共查询到20条相似文献,搜索用时 93 毫秒
1.
人类对太阳系形成和演化的探索从很早就开始了,特别是对彗星的考察,使人类有望揭开太阳系形成的秘密,因为从彗星上能够找到太阳系形成和演化的线索。彗星由冰、气体和尘埃构成,这些物质来自约45亿年前太阳系形成早期的原始残骸。继美国航宇局(NASA)的“星尘”彗星探测器于2004年1月成功追上怀尔德-2彗星,并拍摄照片和收集其彗尾物质后, 相似文献
2.
3.
4.
5.
2005年1月12日,举世注目的“深入撞击”彗星探测器在德尔它2火箭的托举下,从卡纳维拉尔角空军基地发射升空。这一价值3.3亿美元的彗星探测器,将在飞行4.31亿千米之后,于2005年7月4日,撞击“腾佩尔”彗星,以研究彗星内部的秘密。该项目主要负责人赫恩教授认为:“从太阳系形成至今,只有彗星的内部物质是一直没有变化的。在这之前,我们并不了解彗星内部的情况,因此我们希望通过这次‘深入撞击’来收集彗星内部的信息。”此举是人类第一个实际接触并探索彗星的空间计划。俄罗斯发射白杨导弹2004年12月24日,俄罗斯战略导弹部队从普列谢茨克航天发… 相似文献
6.
7.
8.
小行星和彗星从何而来?它们之间 是什么关系?只有通过反复的探测和研究才能破解。小行星和彗星是太阳系的成员,对它们进行探测和研究,也是解开太阳系形成和发展(其中包括地球上生命的形成和发展)之谜的重要环节。这也正 相似文献
9.
彗星是由太阳系诞生初期的物质构成的.由于它自身的温度极低并处在温度极低的宇宙空间,因此在太阳系诞生46亿年来,彗星几乎始终保持着形成初期的状况,对它进行研究将有助于人类揭开太阳系形成之谜。 相似文献
10.
欧洲航天局发射的彗星探测器“罗塞塔”已经在太空中翱翔了6年时间,它的最终使命是在2014年与一颗彗星会合,并探索太阳系形成初期的奥秘。但在此之前的漫长旅途中,“罗塞塔”也顺便走访了其他天体, 相似文献
11.
陨石、流星体与小行星及彗星的演化关系 总被引:1,自引:0,他引:1
小行星、彗星和流星体(meteoroid)都是绕太阳公转的小天体,它们只是在轨道特性和物理-化学性质方面有所不同,流星体泛指在行星际空间运行的、质量从10~(-16)克微流星体或微尘到10~8克的所有小天体,当它们闯入地球大气时与大气剧烈碰撞而产生发光的流星(meteor)现象,落到地面的流星体残余则称为陨石或陨星(meteorite)。 相似文献
12.
C F Chyba 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1995,15(3):45-48
Comets in our solar system appear to have provided a bridge between the cold, volatile-rich outer solar system, and the warm, but volatile-poor inner solar system. Excluding tidal and possible extinct radionuclide heating sources, only in the inner solar system are temperatures high enough for liquid water, and therefore life as we know it, to exist for times comparable to the age of the solar system. Comets may have been crucial for providing biogenic volatiles and perhaps organic molecules to this warm environment. It is therefore interesting from an exobiological point of view to ask if comets exist in other planetary systems. Most attempts to detect comets around other stars or in interstellar space have failed. However, there is growing spectroscopic evidence for comet-like bodies orbiting the star Beta Pictoris. 相似文献
13.
T Owen D Cruikshank C de Bergh T Geballe 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1995,16(2):41-49
There are now a large number of small bodies in the outer solar system that are known to be covered with dark material. Attempts to identify that material have been thwarted by the absence of discrete absorption features in the reflection spectra of these planetesimals. An absorption at 2.2 micrometers that appeared to be present in several objects has not been confirmed by new observations. Three absorptions in the spectrum of the unusually red planetesimal 5145 Pholus are well-established, but their identity remains a mystery. 相似文献
14.
等离子体彗星的某些相关分析 总被引:2,自引:0,他引:2
本文进行了彗星的分类统计,给出了"太刚活动"和"等离子体彗星出现频数"的统计,表示出它们之间无相关性。作了"太阳活动"与"彗星事件"的相关分析,表明其相关性是弱的;但是,"太阳风风速"与"彗星事件"的相关性较强。最后,用我国自己的资料作为一个实例,讨论了等离子体彗星的象差角及其扭折骚扰。 相似文献
15.
《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1987,7(5):121-124
The origins of the three kinds of extra-terrestrial bodies, meteorites, asteroids and comets can be traced to the origin of solar system. From a study of their properties, a generic relatinship of the form interstellar gas and dust condensing in the primitive solar nebula leading to the formation of comets, the comets getting degassed and ablated to become asteroids and the asteroids on fragmentation due to collisions becoming meteorites, is advocated here. The isotopic abundances of carbon are suggested as the key to unlock the mystery of this relationship. 相似文献
16.
