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91.
Gernot E. Groemer Michael Storrie-Lombardi Birgit Sattler Oliver Hauser Klaus Bickert Eva Hauth Stefan Hauth Ulrich Luger Daniel Schildhammer Daniel Foeger Jan Klauck 《Acta Astronautica》2011,68(1-2):218-225
As part of the “PolAres” research programme, we are investigating techniques to detect and reduce forward contamination of the Mars regolith during human exploration. We report here on the development of a spacesuit simulator-prototype dubbed “Aouda.X,” document the inability of current technology to produce a static charge sufficient to minimize dust transport on the suit, and present preliminary results employing laser induced fluorescence emission (L.I.F.E.) techniques to monitor fluorescent microspherules as biological contamination proxies. 相似文献
92.
We analysed new UBVRI CCD photometry of the massive, blue SMC cluster NGC 330 and its surrounding field. The age structure and a new reddening value for the stellar population in this region of the SMC are derived and the implications for star formation in this part of the SMC and for stellar evolution are discussed.Based on observations obtained at ESO, La Silla 相似文献
93.
Anthony R. Yeates Tahar Amari Ioannis Contopoulos Xueshang Feng Duncan H. Mackay Zoran Mikić Thomas Wiegelmann Joseph Hutton Christopher A. Lowder Huw Morgan Gordon Petrie Laurel A. Rachmeler Lisa A. Upton Aurelien Canou Pierre Chopin Cooper Downs Miloslav Druckmüller Jon A. Linker Daniel B. Seaton Tibor Török 《Space Science Reviews》2018,214(5):99
Seven different models are applied to the same problem of simulating the Sun’s coronal magnetic field during the solar eclipse on 2015 March 20. All of the models are non-potential, allowing for free magnetic energy, but the associated electric currents are developed in significantly different ways. This is not a direct comparison of the coronal modelling techniques, in that the different models also use different photospheric boundary conditions, reflecting the range of approaches currently used in the community. Despite the significant differences, the results show broad agreement in the overall magnetic topology. Among those models with significant volume currents in much of the corona, there is general agreement that the ratio of total to potential magnetic energy should be approximately 1.4. However, there are significant differences in the electric current distributions; while static extrapolations are best able to reproduce active regions, they are unable to recover sheared magnetic fields in filament channels using currently available vector magnetogram data. By contrast, time-evolving simulations can recover the filament channel fields at the expense of not matching the observed vector magnetic fields within active regions. We suggest that, at present, the best approach may be a hybrid model using static extrapolations but with additional energization informed by simplified evolution models. This is demonstrated by one of the models. 相似文献
94.
David Arnas Daniel Casanova Eva Tresaco 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2021,67(11):3683-3695
4D Lattice Flower Constellations is a new constellation design framework, based on the previous 2D and 3D Lattice theories of Flower Constellations, that focus on the generation of constellations whose satellites can have different semi-major axis and still present a constellation structure that is maintained during the dynamic of the system. This situation can arise when dealing with satellites with very different instruments, or when it is of interest to coordinate two different constellations. In that sense, 4D Lattice Flower Constellations constitutes the most general representation of the Flower Constellation formulation. In addition, the effects of the perturbation are taken into account in order to generate distributions that maintain their initial design configuration under this perturbation for longer periods of time with a low fuel budget. Finally, examples of application are presented, showing the possibilities in satellite constellation design of this new approach. 相似文献
95.
We give an overview of recent efforts to model Type Ia supernovae and related astrophysical transients resulting from thermonuclear explosions in white dwarfs. In particular we point out the challenges resulting from the multi-physics multi-scale nature of the problem and discuss possible numerical approaches to meet them in hydrodynamical explosion simulations and radiative transfer modeling. We give examples of how these methods are applied to several explosion scenarios that have been proposed to explain distinct subsets or, in some cases, the majority of the observed events. In case we comment on some of the successes and shortcoming of these scenarios and highlight important outstanding issues. 相似文献
96.
Jing Sun Geshi Tang Fengchun Shu Xie Li Shushi Liu Jianfeng Cao Andreas Hellerschmied Johannes Böhm Lucia McCallum Jamie McCallum Jim Lovell Rüdiger Haas Alexander Neidhardt Weitao Lu Songtao Han Tianpeng Ren Lue Chen Mei Wang Jinsong Ping 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2018,61(3):823-829
The APOD (Atmospheric density detection and Precise Orbit Determination) is the first LEO (Low Earth Orbit) satellite in orbit co-located with a dual-frequency GNSS (GPS/BD) receiver, an SLR reflector, and a VLBI X/S dual band beacon. From the overlap statistics between consecutive solution arcs and the independent validation by SLR measurements, the orbit position deviation was below 10?cm before the on-board GNSS receiver got partially operational. In this paper, the focus is on the VLBI observations to the LEO satellite from multiple geodetic VLBI radio telescopes, since this is the first implementation of a dedicated VLBI transmitter in low Earth orbit. The practical problems of tracking a fast moving spacecraft with current VLBI ground infrastructure were solved and strong interferometric fringes were obtained by cross-correlation of APOD carrier and DOR (Differential One-way Ranging) signals. The precision in X-band time delay derived from 0.1?s integration time of the correlator output is on the level of 0.1?ns. The APOD observations demonstrate encouraging prospects of co-location of multiple space geodetic techniques in space, as a first prototype. 相似文献
97.
