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A/AC.105/C.1/109 V1407675.doc (English)A/AC.105/C.1/109 V1407674.doc (Chinese)
United Nations联合国
A/AC.105/C.1/109A/AC.105/C.1/109
General Assembly大 会
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14 November 201414 November 2014
Original: EnglishChinese Original: English
A/AC.105/C.1/109A/AC.105/C.1/109
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Committee on the Peaceful和平利用外层空间委员会
Uses of Outer Space科学和技术小组委员会
Scientific and Technical Subcommittee Fifty-second session第五十二届会议
Vienna, 2-13 February 20152015年2月2日至13日,维也纳
Item 7 of the provisional agenda临时议程项目7
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A/AC.105/C.1/L.341.A/AC.105/C.1/L.341。
Space debris空间碎片
National research on space debris, safety of space objects with nuclear power sources on board and problems relating to their collision with space debris各国对空间碎片、携载核动力源空间物体的安全
Note by the Secretariat及其与空间碎片碰撞问题的研究 秘书处的说明
I. Introduction一. 导言
In its resolution 69/85, the General Assembly expressed its deep concern about the fragility of the space environment and the challenges to the long-term sustainability of outer space activities, in particular the impact of space debris, which is an issue of concern to all nations.1. 大会在其第69/85号决议中深为关切空间环境的脆弱性和外层空间活动长期可持续性面临的挑战,尤其是空间碎片的影响;这个问题事关所有国家。
It considered it essential that States pay more attention to the problem of collisions of space objects, especially those with nuclear power sources, with space debris, and other aspects of space debris, and called for the continuation of national research on that question, for the development of improved technology for the monitoring of space debris and for the compilation and dissemination of data on space debris.它认为各国必须更加关注空间物体尤其是携载核动力源的空间物体与空间碎片碰撞的问题和空间碎片所涉其他方面问题;呼吁各国继续研究这个问题,开发更完善技术来监测空间碎片,汇编和传播关于空间碎片的数据。
The Assembly also considered that, to the extent possible, information thereon should be provided to the Scientific and Technical Subcommittee and agreed that international cooperation was needed to expand appropriate and affordable strategies to minimize the impact of space debris on future space missions.大会还认为应尽可能向科学和技术小组委员会提供这方面的资料;并商定需要通过国际合作推广适当且负担得起的战略,以尽量减少空间碎片对未来空间飞行任务的影响。
At its fifty-first session, the Scientific and Technical Subcommittee agreed that research on space debris should continue and that Member States should make available to all interested parties the results of that research, including information on practices that had proved effective in minimizing the creation of space debris (A/AC.105/1065, para.2. 科学和技术小组委员会第五十一届会议商定,应当继续开展空间碎片研究,各会员国应当向所有利益相关方提供研究成果,包括介绍在尽可能减少空间碎片的产生方面证明行之有效的做法(A/AC.105/1065,第103段)。
103).小组委员会还商定应当邀请会员国和在委员会享有常驻观察员地位的国际组织提交关于对空间碎片、携载核动力源空间物体的安全以及这类空间物体与空间碎片碰撞问题和落实碎片减缓准则的方式的研究报告(A/AC.105/1065,第104段),并以此为基础而在2014年7月31日的一份普通照会中发出在2014年10月20日之前提交报告的邀请,以便能够将此类资料提交小组委员会第五十二届会议。
The Subcommittee also agreed that Member States and international organizations with permanent observer status with the Committee should be invited to provide reports on research on space debris, the safety of space objects with nuclear power sources on board, problems relating to the collision of such space objects with space debris and ways in which debris mitigation guidelines were being implemented (A/AC.105/1065, para.3. 本文件由秘书处根据三个会员国即奥地利、德国和瑞士以及在委员会享有常驻观察员地位的三个非政府组织即空间研究委员会(空间研委会)、世界安全基金会和航天新一代咨询理事会提供的资料编写。
