基于天文高速成像的空间碎片精密测量研究

As world-wide aerospace activities rise, the space debris issue comes into global concern. The research to accurately monitor space debris is becoming more important, as to deal with the threat of space debris. Measuring and determining the orbit of space debris with single station is critical technique and is widely concerned, but requires more accurate angular measurements. For the high angular rate of space debris, a compatible technique is proposed to enhance angular precision. The technique is based on fast imaging, that celestial positioning is done within a small field-of-view. By equipping high frame-rate and high sensitivity EMCCD camera on existing satellite laser ranging (SLR) system, it is feasible to take image of space debris with background stars, enabling accurate angular measurements to 1 arcsec precision with range measurements to 1 meter precision. Predicted orbit of 3-5 day would be available for space debris, positive for stations to maintain tracking operations, ensuring further applications such as precise cataloging and collision avoidance. Orbit determination using very short-arc angular and range measurements in single station with mentioned precision would be possible. As a result, a single SLR station is able to sustainably track space debris, without the need of other networking stations. This technique is suitable for China to enhance space debris tracking capability.

随着全球航天活动的活跃，空间碎片问题逐渐引起关注。应对空间碎片威胁，空间碎片精密监测研究日益重要，空间碎片单站测定轨作为关键技术受到重视，为实现单站定轨，空间碎片测角精度还需提高。针对空间碎片运行速度快的特点，本课题提出基于天文高速成像的小视场天文定位方法，提高测角精度，且完全兼容原有系统。通过在现有的卫星激光测距(SLR)系统上装备高速高灵敏度相机，可以对空间碎片与背景恒星成像，实现精密测角，可实现1角秒级测角精度，1米级测距精度。该方法能提供高精度联合资料，可提高空间碎片定轨精度。本课题最终可提供空间碎片3-5天预报轨道，有利于观测站维持轨道精度，为精密编目、碰撞规避等进一步应用打下基础。本课题研究完成后，单个SLR测站无需组网即可持续监测空间碎片，适合中国国情，能显著提升我国的空间碎片监测能力。

本项目基于天文定位理论和高速成像设备，对人造卫星跟踪过程中的快变化现象进行成像分析。项目进行高速成像的仿真分析，主要对概念系统中的工作帧速、靶面照度等参数进行了分析，推算了概念系统在不同工作条件下的极限星等、信噪比性能。采用叠加增强的方法先确定中心物体位置，作为参照物进行图像的配准，根据恒星的相对运行方向来识别暗弱星象。进行了图形图像处理系统的搭建。在长春人卫站60cm激光测距系统上添加导星望远镜，使用中速成像设备进行了实时的图像采集与识别试验。获取了多次卫星过境的图像序列和对应的激光测距资料。项目实现了自动采集恒星位置数据的功能，用于望远镜指向偏差的修正。通过实时自动数据分析，实现了指向偏差模型的全自动采集和修正，所费时间大为减少。该方法能提供高精度联合资料，提高空间目标定轨精度，实现了单站测距资料改进轨道。对非合作目标进行观测定轨试验，轨道精度可满足激光测距所需的预报精度要求，可以维持激光测距站对空间碎片目标的独立观测。