Assessing the Risk of Orbital Debris Impact

A Space Debris Impact Risk Analysis Tool (SDIRAT) was developed and implemented to assess the orbital debris impact risk on a specified target in Earth orbit, in terms of flux, relative velocity, impact velocity, direction of the incoming particles, debris mass and diameter. Based on a deterministic approach, SDIRAT uses a realistic orbital debris population where each representative particle is identified by its rectangular coordinates (position and velocity) at a reference epoch. Using this information, some geometrical algorithms were developed and implemented to evaluate the contribution of each particle to the incoming flux. The position of the particle with respect to a specified target drives the selection criteria to reject, or select, it as a possible projectile. On the other hand, the relative velocity vector can be used to estimate the impact direction of the incoming flux. SDIRAT was conceived as a general tool for a variety of scenarios, such as low circular and elliptical orbits, up to the geosynchronous ring. This paper presents some examples of possible applications, including the computation of the incoming debris flux on SAX (low Earth orbit), SIRIO (geosynchronous orbit) and the IRIS upper stage (elliptical orbit). Other applications assess the impact risk for the Soviet Radar Ocean Reconnaissance Satellites Cosmos 1900 and Cosmos 1932.     

Continuum Model for Space Debris Evolution with Account of Collisions and Orbital Breakups

The paper discusses the mathematical modeling of long-term orbital debris evolution taking into account mutual collisions of space debris particles of different sizes. Investigations and long-term forecasts of orbital debris environment evolution in low Earth orbits are essential for future space mission hazard evaluation and for adopting rational space policies and mitigation measures. The paper introduces a new approach to space debris evolution mathematical modeling based on continuum mechanics incorporating partial differential equations. This is an alternative to the traditional approaches of celestial mechanics incorporating ordinary differential equations to model fragments evolution. The continuum approach to orbital debris evolution modeling has essential advantages for describing the evolution of a large number of particles, because it replaces the traditional tracking of space objects by modeling the evolution of their density of distribution.     

SDEEM2015空间碎片环境工程模型

文章介绍了哈尔滨工业大学空间碎片高速撞击研究中心\"十二五\"期间发布的空间碎片环境工程模型(SDEEM 2015)。该模型可实现LEO空间碎片环境描述,空间碎片撞击风险评估以及地基探测结果仿真,还可输出LEO航天器不同轨道位置处空间碎片撞击通量随撞击方位角、撞击速度及碎片尺寸的分布规律,地基探测设备探测区域内空间碎片空间密度及通量的分布情况等信息。SDEEM 2015适用轨道高度范围为200~2000 km,时间范围为1959年—2050年,所考虑的空间碎片来源包括解体碎片、Na K液滴、固体火箭发动机喷射物、溅射物和剥落物。     

Effect of Multi-wall System Composition on Survivability for Spacecraft Impacted by Orbital Debris

Long-duration spacecraft in low earth orbit such as the International Space Station (ISS) are highly susceptible to high-speed impacts by pieces of debris from past earth-orbiting missions. Among the hazards that accompany the penetration of a pressurized manned spacecraft are critical crack propagation in the module wall, crew hypoxia, and uncontrolled thrust due to air rushing out of the module wall hole. A Monte Carlo simulation tool was used to determine the effect of spacecraft wall construction on the survivability of ISS modules and crew following an orbital debris penetration. The simulation results indicate that enhanced shield wall designs (i.e., multi-wall systems with heavier inner bumpers) always lead to higher overall survivability of the station and crew due to an overwhelming decrease in likelihood of module penetration. The results of the simulations also indicate that changes in crew operations, equipment locations, and operation procedures can significantly reduce the likelihood of crew or station loss following an orbital debris penetration.     

环月探测器短弧定轨精度的仿真结果分析

以我国正在实施的探月计划嫦娥一号月球探测器飞行测控需求为背景,利用数值仿真的方法,考虑现有USB卫星测控网和中国科学院VLBI射电天文观测网分布,在观测弧段受到限制的前提下,探讨了环月探测器测轨手段和测控弧段的选择及其相应的定轨精度。     

近地热环境参数对航天器温度影响浅析

介绍了目前国际上普遍采用的近地轨道热环境参数与传统参数之间的差异。对不同轨道的两个航天器,分别按两种参数取值进行了温度计算。结果表明,与国际上目前采用数值相比,采用传统的热环境参数值会使得计算的高温工况外热流偏低,而使低温工况时外热流偏高,从而对航天器内部温度会造成1℃～2℃的偏差。     

常推力机动模型在低轨卫星定轨预报中的应用

轨道机动控制在低轨卫星在轨活动中十分常见,尤其近年来电推进技术的发展,其具备比冲高、推力稳定的特性,在低轨卫星中得到广泛应用。轨道机动控制会引起轨道参数变化,需要通过定轨手段,确定控后轨道,而常规定轨方法不考虑机动模型,需要一段时间的无轨控的测量数据进行定轨,由于短时间内无法获取足够的测量数据,尤其针对电推进器卫星,单次机动时间长,且控制频次高,无轨控测量数据更为有限,导致估计大气阻力系数误差偏大,通常不估计,预报精度相对有限,只能降低轨道控制频次,获取更多测量数据定轨,导致轨控时长增加。因此,考虑在定轨模型中加入机动模型,对推进器的推力大小和方向构建模型,并引入推力大小和方向变量,利用轨控阶段的测量数据,实现大气参数估计、推力器推力大小和方向估计,利用最小二乘法实现对机动状态下的推进器摄动模型构建与求解,获取相对可靠的轨道根数和大气参数,通过实际GNSS数据和轨道机动验证,采用机动模型的定轨精度与无轨控阶段的定轨精度基本一致,并且由于采用更长的测量数据,可以获取更为可靠的大气阻力系数,提高频繁机动情况下的低轨卫星预报精度。     

