共查询到19条相似文献,搜索用时 109 毫秒
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C型小行星主要由硅酸盐矿物和含碳有机质组成,保存了太阳系形成初期的原始物质,是认识太阳系形成初期的重要物质,对研究水和生命起源与演化具有重要科学意义。目前对小行星物质组成的认识主要基于光谱特征分析,但长期的空间风化作用会改变小行星表面物质的光谱特征,所以认识小行星的物质组成需要准确厘清空间风化对光谱的影响。随着中国小行星探测工程的推进,迫切需要深入认识C型小行星的光谱特征及对空间风化的响应规律。为此,分析了C型小行星的反射率、水和有机质吸收等光谱特征以及空间风化的影响,提出研究存在的主要问题,进而指出了该研究方向的未来发展趋势和研究重点。 相似文献
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宁强陨石的岩石学、矿物学及化学组成的研究表明,宁强陨石属于异常的CV3碳质球粒陨石,稀有气体和宇宙射线暴露年龄的测定结果与岩石学及化学组成的研究结果是一致的,宁强陨石的宇宙射线暴露年龄为42.2Ma,在CV3球粒陨石中是最高的,U/Th-4He及40K-40Ar气体保存年龄分别为4170±160Ma和4260±70Ma,这与碳质球粒陨石的气体保存年龄为4200Ma是一致的. 相似文献
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本文测定了清镇高铁群3型非平衡顽火辉石球粒陨石(EH3)的可见和近红外反射光谱,发现其反射光谱既不同于显示Ni、Fe金属光谱特征的EH4(Abee)顽火辉石球粒陨石,也不同于显示陨硫铁光谱特征的EH5型和EL6型平衡顽火辉石球粒陨石.清镇陨石独特的反射光谱特征可能是由于其铁纹石粒子表面存在光学厚度的吸积薄膜.吸积薄膜物质很可能是与铁纹石密切共生的陨硅磷镍铁矿,也可能是它与硫化矿物的混合物.在清镇陨石中,含吸积薄膜的铁纹石粒子可能具有很低的氧逸度,它们极易被大气氧化而失去原有的反射光谱特征.文中讨论了EH3、EH4、EH5和EL6型顽火辉石球粒陨石具有不同反射光谱特征的宇宙化学机理. 相似文献
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2013年2月15日,一颗小行星从距地面约2.7万千米的高空掠过地球。据美国航空航天局估计,平均每40年就有一颗小行星在地球附近掠过。同一日,一颗陨石在俄罗斯上空爆炸,导致1000余人受伤。在俄罗斯历史上,遭受这种天灾还是第一次。两起事件的发生让如何保护地球安全成为关注焦点。 相似文献
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根据各类陨石的模式化学组成或矿物组成,采用比容叠加法计算了铁陨石,EH和EL群顽辉石球粒陨石,H,L和LL群普通球粒陨石这几种主要陨石类型的Hugoniot参数,计算结果与已表的同灰型陨石的冲击波压缩数据一致。 相似文献
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太阳震荡可以在短时间内引起太阳光强度和光谱线心波长的剧烈变化,通过探测太阳光强度和光谱线心波长并记录时间,可以获得直接接收的太阳光到达时间和经天体反射的太阳光到达时间之间的时间延迟,可以利用时间延迟作为量测量提供航天器的位置信息。提出了一种基于太阳震荡时间延迟量测的自主天文导航方法;建立了基于时间延迟的隐式量测模型,并应用了IUKF方法。仿真结果表明:本文所提出的导航方法,应用在转移轨道上的位置误差和速度误差分别约为3.55 km和0.077 m/s,环绕轨道分别为1.76 km和1.57 m/s。同时也研究了3种因素对导航性能的影响。 相似文献
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由于双体小行星独特的运动形式可为行星的演化提供重要线索,因而成为小行星探测中的热点目标。基于双椭球体模型研究了双小行星系统的相对运动、平衡态及稳定性。首先基于双椭球的全二体模型建立了双星系统相对运动的动力学方程;其次利用拉格朗日方程,通过求解系统角动量和能量,建立了双星系统平衡态对应的状态约束;最后给出了通过零速度状态曲面判断双星系统平衡态稳定性的一般性方法,在此基础上分析了小行星物理参数变化对系统平衡态稳定性的影响。研究可为未来双体小行星系统探测任务中的轨道设计与控制提供重要的理论参考。 相似文献
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R. Duffard K. Kumar S. Pirrotta M. Salatti M. Kubínyi U. Derz R.M.G. Armytage S. Arloth L. Donati A. Duricic J. Flahaut S. Hempel A. Pollinger S. Poulsen 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
We propose a dual-rendezvous mission, targeting near-Earth asteroids, including sample-return. The mission, Asteroid Sampling Mission (ASM), consists of two parts: (i) flyby and remote sensing of a Q-type asteroid, and (ii) sampling of a V-type asteroid. The targeted undifferentiated Q-type are found mainly in the near-Earth space, and to this date have not been the target of a space mission. We have chosen, for our sampling target, an asteroid from the basaltic class (V-type), as asteroids in this class exhibit spectral signatures that resemble those of the well-studied Howardite–Eucrite–Diogenite (HED) meteorite suite. With this mission, we expect to answer specific questions about the links between differentiated meteorites and asteroids, as well as gain further insight into the broader issues of early Solar System (SS) evolution and the formation of terrestrial planets. To achieve the mission, we designed a spacecraft with a dry mass of less than 3 tonnes that uses electric propulsion with a solar-electric power supply of 15 kW at 1 Astronomical Unit (AU). The mission includes a series of remote sensing instruments, envisages landing of the whole spacecraft on the sampling target, and employs an innovative sampling mechanism. Launch is foreseen to occur in 2018, as the designed timetable, and the mission would last about 10 years, bringing back a 150 g subsurface sample within a small re-entry capsule. This paper is a work presented at the 2008 Summer School Alpbach,“Sample return from the Moon, asteroids and comets” organized by the Aeronautics and Space Agency of the Austrian Research Promotion Agency. It is co-sponsored by ESA and the national space authorities of its Member and Co-operating States, with the support of the International Space Science Institute and Austrospace. 相似文献
