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91.
Athena Coustenis Jonathan Lunine Jean-Pierre Lebreton Dennis Matson Christian Erd Kim Reh Patricia Beauchamp Ralph Lorenz Hunter Waite Christophe Sotin Leonid Gurvits Mathieu Hirtzig 《Earth, Moon, and Planets》2009,105(2-4):135-142
The Titan Saturn System Mission (TSSM) concept is composed of a TSSM orbiter provided by NASA that would carry two Titan in situ elements provided by ESA: the montgolfière and the probe/lake lander. One overarching goal of TSSM is to explore in situ the atmosphere and surface of Titan. The mission has been prioritized as the second Outer Planets Flagship Mission, the first one being the Europa Jupiter System Mission (EJSM). TSSM would launch around 2023–2025 arriving at Saturn 9 years later followed by a 4-year science mission in the Saturn system. Following delivery of the in situ elements to Titan, the TSSM orbiter would explore the Saturn system via a 2-year tour that includes Enceladus and Titan flybys before entering into a dedicated orbit around Titan. The Titan montgolfière aerial vehicle under consideration will circumnavigate Titan at a latitude of ~20° and at altitudes of ~10 km for a minimum of 6 months. The probe/lake lander will descend through Titan’s atmosphere and land on the liquid surface of Kraken Mare (~75° north latitude). As for any planetary space science mission, and based on the Cassini–Huygens experience, Earth-based observations will be synergistic and enable scientific optimization of the return of such a mission. Some specific examples of how this can be achieved (through VLBI and Doppler tracking, continuous monitoring of atmospheric and surface features, and Direct-to-Earth transmission) are described in this paper. 相似文献
92.
Dominik C. HEZEL Leonid DUBROVINSKY Lutz NASDALA Jean CAUZID Alexandre SIMIONOVICI Marko GELLISSEN Thorbjörn SCHÖNBECK 《Meteoritics & planetary science》2008,43(7):1127-1136
Abstract— A new olivine‐pigeonite ureilite containing abundant diamonds and graphite was found in the United Arab Emirates. This is the first report of a meteorite in this country. The sample is heavily altered, of medium shock level, and has a total weight of 155 g. Bulk rock, olivine (Fo79.8–81.8) and pyroxene (En73.9–75.2, Fs15.5–16.9, Wo8.8–9.5) compositions are typical of ureilites. Olivine rims are reduced with Fo increasing up to Fo96.1–96.8. Metal in these rims is completely altered to Fehydroxide during terrestrial weathering. We studied diamond and graphite using micro‐Raman and in situ synchrotron X‐ray diffraction. The main diamond Raman band (LO = TO mode at ?1332 cm?1) is broadened when compared to well‐ordered diamond single crystals. Full widths at half maximum (FWHM) values scatter around 7 cm?1. These values resemble FWHM values obtained from chemical vapor deposition (CVD) diamond. In situ XRD measurements show that diamonds have large grain sizes, up to >5 μm. Some of the graphite measured is compressed graphite. We explore the possibilities of CVD versus impact shock origin of diamonds and conclude that a shock origin is much more plausible. The broadening of the Raman bands might be explained by prolonged shock pressure resulting in a transitional Raman signal between experimentally shock‐produced and natural diamonds. 相似文献
93.
Mineralogy and Petrology - The concentrations of 26 trace elements have been determined by laser ablation ICP-MS in zircons from four samples of basic rocks of the Korosten... 相似文献
94.
Leonid V. Zamana 《中国地质》2010,37(3):582-586
本文通过对在外贝加尔大骨节病区水文地球化学研究结果表明,该地区天然水呈现出高浓度的磷(高达3.5mg/L),同时,锰、硅、铅等元素也呈现出高浓度的地球化学特征。分析水文地球化学数据,认为大骨节病可能与生物地球化学性质的多种因素有关系。进一步研究大骨节病的成因机制需要新的可靠的环境地球化学数据。 相似文献
95.
96.
Michael S. Zhdanov Vjacheslav V. Spichak Leonid Yu. Zaslavsky 《Physics of the Earth and Planetary Interiors》1990,60(1-4):53-61
A method for numerical modeling of quasi-stationary electromagnetic fields in axially symmetric media is proposed. It is based on the direct finite-element method and the use of special basis functions. Assuming cylindrical coordinates r, φ, z, the three-dimensional solution is presented as a superposition of fields with the azimuthal dependence exp(inφ). For each case this results in a system of two equations of elliptical type in two scalar functions in the (r, z) plane.