Some Technical Issues of an Optically Focused Small Space Debris Tracking and Cataloging System

Congressional language in the 1998 US Senate Armed Services Committee authorization bill directed ... the Secretary of the (United States) Air Force to undertake a design study of a system that could catalog and track debris down to one centimeter in size out to 1000kilometer in altitude. The US Air Force Research Laboratory, in conjunction with other US National Laboratories and the National Aeronautics and Space Administration (NASA) conducted a study that examined what technical systems and operations would be required to perform such a mission. This paper outlines the study process, details the findings, draws conclusions, and makes recommendations as to what would be needed to develop an optically based system capable of cataloging and tracking small debris in low Earth orbit.     

摆动扫描地球敏感器数学模型及飞行试验结果

描述了东方红三号卫星(DFH-3)控制系统设计和数学仿真中采用的摆动扫描地球敏感器IRES-01的数学模型,东方红三号卫星近三年飞行试验结果与数学仿真结果基本一致,证明数学模型是正确的。     

对地定向三轴稳定卫星的圆锥扫描地球敏感器的数学模型

本文介绍了对地定向三轴稳定卫星的圆锥扫描式地球敏感器的姿态测量原理、输出几何关系和数学模型，并以实际例子说明大角度姿态控制时必须注意敏感器输出的轴间耦合问题     

GTO卫星飞行温度预计方法与在轨验证

为了提高GTO轨道卫星温度预计的准确度,文章建立了卫星瞬态热分析模型。针对GTO特定工况,采用时段平均当量法模拟太阳翼变化规律供电时仪器间断工作热耗,并在整星热分析中应用PSCHG函数模拟贮箱推进剂相变换热以及推进系统管路温度预计方法等,准确地预计了GTO卫星在轨瞬时温度及变轨期间推进系统温度,验证结果表明：温度预计值...     

测试发射控制软件确认测试环境的实现

测试发射控制软件确认测试环境以某型号的测试发射控制软件为对象 ,采用基于功能的测试方法和确认测试技术加以实现。本文介绍了被测软件的体系结构和运行环境 ,阐述了被测软件确认测试方案的设计思想及测试环境的具体实现     

轨姿控推进系统用电磁阀性能仿真研究

轨姿控推进系统采用电磁阀控制内部流体通路的开启与断流,从而实现其重复启动和脉冲工作.在轨姿控推进系统快速稳定工作问题的研究中,电磁阀的性能对推进系统至关重要.针对轨姿控推进系统用电磁阀,基于电磁学及运动学等基本原理,建立了电磁阀动态数学模型,利用Matlab Simulink软件进行了动态仿真,得到了电磁阀动态响应特性;采用CFD软件对阀门内部流场进行数值模拟仿真,获得了精确的静态流阻特性,直观展现了电磁阀动态流场,为电磁阀的性能优化和轨姿控推进系统的性能提高提供依据.     

伽利略系统搜救服务端到端验证项目系统概念与性能分析

作为中欧合作伽利略卫星导航项目的重要组成部分,伽利略搜救服务前向链路端到端验证项目是中国区伽利略合作项目中唯一一个系统级项目。项目的主要目的是通过端到端验证项目检验伽利略搜救服务前向链路的服务性能,确认设计技术指标和对本地用户终端地面系统模拟器FLVE的性能预测。文章在此介绍了EEV系统组成和定位方法。在演示验证阶段,EEV项目组还设计了一个软件仿真平台用于在伽利略在轨测试卫星发射之前分析EEV系统性能。进行了由360个地球表面均匀分布的求救信标发射信号被全部伽利略卫星星座转发,时间跨度为15天的定位精度和覆盖范围分析。在FOA和TOA分别达到10μs和0.1Hz的情况下,FLVE定位精度为5km的覆盖范围达到半径5000km。FOA和TOA在恶劣情况下为15μs和0.2Hz的情况下,覆盖范围缩减为4000km,但还是达到了国际同类本地用户终端地面系统的先进水平。     

复杂系统仿真概念模型研究进展及方向

介绍了仿真领域里的概念模型的发展过程及研究现状，针对复杂系统仿真提出了复杂系统仿真概念模型，研究了复杂系统仿真概念模型的内涵和评价建模方法优劣的标准，探讨了关于复杂系统仿真概念模型的建模语言、描述方法、建模过程、验证方法和辅助工具五个研究方面的研究方法及方向。     

卫星对地观测技术在防灾救灾中的作用研究

充分利用各种对地观测技术,从信息化的角度支持防灾救灾行动,已被列入政府的重要工作内容。总结前一阶段的经验,从灾前、灾期、灾后的全过程系统地考虑如何充分发挥卫星对地观测技术的防灾救灾作用,是一个值得研究的问题。文章从防灾预案、灾期救援和灾后重建三个方面研究了卫星对地观测技术在防灾救灾全过程中发挥作用的技术途径。     

廊坊市新农村建设中的生态环境存在的问题及对策

和全国其他地方一样,廊坊市在大力推进社会主义新农村建设的过程中,也面临着农村生态环境恶化的困境。为了实现农业生产发展和农村生态环境保护之间的平衡,政府应当加大公共财政支出向农村地区倾斜的力度,坚持规划先行、服务跟进的原则,切实改善人居环境,强化农村生态环境保护法制的实施,把新农村建设成为生态良好的新农村。