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Yue Wang Shijie Xu Mengping Zhu 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
The full dynamics of spacecraft around an asteroid, in which the spacecraft is considered as a rigid body and the gravitational orbit–attitude coupling is taken into account, is of great value and interest in the precise theories of the motion. The spectral stability of the classical relative equilibria of the full spacecraft dynamics around an asteroid is studied with the method of geometric mechanics. The stability conditions are given explicitly based on the characteristic equation of the linear system matrix. It is found that the linearized system decouples into two entirely independent subsystems, which correspond to the motions within and outside the equatorial plane of the asteroid respectively. The system parameters are divided into three groups that describe the traditional stationary orbit stability, the significance of the orbit–attitude coupling and the mass distribution of the spacecraft respectively. The spectral stability of the relative equilibria is investigated numerically with respect to the three groups of system parameters. The relations between the full spacecraft dynamics and the traditional spacecraft dynamics, as well as the effect of the orbit–attitude coupling, are assessed. We find that when the orbit–attitude coupling is strong, the mass distribution of the spacecraft dominates the stability of the relative equilibria; whereas when the orbit–attitude coupling is weak, both the mass distribution and the traditional stationary orbit stability have significant effects on the stability. We also give a criterion to determine whether the orbit–attitude coupling needs to be considered. 相似文献
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Andrea DAmbrosio Christian Circi Xiangyuan Zeng 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2019,63(11):3691-3705
Solar-photon sails can be useful for missions towards and about asteroids. Indeed, for the interplanetary transfer phase, missions to asteroids often require a large variation in inclination and solar-photon sails perform very well for such high energy missions. In the same way, solar-photon sails are also expected to perform well in the phase about the asteroid. This paper studies single and binary asteroids’ hovering regions by using a sailcraft. In order to consider a sailcraft with its own mass and shape, the mutual polyhedral method (usually used to study asteroid dynamics) is used; therefore, the sailcraft is designed by means of tetrahedra. The procedure to obtain the hovering regions about a single asteroid is presented and an accurate analysis of the control variables is carried out. Moreover, control torques required to maintain hovering orbits are obtained by considering the gravitational torques acting on the sailcraft due to the asteroid. In the end, the theory for hovering orbits is extended to binary-asteroid systems and applied to the binary system 1999 KW4. 相似文献