【作者】 王若璞；

【导师】 郑勇；

【作者基本信息】 解放军信息工程大学 ， 大地测量学与测量工程， 2010， 博士

【摘要】 自从人类发射第一颗人造地球卫星至今,空间技术取得了飞速发展和巨大成就,但与此同时也造成了近地空间范围内长期存留大量的空间碎片,并且这些数量日益增长的空间碎片已经影响到了人类正常的空间活动。论文针对空间碎片环境模型的建立与应用进行了系统的研究,主要研究成果及贡献有:1)在对历史航天发射活动总结的基础上,分析了空间碎片环境的演化过程以及目前的基本情况。利用编目空间物体数据资料统计分析了空间物体在轨道长半轴、偏心率与轨道倾角等方面的分布特征,结果表明,在大倾角、近圆轨道上运行的空间目标是空间物体的主体,并且在距离地面高度2000千米以下的LEO区域、半同步轨道以及同步轨道区域有峰值分布。2)建立了空间碎片环境模型的体系结构,包括碎片来源数学模型、目前碎片环境分析与评估、未来碎片环境预测以及空间碎片减缓措施与效果评估。3)对空间碎片各种来源进行了研究,并且针对空间碎片的不同来源,参考国内外研究成果,研究分析了碎片来源数学模型,包括爆炸与碰撞引发的解体碎裂模型、固体火箭发动机的喷射物模型、NaK合金冷却剂泄漏模型、Westford铜针簇碎片模型以及微粒撞击大型物体表面溅射模型。4)研究了小尺寸解体碎片的面质比分布,在理论分析的基础上,对NASA标准解体模型中的碎片面质比分布进行了改进,使改进后的解体碎片面质比分布更加符合实际情况。5)根据气体动力学理论,对空间物体之间发生碰撞的概率进行研究,给出了碰撞概率的具体数学表达式。研究了基于空间离散化计算空间碎片密度与通量的方法,对空间物体之间的碰撞几何进行了分析。6)对空间碎片的密度分布进行了计算与分析,结果表明在距地面750～1000千米高度之间有最高的密度分布值,在1400～1500千米高度处、半同步轨道以及地球同步轨道区域有密度分布峰值,并且在低地球轨道上高纬度区域的碎片密度比低纬度区域高。7)为评定常用轨道上的空间碎片通量,在LEO区域选择了国际空间站(ISS)与欧空局的ENVISAT卫星轨道,在GEO区域选择了BEIDOU 1A卫星轨道为代表进行了碎片通量的计算与分析。结果表明,各个轨道区域上碰撞通量随着空间碎片尺寸的增大而减小且与碎片空间密度相关,ENVISAT卫星轨道上米级尺寸处碰撞通量比国际空间站轨道高出约两个数量级。8)针对未来空间碎片环境预测问题,提出了两种对未来空间活动情况的预测方法:稳态估计与任务需求估计方法。9)基于稳态估计方法,在历史空间交通量分析的基础上定义了例常业务情况,并在该情况下对可跟踪探测空间碎片的数量与空间密度的增长进行预测,结果表明,如果不采取减缓措施,则未来可跟踪碎片的总数量及空间密度近似线性增长,50年后数量将是目前水平的2～3倍。10)基于任务需求估计方法,针对未来空间交通量变化、卫星星座以及纳卫星群的部署对空间碎片环境长期演变的影响进行了研究。结果表明,空间碎片环境的长期演变对未来交通量变化敏感,特别是在没有减缓措施情况下,若未来交通量增加两倍或两倍以上,则空间碎片总数预计将以指数规律增长。另外,部署在最拥挤轨道区域的大型星座及大规模纳星群对空间碎片环境也有较大影响。11)对空间碎片的减缓措施进行了相关研究,指出在空间活动中限制操作性物体的释放、钝化以防止在轨爆炸解体、防止故意解体与碰撞事件的发生、航天器寿命后处理以限制轨道寿命等措施是空间碎片减缓的经济、可行的方法。12)对空间碎片减缓措施实施效果进行了研究。针对采取钝化与限制释放操作性碎片、航天器任务寿命后处理措施以及综合实施各种减缓措施进行了仿真计算,结果表明,实施各种减缓措施均可降低未来空间碎片总数的增长速率,但单纯采取一种措施不足以稳定未来空间碎片环境,空间物体总数量增长的趋势并不会改变。综合实施各种减缓措施基本上可以将碎片的空间密度稳定在目前的水平,能够有效防止空间碎片环境的进一步恶化。更多还原

