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This paper provides an overview and summary of U.S. extravehicular activity accomplishments of the last 26 years, Space Shuttle missions having scheduled extravehicular activities to be performed over the next several years, extravehicular activities expected to be necessary to support Space Station Freedom assembly tasks and operations, and potential extravehicular activity roles of the NASA Space Exploration Initiative Program.  相似文献   

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In the first part of this study of the substorm of March 12, 1991, the space-time structure of substrorm disturbance and dynamics of auroral ions were considered. This second part presents an analysis of measurements of auroral electrons onboard the CRRES satellite. It is demonstrated that enhancements of the electron flux (injections) during large-scale and local dipolarizations of the magnetic field are determined by a combination of field-aligned, induction, and betatron mechanisms of acceleration with an effect of displacement of the drift shells of particles. The relative contributions of these mechanisms in relation to the energy of auroral electrons are determined.  相似文献   

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Ethical issues have for long been limited to the fields of medicine and biotechnology, whereas to-day such matters encompass a growing number of engineering activities. 21st century citizens are more equiring about technoscientific claims and accomplishments. Has their impact on society and the ecological environment been measured and quantified? With all this accumulated knowledge and progress do they have the ability and means to resolve these self-created difficulties? Or will a totally new approach have to be sought? The debates include space activity not only because of the public funding needed but also because of the possible consequences on humans as well as the terrestrial, orbital or outer environment. Since the fall of 1998, CNES has undertaken the study of the role played by space activities in to-day's society and that of the future, seeking to clarify the objectives of the former with the expectations of the latter, and how they converge. The purpose of this study is to determine precisely the ethical responsibility of the space agencies and to pursue more sociological and philosophical research on the ethical scope of space activities.  相似文献   

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The Second United Nations Conference on the Exploration and Peaceful Uses of Outer Space ( 82) identified crucial problems and made recommendations on strategies for developing countries to bridge the gap with advanced nations in the area of space technology. This article addresses some issues which, although implicit in the Report, are not discussed in detail therein. The role of space science and related scientific research is particularly emphasized. Close attention is paid to the role of human factors, such as the motivation to conduct research, the motivation to engage in international cooperation, and the motivation to utilize and exploit space. Possible opportunities for space research for developing countries, as well as relevant issues concerning management of space, are briefly discussed.  相似文献   

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