“Furoshiki satellite” - a large membrane structure as a novel space system

We have been studying a large membrane space structure named “Furoshiki Satellite,” as a promising candidate of a future space system for those missions requiring large area in space such as solar power generation, a large communication antenna, or a large radiator. This membrane is folded in a very small volume during launch and is deployed and controlled by a set of several satellites at its corners or using centrifugal force generated by rotating the central satellite. It is expected that such a structure will reduce the weight per area of the space structure and, if the control technology is properly applied, it can be efficiently folded during launch and easily deployed after release. This paper shows the concept of Furoshiki Satellite, its applications, and its dynamics on orbit and how to control it. A nano-satellite project on demonstrate the concept of Furoshiki Satellite will also be described briefly.     

Early commercial demonstration of space solar power using ultra-lightweight arrays

Space solar power shows great promise for future energy sources worldwide. Most central power stations operate with power capacity of 1000 MW or greater. Due to launch size limitations and specific power of current, rigid solar arrays, the largest solar arrays that have flown in space are around 50 kW. Thin-film arrays offer the promise of much higher specific power and deployment of array sizes up to several MW with current launch vehicles. An approach to early commercial applications for space solar power to distribute power to charge hand-held, mobile battery systems by wireless power transmission (WPT) from thin-film solar arrays in quasi-stationary orbits will be presented. Four key elements to this prototype will be discussed: (1) Space and near-space testing of prototype wireless power transmission by laser and microwave components including WPT space to space and WPT space to near-space HAA transmission demonstrations; (2) distributed power source for recharging hand-held batteries by wireless power transmission from MW space solar power systems; (3) use of quasi-geostationary satellites to generate electricity and distribute it to targeted areas; and (4) architecture and technology for ultra-lightweight thin-film solar arrays with specific energy exceeding 1 kW/kg. This approach would yield flight demonstration of space solar power and wireless power transmission of 1.2 MW. This prototype system will be described, and a roadmap will be presented that will lead to still higher power levels.     

The critical satellite technical issues of future pervasive broadband low-cost communication networks

Using a baseline design for a 30/20 GHz system, this paper addresses the critical technical issues of signal waveform design, projected spacecraft technology, satellite launch options and satellite cost. With DPCM (differential pulse-coded modulation) video signal encoding, 32 Mb/s user-to-user data rate per channel, 10% overhead, two orthogonal polarizations, and crosstalk loss limited to 1 dB, TFM (tamed frequency modulation—a type of QPSK) permits about 75 channels/GHz of frequency allocation, i.e. about twice the capacity possible with MSK or SFSK (types of QPSK). The BOM (beginning of mission) weight and power of a baseline 400-channel multi-beam satellite is about 1800 kg and 5000 W. Each 35 Mb/s channel can support 1–10 video channels depending on the signal processing at the ground terminals. These weight and power estimates assume hardened digital logic, composite material for a multibeam antenna structure, high-efficiency solar cells (45 W/kg), NiH₂ batteries and 10W/20 GHz power amplifiers. If more speculative late-1980s solar cell technology is assumed, then the BOM weight decreases about 10–15%. Using the Space Transportation System being developed by NASA, geosynchronous deployment options are shown as a function of communications capacity. Based on a cost model for large communication satellites, the total space segment cost of two active satellites and one spare would be about $485M. This system would have a peak capacity of 14 Gb/s or 400-35 Mb/s simultaneous one-way channels. Demonstration and/or initial system (ground plus space) costs would be significantly less. It is concluded that the above baseline satellite appears to be technically feasible in the late-1980s.     

空间环境研究的现状与展望

空间环境研究的内容包括空间环境模式研究、空间环境效应研究和空间环境实验研究。当前国外空间环境研究注重对大型软件组织多学科、多单位长期合作研究;模式研究与实验研究紧密结合;注意开发对工程适用的模式;工作重点是太阳帆板带电和低轨卫星表面带电。建议我国在今后的空间环境研究中加强联合,集中攻克急需的大型软件;加强对材料特性的实验研究;着手发射环境效应卫星;开拓空间环境研究的新领域;在空间环境效应研究中加强卫星研制单位、卫星操作部门与环境效应研究单位的合作。     

运载火箭三级无动力飞行段晃动稳定性研究

对某运载火箭三级无动力飞行段偏航通道晃动的不稳定现象进行了研究。在贮箱内推进剂沉底的条件下，采用等效弹簧．质量晃动模型，通过晃动方程的推导，证明了液体晃动只与火箭飞行中的惯性力有关，而与重力无关。由此认为偏航通道晃动不稳定是虚假的，适当修改偏航通道晃动方程形式，就可以解决偏航通道晃动不稳定问题。     

