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101.
China's opaque politics present particular difficulties for US space policy. Heavily invested in and reliant on space, the US will closely monitor China's burgeoning space program. New space powers, and the increasing use of space generally will further create significant challenges, most particularly to the reliance of states on space for national security. In order to maintain its space capabilities, the US will have to decide between securing this via multilateral and co-operative uses of space, or through trying to maintain a level of dominance over other space actors. While very gradually shifting away from the latter position, Washington's policy choices are complicated by the lack of a clear Chinese space strategy. While the Chinese space program, and its wider intentions, are opaque, tenure of a more cooperative approach course might prove fragile. 相似文献
102.
Mark A. Skinner Ray W. Russell Tom Kelecy Steve Gregory Richard J. Rudy Daryl L. Kim Kirk Crawford 《Acta Astronautica》2014
There exists a population of defunct satellites in the geo-stationary arc that potentially pose a hazard to current and future operational satellites. These drifting, non-station-kept objects have a variety of ages and sizes, and many are trapped in libration orbits around the Earth?s two gravitational potential wells (the non-spherical nature of the Earth gives rise to two geo-potential wells or “stable points” that affect objects in geostationary and geosynchronous orbits), whereas others were boosted to higher altitudes into so-called “graveyard” orbits. 相似文献
103.
Space ethics and protection of the space environment 总被引:1,自引:1,他引:0
The construction of the International Space Station in low Earth orbit and the formulation of plans to search for life on Mars indicate that mankind is intent on making the space environment part of its domain. Publicity surrounding space tourism, in-space ‘burials’ and the sale of lunar ‘real estate’ suggests that, some time in the 21st century, the space environment will become an extension of our current terrestrial business and domestic environment. This prompts the question of our collective attitude towards the space environment and the degree to which we should regulate its use and protect it for future generations. This article offers a pragmatic view of an ethical code for space exploration and development, as far as it relates to the protection of the space environment. 相似文献
104.
Mark.J 《世界航空航天博览》2006,(3):54-55
2005年12月,英国国防部的“狂风”F.3维持项目(FSP)达到了一个重大里程碑。在美海军空中作战中心应于加利福尼亚州的穆古角靶场,1架英国皇家空军(RAF)的“狂风”F3防空战斗机首次成功试射了美国雷声公司的AIM-120-C5中距空-空导弹,这也星RAF首次试射该型导弹。 相似文献
105.
航天部队与现代战争的革命 总被引:1,自引:0,他引:1
Mark.J 《世界航空航天博览》2005,(11):73-75
太空战是21世纪信息化战争的制高点,谁拥有制天权,谁就拥有制空权制海权和制信息权,美丽的天堂将成为航天大国争夺的焦点。一场争夺太空,利用太空,抢占制高点的战争将有可能发生。技术的突飞猛进可从根本上改变现代战争的进程。在信息收集、处理和传递为主的技术推动下,这场革命对军事行动产生的影响之大,决不亚于本世纪初飞机或坦克的投入使用。因此.航天部队在正进行的革命中正扮演着主角,具有收集、处理和传递信息的独特能力。 相似文献
106.
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108.
The shallow habitable region of cratonal crust deforms with a strain rate on the order of approximately 10(19) s(1). This is rapid enough that small seismic events are expected on one-kilometer spatial scales and one-million-year timescales. Rock faulting has the potential to release batches of biological substrate, such as dissolved H(2), permitting transient blooms. In addition, the steady-state deformation of the brittle crust causes numerous small faults to be permeable enough (on the order of approximately 10(15) m(2)) for water to flow on a kilometer scale over relatively short geological times ( approximately 10(5) yr). Hence, active faults act as concentrated niches capable of episodically tapping resources in the bulk volume of the rock. Radiolysis and ferrous iron are potentially bases of sustainable hard-rock niches. 相似文献
109.
Pettis CR Drake M Witten ML Truitt J Braun E Lindberg K McNeil G Hall JN 《Acta Astronautica》2002,50(6):393-398
Background: Both microgravity and simulated microgravity models, such as the 45HDT (45 degrees head-down tilt), cause a redistribution of body fluids indicating a possible adaptive process to the microgravity stressor. Understanding the physiological processes that occur in microgravity is a first step to developing countermeasures to stop its harmful effects, i.e., (edema, motion sickness) during long-term space flights. Hypothesis: Because of the kidneys' functional role in the regulation of fluid volume in the body, it plays a key role in the body's adaptation to microgravity. Methods: Rats were injected intramuscularly with a radioactive tracer and then lightly anesthetized in order to facilitate their placement in the 45HDT position. They were then placed in the 45HDT position using a specially designed ramp (45HDT group) or prone position (control group) for an experimental time period of 1 h. During this period, the 99mTc-DTPA (technetium-labeled diethylenepentaacetate, MW=492 amu, physical half-life of 6.02 h) radioactive tracer clearance rate was determined by measuring gamma counts per minute. The kidneys were then fixed and sectioned for electron microscopy. A point counting method was used to quantitate intracellular spaces of the kidney proximal tubules. Results: 45HDT animals show a significantly (p=0.0001) increased area in the interstitial space of the proximal tubules. Conclusions: There are significant changes in the kidneys during a 1 h exposure to a simulated microgravity environment that consist primarily of anatomical alterations in the kidney proximal tubules. The kidneys also appear to respond differently to the initial periods of head-down tilt. 相似文献
110.
Mark E. Brender 《Space Policy》1987,3(4):293-297
The images and information available from remote-sensing satellites are potentially valuable to a large market. The news media is part of this market, ready to make major use of new near real-time information offered by the latest technology, which can provide images with resolution of less than 10 metres. A media business consortium (‘Mediasat’) could be created. However, the US Land Remote Sensing Commercialization Act of 1984 places tough licensing restrictions on any US company wanting to put a camera into orbit. The author argues that these restrictions clash with the US Constitutional right of freedom of information, and the press's right to gather information. 相似文献