遥感相机通信适配器的设计与实现

卫星平台搭载与卫星星务计算机系统通信接口类型不一致的遥感相机时,星务计算机系统与遥感相机间无法进行通信,导致遥感相机不能正常工作。针对星务计算机系统与遥感相机计算机控制系统通信接口类型的不一致,设计并实现了遥感相机通信适配器。通过遥感相机通信适配器,完成遥感相机计算机控制系统和星务计算机系统间通信接口的转换,实现了二者之间的通信。在工程应用上,首次利用遥感相机通信适配器解决了星务计算机系统与遥感相机计算机控制系统通信接口类型不一致的问题,提供了解决二者之间通信接口类型不一致的新途径,为今后卫星平台搭载与卫星星务计算机系统通信接口类型不一致的遥感相机做了成功的实践。     

空间红外遥感相机制冷机微振动对MTF影响分析

空间红外遥感相机内部活动部件微振动载荷会引起相机光学元件产生刚体位移和面形变化,从而影响相机的在轨光学成像品质。文章基于某空间红外遥感相机内部扰振源的测试结果,建立了适用于微振动分析的相机精细有限元模型,经分析计算,确定了基于Zernike多项式曲面拟合和调制传递函数(MTF)分析的方法和流程;最后结合某空间红外遥感相机进行MTF影响分析,结果显示制冷机微振动对该相机MTF影响在工程可接受的范围内。     

国外几种星载光学遥感器的发展情况简介

文章介绍了国外空间对地观测的侦察相机、测绘相机以及其它星载光学遥感器的发展情况和近期态势。其中提到了它们在载体上对地观测的分辨率、光谱带宽、地面覆盖等性能指标,还介绍了相机或光学遥感器本身的性能参数。文章还对测绘相机专门提到了分类情况以及光学小卫星的发展态势,重点指出了不同光学遥感器所在卫星平台的姿态稳定性、指向和指向改变精度。     

中波红外面阵遥感相机相对辐射定标方法研究

为了促进中波红外面阵遥感相机遥感数据的应用,提出了一种在轨相对辐射定标方法。该方法根据两点定标原理,以中波红外面阵遥感图像数据为基础,利用在轨其他卫星数据获得相机入瞳处辐亮度,计算出非均匀性系数,从而实现在轨相对辐射定标。它为同类红外面阵遥感相机在轨相对辐射定标提供了一种新的思路,同时也可作为星上黑体标的一种校验手段。     

关于星载光学遥感相机信噪比指标的讨论

星载光学遥感相机信噪比是仪器的一个非常重要的性能指标,信噪比的大小对测绘高程定位精度有很大影响。文章通过计算机仿真实验定量研究了光学遥感相机信噪比与测绘卫星高程定位精度之间的关系,包括三维地物模型建立与模拟成像、特征点提取与匹配、高程值计算等。实验结果表明在计算机仿真得到的理想图像中,当图像调制传递函数值为0.15时,信噪比应大于35dB才能满足测绘高程定位精度的要求。考虑到遥感相机在轨运行时大气和真实场景的影响,光学遥感相机信噪比应大于40dB。     

返回式遥感卫星有效载荷

文章介绍了返回式遥感卫星有效载荷的分类和特点、返回式相机系统组成、返回式国土普查相机、星相机和测绘相机;重点介绍国土普查相机的设计要求、工作原理,组成及功能等设计考虑。     

自适应UKF在空间相机热平衡试验中的应用研究

光学遥感相机热平衡试验是研制遥感相机的必要手段,是准确获取相机热态特性的试验方法。根据试验条件的不同,试验往往需要数小时至数十小时不等的时间,才能使遥感相机达到稳态平衡温度。为缩短热平衡试验时间,提出了一种基于自适应无味卡尔曼滤波(AUKF)的热平衡试验温度快速预测方法,只需利用较短时间的温度采样数据,就能快速预测温度变化规律,获得稳态温度,大幅度提高了热平衡试验的效率。以某遥感相机热平衡试验中升温过程和降温过程的温度变化数据为例,预测了测温点从初始温度状态到达稳态温度状态这一过程的温度变化曲线,验证了基于自适应无味卡尔曼滤波的热平衡试验温度快速预测方法的有效性和可行性。     

