Small satellites for Latin America

This paper presents a summary report and the major results of a Workshop on Small Satellites for Latin America, held at the National Institute for Space Research (INPE) in São José dos Campos, Brazil, at the initiative of the Sub-Committee on Small Satellites for Developing Nations of the International Academy of Astronautics (IAA).     

地球系统科学的发展及对地球观测的影响

随着人类活动的加剧与地球本身发展周期的影响,人类面临着愈来愈大的挑战。地球系统的全球化与对地观测技术的进步等推动了地球系统科学的产生和发展。为深刻认识全球变化,制订正确的政策,多个国家建立了对地观测系统。阐述了地球系统科学的主要内容,并以美国EOS和欧盟GMES为例,论述了对地观测计划及其发展趋势。     

A low cost multimission bus for small satellites applications

This article presents the AEROSPATIALE ESPACE & DEFENSE industrial approach for the CNES PROTEUS platform. Three major targets were assigned to the PROTEUS platform. A very wide field of missions (orbits, attitude, instruments and launch vehicle compatibility) will be implemented on PROTEUS platform at a very attractive cost and within a 24 months delivery time. A cost driven system methodology has been established to produce a recurring platform at a very attractive cost. Cost reductions choices were analysed and selected on organisation, engineering, procurement, quality and industrialisation.     

近地轨道飞行器的光辐射背景环境

文章简要介绍了在可见光和红外波段深空和地球高层大气的光辐射源和辐射特性,包括辐射机制和强度、辐射的各向异性等,通过比较表明空间红外波段的背景辐射明显高出可见光波段近1个数量级;分析了在地球大气外进行对地观测时大气辉光辐射的角分布,指出了辐射的临边增亮特性。以上研究对于研制和开发新型航天器、利用太空资源以及未来的深空探测都具有实用价值。     

Queuing theory application in imaging service analysis for small Earth observation satellites

The performance of Earth observation satellites is usually analyzed by real data or system simulation, which is accurate but not systematic. Modelling satellite service systems with queueing theory and analysing the performance statistics systematically will provide a useful guide in designing satellite systems. Earth observation satellites could be regarded as a two tandem server system with a finite buffer in between, providing two-stage service: image capture and image download service. In this paper, we introduce the queueing models for different service systems: the pure image capture service system, the two-stage service system with Poisson distribution download service, the pure download service system, and the two-stage system with general download service. Formulated solutions are given and some results are shown. From this work we can see queueing theory provides a good way to analyse the performance of small earth observation satellites, which is useful for system mission analysis and optimisation in design stage.     

面向低成本微纳卫星的快速试验体系研究

文章结合微纳卫星典型特点,分析了由此带来的试验新需求;对比传统卫星试验标准和即将发布的国外微纳卫星试验标准草案,提出在充分继承传统卫星试验技术成果基础上,针对国内微纳卫星发展现状,兼顾灵活性和COTS(commercial off-the-shelf)产品可靠性保证需求,构建国内微纳卫星快速试验体系的总体思路。     

Multifunctional astronomical self-organizing system of autonomous navigation and orientation for artificial Earth satellites

We describe the methods and algorithms of a multifunctional astronomical system of the autonomous navigation and orientation for artificial Earth satellites based on the automatization of the system approach to the design and programming problems of the subject area.     

卫星编队飞行的地球扁率摄动分析

本文研究了地球扁率J2项摄动对卫星编队飞行的影响。首先，给出了编队飞行数学描述，推导了轨道根数和相对运动状态的关系式；然后，将卫星编队的受摄影响分解为整体摄动和相对摄动，分别得到了解析解，重点分析了相对摄动规律。研究结果对卫星编队的设计有一定的参考价值。     

21世纪初对地观测卫星的发展和创新模式

随着国民经济的快速发展，空间对地观测系统对资源、环境以及各行各业的规划越来越起着不可替代的作用。本文重点分析了该领域２１世纪初的发展趋势及新的应用模式，概括了适应未来应用需求的综合性、集成化发展创新思路。     

Low cost orbit transfer of inoperative satellites by a service vehicle

Tumble Orbit Transfer, which is an effective method of re-orbiting inoperative satellites is described. This is done by an independent service vehicle equipped with a long arm and a grapple mechanism on top of it. After grappling the target satellite, the service vehicle orients its axis perpendicular to the orbit velocity vector. Then a thruster is activated to give an impulse on the service vehicle, which simultaneously causes velocity change and tumbling of the combined system. Since the angular momentums of two masses are exchanged periodically, separation at a selected instance will bring each mass into different orbits, one with a higher energy and the other with a lower. Separation soon after the impulse application puts the target satellite into an elliptical orbit, and separation after a half orbital period puts it into a higher circular orbit, assuming the original orbit is circular. The amount of total impulse is exactly half of that required in a conventional method. In case the service vehicle returns to the original orbit after injecting the target into the new orbit. The required total impulse is further reduced to one-third maximum. Another important feature of this method is the ease of capturing. Because the dominant force during and after the impulse application is tension through the arm, bending rigidity in the capture mechanism is not required. Therefore, a simple grapple will be enough for this maneuver. Small fuel requirements and simple capturing make this method attractive for transferring orbiting objects, and only this will provide a method of re-orbiting inoperative satellites of arbitrary shape.     