104), and on this basis an invitation was issued in a note verbale dated 31 July 2014 to provide the reports by 20 October 2014, so that the information could be made available to the Subcommittee at its fifty-second session. The present document has been prepared by the Secretariat on the basis of information received from three Member States, namely Austria, Germany and Switzerland, and from three non-governmental organizations with permanent observer status with the Committee, namely the Committee on Space Research (COSPAR), the Secure World Foundation (SWF) and the Space Generation Advisory Council (SGAC). Information provided by SGAC, which includes pictures and figures related to space debris, will be made available as a conference room paper at the fifty-second session of the Scientific and Technical Subcommittee.列有空间碎片相关图片和数字的由航天新一代咨询理事会提供的资料将作为科学和技术小组委员会第五十二届会议的会议室文件提供。
II. Replies received from Member States二. 从会员国收到的答复
Austria奥地利
[Original: English][原件:英文]
[20 October 2014][2014年10月20日]
Since 1982, the Institute for Space Research of the Austrian Academy of Sciences has operated a satellite laser ranging (SLR) station at the Lustbühel Observatory in Graz. Day and night, seven days a week, this station measures distances to more than 60 retro-reflector equipped satellites, such as geodetic satellites, global navigation satellite system (GNSS) satellites (GALILEO, GPS, GLONASS, COMPASS, etc.), Earth observation satellites, and various scientific and research satellites.自从1982年以来,奥地利科学院空间研究所在格拉茨Lustbühel天文台设有卫星激光测距台站,该台站每周七天日夜工作,对60多个配备后向反光仪的卫星的距离进行测量,这些卫星包括测地卫星、全球导航卫星系统(伽利略系统、全球定位系统、全球轨道导航卫星系统、北斗卫星导航系统等)的卫星、地球观测卫星及各种科学和研究卫星等。
The single-shot accuracy of the Graz measurements is about 2 to 3 mm; distance differences down to 0.2 mm can be distinguished.格拉茨单点测量的准确度约为2到3毫米;可以判别的距离差一直到0.2毫米。
With these results, the Graz SLR station is considered one of the most accurate in the world.由于取得了这些成果,格拉茨卫星激光测距台站被视为世界上最为准确的台站之一。
In 2012 the Graz laser station started to test laser ranging of space debris objects.2012年,格拉茨激光台站着手测试空间碎片物体的激光测距。
New specialized single-photon detectors were developed, and the laser ranging software for space debris tracking was adapted.开发了新型专业化单一光子探测器,并且因应开发了有关空间碎片追踪的激光测距软件。
For the first time photons diffusely reflected by space debris objects were measured to determine the distance to those objects.首次对由空间碎片物体漫光反射的光子进行了测量,以便确定与这些物体之间的距离。
Although the accuracy of the measurements is not in the millimetre range, given that the selected debris objects are one to a few metres in size, this approach does allow for significantly better orbit determination.虽然测量的准确度不在毫米的幅度内,但由于若干碎片物体的面积在一至数米之间,这种做法仍然大大改进了对轨道的确定。
Additional improvements to orbit determination are possible if other SLR stations are able to detect the diffusely reflected Graz photons.如果德国航天中心其他台站能够检测到漫光反射的格拉茨的光子,则有可能进一步改进对轨道的确定。
In 2012 the first such experiment was successful: photons emitted in Graz were diffusely reflected by the bodies of satellites and detected at the Zimmerwald SLR station in Switzerland, which for this purpose had been synchronized with the Graz station.2012年,第一次这类实验取得了成功:格拉茨发射的光子由一颗卫星的星体漫光反射,并且在德国航天中心瑞士齐美尔瓦尔德台站检测到了这颗卫星,已经为此目的对该台站加以调试以便同格拉茨的台站保持同步。
This method can be extended without problems to several other receive-only stations.这一方法能够推广至其他几个只受站,而不会造成任何问题。
Since 2013 the Graz laser station has been involved in the space situational awareness programme of the European Space Agency.自从2013年以来,格拉茨激光台站参与了欧洲空间局的空间态势认知方案。
In the coming years cooperation will be increased at the European and international levels.今后几年将在欧洲和国际层面上加强合作。
Germany德国