【Abstract】 The dissertation mainly focuses on the theory and application about space debris environment model, the main works and contributions are summarized as follows:1、On the basis of historical launches analysis, evolution and current space debris environment is discussed. The distribution of semimajor axis, eccentricities and inclination of the cataloged space objects orbit is analyzed. And the result is that the majority of space objects are in the high inclination and near-circular orbits, with peak concentrations in low-Earth orbits, at altitudes below 2,000km, in the orbits of semi-synchronous about 12-hour periods, and in the geostationary ring.2、The system of space debris envrionment model is established, including debris source models, current space debris envrionment assessment, prediction of future space debris environment and effects of debris mitigation measures.3、On the basis of research of the generation process of space debris by various source terms, the breakup model, solid rocket motor firings model, NaK coolant droplets release model, West-Ford needles model and ejecta model are established and analyzed in detail.4、NASA standard breakup model turned out to have a shortcoming in the representation of the particles’area-to-mass ratio for fragments in the submillimetre regime. On the basis of theoretic analysis, this shortcoming has been corrected.5、According to the laws of kinetic gas theory, the expression of impact probability of space objects is given. Spatial density and flux of space debris based on volume discretization is discussed. And collision geometries of space debris are analyzed.6、The spatial density of space debris is calculated and analyzed. Peak concentrations in LEO regime are at altitude shells between 750km and 1000km, and near 1450km. In the super-LEO regime, peak concentrations are in the orbits of semi-synchronous ~12-hour periods, and in the geostationary ring.7、For the LEO regime two sample orbits are used to sense space debris environment: one is the orbit of the International Space Station (ISS), the other is the orbit of ESA’s ENVISAT satellite. And the flux on the orbit of BEIDOU 1A satellite is calculated and analyzed for the geostationary ring.8、Two different types of future launch traffic model are studied: the steady-state model and the mission model.9、The steady-state model is based on the assumption that the historical launch activity of the past few years is typical of future activity, with a constant, average overall launch rate. After the historical launch activities analysis, business-as-usual (BAU) forcast scenario is defined. For BAU scenario, the number and the spatial density of the cataloged objects after fifty years is calculated. A near-linear increase can be observed, and the total number is 2 to 3 times the current number. 10、The mission model is purely based on estimates of the future uses of space such as new technology, new launchers, new space architectures, and speculations of civil, military, and commercial objectives and benefits. The research based on mission model revealed that the long-term evolution of space debris environment is sensitive to variations of traffic rate. The deployment of satellite constellations and nano-satellite swarms in narrow altitude and inclination bands can strongly increase local spatial densities and collision risk levels.11、The effective debris mitigation measures in view of operational, technical, and economic feasibility versus improvements in environmental stability are as follows:·prevention of on-orbit explosions·reduction of mission-related objects·collision avoidance between trackable objects·post-mission disposal of space systems12、The effectiveness of debris mitigation measures is studied. Each mitigation measure can reduce the absolute growth of potentially hazardous objects, but a trend towards increasing growth rates is maintained, indicating that single mitigation measure is a necessary but not sufficient condition to provide a stable space debris environment for future generations.However, if full mitigation is applied, the space debris environment in LEO can reach a stable level, with no growth of total population, despite continuing space operations at present deployment rates.更多还原