一种卫星对地观测需求分析方法

针对卫星对地观测任务需求分析方法研究的复杂性和迫切需要,文章通过把文本化的卫星观测需求编码成数值向量的形式,提出需求之间的相似度度量方法。进而基于无监督学习的相关理论和算法,给出向量化表示的需求聚类算法。同时为了能在二维平面直观展示分析高维需求数据,在引入需求之间距离计算方法的基础上介绍了高维数据的降维算法,并且通过测试数据验证了算法的有效性和可行性。通过把繁杂的需求信息转换成高维空间向量,能大大降低分析人员对领域专业知识的依赖,提升需求分析的效率和科学性。     

GEO中高分辨率民用光学对地观测卫星发展研究

调研了国外地球静止轨道(GEO)中高分辨率民用光学对地观测卫星的发展情况,其中包括"通信-海洋-气象卫星"(COMS)、GEO-Africa和GEO-Oculus等卫星;分析了卫星的任务范围和主要功能;对卫星总体设计方案和采用的主要技术途径进行了归纳和对比。对发展GEO中高分辨率民用光学对地观测卫星需要注意的探测器选型、高稳定度姿态控制、微振动抑制、夜晚阶段的热控等相关问题进行了分析,可为中国发展同类卫星提供参考。     

高性能卫星用490N轨控发动机研究进展

阐述了卫星用第三代高性能490N轨控发动机的研究进展，主要介绍了发动机的设计概况、试验验证情况以及关键技术攻关情况。对后续研制工作提出了初步设想。     

遥感小卫星地面站的系统技术设计

针对遥感小卫星工作方式的特殊性，根据系统的总体指标，对通信线路进行分析与设计，确定了优化的地面站主要技术参数，并对信息传输的实时性和可靠性作出分析     

低轨对地观测卫星凝视成像仪探讨

文章介绍了典型空间信息获取方式及特点，阐述了低轨对地观测卫星凝视成像面临的问题及解决对策，对两种低轨对地观测卫星凝视成像仪及其应用进行了探讨。     

低轨对地观测卫星凝视成像仪探讨

文章介绍了典型空间信息获取方式及特点,阐述了低轨对地观测卫星凝视成像面临的问题及解决对策,对两种低轨对地观测卫星凝视成像仪及其应用进行了探讨。     

对地观测卫星访问区域目标时间窗口快速算法

为减少对地观测卫星访问区域目标时间窗口的计算,根据建立的卫星对区域目标的观测模型,提出了卫星观测区域目标时间窗口的大圆近似快速算法,给出了算法具体步骤。仿真算例结果表明:时间窗口起点误差小于0.5 s,时间窗口长度误差小于0.723%,计算时间减少了99.87%.     

Estimation of the soil composition by IR observation of the Earth by satellites

A number of missions are in progress for Earth resources satellites to perform soil diagnosis by observing the bare soil thermal response to the heat input from the surrounding atmosphere. Heat capacity missions (and similar missions) are accomplished by measuring the soil temperature at the times of the satellite passes over the soil site.The models which are usually adopted assume that, for atmospheric conditions periodically changing during the day, the surface temperature time dependence is a function of the soil thermal inertia alone (for a dry soil).The present author has shown elsewhere that a more appropriate, two dimensional finite element modelling of the thermal behaviour of the soil, exhibits a dependence of the surface temperature time evolution on both the thermal conductivity (k) and on the volume heat capacity (?c) (for no evaporation at the interface). At least two independent temperature measurements are necessary in order to get information about k and ?c. It is shown that, within the range of values of k and ?c of the usual soils, temperature measurements taken at two successive satellite passes may yield the necessary information on the soil thermophysical properties. Charts can be constructed which will provide information on k and ?c when two soil temperatures are measured at proper times.     

地球观测网络成像任务可调度性预测方法

为了能够快速、合理地分配成像任务,充分发挥对地观测网络的观测效能,对成像任务可调度性预测问题进行了研究,提出一种由协同任务分配组件、任务调度组件、特征提取组件以及任务可调度性预测组件所构成的组件化求解架构。在成像卫星经典调度模型的基础上,提取成像任务特征,并采用变隐含层节点的反向传播（BP）神经网络集成技术求解成像任务可调度性问题。仿真结果表明,集成BP神经网络的平均预测准确度可以达到85%以上。