空间碎片与空间环境

空间碎片起源于人类的航天活动,目前空间碎片的空间密度已经对航天器的安全造成威胁,且其数量仍在高速增长,已成为一个引人瞩目的环境问题,航天器受空间碎片撞击的事件时有发生。大空间碎片的撞击会使航天器姿态和轨道发生改变,更严重的是会导致航天器破损甚至完全解体;小空间碎片的撞击会使航天器表面性能改变,部分器件损伤或失效,使航天器丧失功能。目前地基设备只能对厘米级及更大的碎片进行观测、跟踪和编目,航天器可以根据空间碎片的轨道参数进行规避和机动飞行,以避免撞毁;小空间碎片(<1cm)数量众多,但无法进行轨道测量,只能通过天基直接探测和样品回收获得数据,数值建模和超高速撞击模拟实验是进行小空间碎片风险评估和撞击效应研究的有效方法。对小空间碎片只能采取被动防护的方法,在航天器总体设计、防护结构和材料方面着手,降低空间碎片的威胁。改善空间环境,减少空间碎片的最根本方法是对航天器采取钝化措施,减少空间碎片的产生,理论上还可以采取措施,清扫、清除或回收空间碎片。

SPACE DEBRIS AND SPACE ENVIRONMENT

The space environment which surrounds the Earth is becoming increasingly polluted with space debris. Space debris (also called as "orbital debris") includes both natural micrometeorites and man made orbital debris that is made up of objects like non functioning payloads, used rocket bodies, lens covers, separation devices, insulation, and small pieces from on orbit fragmentation. The space debris originates from human′s space activity, and in turn potentially endangers functional spacecraft, even obstructs any spacecraft in entering the space. Currently, space density of space debris is so high that spacecraft faces very high risk of impacting with orbital debris, and shielding processing against orbital debris has to be considered. Collision with orbital debris which has severely damaged or destroyed a spacecraft did happen, although only sporadically. Current technique and instruments could only measure, track and catalogue nearly all orbital debris larger than 10 cm (LEO) or 1m (GEO), and parts of medium debris (>1cm). The small debris (<1cm) couldn′t be effectually photographed and tracked, no speaking of being catalogued. Characterization of their population must thus be accomplished by sampling the debris flux at particular locations and times and using these data as a basis for estimating the characteristics of the general population. As for the large debris, direct impact with operating spacecraft must be utterly abstained. Elusion from the large debris is effective using the catalogue of space debris made by SSN (US) and SSS(Russia). As for the small debris, shielding is most effective method to protect operating spacecraft against damage by the vast majority of these predominantly small particles, including developing new materials and new designs To improve the space environment, the generation of orbital debris must be effectively controlled, and the growth rate should be gradually reduced. The infallible method, cleaning up the environment remains a technical and economic challenge.$$$$