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61.
R.J.L. Grard L.W. Parker D.T. Young 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1981,1(2):403-407
The surface of a spacecraft is submitted to the bombardment of dust grains and neutral molecules during an atmospheric re-entry or a cometary fly-by. These particles create secondary ions and electrons which form a plasma cloud around the body and control the electric potential of its surface. Computer simulation models are used to predict the structure and dynamic behaviour of the charged particle density distribution for the cases of planar and cylindrical bodies. It is found that an ion and an electron layer form in the vicinity of the surface at distances of the order of the ion and electron Debye lengths, respectively. The potential of the surface is positive on the average and is a function of the electron mean kinetic energy. A positive potential barrier develops at the location of the ion layer and its height is governed by the sum of the electron and ion mean kinetic energies. The threat caused by this interaction to the spacecraft and its instrumentation is discussed and an in-situ observation of this phenomenon is proposed as a possible diagnostic technique of the environment. 相似文献
62.
Shoucri M. Davidheiser R. Hauss B. Lee P. Mussetto M. Young S. Yujiri L. 《Aerospace and Electronic Systems Magazine, IEEE》1995,10(5):37-42
Fog and low visibility conditions have hampered aviation since its inception. Fog-related accidents are numerous, and canceled take-offs and landings due to fog and low visibility conditions (Cat III) have significant economic impact on airlines, parcel carriers and general aviation. Millimeter waves have good propagation properties in weather and give adequate spatial resolution when used to image the forward scene. Passive millimeter wave focal plane array cameras are new sensors which, integrated into future guidance and landing systems, promise to be an effective aid, or alternative, to existing technology for aircraft landings and take-offs under Cat III conditions. They can produce visual-like radiometric images at real time frame rates (up to 30 Hz), and are directly amenable to image fusion with infrared and visible images. TRW has been actively involved in developing and productizing this technology both at the hardware and the system levels 相似文献
63.
Elizabeth Young 《Space Policy》1985,1(2):135-140
This article considers the thinking behind, and the ramifications of, President Reagan's Star Wars ‘vision’. The author argues that the Strategic Defense Initiative (SDI) is incompatible with other aspects of the Reagan administration's own defence policies and that the ‘security shield’ version of it would make future US-Soviet arms agreements impossible. Only the so-called ‘prudent hedge’ research looks viable in the longer term. The SDI's main value will have been in bringing the USSR back to the negotiating table. 相似文献
64.
Overview of the New Horizons Science Payload 总被引:2,自引:0,他引:2
H. A. Weaver W. C. Gibson M. B. Tapley L. A. Young S. A. Stern 《Space Science Reviews》2008,140(1-4):75-91
The New Horizons mission was launched on 2006 January 19, and the spacecraft is heading for a flyby encounter with the Pluto system in the summer of 2015. The challenges associated with sending a spacecraft to Pluto in less than 10 years and performing an ambitious suite of scientific investigations at such large heliocentric distances (>32 AU) are formidable and required the development of lightweight, low power, and highly sensitive instruments. This paper provides an overview of the New Horizons science payload, which is comprised of seven instruments. Alice provides moderate resolution (~3–10 Å FWHM), spatially resolved ultraviolet (~465–1880 Å) spectroscopy, and includes the ability to perform stellar and solar occultation measurements. The Ralph instrument has two components: the Multicolor Visible Imaging Camera (MVIC), which performs panchromatic (400–975 nm) and color imaging in four spectral bands (Blue, Red, CH4, and NIR) at a moderate spatial resolution of 20 μrad/pixel, and the Linear Etalon Imaging Spectral Array (LEISA), which provides spatially resolved (62 μrad/pixel), near-infrared (1.25–2.5 μm), moderate resolution (λ/δ λ~240–550) spectroscopic mapping capabilities. The Radio Experiment (REX) is a component of the New Horizons telecommunications system that provides both radio (X-band) solar occultation and radiometry capabilities. The Long Range Reconnaissance Imager (LORRI) provides high sensitivity (V<18), high spatial resolution (5 μrad/pixel) panchromatic optical (350–850 nm) imaging capabilities that serve both scientific and optical navigation requirements. The Solar Wind at Pluto (SWAP) instrument measures the density and speed of solar wind particles with a resolution ΔE/E<0.4 for energies between 25 eV and 7.5 keV. The Pluto Energetic Particle Spectrometer Science Investigation (PEPSSI) measures energetic particles (protons and CNO ions) in 12 energy channels spanning 1–1000 keV. Finally, an instrument designed and built by students, the Venetia Burney Student Dust Counter (VB-SDC), uses polarized polyvinylidene fluoride panels to record dust particle impacts during the cruise phases of the mission. 相似文献
65.
Yoon Kyung Seo Dong Young Rew Georg Kirchner Eunseo Park Mansoo Choi Sung Yeol Yu Jiwoong Heo Cheong Youn 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
For the development of a telescope that is capable of precisely tracking satellites and high-speed operation such as satellite laser ranging, a special method of telescope operation is required. This study aims to propose a new telescope operation method and system configuration for the independent development of a mount and an operation system which includes the host computer. Considering that the tracking of a satellite is performed in real time, communication and synchronization between the two independent subsystems are important. Therefore, this study applied the concept of time synchronization, which is used in various fields of industry, to the communication between the command computer and the mount. In this case, communication delays do not need to be considered in general, and it is possible to cope with data loss. Above all, when the mount is replaced in the future, only the general communication interface needs to be modified, and thus, it is not limited by replacement in terms of the overall system management. The performance of the telescope operation method developed in this study was verified by applying the method to the first mobile SLR system in Korea. This study is significant in that it proposed a new operation method and system configuration, to which the concept of time synchronization was applied, for the observation system that requires an optical telescope. 相似文献
66.
