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211.
星际探测器轨道的特征与探测目的密切相关,对目标天体两级地区进行探测显然采用的是极轨道(或接近极轨道)。对于这类卫星(或称轨道器),如果轨道半长径较大,则会因第三体报骚动国导致轨道偏心率增大,使其近星距减小到等于目标天体的赤道半径而落到该天体上,结束其运动寿命,即使目标天体不存在大气(如月球等)亦会如此。 相似文献
212.
213.
摘要: 国内外航天器姿轨控系统广泛应用基于1553B内总线的体系结构.针对国内航天器姿轨控系统内部1553B总线数据协议不统一带来的可集成性、可扩展性和通用性差的问题,本文设计了基于ECSS标准的姿轨控系统内1553B数据总线协议,从姿轨控系统内部总线数据业务需求分析出发,提出了四层结构的数据协议体系结构,重点介绍了在应用支持层和链路服务层应用ECSS标准的总线协议设计,并说明了协议的应用情况.应用该国际通用的标准协议,有助于实现国内航天器姿轨控系统内1553B总线数据协议的标准化,进而提升姿轨控系统体系结构的可集成性、可扩展性、以及星载设备(含软件)的通用化. 相似文献
214.
O. Troshichev P. Stauning K. Liou G. Reeves 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
The relationships between the magnetic disturbance onsets, aurora dynamics and particles injections at the geostationary orbit have been analyzed in detail for 25 sawtooth substorms. It is shown that inconsistency between the above signatures of the substorms onset is typical of the powerful sawtooth substorms, unlike the isolated (“classical”) magnetospheric substorms. The distinguishing feature of the aurora in case of saw-tooth substorms is permanently high level of auroral activity irrespective of the magnetic disturbance onsets and the double oval structure of the aurora display. The close relationship between the aurora behavior and the particle injections at geostationary orbit is also broken. The conclusion is made, that the classical concept of the substorm development, put forward by Akasofu (1964) for isolated substorms, is not workable in cases of the sawtooth disturbances, when the powerful solar wind energy pumping into the magnetosphere provides a permanent powerful aurora particle precipitation into the auroral zone. 相似文献
215.
Alankrita Isha Mrigakshi Daniel Matthiä Thomas Berger Günther Reitz Robert F. Wimmer-Schweingruber 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
The radiation environment in space is a major concern for human spaceflight because of the adverse effects of high levels of radiation on astronauts’ health. Therefore, it is essential to perform radiation risk assessments already during the concept studies of a manned mission. Galactic Cosmic Rays (GCR) have been identified to be one of the primary sources of radiation exposure in space. 相似文献
216.
Real-time and accurate fault detection is essential to enhance the aircraft navigation system’s reliability and safety. The existent detection methods based on analytical model draws back at simultaneously detecting gradual and sudden faults. On account of this reason, we propose an online detection solution based on non-analytical model. In this article, the navigation system fault detection model is established based on belief rule base (BRB), where the system measuring residual and its changing rate are used as the inputs of BRB model and the fault detection function as the output. To overcome the drawbacks of current parameter optimization algorithms for BRB and achieve online update, a parameter recursive estimation algorithm is presented for online BRB detection model based on expectation maximization (EM) algorithm. Furthermore, the proposed method is verified by navigation experiment. Experimental results show that the proposed method is able to effectively realize online parameter evaluation in navigation system fault detection model. The output of the detection model can track the fault state very well, and the faults can be diagnosed in real time and accurately. In addition, the detection ability, especially in the probability of false detection, is superior to offline optimization method, and thus the system reliability has great improvement. 相似文献
217.
S. Valk A. Lemaître F. Deleflie 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2009
This paper provides a hamiltonian formulation of the equations of motion of an artificial satellite or space debris orbiting the geostationary ring. This theory of order 1 has been formulated using canonical and non-singular elements for eccentricity and inclination. The analysis is based on an expansion in powers of the eccentricity and of the inclination. The theory accounts for the influence of the Earth gravity field expanded in spherical harmonics, paying a particular attention to the resonance occurring for geosynchronous objects. The luni-solar perturbations are also taken into account. We present the resonant motion and its main characteristics: equilibria, stability, fundamental frequencies and width of the resonant area by comparison with a basic analytical model. Finally, we show some results concerning the long term dynamics of a typical space debris under the influence of the gravitational field of the Earth and the luni-solar interactions. 相似文献
218.
219.
非齐次项为β^nPl(n)的常系数线性递推关系求特解方法 总被引:1,自引:1,他引:0
任传荣 《中国民航学院学报》1998,16(3):74-77
就非齐次项为βn与n的多项式Pl(n)乘积的常系数线性非齐次递推关系,给出了求特解的一般方法。 相似文献
220.
This paper presents an overview of the analysis performed on the lunar orbit and some of the possible contingencies for the European Student Moon Orbiter (ESMO). Originally scheduled for launch in 2014 –2015 as a piggyback payload, it was the only ESA planned mission to the Moon. By way of a weak stability boundary transfer, ESMO is inserted into an orbit around the Moon. Propellant use is at a premium, so the operational orbit is selected to be highly eccentric. In addition, an optimization is presented to achieve an orbit that is stable for 6 months without requiring orbit maintenance. A parameter study is undertaken to study the sensitivity of the lunar orbit insertion. A database of transfer solutions across 2014 and 2015 is used to study the relation between the robustness of weak capture and the planetary geometry at lunar arrival. A number of example recovery scenarios, where the orbit insertion maneuver partially or completely fails, are also considered. 相似文献