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191.
J.-P. Bibring P. Lamy Y. Langevin A. Soufflot M. Berthé J. Borg F. Poulet S. Mottola 《Space Science Reviews》2007,128(1-4):397-412
CIVA (Comet Infrared and Visible Analyser) is an integrated set of imaging instruments, designed to characterize the 360∘ panorama (CIVA-P) as seen from the Rosetta Lander Philae, and to study surface and subsurface samples (CIVA-M). CIVA-P is
a panoramic stereo camera, while CIVA-M is an optical microscope coupled to a near infrared microscopic hyperspectral imager.
CIVA shares a common Imaging Main Electronics (IME) with ROLIS. CIVA-P will characterize the landing site, with an angular
sampling (IFOV) of 1.1 mrad: each pixel will image a 1 mm size feature at the distance of the landing legs, and a few metres
at the local horizon. The panorama will be mapped by 6 identical miniaturized micro-cameras covering contiguous FOV, with
their optical axis 60∘ apart. Stereoscopic capability will be provided by an additional micro-camera, identical to and co-aligned with one of the
panoramic micro-camera, with its optical axis displaced by 10 cm. CIVA-M combines two ultra-compact and miniaturised microscopes,
one operating in the visible and one constituting an IR hyperspectral imaging spectrometer: they will characterize, by non-destructive
analyses, the texture, the albedo, the molecular and the mineralogical composition of each of the samples provided by the
Sample Drill and Distribution (SD2) system. For the optical microscope, the spatial sampling is 7 μm; for the IR, the spectral range (1–4 μm) and the spectral sampling (5 nm) have been chosen to allow identification of most minerals, ices and organics, on each
pixel, 40 μm in size. After being studied by CIVA, the sample could be analysed by a subsequent experiment (PTOLEMY and/or COSAC). The
process would be repeated for each sample obtained at different depths and/or locations. 相似文献
192.
J.-P. Bibring H. Rosenbauer H. Boehnhardt S. Ulamec J. Biele S. Espinasse B. Feuerbacher P. Gaudon P. Hemmerich P. Kletzkine D. Moura R. Mugnuolo G. Nietner B. Pätz R. Roll H. Scheuerle K. Szegö K. Wittmann 《Space Science Reviews》2007,128(1-4):205-220
The paper describes the Rosetta Lander named Philae and introduces its complement of scientific instruments. Philae was launched
aboard the European Space Agency Rosetta spacecraft on 02 March 2004 and is expected to land and operate on the nucleus of
67P/Churyumov-Gerasimenko at a distance of about 3 AU from the Sun. Its overall mass is ~98 kg (plus the support systems remaining
on the Orbiter), including its scientific payload of ~27 kg. It will operate autonomously, using the Rosetta Orbiter as a
communication relay to Earth. The scientific goals of its experiments focus on elemental, isotopic, molecular and mineralogical
composition of the cometary material, the characterization of physical properties of the surface and subsurface material,
the large-scale structure and the magnetic and plasma environment of the nucleus. In particular, surface and sub-surface samples
will be acquired and sequentially analyzed by a suite of instruments. Measurements will be performed primarily during descent
and along the first five days following touch-down. Philae is designed to also operate on a long time-scale, to monitor the
evolution of the nucleus properties. Philae is a very integrated project at system, science and management levels, provided
by an international consortium. The Philae experiments have the potential of providing unique scientific outcomes, complementing
by in situ ground truth the Rosetta Orbiter investigations.
Philae team members are listed in the acknowledgements 相似文献
193.
K. Issautier C. Perche S. Hoang C. Lacombe M. Maksimovic J.-L. Bougeret C. Salem 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2005,35(12):2141-2146
We present the solar wind plasma parameters obtained from the Wind spacecraft during more than nine years, encompassing almost the whole solar cycle 23. Since its launch in November 1994 Wind has frequently observed the in-ecliptic solar wind upstream of the Earth’s bow shock. The WIND/WAVES thermal noise receiver was specially designed to measure the in situ plasma thermal noise spectra, from which the electron density and temperature can be accurately determined. We present and discuss histograms of such measurements performed from 1994 to 2003. Using these large data sets, we study the density and core temperature variations with solar activity cycle and with different regimes of the solar wind. We confirm the anticorrelation of the electron density with the sunspot number, and obtain a positive correlation of the core temperature, with the sunspot number. 相似文献
194.