师用 《中国空间科学技术》1992,12(5):18-26
叙述了某型号卫星碳纤维复合材料承力筒长桁预制件的研制技术。运用介电损耗仪研究树脂基体在固化过程中的性能变化,以确定预浸料吸胶及预制件预压的工艺规范。预制件的成型采用软硬模相结合的方法,所研制的长桁预制件的性能满足了碳承力筒研制总工艺的要求,并通过了碳承力筒的地面力学性能试验。 相似文献
67.
D. T. Young J. E. Nordholt J. L. Burch D. J. McComas R. P. Bowman R. A. Abeyta J. Alexander J. Baldonado P. Barker R. K. Black T. L. Booker P. J. Casey L. Cope F. J. Crary J. P. Cravens H. O. Funsten R. Goldstein D. R. Guerrero S. F. Hahn J. J. Hanley B. P. Henneke E. F. Horton D. J. Lawrence K. P. McCabe D. Reisenfeld R. P. Salazar M. Shappirio S. A. Storms C. Urdiales J. H. Waite Jr. 《Space Science Reviews》2007,129(4):327-357
The Plasma Experiment for Planetary Exploration (PEPE) flown on Deep Space 1 combines an ion mass spectrometer and an electron
spectrometer in a single, low-resource instrument. Among its novel features PEPE incorporates an electrostatically swept field-of-view
and a linear electric field time-of-flight mass spectrometer. A significant amount of effort went into developing six novel
technologies that helped reduce instrument mass to 5.5 kg and average power to 9.6 W. PEPE’s performance was demonstrated
successfully by extensive measurements made in the solar wind and during the DS1 encounter with Comet 19P/Borrelly in September
2001.
P. Barker is deceased. 相似文献
68.
D. C. Hyland H. A. Altwaijry S. Ge R. Margulieux J. Doyle J. Sandberg B. Young X. Bai J. Lopez N. Satak 《Cosmic Research》2010,48(5):430-436
In the later stages of a combined mission of exploration and damage mitigation of a hazardous Near Earth Asteroid (NEA), sufficiently
detailed tracking, orbit prediction, mass distribution, and physical properties data have been accumulated. It may be desirable
to implement a “slow push” damage mitigation technique that is capable of altering the NEA orbit continuously and permanently.
This possibility was suggested in a companion paper that outlined an archetypal exploration/mitigation mission to the NEA
99942 Apophis, which is achieved using a novel albedo change approach. The details and apparatus used in the albedo modification
technique are described in the paper. We describe the design details and the constraints on particle size (to prevent electrostatic
levitation and escape) and on the dispensing speed (to achieve the desired coverage zone and prevent particles from orbiting
or escaping). 相似文献
69.
Peter R. Young Hui Tian Hardi Peter Robert J. Rutten Chris J. Nelson Zhenghua Huang Brigitte Schmieder Gregal J. M. Vissers Shin Toriumi Luc H. M. Rouppe van der Voort Maria S. Madjarska Sanja Danilovic Arkadiusz Berlicki L. P. Chitta Mark C. M. Cheung Chad Madsen Kevin P. Reardon Yukio Katsukawa Petr Heinzel 《Space Science Reviews》2018,214(8):120
The term “ultraviolet (UV) burst” is introduced to describe small, intense, transient brightenings in ultraviolet images of solar active regions. We inventorize their properties and provide a definition based on image sequences in transition-region lines. Coronal signatures are rare, and most bursts are associated with small-scale, canceling opposite-polarity fields in the photosphere that occur in emerging flux regions, moving magnetic features in sunspot moats, and sunspot light bridges. We also compare UV bursts with similar transition-region phenomena found previously in solar ultraviolet spectrometry and with similar phenomena at optical wavelengths, in particular Ellerman bombs. Akin to the latter, UV bursts are probably small-scale magnetic reconnection events occurring in the low atmosphere, at photospheric and/or chromospheric heights. Their intense emission in lines with optically thin formation gives unique diagnostic opportunities for studying the physics of magnetic reconnection in the low solar atmosphere. This paper is a review report from an International Space Science Institute team that met in 2016–2017. 相似文献
70.
J. Kleczek H. Nussbaumer K. A. van der Hucht J. P. de Greve G. Ooms R. J. Rutten H. van der Laan F. W. Jäger G. C. M. Reijnen w. Bijleveld J. Kistemaker C. de Jager E. R. Mustel Y. Ne'eman E. R. Priest H. Stiller W. Seifert O. Namba M. Kuperus Roel Hoekstra F. L. H. M. Stumpers S. Frank J. T. F. Zimmerman C. de Loore R. Gendrin J. Schrijver P. S. Mulder K. A. Pounds R. S. Young L. Houziaux O. Engvold B. J. Bok W. de Graaff 《Space Science Reviews》1983,36(4):415-432