\ Fourier\ and autocorrelation have been employed
to detect periodicities in the variation of these parameters[ The method of {successive approximations| was applied to the area time!
series\ and periods of 14\ 05\ 4 and 2 months and a trend 21 months were identi_ed and an analytical expression _t was given\
with an accuracy of 67)[ Only some periods "5
07 months# describe the main trends of the variation\ the shorter "1
4 months#
exhibit a stochastic variability\ while the longer ones which approach the total record represent a trend[ The obtained signi_cant
periods and long term trends\ common in all methods\ are] for latitude^ 2[529[1\ 5[129[4\ 06[422[9 months\ a sporadic one of 03[2
months and a trend of 29
24 months\ for longitude^ 2[829[03\ 6[229[4\ 04[521 and 08[721[4 months\ a sporadic one of 420
months\ and a trend of 29
39 months^ for area^ 05[523[9 and 1523 months\ and sporadic ones 04
06 months and a trend of 2126
months\ and for rotation^ 3[729[4\ 7[229[3\ 04[121[2\ 1922 months\ a sporadic one of 4
5 months and a trend of 29
24 months[
These periodic terms form a network of periodicities overlapping one upon each other[ Various tests of signi_cance and stationarity
were applied to examine the reliability and variability of the periodic components[
The results of these periodic:quasi!periodic components are discussed in relation to the sunspot numbers\ cometary impacts and
Jovian atmospheric features.

Depuis que nous savons que l’univers est en expansion, de nombreuses observations ont été réalisées pour tenter de tirer le maximum de connaissances des images que nous parvenons à en prendre. Guidé par un spécialiste de l’instrumentation, équipé des clichés les plus récents, nous nous interrogerons sur la dynamique de progression du savoir et sur la vie de foi du chercheur. Conférence faite en dialogue avec Philippe Gagnon.

Ce travail a avant tout permis de confirmer que la distribution des diamètres des astroblèmes terrestres est conforme à la loi de Benford. Il présente en second lieu une méthode originale qui, appliquée à la classification des structures établie par Jarmo Moilanen (2009), exploite les écarts observés entre les jeux de données et la loi de Benford afin d’affecter une probabilité statistique à chaque structure en attente de validation au regard de son diamètre. Une liste des structures qui répondent aux critères permettant de minimiser les écarts entre la loi de Benford et la distribution des diamètres des astroblèmes véritables (dont les preuves sont jugées suffisantes par la communauté scientifique) est proposée. Une analyse similaire a été menée sur un jeu de données composite intégrant également les structures dont la probabilité qu’elles soient des astroblèmes est forte (jeu de données DS #2). Les critères étant différents, d’autres objets ont été identifiés et complètent la liste originelle. Au total, 198 structures potentiellement intéressantes sont identifiées pour ces deux listes. Les résultats obtenus dans le cadre de ce travail ne peuvent pas servir d’appui à la validation d’une structure. En revanche, ils constituent un faisceau statistique complémentaire permettant d’orienter la recherche de nouveaux astroblèmes en identifiant de bons candidats potentiels au statut d’astroblèmes véritables.

The box and flux model is a mathematical tool used to describe and forecast the major and trace elements perturbations of the Earth biogeochemical cycles. This mathematical tool describes the biogeochemical cycles, using kinetics of first, second and even third order. The theory and history of the box and flux modeling are shortly revised and discussed within the framework of Jim Lovelok&#39;s Gaia theory. The objectives of the investigation were to evaluate the natural versus anthropic load of Potentially Toxic Elements (PTEs) of the Scottish soils, investigate the soil components adsorbing and retaining the PTEs in non-mobile species, evaluate the aging factor of the anthropic PTEs and develop a model which describes the leaching of PTEs in layered soils. In the Scottish land, the soil-to-rock enrichment factorinversely correlates with the boiling point of the PTEs. The same is observed in NW Italy and USA soils, suggesting the common source of the PTEs. The residence time in soil...

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With the discovery of Na-sulfate minerals (thenardite, mirabilite) on Mars and Europa, recent studies using these minerals have focused on their ability to assist in the detection of biosignatures. On Earth, biotic and biotic processes can assist in the formation and deposition of these minerals. A primary objective of these studies is the detection of bio/organic compounds that may be associated with the mineral. These biosignatures would imply biological involvement during mineral formation. The following research presents a series of natural and synthetic investigations to determine if biological activity is associated with Na-sulfate mineralization, and if these minerals can assist in detecting bio/organic compounds. Evidence for biological activity associated with the formation of Na-sulfate deposits in the basaltic subsurface of Craters of the Moon National Monument, Idaho was examined by laser desorption Fourier transform mass spectrometry (LD-FTMS), infrared spectroscopy and...

In this paper we develop further the model for the migration of planets introduced in Del Popolo et al. We first model the protoplanetary nebula as a time-dependent accretion disc, and find self-similar solutions to the equations of the accretion disc that give us explicit formulae for the spatial structure and the temporal evolution of the nebula. These equations are then used to obtain the migration rate of the planet in the planetesimal disc, and to study how the migration rate depends on the disc mass, on its time evolution and on some values of the dimensionless viscosity parameter α . We find that planets that are embedded in planetesimal discs, having total mass of 10-4 -0.1Msolar , can migrate inward a large distance for low values of α (e.g., α ~=10-3 -10-2 ) and/or large disc mass, and can survive only if the inner disc is truncated or because of tidal interaction with the star. Orbits with larger a are obtained for smaller values of the disc mass and/or for larger values of α . This model may explain several orbital features of the recently discovered giant planets orbiting nearby stars.

Key scientific objectives of Mercury explorations are discussed, and the methods by which remote observations of Mercury can be carried out from earth and from space are examined. Attention is also given to the scientific rationale and technical concepts for missions to Mercury. It is pointed out that multiple Venus-Mercury encounter trajectories exist which, through successive gravity assists, reduce mission performance requirements to levels deliverable by available systems, such as Titan-Centaur, Atlas-Centaur, and Shuttle/TOS. It is shown that a single launch in July of 1994, using a Titan-Centaur combination, could place a 1477-kg payload into orbit around Meercury. The components of a Mercury-orbiter payload designed to study surface geology and geochemistry, atmospheric composition and structure, the local particle and fields environment, and solid-body rotation dynamics are listed.