[Original: English][原件:英文]
[27 October 2014][2014年10月27日]
In Germany, research activities on issues related to space debris are being carried out in all relevant fields, such as space debris environment modelling, observation of space debris, studies of the effects of hypervelocity impact on spacecraft, and protection of space systems from impact of micro-meteoroids and space debris.在德国,有关空间碎片问题的研究活动正在所有相关领域展开,例如空间碎片环境建模、空间碎片观测、有关超高速撞击对航天器影响的研究以及保护航天系统以免遭到微型流星体和空间碎片的撞击。
German experts actively participate in relevant international forums in the field of space debris research, inter alia in the Inter-Agency Space Debris Coordination Committee (IADC) and in international standardization activities in the field of space debris mitigation.德国专家积极参加了空间碎片研究领域的相关国际论坛,尤其是机构间空间碎片协调委员会(空间碎片协委会)和空间碎片缓减领域的国际标准化活动。
For space projects sponsored by the Space Administration of the German Aerospace Centre (DLR), space debris mitigation requirements are a mandatory part of the product assurance and safety requirements for DLR space projects.对于由德国航天中心空间管理机构主办的空间项目,空间碎片缓减要求是德国航天中心空间项目产品保证和安全要求的一个规定部分。
These requirements ensure the implementation of internationally recognized mitigation measures, including those identified in the Space Debris Mitigation Guidelines of IADC and those of the Committee on the Peaceful Uses of Outer Space.这些要求确保了国际公认缓减措施的执行,包括空间碎片协委会《空间碎片缓减准则》与和平利用外层空间委员会所确定的措施。
The general objectives are to limit the creation of new space debris and thus to limit the risk to current and future space missions and the risk to human life.其总体目标是,限制制造新的空间碎片,并从而限制对现有和今后空间飞行任务以及对人的生命所造成的危害。
The measures to be adopted in order to achieve these objectives include the conduct of a formal space debris mitigation assessment and specific design measures, inter alia to prevent the release of mission-related objects, fragmentations, malfunctioning and on-orbit collisions, together with measures pertaining to passivation, end-of-life disposal and re-entry safety.为实现这些目标而应当采取的措施包括进行正式的空间碎片缓减评估并执行具体的设计措施,除其他外是为了防止与飞行任务有关的物体的释放、这些物体的碎片化、丧失功能及其在轨碰撞,同时还将采取与钝化处理、生命终了的处置以及再进入安全有关的措施。
Development work has been carried out at the German Space Operations Centre to enhance the collision avoidance system used for German civil satellite missions, with various tools supporting the evaluation and analysis of critical conjunctions.在德国空间作业中心开展了开发工作以加强德国民用卫星飞行任务所用避免碰撞系统,该系统拥有支持评价和分析关键交会的各种工具。
At the end of 2013, the thresholds for the satellite constellation TerraSAR-X/Tandem-X were increased, which resulted in up to 10 warnings per day.2013年年底,提高了卫星星座TerraSAR-X/Tandem-X的门槛,从而每天至多发出10次警告。
Since August 2013, 189 critical events have been analysed for those two satellites and four collision avoidance manoeuvres have been executed.自从2013年8月以来,针对这两颗卫星分析了189个关键事件,并且执行了四次避免碰撞的机动。
An optical space debris observation station has been installed for scientific purposes by the DLR Institute of Technical Physics.德国航天中心技术物理学研究所为科学目的安装了光学空间碎片观测站。
The station is equipped with a 17 inch Dall-Kirkham telescope and various high-end camera systems.该台站配备了17寸的达尔-奇克汉卡望远镜和各种高端照相机系统。
Since 2013, various objects in low-Earth orbit down to 0.1 m in size can be passively monitored using optical means.自从2013年以来,使用光学手段即可被动监测小至面积为0.1米的低地轨道上的各种物体。
Image analysis of optically detected tracks, especially of uncatalogued objects, makes it possible to deduce initial orbits for precise tracking.对于可光学检测轨特别是对编入目录的物体的图像分析,使得有可能为开展精确追踪而推演出初始物体。
In continuous tracking mode, a closed loop accuracy of 2 inches is reached.不中断追踪方式达到了闭合环路为2寸的准确度。
