卫星遥感产业化途径探讨

遥感卫星主要由民用遥感卫星和军用遥感卫星两大类组成, 目前民用遥感卫星主要有:气象卫星、海洋卫星、地球观测卫星、环境与灾害监测卫星等;军用遥感卫星主要有:成像侦察卫星、导弹预警卫星、军事气象及海洋环境卫星等。     

小卫星编队与反卫星卫星

反卫星卫星几乎是跟卫星同步发展起来的,俄罗斯既是最早发展卫星技术的国家,也是最早发展反卫星卫星技术的国家。上世纪90年代以后,随着小卫星的出现而发展起来了小卫星编队。小卫星编队的目的是用编队分布式概念来实现通信、侦察和导航等任务,进而用若干个小卫星虚拟一个大卫星。小卫星编队和反卫星卫星产生于不同时代和不同目的,本来是不相干的问题,却出现了巧合。笔者认为,反卫星卫星是小卫星编队的一种特殊应用,小卫星编队的关键技术是反卫星卫星技术的基础,可以说,掌握小卫星编队技术的国家,就具备了反卫星卫星的能力。     

中继卫星支持航天器实时精密定轨技术研究

通过分析美国跟踪与数据中继卫星系统卫星增强服务,结合我国数据中继卫星系统和北斗卫星导航系统发展现状,总结得到对我国发展数据中继卫星系统卫星增强服务,以实现低轨道航天器实时精密定轨的几点启示:加快建设北斗卫星导航系统全球增强系统;通过冗余提高北斗卫星导航系统全球增强系统可靠性;增加我国数据中继卫星支持广播的能力;建立我国数据中继卫星系统卫星增强服务标准;增加多系统联合定位技术支持;与北斗卫星导航系统D2导航电文配合使用;进行数据中继卫星系统卫星增强服务试验以积累技术经验。     

美国近几年使用的侦察卫星

在过去的5年半期间,美国防部向地球轨道发射了大量的军用卫星。其中有光学成像卫星、雷达成像卫星、海洋监视卫星、信号情报收集卫星、早期预警卫星,通信卫星、气象卫星、导航卫星等,本文仅就前三类卫星作一介绍。     

卫星应用产业的生力军——中国东方红卫星股份有限公司

中国东方红卫星股份有限公司（简称“中国卫星”）是中国航天科技集团公司所属中国空间技术研究院的上市公司,是专业从事小卫星及微小卫星研制、卫星地面应用系统级设备制造和卫星运营服务的航天高新技术企业。中国卫星在卫星地面应用系统及设备制造方面,拥有地面站系统集成、卫星导航、卫星通信、卫星遥感、信息传输与图像处理五大领域多类产品;在卫星运营服务方面,具备提供广播电视高清信号传输、移动位置服务、数据采集等多项运营服务能力。     

跟踪与数据中继卫星控制系统技术

综述了跟踪与数据中继卫星的控制系统技术。文章介绍了美国第一代中继卫星TDRS-A～G、美国第二代中继卫星TDRS-H～J、欧洲试验中继卫星ARTEMIS、日本的试验卫星ETS-VI、试验中继卫星COMETS以及实用中继卫星DRTS等卫星的特点及关键控制技术,同时描述了部分中继卫星的控制方法,对我国中继卫星控制系统方案的确定具有一定的借鉴意义。     

“海洋”一号D卫星发射圆满成功 打造中国首个海洋民用卫星星座

正2020年6月11日,"海洋"一号D卫星搭乘"长征"二号C运载火箭,由太原卫星发射中心成功发射。随后,卫星太阳翼顺利展开,卫星在轨运行稳定,状态良好,标志着卫星发射取得圆满成功。"海洋"一号D卫星是我国海洋水色系列卫星的第4颗卫星,属于我国民用空间基础设施规划海洋业务卫星。卫星由中国空间技术研究院航天东方红卫星有限公司抓总研制。卫星采用中国空间技术研究院航天东方红卫星有限公司自主研发的CAST2000小卫星平台,设计寿命5年。卫星采用太阳同步轨道,星上配置5个载荷,     

卫星隐身概念研究

人类对卫星的依赖日益增加,而空间军事化的步伐正在加快,卫星的安全和生存能力越来越受到重视.根据卫星暴露性、脆弱性的特点,提出卫星隐身的概念;分析在轨卫星面临卫星探测网探测、跟踪、侦察和监视的威胁,阐述了国外卫星隐身技术的发展,分析卫星隐身的特点和技术途径设想,梳理卫星隐身的关键技术;最后指出卫星隐身是势在必行的趋势.     

