Deorbiter CubeSat mission design

This paper presents the mission design for a CubeSat-based active debris removal approach intended for transferring sizable debris objects from low-Earth orbit to a deorbit altitude of 100 km. The mission consists of a mothership spacecraft that carries and deploys several debris-removing nanosatellites, called Deorbiter CubeSats. Each Deorbiter is designed based on the utilization of an eight-unit CubeSat form factor and commercially-available components with significant flight heritage. The mothership spacecraft delivers Deorbiter CubeSats to the vicinity of a predetermined target debris, through performing a long-range rendezvous maneuver. Through a formation flying maneuver, the mothership then performs in-situ measurements of debris shape and orbital state. Upon release from the mothership, each Deorbiter CubeSat proceeds to performing a rendezvous and attachment maneuver with a debris object. Once attached to the debris, the CubeSat performs a detumbling maneuver, by which the residual angular momentum of the CubeSat-debris system is dumped using Deorbiter’s onboard reaction wheels. After stabilizing the attitude motion of the combined Deorbiter-debris system, the CubeSat proceeds to performing a deorbiting maneuver, i.e., reducing system’s altitude so much so that the bodies disintegrate and burn up due to atmospheric drag, typically at around 100 km above the Earth surface. The attitude and orbital maneuvers that are planned for the mission are described, both for the mothership and Deorbiter CubeSat. The performance of each spacecraft during their operations is investigated, using the actual performance specifications of the onboard components. The viability of the proposed debris removal approach is discussed in light of the results.     

天基轻气炮发射清除低轨碎片方案及关键技术分析

文章分析了现有的空间碎片清除方式,并以800~1200 km低地球轨道高度上1~10 cm量级的空间碎片为清除目标,提出了天基轻气炮清除碎片的新方法。首先分析了轻气炮有效载荷在典型参数下的弹丸加速能力;之后根据将碎片降轨使其坠入大气层烧毁的设想,提出天基轻气炮共面清除碎片的方式,并选择轨道高度800 km的圆轨道作为碎片运行轨道进行可行性分析。计算表明,对半径10 cm、厚度1 cm的铝合金圆板碎片(质量211.95 g),使用初速1 km/s、重10 g的黏性弹丸可按任务方案达到清除效果。此外,计算出该参数弹丸对轨道高度800~1200 km的圆轨道上可清除的最大碎片质量为500~825 g,证明轻气炮弹丸对1~10 cm的碎片具有较强的清除能力。最后,分析了以轻气炮为有效载荷的航天器在完成清除碎片任务时的关键技术。     

改进剥层应变法测量铝合金预拉伸厚板内部残余应力分布

铝合金预拉伸板已广泛应用于航空整体结构件的制造,其内部初始残余应力引起的加工变形已严重制约新型飞机的研制和生产。测量残余应力的方法很多,但一般只能测量工件的表面和浅表层,而厚板内部残余应力测量一直是工程中的难点。文中针对铝合金预拉伸厚板的特点,提出了测量其内部残余应力的方法,并运用弹性力学理论进行了理论推导,得到了应力-应变关系矩阵。用该方法测量了7050T7451铝合金厚板内部残余应力,并对测试结果进了分析和比较。结果表明,本文提出的方法有效地解决了厚板内部残余应力测量的难题,有较高的工程应用价值。     

航天器总装多余物控制方法探讨

带有多余的航天产品存在重大的质量事故隐患。文章对航天器总装中的多余物进行了分类,从而分析多余物产生的机理有4大来源:总装工艺过程、零组件及人员带入、贮存过程、有害气体。介绍了多余物的危害,提出了系统控制多余物的思路和多余物常用检查及排除的方法。     

飞机附件的维修间隔决策

研究了飞机附件软时限的设定和管理方法,该方法可将附件的故障发生机率和运行风险控制在可接受水平,减少航空公司因机务原因的延误,提高飞机可利用率。     

现代喷气战斗机的发动机安装设计

发动机安装设计是飞机设计的一项重要工作,战斗机的发动机安装设计工作尤为重要且任务复杂.本文在收集整理大量文献资料的基础上,概述现代战斗机发动机的安装设汁,重点剖析了国外八个型号战斗机的发动机安装设计实例,比较各型战机的发动机安装设计异同,包括安装形式设计和安装节等结构部件的细节设计等.通过实例剖析和异同比较,有助于深入理解发动机安装设计的特点和规律,发展我国有自身特色的发动机安装设计解决方案.     

Active debris removal of multiple priority targets

Today’s space debris environment shows major concentrations of objects within distinct orbital regions for nearly all size regimes. The most critical region is found at orbital altitudes near 800 km with high declinations. Within this region many satellites are operated in so called sun-synchronous orbits (SSO). Among those, there are Earth observation, communication and weather satellites. Due to the orbital geometry in SSO, head-on encounters with relative velocities of about 15 km/s are most probable and would thus result in highly energetic collisions, which are often referred to as catastrophic collisions, leading to the complete fragmentation of the participating objects. So called feedback collisions can then be triggered by the newly generated fragments, thus leading to a further population increase in the affected orbital region. This effect is known as the Kessler syndrome.     

强光光学零件加工误差频谱分析与控制方法研究

本文利用功率谱密度分析磁流变抛光表面的敏感频率误差,发现走刀步距与中高频误差具有直接的关联性,通过小波算法确定其分布区域后,采用大束径的光顺抛光法对敏感频率误差进行控制,测试结果表明中高频误差得到了有效控制。本研究对强光光学零件加工误差的频谱分析、表征和控制具有指导意义。     

开放逻辑及其实现技术

定义了一个建立在一阶谓词基础上的开放的逻辑系统,它由证明演算和假设演算组成。本文在文献[1]的基础之上对假设演算进行了某些扩充,使得假设演算中所构造的删除规则集是完备的;并说明了对任一语句的可判定性。为便于机器实现,文中引入了删除推演序列的概念;并给出了如何构造删除规则的与或树以及如何生成删除推演序列的步骤。最后,讨论了开放逻辑系统的具体实现技术。     

载人航天器空气环境参数控制非定常仿真分析

为支持乘员在轨驻留,载人航天器需通过空气环境控制系统将众多设计参数和空气环境参数控制在指标范围内。文章建立了一种载人航天器空气环境非定常控制仿真分析模型,包括舱体模块、航天员模块、舱压控制模块、温湿度控制模块以及CO2净化模块。利用该模型分析了载人航天器空气环境参数随乘员代谢水平的非定常变化趋势,并评估了控制系统的工作性能。结果表明:乘员代谢水平变化对空气环境参数有显著影响,通过调节控制系统运行参数可将各空气参数控制在有效指标范围内。人区温度与O2分压、CO2分压和人区湿度有密切的影响关系,不可孤立地进行分析。为载人航天器空气环境参数控制系统的设计和流程改进提供了依据。