一种高速低噪声信号处理电路的方案研究

文章针对中国遥感高分辨率传输型相机的发展趋势，提出了一种高速低噪声的遥感CCD相机信号处理电路的设计方案。从信号完整性理论出发，利用Cadence软件进行了仿真与验证，取得了良好的效果。     

CBERS-02B卫星HR相机遥感影像区域网平差技术

针对CBERS-02B卫星HR相机遥感影像的几何定位精度不高,不能满足有些用户的要求,提出了基于有理多项式（Rational Polynomial Coefficient,RPC）模型的区域网平差技术,并利用多幅CBERS-02B卫星HR相机遥感影像进行了区域网平差试验,结果表明该方法能有效地提高遥感影像的几何定位精度...     

国外长焦距高分辨率遥感相机桁架结构研究

桁架结构具有构型简单、拆装和运输方便等优点,被大量用于航空航天、桥梁、建筑、车辆以及船泊等领域.文章介绍和分析了国际上长焦距、高分辨率空间及地面遥感相机桁架结构设计技术;探索和总结了相机桁架结构的布局特点、设计方法和装调技术等关键问题,为我国高分辨率遥感相机的研制提供参考.     

Modelling of Ejecta as a Space Debris Source

When a micro-debris or a micrometeoroid impacts a spacecraft surface, a large number of secondary particles, called ejecta, are produced. These particles can contribute to a modification of the debris environment: either locally by the occurrence of secondary impacts on the components of complex and large space structures, or at great distance by the formation of a population of small orbital debris. This paper describes firstly, the ejecta overall production, and secondly, the lifetime and the orbital evolution of the particles. Finally the repartition of ejecta in LEO is computed. Some results describing the population as a function of size and altitude are presented.     

Lunette: A network of lunar landers for in-situ geophysical science

Over the last 3 years, a team at JPL has worked to design a new concept for a small, low cost lander applicable to a variety of in-situ lunar exploration activities. This concept, named Lunette, originated as a design which would exploit potential excess capacity of EELV launches by being compatible with the EELV Secondary Payload Adapter (ESPA). The original Lunette mission concept would have allowed up to six low cost landers to be delivered to a targeted region of the moon, with landings separated by a few km, allowing establishment of a regional network with a single, shared launch. The original concept faced limits in the extent of regional distribution of landing sites since all six landers were dependent on a single solid rocket braking motor. In the last year the Lunette team has focused on a modification of the original ESPA-based concept to a design that would allow launch of multiple individual landers (each with its own braking stage) on a single launch vehicle, where each lander would be capable of independent targeting and landing. With such an implementation, the entire lunar surface could be accessed for establishment of network nodes that could enable high priority geophysical measurements on a scale not seen since Apollo. The present paper discusses the current state of the design of the Lunette geophysical network lander, as well as describing mission design, science operations, and an innovative design solution allowing the lander to take critical data continuously, even over the lunar night, without the need for radioisotope power systems.     

磁阻尼对火星探测器降落过程的动力学效应

火星稀薄的大气使得探测器再入火星时难以获得足够的减速阻力,为此,文章提出利用磁阻尼增加阻力的概念。高速再入的探测器与火星大气剧烈摩擦产生等离子体,利用探测器上的磁偶极场将等离子体捕获,同时在火星大气中形成一个“磁泡”区域并跟随探测器。由“磁泡”束缚的等离子体与来流的中性气体发生碰撞获得动量,又通过磁场作用将动量传递给探测器,从而使探测器获得一定的减速阻力。在磁阻尼的作用下,在同样的开伞高度探测器速度可降至更低,而低速开伞又可提高阻力伞打开的可靠性。因此,磁阻尼不仅可加快降低再入速度,而且还有助于提高探测器着陆火星的安全性。     