日本的几种卫星

技术试验卫星I——“菊花”科学卫星5号——“极光”科学卫星6号——“磁层”试验卫星4号——“淡青4号”科学卫星4号——“天鹅”科学卫星7号——“火鸟”科学卫星8号——“天马”科学卫星9号——“太空”彗星探测器——“先驱”日本的几种卫星     

美国成像侦察卫星的发展

美国从20世纪60年代开始发射照像侦察卫星,锁眼(Keyhole)系列卫星和长曲棍球卫星是其中重要的代表。这两种卫星可分为3类:1)胶片返回式照像侦察卫星;2)光电传输式照像侦察卫星;3)雷达成像侦察卫星。文章主要介绍锁眼系列卫星和长曲棍球卫星的发展、所用遥感器性能及成像能力等。     

Mathematical models of high temperature flow in gas ducts of rocket engines

Results are given on certain dynamic properties of a high temperature and pressure gas flow. The investigation concerns the effect of sonic processes on the transfer of external signals by the flow and of the gas nonidealities on the properties of a linear and a nonlinear mathematical model of the jet nozzle. The investigation was conducted by the method of small parameters for differential equations of the dynamics of the gas flow, with the help of invariants of these equations, and estimates of solutions with arbitrary signals of a specific class. The results lead to estimates of errors due to usual simplifications of gas flow models such as linearization of jet nozzle equations and neglect of sonic processes. The errors of the latter kind are shown to depend on the Mach number and smoothness of signals. Accurate and approximate models of nozzle flow are obtained useful for controllability analysis of rocket engines. Some computation examples are given.     

The Use of Quaternions in the Optimal Control Problems of Motion of the Center of Mass of a Spacecraft in a Newtonian Gravitational Field: I

The problem of optimal control is considered for the motion of the center of mass of a spacecraft in a central Newtonian gravitational field. For solving the problem, two variants of the equations of motion for the spacecraft center of mass are used, written in rotating coordinate systems. Both the variants have a quaternion variable among the phase variables. In the first variant this variable characterizes the orientation of an instantaneous orbit of the spacecraft and (simultaneously) the spacecraft location in this orbit, while in the second variant only the instantaneous orbit orientation is specified by it. The suggested equations are convenient in the respect that they allow the general three-dimensional problem of optimal control by the motion of the spacecraft center of mass to be considered as a composition of two interrelated problems. In the first variant these problems are (1) the problem of control of the shape and size of the spacecraft orbit and (2) the problem of control of the orientation of a spacecraft orbit and the spacecraft location in this orbit. The second variant treats (1) the problem of control of the shape and size of the spacecraft orbit and the orbit location of the spacecraft and (2) the problem of control of the orientation of the spacecraft orbit. The use of quaternion variables makes this consideration most efficient. The problem of optimal control is solved on the basis of the maximum principle. Several first integrals of the systems of equations of the boundary value problems of the maximum principle are found. Transformations are suggested that reduce the dimensions of the systems of differential equations of boundary value problems (without complicating them). Geometrical interpretations are given to the transformations and first integrals. The relation of the vectorial first integral of one of the derived systems of equations (which is an analog of the well-known vectorial first integral of the studied problem of optimal control) with the found quaternion first integral is considered. In this paper, which is the first part of the work, we consider the models of motion of the spacecraft center of mass that employ quaternion variables. The problem of optimal control by the motion of the spacecraft center of mass is investigated on the basis of the first variant of equations of motion. An example of a numerical solution of the problem is given.     

Capabilities to Control the Throw-Weight of Ballistic Missiles by the Mobile Radar Data

The methods of estimating the throw-weight of ballistic missiles are analyzed on the basis of radar observations of different phases of BM trajectory from the instant of launch to the instant of impact of detachable elements. Approximate estimations of the accuracy of resulting estimations of mass, which are achieved by modern radars obtaining the data from three main phases of the BM trajectory, are given.     

Analysis of the Accuracy of Ballistic Descent from a Circular Circumterrestrial Orbit

The problem of the transportation of the results of experiments and observations to Earth every so often appears in space research. Its simplest and low-cost solution is the employment of a small ballistic reentry spacecraft. Such a spacecraft has no system of control of the descent trajectory in the atmosphere. This can result in a large spread of landing points, which make it difficult to search for the spacecraft and very often a safe landing. In this work, a choice of a compromise scheme of the flight is considered, which includes the optimum braking maneuver, adequate conditions of the entry into the atmosphere with limited heating and overload, and also the possibility of landing within the limits of a circle with a radius of 12.5 km. The following disturbing factors were taken into account in the analysis of the accuracy of landing: the errors of the braking impulse execution, the variations of the atmosphere density and the wind, the error of the specification of the ballistic coefficient of the reentry spacecraft, and a displacement of its center of mass from the symmetry axis. It is demonstrated that the optimum maneuver assures the maximum absolute value of the reentry angle and the insensitivity of the trajectory of descent with respect to small errors of orientation of the braking engine in the plane of the orbit. It is also demonstrated that the possible error of the landing point due to the error of specification of the ballistic coefficient does not depend (in the linear approximation) upon its value and depends only upon the reentry angle and the accuracy of specification of this coefficient. A guided parachute with an aerodynamic efficiency of about two should be used at the last leg of the reentry trajectory. This will allow one to land in a prescribed range and to produce adequate conditions for the interception of the reentry spacecraft by a helicopter in order to prevent a rough landing.     