A laser system for time-of-flight laser ranging is currently being installed.目前正在安装用于飞行时间激光测距的激光系统。
In combination with passive optical tracking this system will allow for three-dimensional tracking of orbital objects during station passage to an accuracy of a few metres.该系统结合被动式光学追踪即可在台站争取达到准确度为几米的过程中将能展开对光学物体的三维追踪。
Efforts are under way to develop a network of optical stations set up by the German Space Operations Centre in close cooperation with the Astronomical Institute of the University of Bern, Switzerland.正在努力开发由德国空间作业中心与瑞士伯尔尼大学天文学研究所密切合作而设立的光学台站联络网,该联络网计划用于持续监测地球静止轨道圈,其望远镜将使用远程控制机器人的手段操作。
It is intended for continuous monitoring of the geostationary ring, and its telescopes are operated telerobotically.所捕捉的数据将得以能够追踪和预测大于约50厘米的静地物体的轨道。
The data captured will make it possible to track and predict the orbit of geostationary objects larger than approximately 50 cm. The Sutherland Observatory in South Africa has been chosen as the location for the first telescope, to be set up in 2015.已经选定南非萨瑟兰观测站作为拟在2015年设立的第一台望远镜的地点。
A first test campaign has been successful, and the results were even better than expected.首次测试活动取得成功,结果甚至超过预期。
The objective of another planned project is to establish a European node of the Falcon Telescope Network.另一项计划中项目的目标是,建立猎鹰望远镜网络欧洲节点。
It should provide academia with opportunities to participate in meaningful, hands-on and authentic science experiments.它应该让学术界有各种机会参与意义重大的实地和实际科学实验。
This should encourage students to engage in science through a variety of projects and initiatives utilizing the unique resources available within the Network and conduct space situational awareness (SSA) research and improve SSA catalogues.这应当鼓励学生利用在该网络内部所可使用的独一资源而通过各种项目和举措参与科学工作,开展空间态势认知研究并改进空间态势认知目录。
The Falcon Telescope Network, a global network of small aperture telescopes, has been developed by the Center for Space Situational Awareness Research in the Department of Physics at the United States Air Force Academy in collaboration with educational partners.猎鹰望远镜网络是一个由小型孔径望远镜组成的全球网络,该网络由美国空军学院物理系空间态势认知研究中心与教育合作伙伴协作开发。
It is shared with university partners within the United States of America and internationally for the purpose of undergraduate space situational awareness and astronomy research education and community science, technology, engineering, and mathematics outreach.与美利坚合众国内部各大学合作伙伴共享该网络并且在国际上予以共享,目的是开展大学本科生空间态势认知和天文学研究教育以及社区科学、技术、工程和数学推介活动。
In order to develop an autonomous space surveillance capability, a country must have the basic capability of utilizing sensor data, for instance to establish a space object catalogue.为了开发自主空间侦察能力,一国必须具备利用感应器数据等建立空间物体目录的基本能力。
As a first step a project is being prepared to develop and implement key technologies for cataloguing space debris.作为该项工作的第一个步骤,正在准备开发和落实编制空间碎片目录的关键技术。
A sensor simulator will be used that simulates measurement data.将利用感应模拟器模拟测量数据。
These data will allow further development of key functionalities such as object correlation, orbit determination and implementation of an object database.这些数据将能有助于进一步开发物体关联性、轨道确定及物体数据库落实之类关键功能。
Complementary methods for orbit determination and propagation are being investigated so as to have fast and accurate methods available within the process chain of a simulated space surveillance system.正在调查关于轨道确定和扩展的补充方法,以便形成在被模拟空间侦察系统流程链范围内所可利用的快速准确的方法。
Research is continuing at the Fraunhofer Institute for High-Speed Dynamics to improve the experimental characterization of a new light gas gun facility.弗朗霍夫高速动力学研究所正在继续展开研究,以便改进新型轻汽枪装置的实验特性。