Thér‘se Encrenaz 《Space Science Reviews》2005,116(1-2):99-119
Measurements of the chemical composition of the giant planets provide clues of their formation and evolution processes. According
to the currently accepted nucleation model, giant planets formed from the initial accretion of an icy core and the capture
of the protosolar gas, mosly composed of hydrogen and helium. In the case of Jupiter and Saturn (the gaseous giants), this
gaseous component dominates the composition of the planet, while for Uranus and Neptune (the icy giants) it is only a small
fraction of the total mass. The measurement of elemental and isotopic ratios in the giant planets provides key diagnostics
of this model, as it implies an enrichment in heavy elements (as well as deuterium) with respect to the cosmic composition.
Neutral atmospheric constituents in the giant planets have three possible sources: (1) internal (fromthe bulk composition
of the planet), (2) photochemical (fromthe photolysis ofmethane) and(3) external (from meteoritic impacts, of local or interplanetary
origin). This paper reviews our present knowledge about the atmospheric composition in the giant planets, and their elemental
and istopic composition. Measurements concerning key parameters, like C/H, D/H or rare gases in Jupiter, are analysed in detail.
The conclusion addresses open questions and observations to be performed in the future. 相似文献
195.
This article proposes a novel stable clustering design method for hierarchical satellite network in order to increase its stability, reduce the overhead of storage and exert effective control of the delay performances based on a 5-dimensional vector model. According to the function of stability measurement and owing to the limitation of minimal average routing table length, the hierarchical satellite network is grouped into separate stable connected clusters to improve destruction resistance and reconstruction ability in the future integrated network. In each cluster, redundant communication links with little contribution to network stability and slight influences on delay variation are deleted to satisfy the requirements for stability and connectivity by means of optimal link resources, and, also, the idea of logical weight is introduced to select the optimal satellites used to communicate with neighboring cluster satellites. Finally, the feasibility and effectiveness of the proposed method are verified by comparing it with the simulated performances of other two typical hierarchical satellite networks, double layer satellite constellation(DLSC) and satellite over satellite(SoS). 相似文献
196.
应用七孔探针定量流场测试技术,在低速风洞中通过定量测试细长旋成体背风区三维空间流场,研究了零侧滑条件下细长旋成体在典型大迎角情况下(迎角为55°)背风区附体和离体涡系的空间演化规律,加深了对细长旋成体背风区不对称涡系空间结构的认识。解释了截面侧向力沿模型体轴分布为幅值递减波形的形成机制。给出了有、无头部小扰动片及小扰动片非定常摆动控制三种情况下的细长体背风区不同的多涡空间结构。细长旋成体背风区横截面的涡量和总压分布测量结果表明在模型头部固定小扰动片可以改变非对称涡的非对称特性,但不能使非对称涡变为对称涡,而在头部非定常小扰动的控制下模型背风区流动呈现对称涡的流态特征。 相似文献
197.
金属基纳米复合材料的制备技术研究 总被引:17,自引:1,他引:17
综述了复合材料家族中的新成员——金属基纳米复合材料制备技术的国内外研究现状和本课题组近期取得的研究成果,对6大类工艺方法的机理、特点、适用范围和现阶段开发程度,以及由这些制备工艺所开发出的新材料的优异的机械、物理、化学性能进行了全面分析,并综合评价了各种工艺的优缺点。在展望金属基纳米复合材料广阔的应用前景基础上,指出了其制备技术未来的发展方向。 相似文献
198.
199.
200.
在空间电推进的研发和规划中,推力的精确测量具有非常重要的意义。近年来,随着电推进复杂程度和任务难度的不断增加,对其推力性能评价技术及方法提出了更高的要求。针对该需求,介绍了当前空间电推进的推力测量方法及其工作原理、技术特点和应用案例。测力方式主要有直接测量和间接测量,其中直接测量主要包括天平式、扭转式、摆式,间接测量主要包括靶式和悬臂梁式。通过对比分析各种测力方式之间的区别和优缺点,为开发者的测力系统设计提供了相应的参考。对测力过程中的系统设计、系统标定、系统响应、系统响应的测量以及计算推力五个环节中可能出现的各种关键问题分别进行了详细阐述,并提出针对性的改进方法,同时结合空间电推进领域的发展趋势及其对推力测量的需求,为未来的研究给出了针对性的建议。 相似文献