Optimal interplanetary rendezvous combining electric sail and high thrust propulsion system

The aim of this paper is to study, from a mission analysis point of view, the performance of a hybrid propulsion concept for a two-dimensional transfer towards a planet of the Solar System. The propulsion system is obtained by combining a chemical thruster, used for the phases of Earth escape and/or target planet capture, with an electric sail, which provides a continuous thrust during the heliocentric transfer. Two possible mission scenarios are investigated: in the first case the sailcraft reaches the target planet with zero hyperbolic excess velocity, thus performing a classical rendezvous mission in a heliocentric framework. In the second mission scenario, a given final hyperbolic excess velocity relative to the planet is tolerated in order to decrease the mission flight time. The amount of final hyperbolic excess velocity is used as a simulation parameter for a tradeoff study in which the minimum flight time is related to the total velocity variation required by the chemical thruster to accomplish the mission, that is, for Earth escape and planetary capture.     

Technology considerations relevant to an exobiology surface-science approach for Europa

If Europa is to be of primary exobiological interest, namely, as a habitat for extant life, it is obvious that (a) a hydrosphere must prevail beneath the cryosphere for a long time, (b) internal energy sources must be present in a sufficient state of activity, and (c) a reasonable technical means must be available for assessing if indeed life does exist in the hypothesized hydrosphere. This discussion focuses on the last point, namely, technological issues, because the trend of the compounding evidence about Europa indicates that the first two points are likely to be true. First, we present a consideration of time-of-flight mass spectroscopy conducted in situ on the cryosphere surface of Europa during a first landed robotic mission. We assert that this is a reasonable technical means not only for exploring the composition of the cryosphere itself, but also for locating any biomolecular indicators of extant life brought to the surface through cryosphere activity. Secondly, this work also addresses practical issues inherent in any kind of instrumental interrogation of a surface whose properties are governed by radiation chemistry. This includes advocating the construction of a Europan surface simulator to familiarize instrumental system developers with the spacecraft- and instrument-scale conditions under which such an interrogation would take place on Europa. Such a simulator is mandatory in certification of the functional utility of a flight instrument.     

Solving Optimization Problems for the Flight Trajectories of a Spacecraft with a High-Thrust Jet Engine in Pulse Formulation for an Arbitrary Gravitational Field in a Vacuum

A mathematically well-posed technique is suggested to obtain first-order necessary conditions of local optimality for the problems of optimization to be solved in a pulse formulation for flight trajectories of a spacecraft with a high-thrust jet engine (HTJE) in an arbitrary gravitational field in vacuum. The technique is based on the Lagrange principle of derestriction for conditional extremum problems in a function space. It allows one to formalize an algorithm of change from the problems of optimization to a boundary-value problem for a system of ordinary differential equations in the case of any optimization problem for which the pulse formulation makes sense. In this work, such a change is made for the case of optimizing the flight trajectories of a spacecraft with a HTJE when terminal and intermediate conditions (like equalities, inequalities, and the terminal functional of minimization) are taken in a general form. As an example of the application of the suggested technique, we consider in this work, within the framework of a bounded circular three-point problem in pulse formulation, the problem of constructing the flight trajectories of a spacecraft with a HTJE through one or several libration points (including the case of going through all libration points) of the Earth–Moon system. The spacecraft is launched from a circular orbit of an Earth's artificial satellite and, upon passing through a point (or points) of libration, returns to the initial orbit. The expenditure of mass (characteristic velocity) is minimized at a restricted time of transfer.     