《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1987,7(5):109-120
Many small bodies in the solar system, including planetary satellites, comets, and asteroids, have a surface component consisting at least in part of a very low albedo (0.06 or less) solid substance of neutral or red color in the wavelength region 0.3–2.5 μm. Laboratory spectra of organic residues from meteorites and mixtures with hydrous silicates suggest that complex mixtures of complex organic molecules (kerogens) together with aqueous alteration products of igneous minerals may be the source of the dark matter that is distributed so widely throughout the solor system. 相似文献
17.
《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1987,7(5):7-11
Solar wind particles, especially H, C, N, O, S, and P-ions, may undergo specific chemical reactions with gaseous or solid matter of comets when in the energy region of a few 10 to some eV. Each component of the solar wind, even if not chemically reactive itself, creates a multiplicity of energetic secondary particles by knock-on processes with the cometary matter. These are responsible for the majority of the so called “hot” chemical processes. Endothermic reactions with high activation energy and atom molecule interactions are possible and may add to the classical exothermic ion-molecule or radical reactions. Other sources of hot atoms or ions in comets are: cosmic rays, acceleration or pick-up processes and turbulences in comae and gas or dust tails, and photon absorption induced dissociation. The products of hot chemical reactions, short period comets experience on their orbits, add to those formed in the individual component ice or dust grains by strong fluxes of energetic particles in times prior to the accretion to a comet. 相似文献
18.
S A Liebman R A Pesce-Rodriguez C N Matthews 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1995,15(3):71-80
Hydrogen cyanide polymerizes readily to a black solid from which a yellow-brown powder can be extracted by water and further hydrolyzed to alpha-amino acids. These macromolecules could be major components of the dark matter observed on many bodies in the outer solar system, including comets and asteroids. Primitive Earth might therefore have been covered with HCN polymers through bolide bombardment or be terrestrial synthesis. Several instrumental methods were used for the separation and identification of these intriguing polymeric materials, including photoacoustic Fourier transform infrared spectroscopy, supercritical fluid extraction chromatography and pyrolysis mass spectrometry. Our integrated analytical approach revealed fragmentation patterns and chemical functionalities consistent with the presence of polymeric peptide precursors both in HCN polymers and in the Murchison meteorite. 相似文献
19.
I Mann T Mukai H Okamoto 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1995,16(2):37-40
The analysis of interplanetary dust shows that the majority of particles in out-of-ecliptic regions comes from comets and also that near solar dust, in the ecliptic regions, results most probably largely from comets. The intense radiation flux in the solar vicinity is expected to cause strong modifications in the material composition and surface structure of interplanetary dust particles and hence the analysis of near solar dust provides interesting insights into the evolution of meteoritic, especially cometary materials. Because of the lack of in-situ measurements our present knowledge concerning these processes derives from remote sensing, i.e. observations of the solar F-corona. In particular these are observations of albedo, polarization and colour temperature given in terms of average particle properties. For example the analysis of near infra-red F-corona data points to the existence of a strong component of irregularly structured silicate particles, most probably of cometary origin. The data may indicate a subsequent sublimation of different particles or different constituents of the particles. Here we compare particle properties derived from F-corona observations with model calculations of single particle properties and discuss perspectives of future analysis of cometary dust in the interplanetary cloud. 相似文献
20.
J M Greenberg C X Mendoza-Gomez 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1992,12(4):169-180
The evidence that living organisms were already extant on the earth almost 4 Gyr ago and that early bombardment by comets and asteroids created a hostile environment up to about this time has revived the question of how it was possible for prebiotic chemical evolution to have provided the necessary ingredients for life to have developed in the short intervening time. The actual bracketed available temporal space is no more than 0.5 Gyr and probably much less. Was this sufficient time for an earth-based source of the first simple organic precursor molecules to have led to the level of the prokaryotic cell? If not, then the difficulty would be resolved if the ancient earth was impregnated by organic molecular seed from outer space. Curiously, it seems that the most likely source of such seeds was the same a one of the sources of the hostile enviroment, namely the comets which bombarded the earth. With the knowledge of comets gained by the space missions it has become clear that a very large fraction of the chemical composition of comet nuclei consists of quite complex organic molecules. Furthermore it has been demonstrated that comets consist of very fluffy aggregates of interstellar dust whose chemistry derives from photoprocessing of simple ice mixtures in space. Thus, the ultimate source of organics in comets comes from the chemical evolution of interstellar dust. An important and critical justification for assuming that interstellar dust is the ultimate source of prebiotic molecular insertion on the earth is the proof that comets are extremely fluffy aggregates, which have the possibility of breaking up into finely divided fragments when the comet impacts the earth's atmosphere. In the following we will summarize the properties of interstellar dust and the chemical and morphological structure of comets indicated by the most recent interpretations of comet observations. It will be shown that the suitable condition for comets having provided abundant prebiotic molecules as well as the water in which they could have further evolved are consistent with theories of the early earth environment. 相似文献