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101.
Ke Du Shijie Li Ingo Leya Thomas Smith Dongliang Zhang Peng Wang 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2021,67(12):4089-4098
The Kumtag meteorite strewn field was found in the Kumtag desert, 132 km south of Hami city in the Xinjiang province, China. It is an ellipse of 2.5 × 7.9 km, with a long axis extending along the northeast-southwest direction. The largest individual meteorite of the strewn field weighs about 10 kg; the smallest individual has a mass of only 27 g. In total, more than 100 individuals with a total mass of more than 180 kg were collected. The location and the distribution of the fragments suggest that the Kumtag meteoroid entered the atmosphere in the direction Northeast-Southwest. All meteorites collected in this strewn field are samples from the same unique meteorite shower. The Kumtag meteorite is an H5 ordinary chondrite with a shock stage S2, and a weathering grade W2. The cosmic ray exposure age of Kumtag is 6.7 ± 0.8 Ma, which is rather typical for H chondrites and which indicates that Kumtag was derived from the massive impact event on its parent body ~7 Ma ago. A significant amount of He has been lost during certain unknown processe(s) before the Kumtag meteorite was ejected from its parent body. 相似文献
102.
Xiang Wang Chen Zhou 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2018,61(9):2252-2258
Incoherent scatter radar (ISR) is the most powerful ground-based measurement facility to study the ionosphere. The plasma lines are not routinely detected by the incoherent scatter radar due to the low intensity, which falls below the measured spectral noise level of the incoherent scatter radar. The plasma lines are occasionally enhanced by suprathermal electrons through the Landau damping process and detectable to the incoherent scatter radar. In this study, by using the European Incoherent Scatter Association (EISCAT) UHF incoherent scatter radar, the experiment observation presents that the enhanced plasma lines were observed. These plasma lines were considered as manifest of the suprathermal electrons generated by the high-frequency heating wave during the ionospheric modification. The electron density profile is also obtained from the enhanced plasma lines. This study can be a promising technique for obtaining the accurate electron density during ionospheric modification experiment. 相似文献
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106.
《Air & Space Europe》1999,1(1):51-54
The availability of new Communication, Navigation and Surveillance technologies provides the basis to move towards advanced Air Traffic Management (ATM) concepts. Some of these concepts will impact the airborne Flight Management System (FMS) by introducing new functions with different flight time horizons. In this discussion, two main flight time horizon are defined:The tactical flight time horizon is between 30s and 10mn ahead of the aircraft current position. Airborne separation from traffic, terrain and adverse weather will be introduced in this time horizon as a tactical function.The strategic flight time horizon is more than 10mn ahead of the aircraft current position. Weather datafusion, enroute inflight replanning assistance and air-ground trajectory negotiation will be introduced in this time horizon as strategic functions.The organisation of the associated future flight management system can be synthesised in the scheme (figure 1). The data to be displayed to the pilot for his flight awareness are functions of the flight phase, the type of airspace and of the type of situation encountered.Globally these data can be shared as functions of their flight time horizons, and their topic, as it is described in the table below. In the cells are indicated the flight objects that these data address.SEXTANT as a major avionics manufacturer is leading research and development activities in the area of ATM related airborne flight management functions. Their existing or expected findings are described in this article. 相似文献
107.
《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1999,23(5-6):1167-1176
The connection between normal and active galaxies is reviewed, by summarizing our progress on answering nine key questions. (1) Do all galaxies contain massive dark objects (MDOs)? (2) Are these MDOs actually supermassive black holes? (3) Why are the dark objects so dark? (4) Do all galaxies contain an Active Galactic Nucleus (AGN)? (5) Are the “dwarf AGN” really AGN? (6) Does AGN activity correlate with host galaxy properties? (7) How are AGN fuelled? (8) Is AGN activity related to starburst activity? (9) How do quasars relate to galaxy formation? 相似文献
108.
《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1999,23(11):1813-1816
Lunar laser altimeter (LALT) has been developed for the Japanese lunar exploration SELENE (SELenological and ENgineering Explorer) in 2003. Lunar laser altimetry and two other selenodetic missions are put together and called RISE (Researches In SElenodesy) project that has been developed mainly by National Astronomical Observatory of Japan. Main objective of this measurements is to construct a more global and accurate topographic model of the moon than Clementine's GLTM-2. The newly developed topography of the moon will make a great contribution to many problems of lunar geology, geophysics, and the reduction of lunar occultation data. In order to expand the coverage in latitude, LALT has a function of slant ranging in the direction about 40 degrees aside from nadir. LALT is designed to have a capability of detecting most of returned pulses from the lunar surface even for the slant ranging with proper threshold level. 相似文献
109.
《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1999,23(5-6):1025-1028
We report on high resolution studies of the nuclear region of NGC 3079 using H2O maser, continuum emission and HI absorption with both Japan VLBI Netowrk and global VLBI Network including the VLBA, the phased VLA and Effelsberg 100-m telescope. We identify the nucleus and rotation axis of the central 10 pc region, and suggest a rotating torus to explain the results. 相似文献
110.
《Acta Astronautica》1999,45(2):75-83
Similarity solutions for pointed-nose slender circular cones performing small-amplitude pitching oscillatons in hypersonic flow at zero angles of attack, are obtained in this paper. A three-dimensional unsteady hypersonic flow perturbation theory found recently by the present author for the pitching oscillations of such bodies is further studied here. It is shown that the equations can be reduced to four sets of boundary-value problems on ordinary differential equations by seeking a perturbation solution in the reduced frequency parameter k. Closed-form simple formulas for the stability derivatives are obtained showing the effect of all the parameters included in the problem except k. The obtained results show good agreement with the few available results. 相似文献