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901.
Gyula Greschik 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
In order to assess space tow solar sail stability and control feasibility, slew simulations are performed for a simplified but dynamically representative km-class tow-like sail of sixteen 25 m square units (10,000 m2 total area and 110 kg gross mass) with a 250 kg payload. It is seen that, for the dimensions considered, the space tow concept is structurally sound and its control is feasible. While observed instabilities are identified as numeric in nature and are eliminated accordingly, their very occurrence highlights the need for a refinement of the model for future studies. The analyses are carried out with custom software implementing non-standard implicit-iterative time integration with innovative elements. A new damping model, specifically tailored for the analysis of truly gossamer systems such as solar sails, is also proposed. 相似文献
902.
分析了现有三坐标测量机误差检测方法,提出了对称联系组合定标法。详细论述了该方法的测量原理及其简练新颖的数学模型,并通过实验比对,验证了该方法的正确性和实用性。 相似文献
903.
Daniel Gómez Luis N. Martín Pablo Dmitruk 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
Because of its proximity, our Sun provides a unique opportunity to perform high resolution observations of its outer layers throughout the whole electromagnetic spectrum. We can also theoretically model most of the fascinating physical phenomena taking place on the Sun, as well as their impact on the solar system. 相似文献
904.
W. Wang A.G. Burns S. Solomon T.L. Killeen 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2005,36(12):2486-2491
Current first-principles global models of the coupled thermosphere–ionosphere (T–I) system use grids that are too coarse to simulate the mesoscale and small-scale structures that occur in this complex system. These small-scale and mesoscale structures have a great effect on global-scale neutral and plasma distributions and have important consequences for daily space weather. In this paper, we present a new first-principles, high-resolution, T–I nested grid (TING) polar cap model that incorporates multiple nesting levels and two-way interaction. The TING model simulation of the electron densities and temperatures demonstrates the importance of high spatial resolution. It is found that both the mid-latitude electron density trough and its associated dawn electron temperature peak are more pronounced and structured in the nested grid than in the coarse grid. Using the TING model to simulate ionospheric F2 region electron density variations with geomagnetic activity and universal time (UT) is also discussed. 相似文献
905.
U.M. Leloglu E. Kocaoglan 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008
Although it is generally agreed that the outer space should be used for the benefit of all mankind, only a fraction of the countries have the necessary technological base for accessing space. Space technology, with its implications on science, economy and well-being of citizens, is mostly chosen as one of the priority areas for technological development by developing countries. However, there is already an over-capacity in global space industry and there are doubts on necessity of additional capacity establishment by developing countries. In this study, the importance and benefits of capacity-building in these countries are emphasized and the advantages and disadvantages that developing countries have in the framework of space technology acquisition are briefly presented. The feasibility of certain levels of space technology is discussed and the necessity of combining existing indigenous capabilities with technology obtained from foreign sources in the optimal way is stressed. We have also mentioned various general mechanisms of technology transfer and argued the importance of licensing in catching-up developed countries. After considering the necessary conditions of efficiency of technology, such as establishment of regional centers of space science and technology education by United Nations, joint development of space systems, complete technology transfer packages, cooperative space projects within regional organizations, coordinated constellations and special agreements with large space agencies, which are specific mechanisms already in use, are reviewed. Some typical examples of mechanisms are also given with special emphasize on small satellite technology that makes access to space affordable for many countries. Through sharing and analyzing the experience of developing countries in their odyssey of space capacity-building, the difficulties can be negotiated and the vicious circles can be broken. This study, in our view, is a step to incite a general discussion of obstacles and opportunities for developing countries, that could help them in using their limited resources effectively, hence, enable them to offer better conditions to their citizens and to contribute space science to a larger extend. 相似文献
906.
Marc S. Allen Paul L. Hertz 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
NASA research programs offer many opportunities for productive partnerships with investigators in other countries. While spacecraft projects are complex and very expensive, there are other, lower-cost partnerships that can yield important scientific results and offer excellent opportunities for building up new space and Earth science programs and for training new researchers. 相似文献
907.
Robert J. Rovetto 《Space Policy》2013,29(4):225-228
The question is: should the United States and nations at large pursue a human spaceflight program (and if so, why)? I offer an unwavering positive answer to this question, and state the reasons for it while considering the broad challenges and benefits of (human) spaceflight. Space exploration is a human activity that is intrinsically forward-looking, and as such, has positive potential. Both national and international space programs can galvanize the population, inspire the youth, foster job-creation, and motivate the existing workforce. The nature of the enterprises involved—their scale, novelty, and complexity—requires a steady and continuous upward progression toward greater societal, scientific and technological development. That is, in order to overcome the challenges of human spaceflight, progress is required. More to the point, the survival of humanity depends on expanding beyond the confines of our planet. Human spaceflight, in short, presents us with an opportunity to significantly advance the nation and the global community. 相似文献
908.
双臂空间机器人利用内部运动的姿态控制 总被引:3,自引:0,他引:3
本文对双臂自由漂浮空间机器人系统的姿态控制问题进行了研究 ,推导出了系统的运动学模型 ,证明了系统具有非完整的力学结构 ,并且提出了一种利用内部运动的机器人本体姿态控制算法。该算法可使机器人本体的姿态在机械臂完成任务的过程中保持不变或变化最小 ,仿真结果验证了算法的有效性。 相似文献
909.
发展迅速的空间技术为人类铺设了通向太空和开发利用太空资源的道路。回顾过去,空间开发成就卓著。展望21世纪,空间事业前景光辉,人类将在太空开辟新天地,中国人也将遨翔太空。 相似文献
910.