The facility is capable of accelerating particles in the size range of 100 µm to 2 mm to hypervelocity.该装置能够把体积在100微米到2毫米幅度内的粒子加速至超高速度。
The purpose of this facility is to reach higher-impact velocities as compared to standard light gas gun facilities, and at the same time reduce facility wear.该装置的目的是,使得撞击速度高于标准轻气枪装置,同时又减少该装置的磨损。
This will result in improved performance with regard to laboratory-scale experimental impact testing of the survivability of spacecraft components in a space debris environment.这将导致在空间碎片环境中就航天器零部件存活性所作的实验室规模实验撞击测试性能的改进。
As space objects enter denser regions of the atmosphere, friction with the Earth’s atmosphere generates heat owing to the high velocity of the orbiting space object.在空间物体进入大气层较稠密区域时,由于在轨道上运行的空间物体速度很快,与地球大气层之间的摩擦产生了热量。
The thermal energy can melt or vaporize the entire space object or parts of it.热能可以溶化或气化整个或部分空间物体。
In many cases the space object burns up completely during the atmospheric re-entry, but parts of it can also survive the re-entry process and hit the ground.在许多情况下,空间物体在再进入大气层期间完全烧毁,但这些物体的一部分也可能在再进入过程中存活下来并坠落地面。
In order to better understand the process during the fragmentation of a space object and to enable analysts to pre-estimate the risk for people and property on the ground, a new project is under preparation to develop validation methods.为了更好理解空间物体碎片化进程,并使得分析人员能够预先估计对地面上人员和财产所构成的威胁,正在准备一项开发校准方法的新项目。
The project will make it possible to analyse the atmospheric re-entry and the fragmentation process associated with it, and to evaluate the risk for inhabited areas with regard to surviving parts.该项目将使对再入大气层及相关碎片化进程展开分析成为可能,并且能够评价幸存部分对人居地区所造成的威胁。
Furthermore, an ongoing project at Technische Universität Braunschweig is investigating the effects of active deorbiting of spacecraft at their end of life in accordance with the Space Debris Mitigation Guidelines of the Committee on the Peaceful Uses of Outer Space, and the effects of active debris on the long-term evolution of future space debris.而且,布伦瑞克技术大学的一项进行中项目正在根据和平利用外层空间委员会《空间碎片缓减准则》而对航天器寿命终了阶段使其主动脱离轨道的影响以及活性碎片对未来空间碎片长期演化的影响展开调查。
In this context the criticality of high-risk objects with respect to their effects on the environment in the case of a collision is analysed.在此背景下,将分析高风险物体在发生碰撞时对环境的关键影响。
This approach tries to capture the effects of the collision-cascading process more accurately.这一做法试图更为准确地弄清碰撞级联进程所产生的影响。
In another activity, different disposal strategies for medium-Earth orbit constellation objects are being analysed.在另一项活动中,正在分析针对中地轨道星座物体的不同处置战略。
Of special interest is the long-term risk of collision between disposed-of constellation spacecraft and other constellation and non-constellation objects.特别有意思的是已处置星座航天器及其他星座和非星座物体发生碰撞的长期风险。
Switzerland瑞士
[Original: English][原件:英文]
[20 October 2014][2014年10月20日]
The Astronomical Institute of the University of Bern (AIUB) continues its research efforts to better understand the near-Earth space debris environment.伯尔尼大学天文学研究所继续其加深了解近地空间碎片环境的研究工作。
AIUB uses its 1-metre ZIMLAT telescope, a small robotic telescope named ZimSMART and the new ZimSpace telescope, all located at the Swiss Optical Ground Station and Geodynamics Observatory Zimmerwald near Bern to discover and physically characterize small-size debris.伯尔尼大学天文学研究所为此使用了1米长的ZIMLAT望远镜、称作ZimSMART的小型程控望远镜和新型ZimSpace望远镜,所有这些均设在伯尔尼附近的瑞士光学地面台站和齐美尔瓦尔德地球动力学观测站,目的是发现小型碎片并确定其物理特性。
A major result of this research has been the creation of a unique catalogue of high area-to-mass ratio debris in geostationary and highly elliptical orbits.该研究的一项重大成果是,创设了地球同步转移轨道和高椭圆轨道面积与质量高比碎片独一目录。
