Comparison between polar regions of Mars from HEND/Odyssey data     

M.L. Litvak  I.G. Mitrofanov  A.B. Sanin  W.V. Boynton  D. Hamara  R.S. Saunders 《Icarus》2006,180(1):23-37

In this paper, we have analyzed neutron spectroscopy data gathered by the High Energy Neutron Detector (HEND) instrument onboard Mars Odyssey for comparison of polar regions. It is known that observation of the neutron albedo of Mars provides important information about the distribution of water-ice in subsurface layers and about peculiarities of the CO₂ seasonal cycle. It was found that there are large water-rich permafrost areas with contents of up to ∼50% water by mass fraction at both the north and south Mars polar regions. The water-ice layers at high northern latitudes are placed close to the surface, but in the south they are covered by a dry and relatively thick (10-20 cm) layer of soil. Analysis of temporal variations of neutron flux between summer and winter seasons allowed the estimation of the masses of the CO₂ deposits which seasonally condense at the polar regions. The total mass of the southern seasonal deposition was estimated as 6.3×¹⁰¹⁵ kg, which is larger than the total mass of the seasonal deposition at the north by 40-50%. These results are in good agreement with predictions from the NASA Ames Research Center General Circulation Model (GCM). But, the dynamics of the condensation and sublimation processes are not quite as consistent with these models: the peak accumulation of the condensed mass of CO₂ occurred 10-15 degrees of Ls later than is predicted by the GCM.  相似文献   

X-ray of gamma-ray bursts observable by HEAO-B     

I. G. Mitrofanov 《Astrophysics and Space Science》1981,80(2):303-306

On grounds of Mazetset al. (1980a) conclusion that all gamma-ray bursts recorded were emitted at the distance 1 kpc from the Sun it is shown that bursts from the Galaxy and from another galaxies may be observable byEinstein Observatory (HEAO-B). The HEAO-B observing programs are considered and the numbers of possibly recorded events are estimated. It is concluded that the important information about sources of gamma-bursts may be obtained in this way.  相似文献   

Geodynamic setting of gold ore deposits of the neoproterozoic bodaibo trough     

Academician of the RAS M. I. Kuz’min  V. V. Yarmolyuk  A. I. Spiridonov  V. K. Nemerov  A. I. Ivanov  G. L. Mitrofanov 《Doklady Earth Sciences》2006,407(2):397-400

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Geodynamic setting of gold ore deposits of the neoproterozoic bodaibo trough     

M. I. Kuz&#;min  V. V. Yarmolyuk  A. I. Spiridonov  V. K. Nemerov  A. I. Ivanov  G. L. Mitrofanov 《Doklady Earth Sciences》2006,407(3):397-400

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U-Pb isotopic study of the gabbronorite–anorthosite drusite (coronite) body of Vorony Island (Kandalaksha Archipelago,the White Sea)     

M. K. Sukhanov  F. P. Mitrofanov  T. B. Bayanova  A. V. Chistyakov 《Petrology》2016,24(1):75-83

The Precambrian Belomorian mobile belt located between the Karelian craton and the Lapland–Umba granulite belt contains large amount of small rootless mafic–ultramafic intrusions, which are dispersed over a large area and distinguished as the Belomorian drusite (coronite) complex. U-Pb dating of magmatic zircon and metamorphic rutile from the drusite body on Vorony Island showed that it was crystallized at 2460 ± 11 Ma and metamorphosed at 1775 ± 45 Ma. Petrographic and geochemical data confirm that the parental magmas of the drusites belong to the siliceous high-magnesian (boninite-like) series, which also was responsible for the formation of large layered plutons in stable domains of the Baltic Shield.  相似文献   

Comparison of new U-Pb and Sm-Nd isotope data on rocks of the early barren phase and basal ore-bearing rocks in the PGE-bearing Fedorovo-Pana layered massif,Kola Peninsula     

P. A. Serov  E. A. Nitkina  T. B. Bayanova  F. P. Mitrofanov 《Doklady Earth Sciences》2007,416(1):1125-1127

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Seasonal redistribution of water in the surficial Martian regolith: Results from the <Emphasis Type="Italic">Mars Odyssey</Emphasis> high-energy neutron detector (HEND)     

R. O. Kuzmin  E. V. Zabalueva  I. G. Mitrofanov  M. L. Litvak  A. V. Rodin  W. V. Boynton  R. S. Saunders 《Solar System Research》2007,41(2):89-102