Synthesis of a combined system for precise stabilization of the Spektr-UF observatory: II

The paper presents the second part of the results of search studies for the development of a combined system of high-precision stabilization of the optical telescope for the designed Spectr-UF international observatory [1]. A new modification of the strict method of the synthesis of nonlinear discrete-continuous stabilization systems with uncertainties is described, which is based on the minimization of the guaranteed accuracy estimate calculated using vector Lyapunov functions. Using this method, the synthesis of the feedback parameters in the mode of precise inertial stabilization of the optical telescope axis is performed taking the design nonrigidity, quantization of signals over time and level, and errors of orientation meters, as well as the errors and limitation of control moments of executive engine-flywheels into account. The results of numerical experiments that demonstrate the quality of the synthesized system are presented.     

时间、空间及运动的测量原理与时间和空间的理论

本文从分析时间、空间及运动的测量机理出发建立的时间和空间理论。导出了建立在电磁信号单向传递的相对性原理基础上的时空对称的新加里略变换，并证明了麦克斯韦方程对新加里略变换的协变性。阐明了光速不变原理和洛伦兹变换的物理意义和实质。引进了两套自治的速度定义，对应两套自治的变换。讨论了超光速运动的测量机制，相对运动特征出现负值是超光速运动的特征，导出了对应超光速运动的新加里略变换和洛伦兹变换。     

Thermal fatigue in structural components of flying vehicles engines

The paper deals with the problems of deformation and damage of the materials of structural components of complex shape subjected to cyclic loading by convective thermal flows which induces in them non-uniform temperature and thermal-stress fields. A new testing technique is proposed employing the use of models of different shape and, in particular, those of wedge-shape prism type. Variation of the level of thermal stresses and temperatures, as well as of the degree of non-uniformity of temperature and stress fields, is effected by changing the models dimensions under the given thermal loading conditions. It is shown that in simultaneous testing of a great number of models of different size it is possible to obtain information sufficient for deriving the equations of the material state under complex thermo-mechanical loading in aggressive gas flows. Examples are presented of practical application of the technique proposed.     

AP粒度和包覆层对硼燃烧的影响

通过对AP和硼及其混合物进行热分析实验,研究了硼在AP分解过程中参与反应的程度;用氧弹式量热计测试含硼富燃料推进剂的爆热,分析硼在推进剂燃烧过程中的放热。结果表明,对各组分含量相同的含硼富燃料推进剂用AP包覆硼粒子和提高超细AP含量可促使硼在AP分解过程中参与反应,使AP／B(1：1)热分解的放热量增加,提高推进剂的爆热,有利于推进剂中硼的燃烧。     

Optimization of the Flight of a Spacecraft with a Solar Sail from the Earth to Mars with a Perturbation Maneuver near Venus

The trajectories of the fastest flight of a spacecraft (SC) with a solar sail from the Earth's sphere of activity to the Martian sphere of activity including the section of a perturbation maneuver near Venus are investigated. The planetary spheres of activity are assumed to be point-like; i.e., the maneuver section and the initial and final positions of the SC coincide with the corresponding positions of the planets. The initial velocity of the SC is assumed to be equal to the Earth's velocity, so that no leveling of the velocities of the SC and Mars in the final point of the flight is required. The perturbation maneuver is considered as a jump of the heliocentric velocity of the SC at the point of its contact with Venus, which does not change the magnitude of its Venus-centric velocity. The orbits of planets are assumed to be circular and coplanar; the SC trajectory lies at the plane of these orbits. The sail is planar with a specularly reflecting surface. The trajectories of optimum flights are determined as a result of solving the boundary value problem of the Pontryagin maximum principle. The families of solutions to this problem depending on the initial angular positions of Venus and Mars are constructed by the method of continuation over a parameter.     

Estimate of accuracy of determining the orientation of the star sensor system according to the experimental data

The BOKZ-M60 star sensor (Unit for Measuring Star Coordinates) is intended for determining the parameters of the orientation of the axes of the intrinsic coordinate system relative to the axes of the inertial system by observations of the regions of the stellar sky. It is convenient to characterize an error of the single determination of the orientation of the intrinsic coordinate system of the sensor by the vector of an infinitesimal turn of this system relative to its found position. Full-scale ground-based tests have shown that, for a resting sensor the root-mean-square values of the components of this vector along the axes of the intrinsic coordinate system lying in the plane of the sensor CCD matrix are less than 2″ and the component along the axis perpendicular to the matrix plane is characterized by the root-mean-square value of 15″. The joint processing of one-stage readings of several sensors installed on the same platform allows us to improve the indicated accuracy characteristics. In this paper, estimates of the accuracy of systems from BOKZ-M60 with two and four sensors performed from measurements carried out during the normal operation of these sensors on the Resurs-P satellite are given. Processing the measurements of the sensor system allowed us to increase the accuracy of determining the each of their orientations and to study random and systematic errors in these measurements.