航天磁悬浮发射脉冲磁流体供能系统方案分析

针对航天发射低成本、安全可靠运输方式的需要,阐述分析了航天运载器磁悬浮发射概念及其能量供给需求。在重点研究了固体火箭燃料脉冲磁流体发电机的关键技术及发展水平后,基于俄罗斯四台“Sakhalin”脉冲磁流体发电机单元,提出和设计了用于助推发射100吨地面载荷(飞行器和磁悬浮橇体)实现4g加速度的能量供给方案,同时分析磁悬浮发射过程中三相直线电机加速和控制的特点,提出可行的逆变器功率转换系统方案。     

一箭多星发射直接入轨的卫星构型研究

针对中、高轨道一箭多星发射直接入轨的需求,基于卫星与运载火箭的接口、环境条件、包络与操作要求等约束,对卫星构型形式进行了研究。比较了一箭多星发射的几种卫星构型方案（包括中心承力筒式、板筒式、板架式和桁架式构型）,研究了星箭接口选用包带式和点式爆炸螺栓两种连接分离装置的适用性,并据此提出优选桁架式卫星构型和点式爆炸螺栓星箭接口形式,可为卫星结构特性优化和卫星平台通用化奠定基础。     

空间电磁对接的鲁棒非线性轨迹跟踪控制

基于电磁力实现空间对接控制可以避免常规小发动机所固有的推进剂消耗、羽流污染和对接冲击等问题,且性价比高,在小卫星领域应用前景广阔。空间电磁对接控制设计存在强非线性和强耦合性问题,电磁力建模具有不确定性。论文综合应用反馈线性化和鲁棒H∞控制设计方法,采用内外环控制策略,内环采用非线性状态反馈控制实现输入-输出线性化,外环采用鲁棒H∞控制实现对模型乘性不确定性的稳定控制。理论分析与仿真表明,基于内环反馈线性化和外环鲁棒H∞控制的综合设计方法能解决电磁力模型的强非线性问题,对模型不确定性具有较强鲁棒性,轨迹跟踪性能良好。     

文昌发射场通信卫星塔架电缆设计方案及测试验证

海南文昌发射场的高温、高湿、盐雾等环境问题给通信卫星塔架电缆设计提出挑战。为此，文章在借鉴西昌发射场塔架电缆设计的基础上，提出塔架电缆由A1段、A2段和B段3个电缆分支组成；继而针对文昌发射场环境特点详述了塔架电缆在设计、铺设和使用方面关键点；最后对塔架电缆进行了测试验证，给出了测试内容和注意事项。所设计的塔架电缆已在3颗通信卫星正样星上得到验证，测试流程已基本固化，并形成了相应的操作性文件。     

A space exploration strategy that promotes international and commercial participation

NASA has created a plan to implement the Flexible Path strategy, which utilizes a heavy lift launch vehicle to deliver crew and cargo to orbit. In this plan, NASA would develop much of the transportation architecture (launch vehicle, crew capsule, and in-space propulsion), leaving the other in-space elements open to commercial and international partnerships. This paper presents a space exploration strategy that reverses that philosophy, where commercial and international launch vehicles provide launch services. Utilizing a propellant depot to aggregate propellant on orbit, smaller launch vehicles are capable of delivering all of the mass necessary for space exploration. This strategy has benefits to the architecture in terms of cost, schedule, and reliability.     

Pakistan's space programme

Space research in Pakistan is conducted by the Pakistan Space and Upper Atmosphere Research Commission (Suparco). Suparco's programmes consist of the launching of sounding rockets and satellite applications, especially remote sensing and communications. Its long-term goals are to develop communications and remote sensing satellites and to launch lightweight scientific satellites in near-Earth orbits. To train its scientific staff at postgraduate level, Suparco is establishing an Aerospace Institute. The Commission is very active in international forums such as the UN COPUOS, Cospar, IAF and IUCN.     

Numerical form-finding of geotensoid tension truss for mesh reflector

The parabolic surface of most large deployable reflectors is formed by a reflective mesh attached to a cable net. This paper presents a new approach to calculate a geodesic tension truss that ensures both appropriate node positioning and uniform tension. It is based on a force density strategy coupled with geometrical constraints. Uniform tension is achieved by iterations on coefficients of force density. Nodes of net are located on the paraboloid by controlling additional forces. Several applications illustrate the method on various types of net patterns and parabolic surfaces. The accuracy of obtained net is then evaluated by calculation of the systematic surface error due to faceting. Attachment of the net to a rim structure with additional cables is also discussed.     