Richard W. Carlson Ramon Brasser Qing-Zhu Yin Mario Fischer-Gödde Liping Qin 《Space Science Reviews》2018,214(8):121
The processes of planet formation in our Solar System resulted in a final product of a small number of discreet planets and planetesimals characterized by clear compositional distinctions. A key advance on this subject was provided when nucleosynthetic isotopic variability was discovered between different meteorite groups and the terrestrial planets. This information has now been coupled with theoretical models of planetesimal growth and giant planet migration to better understand the nature of the materials accumulated into the terrestrial planets. First order conclusions include that carbonaceous chondrites appear to contribute a much smaller mass fraction to the terrestrial planets than previously suspected, that gas-driven giant planet migration could have pushed volatile-rich material into the inner Solar System, and that planetesimal formation was occurring on a sufficiently rapid time scale that global melting of asteroid-sized objects was instigated by radioactive decay of 26Al. The isotopic evidence highlights the important role of enstatite chondrites, or something with their mix of nucleosynthetic components, as feedstock for the terrestrial planets. A common degree of depletion of moderately volatile elements in the terrestrial planets points to a mechanism that can effectively separate volatile and refractory elements over a spatial scale the size of the whole inner Solar System. The large variability in iron to silicon ratios between both different meteorite groups and between the terrestrial planets suggests that mechanisms that can segregate iron metal from silicate should be given greater importance in future investigations. Such processes likely include both density separation of small grains in the nebula, but also preferential impact erosion of either the mantle or core from differentiated planets/planetesimals. The latter highlights the important role for giant impacts and collisional erosion during the late stages of planet formation. 相似文献
98.
Peslier Anne H. Schönbächler Maria Busemann Henner Karato Shun-Ichiro 《Space Science Reviews》2017,212(1-2):743-810
Space Science Reviews - The concentration and distribution of water in the Earth has influenced its evolution throughout its history. Even at the trace levels contained in the planet’s deep... 相似文献
99.
The Analyzer of Space Plasmas and Energetic Atoms (ASPERA-3) for the Mars Express Mission 总被引:1,自引:0,他引:1
S. Barabash R. Lundin H. Andersson K. Brinkfeldt A. Grigoriev H. Gunell M. Holmström M. Yamauchi K. Asamura P. Bochsler P. Wurz R. Cerulli-Irelli A. Mura A. Milillo M. Maggi S. Orsini A. J. Coates D. R. Linder D. O. Kataria C. C. Curtis K. C. Hsieh B. R. Sandel R. A. Frahm J. R. Sharber J. D. Winningham M. Grande E. Kallio H. Koskinen P. Riihelä W. Schmidt T. Säles J. U. Kozyra N. Krupp J. Woch S. Livi J. G. Luhmann S. McKenna-Lawlor E. C. Roelof D. J. Williams J.-A. Sauvaud A. Fedorov J.-J. Thocaven 《Space Science Reviews》2006,126(1-4):113-164
The general scientific objective of the ASPERA-3 experiment is to study the solar wind – atmosphere interaction and to characterize
the plasma and neutral gas environment with within the space near Mars through the use of energetic neutral atom (ENA) imaging
and measuring local ion and electron plasma. The ASPERA-3 instrument comprises four sensors: two ENA sensors, one electron
spectrometer, and one ion spectrometer. The Neutral Particle Imager (NPI) provides measurements of the integral ENA flux (0.1–60
keV) with no mass and energy resolution, but high angular resolution. The measurement principle is based on registering products
(secondary ions, sputtered neutrals, reflected neutrals) of the ENA interaction with a graphite-coated surface. The Neutral
Particle Detector (NPD) provides measurements of the ENA flux, resolving velocity (the hydrogen energy range is 0.1–10 keV)
and mass (H and O) with a coarse angular resolution. The measurement principle is based on the surface reflection technique.
The Electron Spectrometer (ELS) is a standard top-hat electrostatic analyzer in a very compact design which covers the energy
range 0.01–20 keV. These three sensors are located on a scanning platform which provides scanning through 180∘ of rotation. The instrument also contains an ion mass analyzer (IMA). Mechanically IMA is a separate unit connected by a
cable to the ASPERA-3 main unit. IMA provides ion measurements in the energy range 0.01–36 keV/charge for the main ion components
H+, He++, He+, O+, and the group of molecular ions 20–80 amu/q. ASPERA-3 also includes its own DC/DC converters and digital processing unit
(DPU). 相似文献
100.
Protoplanetary evolution is discussed in both its global and local aspects. The global turbulent evolution implies large scale average chemical fractionation and chondrule-sized grains as the building blocks of planetary and possibly also cometary material. Local processes such as electric discharges and associated flash heating of grains allow for chemical, mineralogical, and morphological alterations of the disk material. Large scale turbulence keeps the disk well stirred, however, time dependent (or intermittent) turbulence, associated with e.g. optical depth variations, could lead to dust sedimentation within the disk and subsequent planetesimal formation. Recent relevant astronomical observations of young T Tauri stars are briefly reviewed. 相似文献