The catalogue has been built up and is maintained in collaboration with the European Space Agency and the Keldysh Institute of Applied Mathematics in Moscow.该目录已经逐步充实,与欧洲空间局和莫斯科克尔德什应用数学研究所协作维持。
The latter is operating the International Scientific Optical Network (ISON) with which AIUB has, for many years, shared observation data in the context of a scientific collaboration endeavour.后者负责国际科学光学网的运行,伯尔尼大学天文学研究所与该科学光学网多年合作,共享在科学协作工作上的观测数据。
ISON is cooperating with the Basic Space Science Initiative of the Office for Outer Space Affairs.国际科学光学网正在与外层空间事务厅基础空间科学举措展开合作。
Recent studies by AIUB have focused on deep surveys for small-size debris in highly elliptical orbits, including geostationary transfer, and Molniya-type orbits.伯尔尼大学天文学研究所的近期研究侧重于对包括地球同步转移等高椭圆轨道以及莫尼亞轨道之类轨道上小型碎片的深度调查。
The observations indicate a substantial population of “unknown” objects in these orbital regions, i.e.这些观测显示,在这些轨道区域的大量“不明”物体,即并未载入所能公开提供的任何轨道目录的物体。
objects that are not contained in any of the publicly available orbit catalogues.确定这些物体的特性对弄清碎片来源及最终设计高效并且在经济上可行的缓减措施十分重要。
Characterizing these objects will be of great importance in order to identify the sources of the debris and eventually design efficient and economically viable mitigation measures.2010年启动了一项研究,以寻找导航卫星星座区域内的小型碎片。
In 2010 a study was initiated to find small-size debris in the region of the navigation satellite constellations.该项研究是在该轨道区域进行的首次这类研究。
That study is the first of its kind in this orbit region.迄今结果表明,当前导航卫星星座发生了某一较大物体的解体。
The results to date indicate a breakup of a larger object in the current navigation satellite constellations.为支持就主动清除低地轨道较大物体而展开的讨论,伯尔尼大学天文学研究所正在使用光学枪曲线的手段开展评估直径700到1000公里轨道上较大碎片物体下跌比率的观测方案。
In support of the discussion on the active removal of large objects from low-Earth orbits, AIUB is conducting an observation programme to assess tumbling rates of large debris objects in orbits at altitudes of 700 to 1,000 km by means of optical light curves.洛桑瑞士联邦理工学院的瑞士航天中心及其合作伙伴继续在其“Clean-mE”方案下展开积极清除碎片领域的研究和开发工作。
The Swiss Space Center at the Swiss Federal Institute of Technology in Lausanne (EPFL) and its partners have continued research and development in the area of active debris removal under its “Clean-mE” programme.在2014年期间,其工作重点是,开展应对非合作性交会挑战的系统研究。
During 2014 their efforts were focused on system studies to address the challenges of non-cooperative rendezvous.洛桑瑞士联邦理工学院在欧洲空间局的一项合同下开展评价工作,使用立方卫星技术对可能的在轨演示展开评估,并努力减少给未来展开的清除较大碎片飞行任务所造成的风险。
EPFL worked under a European Space Agency contract to evaluate possible in-orbit demonstrations using CubeSat technologies and reduce the risk to future large missions for the removal of large debris.立方卫星是质量在1到10公斤间的微型卫星。
CubeSats are nano-satellites whose mass lies between 1 and 10 kg. Proposed CubeSat in-orbit demonstrations include testing of rendezvous sensor technologies and testing of net capture technology.拟议立方卫星在轨演示包括测试交会传感器技术并测试净捕捉技术。
Low-level activities continued on the CleanSpace One project.清洁太空一号项目继续开展低层面活动。
III. Replies received from international organizations三. 从国际组织收到的答复
Committee on Space Research空间研究委员会
[Original: English][原件:英文]
[4 November 2014][2014年11月4日]
More than 55 years of space flight activities since the launch of Sputnik 1, in 1957, have generated a significant number of man-made objects in Earth orbits.自从1957年发射第一颗人造卫星以来太空飞行活动已有超过55年的历史了,这些活动致使大量人造物体运行于地球轨道。
The vast majority of those objects are non-functional and referred to as “space debris”.其中绝大多数物体已经失去其功能,被称作“空间碎片”。