烃类推进剂航天动力技术进展与展望未来

为研究烃类推进剂航天动力技术在中国的后续发展和未来应用方向,对比分析煤油、甲烷和丙烷等典型烃类推进剂的物理化学性质和应用特性,简要介绍烃类推进剂航天动力在一次性运载火箭、可重复使用运载器、高性能上面级推进、无毒空间推进和吸气式推进领域的发展动态及应用状况。当前国内外航天动力系统的发展和应用情况表明,以液氧煤油发动机和液氧甲烷发动机为代表的烃类推进剂航天动力将引领未来高性能低成本航天推进系统的发展趋势,依照中国液氧/烃火箭发动机的研制进展和技术水平,以其为核心的新型动力体系在中国未来的天地往返、载人登月和深空探测等多任务适应性方面具有良好应用前景。     

Optimal satellite formation reconfiguration actuated by inter-satellite electromagnetic forces

The inter-satellite electromagnetic forces generated by the magnetic dipoles on neighboring satellites provide an attractive control actuation alternative for satellite formation flight due to the prominent advantages of no propellant consumption or plume contamination. However, the internal force nature as well as the inherent high nonlinearity and coupling of electromagnetic forces bring unique dynamic characteristics and challenges. This paper investigates the nonlinear translational dynamics, trajectory planning and control of formation reconfiguration actuated by inter-satellite electromagnetic forces. The nonlinear translational dynamic model is derived by utilizing analytical mechanics theory; and analysis on the dynamic characteristics is put forward. Optimal reconfiguration trajectories of electromagnetic force actuated formation are studied by applying optimal control theory and the Gauss pseudospectral method. Considering the high nonlinearity and uncertainty in the dynamic model, an inner-and-outer loop combined control strategy based on feedback linearization theory and adaptive terminal sliding mode control is proposed with finite-time convergence capability and good robust performance. Theoretical analysis and numerical simulation results are presented to validate the feasibility of the proposed translational model, reconfiguration trajectory optimization approach and control strategy.     

卫星进／出地影位置和时间的计算算法

首先推导出地影图锥面方程和卫星运动方程，然后经过合理的简化得到一个四次代数方程。对该四次方程进行求解，得出卫星进出本影和半影位置的近似解，再以此为初值，利用牛顿迭代法进行迭代，得到卫星进出地影位置和相对精确解。最后给出了该算法的数值算例。     

俄罗斯的空间军事能力:1992年～2001年

在过去的10年间,俄罗斯的各种军用卫星的发射率大幅度降低,甚至出现了没有照相侦察卫星在轨的特殊时期。俄罗斯是否由于财政状况,无法维持其军事空间能力呢?还是另有其他原因呢?文章列举了在1992～2001年间,俄罗斯的军用卫星发射情况,分析了其空间计划的前景。     

Power system design of ESMO

The European Student Moon Orbiter (ESMO) spacecraft is a student-built mini satellite being designed for a mission to the Moon. Designing and launching mini satellites are becoming a current trend in the space sector since they provide an economic way to perform innovative scientific experiments and in-flight demonstration of novel space technologies. The generation, storage, control, and distribution of the electrical power in a mini satellite represents unique challenges to the power engineer since the mass and volume restrictions are very stringent. Regardless of these problems, every subsystem and payload equipment must be operated within their specified voltage band whenever they required to be turned on. This paper presents the preliminary design of a lightweight, compact, and reliable power system for ESMO that can generate 720 W. Some of the key components of the EPS include ultra triple-junction (UTJ) GaAs solar cells controlled by maximum power point trackers, and high efficiency Li-ion secondary batteries recharged in parallel.     

长时间在轨上面级动力系统关键技术研究

上面级动力系统提供用于变轨所需要的动力,同时提供姿态控制、推进剂沉底、末速修正功能所需要的动力,将上面级和北斗导航卫星一起送入预定轨道。回顾了从早期的上面级动力系统选型论证到后续的关键技术攻关过程,对比研究了泵压式与挤压式动力系统的技术优势,分析了动力系统研制过程中的主要关键技术,并对关键技术的应用情况进行了总结,最后提出了长时间在轨上面级动力系统的后续发展建议。     

上面级在发射轨道的辐射外热流分析

研究发射轨道的外热流是进行火箭上面级和卫星热控设计的基础。文章给出了基于一组轨道和姿态参数的太阳矢量与地球矢量的计算方法。针对圆柱外形的上面级,分析了其发射轨道外热流的变化规律,利用该计算方法计算了太阳矢量,而太阳矢量在长时间滑行段相对固定,太阳矢量和受晒因子随发射时间而发生大幅度的变化,使得外热流工况变得非常复杂。通过对太阳定姿且绕箭体纵轴慢旋,可改善火箭上面级的飞行热环境,简化卫星和上面级的热控系统设计。     

某运载火箭三级贮箱滑行段热分析计算

为保证某火箭三级发动机二次启动的可靠性，在分析滑行段热环境的基础上，用I-DEAS TMG软件时三级贮箱内增压气体、推进剂、固壁进行气液固三相耦合热分析。建立了简化的有限元模型，并综合考虑高温喷管延伸裙、空间外热流、三级底部各部件的遮挡等因素，计算了滑行段期间不同太阳入射角工况下的温度变化。计算和分析结果表明，高温喷管的辐射是影响三级底部热环境的主要因素。该运载火箭三级各部位温度变化能满足发动机二次启动的要求。