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761.
Jizhang Sang James C. Bennett Craig H. Smith 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
This paper presents a new method for estimating ballistic coefficients (BCs) of low perigee debris objects from their historical two line elements (TLEs). The method uses the drag perturbation equation of the semi-major axis of the orbit. For an object with perigee altitude below 700 km, the variation in the mean semi-major axis derived from the TLE is mainly caused by the atmospheric drag effect, and therefore is used as the source in the estimation of the ballistic coefficient. The method is tested using the GRACE satellites, and a number of debris objects with external ballistic coefficient values, and agreements of about 10% are achieved. 相似文献
762.
P. Alexander M. Rossi 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
Zonal velocity and temperature daily global reanalysis data of 30 years are used to search seasonally steady planetary disturbances in the middle troposphere (400 hPa) and middle stratosphere (10 hPa). Significant wavenumber 1, 2 and 3 modes are found. Constant phase lines of zonal velocity 1 modes exhibit significant inclination angles with respect to the meridians. The winter hemisphere generally shows a more significant presence of structures. The Northern Hemisphere (NH) exhibits all over the year a larger amount of structures and more intense amplitudes than the Southern Hemisphere (SH). Middle latitudes exhibit the most significant cases and low latitudes the least significant ones. Longitudinally oriented land–sea transitions at ±65° and −35° latitudes appear to play a significant role for the presence of steady planetary modes. The stratosphere exhibits a much simpler picture than the troposphere. Large scale structures with respectively NE–SW (NH) and NW–SE (SH) tilts in the observed temperature and zonal velocity constant phase lines recall the quasi-stationary Rossby wave trains that favor the poleward transport of angular momentum. 相似文献
763.
M. Sznajder T. Renger A. Witzke U. Geppert R. Thornagel 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
This paper describes the construction and performance of a VUV-simulator that has been designed to study degradation of materials under space conditions. It is part of the Complex Irradiation Facility at DLR in Bremen, Germany, that has been built for testing of material under irradiation in the complete UV-range as well as under proton and electron irradiation. Presently available UV-sources used for material tests do not allow the irradiation with wavelengths smaller than about 115 nm where common Deuterium lamps show an intensity cut-off. The VUV-simulator generates radiation by excitation of a gas-flow with an electron beam. The intensity of the radiation can be varied by manipulating the gas-flow and/or the electron beam. 相似文献
764.
J. Biele S. Ulamec M. Hilchenbach N.I. Kömle 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
A key aspect for understanding the astrobiological potential of planets and moons in the Solar system is the analysis of material embedded in or underneath icy layers on the surface. In particular in case of the icy crust of Jupiters moon Europa such investigation would be of greatest interest. For a Europa lander to be launched in the 2020–2030 timeframe, we propose to use a simplified instrumented melting probe which is able to access and sample depths of a few meters without the necessity of heavy and complicated drilling equipment. 相似文献
765.
S.V. Chalov H.J. Fahr 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
In this paper we start from the most recently observed fact that the solar wind plasma after passage over the termination shock is still supersonic with a Mach number of about 2. To explain this unexpected phenomenon and to predict the evolution of properties of the downstream plasma flow we here consider a two-fluid proton plasma with pick-up protons as a separate suprathermal, second proton fluid. We then formulate a self-consistent system of hydrodynamical conservation equations coupling the two fluids by dynamical and thermodynamical coupling terms and taking into account the effects of newly incorporated protons due to charge exchange with the H-atoms in the heliosheath. This then allows us to predict that in the most probable case the solar wind protons will become subsonic over a distance of about 30 AU downstream of the shock. As we can also show, it may, however, happen that the plasma mixture later again reconverts to a supersonic signature and has to undergo a second shock before meeting the heliopause. 相似文献
766.
767.
A.K. Sharma D.P. Nade S.S. Nikte P.T. Patil R.N. Ghodpage R.S. Vhatkar M.V. Rokade S. Gurubaran 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
This paper reports the nightglow observations of OI 630.0 nm emissions, made by using all sky imager operating at low latitude station Kolhapur (16.8°N, 74.2°E and dip lat. 10.6°N) during high sunspot number years of 24th solar cycle. The images are analyzed to study the nocturnal, seasonal and solar activity dependence occurrence of plasma bubbles. We observed EPBs in images regularly during a limited period 19:30 to 02:30 LT and reach maximum probability of occurrence at 22:30 LT. The observation pattern of EPBs shows nearly no occurrence during the month of May and it maximizes during the period October–April. The equinox and solstice seasonal variations in the occurrence of plasma bubbles show nearly equal and large differences, respectively, between years of 2010–11 and 2011–12. 相似文献
768.
Q. Liu Z. Wu M. Zhu W.Q. Xu 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
The increase of balloon applications makes it necessary for a comprehensive understanding of the thermal and dynamic performance of scientific balloons. This paper proposed a novel numerical model to investigate the thermal and dynamic characteristics of scientific balloon in both ascending and floating conditions. The novel model consists of a dynamic model and thermal model, the dynamic model was solved numerically by a computer program developed with Matlab/Simulink to calculate the velocity and trajectory, the thermal model was solved by the Fluent program to find out the balloon film temperature distribution and inner Helium gas velocity and temperature field. These models were verified by comparing the numerical results with experimental data. Then the thermal and dynamic behavior of a scientific balloon in a real environment were simulated and discussed in details. 相似文献
769.
S.I. Oronsaye L.A. McKinnell J.B. Habarulema 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
A new version of global empirical model for the ionospheric propagation factor, M(3000)F2 prediction is presented. Artificial neural network (ANN) technique was employed by considering the relevant geophysical input parameters which are known to influence the M(3000)F2 parameter. This new version is an update to the previous neural network based M(3000)F2 global model developed by Oyeyemi et al. (2007), and aims to address the inadequacy of the International Reference Ionosphere (IRI) M(3000)F2 model (the International Radio Consultative Committee (CCIR) M(3000)F2 model). The M(3000)F2 has been found to be relatively inaccurate in representing the diurnal structure of the low latitude region and the equatorial ionosphere. In particular, the existing hmF2 IRI model is unable to reproduce the sharp post-sunset drop in M(3000)F2 values, which correspond to a sharp post-sunset peak in the peak height of the F2 layer, hmF2. Data from 80 ionospheric stations globally, including a good number of stations in the low latitude region were considered for this work. M(3000)F2 hourly values from 1987 to 2008, spanning all periods of low and high solar activity were used for model development and verification process. The ability of the new model to predict the M(3000)F2 parameter especially in the low latitude and equatorial regions, which is known to be problematic for the existing IRI model is demonstrated. 相似文献
770.
Samy El-Jaby Leena Tomi Lembit Sihver Tatsuhiko Sato Richard B. Richardson Brent J. Lewis 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
This paper describes a methodology for assessing the pre-mission exposure of space crew aboard the International Space Station (ISS) in terms of an effective dose equivalent. In this approach, the PHITS Monte Carlo code was used to assess the particle transport of galactic cosmic radiation (GCR) and trapped radiation for solar maximum and minimum conditions through an aluminum shield thickness. From these predicted spectra, and using fluence-to-dose conversion factors, a scaling ratio of the effective dose equivalent rate to the ICRU ambient dose equivalent rate at a 10 mm depth was determined. Only contributions from secondary neutrons, protons, and alpha particles were considered in this analysis. 相似文献