The sizeable population of that space debris constitutes an increasing threat to robotic and manned spacecraft.这些空间碎片中有相当一部分日益威胁到程控机器人航天器和载人航天器。
Over the last two decades, collision and breakup events have amplified concerns that this environmental hazard will become a central issue in the decades to come.在过去二十年内,碰撞和解体事件让人越来越担心这一环境危害将成为今后几十年的一个中心问题。
Although many space actors currently apply a variety of measures to reduce the creation of space debris, this will not be sufficient to control the future growth of the population of space debris because there is already a sufficient amount of derelict debris in Earth orbit to cause collisional breakups in the future, even without any new objects being placed into orbit.虽然许多空间行动方目前使用各种措施来减少空间碎片的形成,但这却不足以控制空间碎片数量今后的增加,其原因是,地球轨道上报废碎片的数量已经十分庞大,足以在今后造成碰撞性解体,即便没有任何新的物体被放置在轨道上。
The prevention of catastrophic collisions, each creating thousands of new fragments, is thus of primary concern for the long-term evolution of the environment.每次发生灾难性碰撞,都会造成数以千计的新的碎片,因而,如何防止这类碰撞的发生,是环境的长期演变所面临的主要问题。
Means to prevent collisions include debris mitigation, collision avoidance and removal of debris from the environment, also termed active debris removal.预防碰撞的手段包括:碎片缓减、避免碰撞和清除环境中的碎片,后者也称作主动清除碎片。
Collision avoidance measures require precise knowledge of the trajectories of all objects that could produce a catastrophic collision.避免碰撞措施需要确切了解可能产生灾难性碰撞的所有物体的运行轨迹。
Today such knowledge is available for a very limited number of objects only.如今只是对数量极为有限的物体才有这类了解。
For active debris removal, and for collision avoidance involving non-functional objects, new technologies need to be developed to change the trajectories of debris objects or to deorbit them.关于主动清除碎片以及涉及非功用性物体的避免碰撞,需要开发新的技术以改变碎片物体的运行轨迹,或使其脱离轨道。
Substantial scientific research is essential to devise efficient and economically viable measures to stabilize the space debris population.展开大量科学研究,是为稳定空间碎片数量而制定高效并且经济上可行的措施的关键。
The Committee on Space Research (COSPAR) has been addressing the topic of space debris for more than a third of a century.空间研究委员会(空间研委会)处理空间碎片专题已经长达三分之一个世纪之多。
For many years the COSPAR Panel on Potentially Environmentally Detrimental Activities in Space (PEDAS) has held multiple sessions about space debris at every COSPAR biannual Scientific Assembly.多年来,空间研委会有关研究对环境潜在危害活动的专题小组在空间研委会每两年举行的科学大会上就空间碎片问题举行了多次会议。
Those sessions have addressed: (a) the characterization of the current and future space debris environment through measurements and modelling; (b) risks posed to spacecraft by collisions with space debris; (c) means to protect spacecraft; (d) strategies and policies to mitigate the creation of new space debris; and (e) the scientific foundation and technical framework for remediating the space debris environment and thereby limiting the proliferation of space debris.这些会议涉及:(a)通过各种措施和建模确定当前和未来空间碎片环境的特点;(b)与空间碎片发生碰撞而对航天器构成的威胁;(c)保护航天器的相关手段;(d)缓减新增空间碎片的战略和政策;以及(e)修复空间碎片环境并从而限制空间碎片激增的科学基础和技术框架。
At the 2014 PEDAS sessions, 38 papers were presented on the theme “Space debris: responding to a dynamic environment”.在2014年关于对环境构成潜在危害的活动专题小组会议上,与会者就“空间碎片:对动态环境的回应”这一主题宣读了38篇论文。
At the 41st Scientific Assembly of COSPAR, in 2016, the PEDAS sessions will be “Space debris: providing the scientific foundation for action”, which is a step forward.在空间研委会第41次科学大会上,关于对环境构成潜在危害的活动专题小组2016年的各场会议将是关于“空间碎片:奠定行动的科学基础”,这是往前迈出的一步。