The development of a Russian communication satellite of small class, operating in the geostationary and high-elliptical orbits

In 1994–1995 Lavochkin Association (Russia) together with the other enterprises in accordance with technical requirements of the Russian Space agency, developed a new Russian communication satellite of a small class that will operate in both the geostationary (GSO) and high-elliptical (HEO) orbits. This satellite may be injected into operational orbits using a SOYUZ-2 launch vehicle (LV) and a FREGAT upper stage (US) from Plesetsk and Baykonur space launch sites (SLS).The main reason for creating such a satellite was to decrease the cost of the support and development of the Russian communication geostationary satellites group.Russian satellites Horizont, Express, Ekran and Gals, which operate in GSO, are the basis of the space segment for communications, radio and TV broadcasting. All of these satellites are injected into GSO by the PROTON LV. PROTON is a launch vehicle of a heavy class. The use of a middle class LV instead of a heavy class will allow to reduce considerably the launch cost. The change of a heavy class LV to a LV of middle class determined one economic reason for this project. Besides, the opportunity to launch S/C into GSO from Russian Plesetsk SLS increases the independence of Russia in the domain of space communications, despite the presence of the contract with Kazachstan about the rent of Baykonur SLS. Finally, use of small satellites with a rather small number of transponders is more effective than the use of big satellites. It will allow also to increase a satellite group (by the launch of additional satellites) precisely in accordance to the development of the ground segment.     

The development of a Russian communication satellite of small class, operating in the geostationary and high-elliptical orbits

In 1994-1995 Lavochkin Association (Russia) together with the other enterprises in accordance with technical requirements of the Russian Space agency, developed a new Russian communication satellite of a small class that will operate in both the geostationary (GSO) and high-elliptical (HEO) orbits. This satellite may be injected into operational orbits using a SOYUZ-2 launch vehicle (LV) and a FREGAT upper stage (US) from Plesetsk and Baykonur space launch sites (SLS).The main reason for creating such a satellite was to decrease the cost of the support and development of the Russian communication geostationary satellites group.Russian satellites Horizont, Express, Ekran and Gals, which operate in GSO, are the basis of the space segment for communications, radio and TV broadcasting. All of these satellites are injected into GSO by the PROTON LV. PROTON is a launch vehicle of a heavy class. The use of a middle class LV instead of a heavy class will allow to reduce considerably the launch cost. The change of a heavy class LV to a LV of middle class determined one economic reason for this project. Besides, the opportunity to launch S/C into GSO from Russian Plesetsk SLS increases the independence of Russia in the domain of space communications, despite the presence of the contract with Kazachstan about the rent of Baykonur SLS. Finally, use of small satellites with a rather small number of transponders is more effective than the use of big satellites. It will allow also to increase a satellite group (by the launch of additional satellites) precisely in accordance to the development of the ground segment.     

Modifying the atlas of low lunar orbits using inert tethers

For long enough tethers, the coupling of the attitude and orbital dynamics may show non-negligible effects in the orbital motion of a tethered satellite about a central body. In the case of fast rotating tethers the attitude remains constant, on average, up to second order effects. Besides, for a tether rotating in a plane parallel to the equatorial plane of the central body, the attitude–orbit coupling effect is formally equal to the perturbation of the Keplerian motion produced by the oblateness of the central body and, therefore, may have a stabilizing effect in the orbital dynamics. In the case of a tethered satellite in a low lunar orbit, it is demonstrated that feasible tether lengths can help in modifying the actual map of lunar frozen orbits.     

基于接触理论的一类带锁定机构的间隙铰链分析模型研究

重点研究一类在我国航天器上得到广泛应用的带有锁定机构的间隙铰链，基于接触理论建立了该类型间隙铰链的分析模型。首先，将铰链零件间的接触力假设为单向的非线性弹簧，并将铰链简化为由非线性弹簧组约束的摆；然后。将展开扭簧假设为线性力矩弹簧，得到包含间隙影响的铰链的力矩-转角关系曲线。通过仿真分析和试验验证，认为铰链的力矩转角关系曲线是分段光滑的。是铰链结构尺寸、零件间隙以及材料特性的函数。呈现出明显的非线性特征。