排序方式: 共有49条查询结果,搜索用时 15 毫秒
41.
Space business competition is presently fueled by two paradoxical phenomena. First, accelerated privatization of space projects leads to the militarization of outer space. Second, this militarization process in turn leads to the increased control of space ventures by a handful of nations. In other words, commerce and the military are going hand in hand to assert national objectives in outer space, no matter what space treaties and international agreements might say, so far. This could be detrimental to the multilateral cooperation spirit that should prevail in many, if not all, outer space ventures, as a consequence of the uniqueness of that environment. 相似文献
42.
Solar Energetic Particle Events: Phenomenology and Prediction 总被引:1,自引:0,他引:1
Space Science Reviews - Solar energetic particle events can cause major disruptions to the operation of spacecraft in earth orbit and outside the earth's magnetosphere and have to be considered... 相似文献
43.
Nordholt Jane E. Wiens Roger C. Abeyta Rudy A. Baldonado Juan R. Burnett Donald S. Casey Patrick Everett Daniel T. Kroesche Joseph Lockhart Walter L. MacNeal Paul McComas David J. Mietz Donald E. Moses Ronald W. Neugebauer Marcia Poths Jane Reisenfeld Daniel B. Storms Steven A. Urdiales Carlos 《Space Science Reviews》2003,105(3-4):561-599
The primary goal of the Genesis Mission is to collect solar wind ions and, from their analysis, establish key isotopic ratios
that will help constrain models of solar nebula formation and evolution. The ratios of primary interest include 17O/16O and 18O/16O to ±0.1%, 15N/14N to ±1%, and the Li, Be, and B elemental and isotopic abundances. The required accuracies in N and O ratios cannot be achieved
without concentrating the solar wind and implanting it into low-background target materials that are returned to Earth for
analysis. The Genesis Concentrator is designed to concentrate the heavy ion flux from the solar wind by an average factor
of at least 20 and implant it into a target of ultra-pure, well-characterized materials. High-transparency grids held at high
voltages are used near the aperture to reject >90% of the protons, avoiding damage to the target. Another set of grids and
applied voltages are used to accelerate and focus the remaining ions to implant into the target. The design uses an energy-independent
parabolic ion mirror to focus ions onto a 6.2 cm diameter target of materials selected to contain levels of O and other elements
of interest established and documented to be below 10% of the levels expected from the concentrated solar wind. To optimize
the concentration of the ions, voltages are constantly adjusted based on real-time solar wind speed and temperature measurements
from the Genesis ion monitor. Construction of the Concentrator required new developments in ion optics; materials; and instrument
testing and handling.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
44.
The Energetic Particle and Plasma Spectrometer Instrument on the MESSENGER Spacecraft 总被引:1,自引:0,他引:1
G. Bruce Andrews Thomas H. Zurbuchen Barry H. Mauk Horace Malcom Lennard A. Fisk George Gloeckler George C. Ho Jeffrey S. Kelley Patrick L. Koehn Thomas W. LeFevere Stefano S. Livi Robert A. Lundgren Jim M. Raines 《Space Science Reviews》2007,131(1-4):523-556
The Energetic Particle and Plasma Spectrometer (EPPS) package on the MErcury Surface, Space ENvironment, GEochemistry, and
Ranging (MESSENGER) mission to Mercury is composed of two sensors, the Energetic Particle Spectrometer (EPS) and the Fast
Imaging Plasma Spectrometer (FIPS). EPS measures the energy, angular, and compositional distributions of the high-energy components
of the in situ electrons (>20 keV) and ions (>5 keV/nucleon), while FIPS measures the energy, angular, and compositional distributions
of the low-energy components of the ion distributions (<50 eV/charge to 20 keV/charge). Both EPS and FIPS have very small
footprints, and their combined mass (∼3 kg) is significantly lower than that of comparable instruments. 相似文献
45.
Patrick Cohendet Ehud Zuscovitch 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1983,3(7):23-31
La technologie spatiale s'est progressivement révélée comme un centre de propulsion technologique et économique pour les pays industriels qui ont pris partie dans l'effort de financement du programme spatial. La question que nous devons nous poser est de savoir dans quelle mesure le savoir et l'expérience accumulés lors du processus de production de cette technologie peut servir d'exemple à la forme de propagation du progrès économique pour les pays en voie de développement. 相似文献
46.
China’s space program is one of the most advanced, rapidly improving and opaque in the world. Insight into the program’s policy-making process could help eliminate misunderstandings, make intentions more clear and promote stability in US–China relations. This case study of China’s first lunar orbiting probe traces the project from initial policy proposal through agenda-setting, policy approval and final policy implementation. It reveals a highly rational decision-making process that is ruled by incrementalism, consensus building, scientific judgment and the use of leading small groups to coordinate among ministries. This research was guided by several relevant theories, including the “fragmented authoritarian” framework of power, the theory of the “policy entrepreneur” and the recently developed “inside access model”. The paper is one of the first published accounts in the English language to detail, from policy proposal to policy implementation, China’s first mission to the Moon. 相似文献
47.
Patrick Collins 《Space Policy》2000,16(2)
Scientists have expended much energy researching SPS but their theories have never yet been realistically tested. It is time for this to change and SPS 2000 — a Japanese-sponsored project to construct and operate a pilot plant to supply electricity to residents of equatorial zones — could provide the means. The project and its benefits are described and the political—economic imperatives for undertaking it presented. The author argues that there are cogent — and practical — reasons for funding a pilot plant, especially given the vast sums spent on other space activities, and on nuclear power, although the latter has never lived up to expectations. 相似文献
48.
Patrick Collins 《Space Policy》1990,6(3)
Astronaut selection involves a battery of medical tests both physical and psychological - not all of them pleasant! Patrick Collins, Director of Undergraduate Studies at Imperial College Management School, London, reports on the tests undergone by hopefuls for the UK Juno mission, and in so doing sheds light on a process that all who have voyaged into space have undergone. 相似文献
49.
NASA has created a plan to implement the Flexible Path strategy, which utilizes a heavy lift launch vehicle to deliver crew and cargo to orbit. In this plan, NASA would develop much of the transportation architecture (launch vehicle, crew capsule, and in-space propulsion), leaving the other in-space elements open to commercial and international partnerships. This paper presents a space exploration strategy that reverses that philosophy, where commercial and international launch vehicles provide launch services. Utilizing a propellant depot to aggregate propellant on orbit, smaller launch vehicles are capable of delivering all of the mass necessary for space exploration. This strategy has benefits to the architecture in terms of cost, schedule, and reliability. 相似文献