The seasonal variation of neutron emissions from Mars in different spectral intervals measured by the HEND neutron detector for the entire Martian year are analyzed. Based on these data, the spatial variations of the neutron emissions from the planet are globally mapped as a function of season, and the dynamics of seasonal variation of neutron fluxes with different energies is analyzed in detail. No differences were found between seasonal regimes of neutron fluxes in different energy ranges in the southern hemisphere of Mars, while the regime of fast neutrons (with higher energies) during the northern winter strongly differs from that during the southern winter. In winter (L _s = 270°–330°), the fast neutron fluxes are noticeably reduced in the northern hemisphere (along with the consecutive thickening of the seasonal cap of solid carbon dioxide). This provides evidence of a temporary increase in the water content in the effective layer of neutron generation. According to the obtained estimates, the observed reduction of the flux of fast neutrons in the effective layer corresponds to an increase in the water abundance of up to 5% in the seasonal polar cap (70°–90°N), about 3% at mid-latitudes, and from 1.5 to 2% at low latitudes. The freezing out of atmospheric water at the planetary surface (at middle and high latitudes) and the hydration of salt minerals composing the Martian soil are considered as the main processes responsible for the temporary increase in the water content in the soil and upper layer of the seasonal polar cap. The meridional atmospheric transport of water vapor from the summer southern to the winter northern hemisphere within the Hadley circulation cell is a basic process that delivers water to the subsurface soil layer and ensures the observed scale of the seasonal increase in water abundance. In the summer northern hemisphere, the similar Hadley circulation cell transports mainly dry air masses to the winter southern hemisphere. The point is that the water vapor becomes saturated at lower heights during aphelion, and the bulk of the atmospheric water mass is captured in the near-equatorial cloudy belt and, thus, is only weakly transferred to the southern hemisphere. This phenomenon, known as the Clancy effect, was suggested by Clancy et al. (1996) as a basic mechanism for the explanation of the interhemispheric asymmetry of water storage in permanent polar caps. The asymmetry of seasonal meridional circulation of the Martian atmosphere seems to be another factor determining the asymmetry of the seasonal water redistribution in the “atmosphere-regolith-seasonal polar caps” system, found in the peculiarities of the seasonal regime of the neutron emission of Mars.  相似文献   

Selection of <Emphasis Type="Italic">Luna-25</Emphasis> landing sites in the South Polar Region of the Moon     

M. V. Djachkova  M. L. Litvak  I. G. Mitrofanov  A. B. Sanin 《Solar System Research》2017,51(3):185-195

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Search for Water in Martian Soil Using Global Neutron Mapping by the Russian HEND Instrument Onboard the US 2001 Mars Odyssey Spacecraft     

Mitrofanov  I. G.  Litvak  M. L.  Kozyrev  A. S.  Sanin  A. B.  Tret'yakov  V. I.  Boynton  W. V.  Shinohara  C.  Hamara  D.  Saunders  S.  Drake  D. M. 《Solar System Research》2003,37(5):366-377

We present the first results of the global neutron mapping of Mars by the Russian High-Energy Neutron Detector (HEND) onboard the US 2001 Mars Odyssey spacecraft. Global neutron maps of Mars in various spectral ranges allow the content of water ice and adsorbed and bound water in a near-surface layer of the planet 1 to 2 m in thickness to be estimated. Huge regions of permafrost with a high (several tens of percent by weight) content of water ice are shown to be present in the north and the south of Mars. The continuous observations of Mars for 12 months, from February 18, 2002, through February 8, 2003, are indicative of significant seasonal variations on Mars where the transition from northern winter to northern summer occurred.  相似文献   

On the bottom relief effect on wind-driven currents in a homogeneous ocean     

V.A. Mitrofanov 《Dynamics of Atmospheres and Oceans》1978,2(3):293-320

The three-dimensional model of stationary wind-driven currents in a homogeneous ocean of a variable depth is investigated. The model is linear but includes horizontal and vertical turbulent mixings. Two cases of the behaviour of the isolines of the function $\text{?/H}$ are considered, namely: (1) all isolines $\text{?/H}$ start at one part of the coastline and end in another part of it, and (2) a certain isoline $\text{?/H}$ exists which is tangential to the coastline. Here ? is the Coriolis parameter, and H is the depth of the ocean. The first case is the simplest one; it arises in particular if H = constant and the coasts are meridional. The second case is marked by the boundary current separation from the coast. The paper deals with the boundary layers which arise at the surface, bottom, side boundary and inside the ocean.  相似文献