The discretization leads to the conservative nine-points difference scheme. The system of linear equations is solved by means of the LU-decomposition technique, the band structure of the matrix being taken into account.
The program is tested using analytical results (DC asymptote) for a near-surface inhomogeneity. Comparison also is made with 2D results (H-polarization) for the model of a local well conducting inclusion in a three-layered Earth. 相似文献
97.
98.
High-pressure and high-temperature in situ X-ray diffraction study of iron and corundum to 68 GPa using an internally heated diamond anvil cell 总被引:1,自引:1,他引:0
Leonid S. Dubrovinsky Surendra K. Saxena Peter Lazor 《Physics and Chemistry of Minerals》1998,25(6):434-441
Using powder X-ray diffraction of heated solids to pressures reaching 68 GPa, the pressure-volume-temperature (PVT) data on
corundum Al2O3 and ɛ-Fe were determined with the following results:
*Corundum,*Iron, *Al2O3*ɛ-Fe
Isothermal bulk*258 (2)*164 (3) modulus K'300, 1 (GPa)
Pressure derivative K300, 1*4.88 (4)*5.36 (16)
Temperature derivative*–0.020 (2)*–0.043 (3) (∂K
T,1
/∂T)
P
(GPa/K)
Molar volume V300,1*25.59 (2)*6.76 (2) (cm3/mol)
Isobaric thermal expansion at 1 atm (0.101 MPa) is given by (K–1):
α
T
=2.6 (2) 10–5+1.81 (9) 10–9
T–0.67 (6)/T
2 for corundum, and α
T
=5.7 (4) 10–5+4.2 (4) 10–9
T–0.17 (7)/T
2 for iron ɛ-Fe.
Received: 1 March 1997 / Revised, accepted: 21 August 1997 相似文献
99.
Olga N. Karasyova Lyudmila I. Ivanova Leonid Z. Lakshtanov Lars Lövgren Staffan Sjöberg 《Aquatic Geochemistry》1998,4(2):215-231
The acid/base properties of the hematite/water interface and surfacecomplexation with gold has been studied by potentiometric titrations in thefour component system H+ – FeOH –AuCl
4
-
– Cl-. Equilibrium measurementswere performed in NaCl media at 298.2 K. In the evaluation of equilibriummodel from experimental data the constant capacitance model was applied. Theacid/base properties were investigated in 0.1 M NaCl in the range 2.6 pH 7.4. The resulting intrinsic constants for protonation anddeprotonation of hydroxyl groups at the surface were log
1,1,0,0(int)
s
= 7.10 ± 0.06 andlog
-1,1,0,0(int)
s
= - 7.80 ±0.06. The density of proton active surface sites was 2.85nm-2 and the specific capacitance 2.5 C V-1 m-2. In the investigation of surface complexation of gold, thepotentiometric titrations were performed in the range 2.0 pH 10.2.Titration data was supplemented with analysis of Au in the aqueous phase byatomic absorbance spectrometry. The equilibrium model proposed consists ofthe following monodentate surface complexes: FeOHAuCl3(log
0,1,1,-1
s
= 1.45 ± 0.03),FeOHAuCl2OH (log
-1,1,1,-2
s
= -3.89 ± 0.02), FeOHAu(OH)3 (log
-3,1,1,-4
s
= -21.94 ± 0.05). Aslightly better fit could be obtained by assuming formation of a bidentatecomplex with the composition(FeO)2Au(OH)H2O. However, based onstructural arguments this complex was rejected. 相似文献
100.
A new natural,super-hard,transparent polymorph of carbon from the Popigai impact crater,Russia 总被引:1,自引:0,他引:1
Ahmed El Goresy Leonid S Dubrovinsky Philippe Gillet Smail Mostefaoui Günther Graup Michael Drakopoulos Alexandre S Simionovici Varghese Swamy Victor L Masaitis 《Comptes Rendus Geoscience》2003,335(12):889-898
A natural shockwave event led to the formation of a new crystalline polymorph of carbon in gneisses from the Popigai crater, Russia. The new species occupies the interior of a multiphase assemblage and is entirely enveloped by lonsdaleite and graphite. Polishing hardness of this new phase is greater than that of lonsdaleite. Micro-beam synchrotron X-ray diffraction, imaging and fluorescence studies revealed a pure transparent carbon phase. The diffraction pattern is indexed in terms of a cubic cell (a=14.697 Å, space group Pm3m.). This species was neither encountered in static or dynamic high-pressure experiment nor predicted by theoretical calculations. To cite this article: A. El Goresy et al., C. R. Geoscience 335 (2003). 相似文献