Four half-day sessions will focus on advances in collision risk assessment for space missions, on-orbit collision assessment, re-entry risk assessments, debris mitigation and debris environment remediation techniques and their effectiveness with regard to long-term environment stability, as well as traditional topics such as ground and space-based observations and methods for using them, in situ measurement techniques, debris and meteoroid environment models, national and international debris mitigation standards and guidelines, hypervelocity accelerator technologies, and on-orbit shielding concepts.每次半天的四场会议将侧重于在空间飞行任务碰撞风险评估、在轨碰撞评估、再进入风险评估、碎片缓减和碎片环境修复手段及其对环境长期稳定的效力等方面取得的进展,以及基于地面和空间的观测及其使用方法、现场测量手段、碎片和流星体环境模式、国家和国际碎片缓减标准和准则、超高速加速器技术以及在轨屏蔽概念等传统专题。
Interdisciplinary and multidisciplinary papers on space weather and near-Earth objects are particularly encouraged.关于空间气象和近地物体的学科间和多学科论文尤其得到鼓励。
The challenges of stabilizing the space debris population are substantial, but spacefaring nations and international scientific organizations such as COSPAR are devoting considerable efforts to promoting the long-term sustainability of operations in near-Earth space for the benefit of all. COSPAR continues to be a leader in promoting a better understanding of the nature and risks of the space debris environment and in encouraging spacefaring nations and organizations to act responsibly in space through each mission phase, including deployment, operations and disposal.在稳定空间碎片数量上面临巨大挑战,但航天国以及空间研委会之类国际科学组织作出巨大努力以集中推动能带来普遍惠益的近地空间作业的长期可持续性。
Secure World Foundation空间研委会继续率先推动加深了解空间碎片环境的性质及其风险并鼓励航天国和各组织在飞行任务的每个阶段均能在空间负责地行动,包括在部署、作业和处置方面。
[Original: English]世界安全基金会 [原件:英文]
[20 October 2014][2014年10月20日]
In 2014, the Secure World Foundation (SWF) continued to work on space debris and on-orbit safety issues as part of its focus on the long-term sustainability of space activities.2014年,世界安全基金会作为其重点关注空间活动长期可持续性工作的一部分,继续开展有关空间碎片和在轨安全问题的工作。
As part of its information awareness activities, SWF was able to provide testimony before the Space Subcommittee of the House Committee on Science, Space, and Technology of the United States of America as part of a hearing on dealing with the threat of space debris.作为其宣传活动的一部分,世界安全基金会得以在美利坚合众国众议院的科学、太空和技术问题委员会的太空问题小组委员会作证,这是为应对空间碎片威胁而举行的听证会的一部分。
The written testimony included a comprehensive overview explaining the importance of space debris mitigation, space traffic management, space debris removal and remediation, and space situational awareness to minimizing the threat space debris poses to space activities.书面证词包括一份全面概要,对空间碎片缓减、空中交通管理、空间碎片的清除和修复以及为尽量减少空间碎片对空间活动之威胁而开展空间态势认知的重要性加以解释。
The testimony also provided the Subcommittee with recommendations on how to improve the implementation by the United States Government of the space debris mitigation guidelines in national regulations and how to improve space situational awareness services to help all satellite operators avoid collisions in space.该证词还就美国政府如何在本国条例中改进对空间碎片缓减准则的执行以及如何为帮助所有空间运营方避免空间碰撞而改进空间态势认知服务向小组委员会提供了建议。
Similarly, SWF staff members regularly raised the issue of space debris in discussions at meetings and conferences about the uses of outer space that might not otherwise have addressed the question.同样,在关于利用外层空间的大大小小的会议上,世界安全基金会工作人员在本来可能不会述及该问题的讨论中经常提出空间碎片问题。
Examples of such initiatives included speeches and presentations at a workshop entitled “Emerging space economies: next steps toward prosperity” held by the Wilton Park international discussion forum, a round table on promoting space security and sustainability hosted by the Council on Foreign Relations and a spotlight talk at the International Symposium on Personal and Commercial Spaceflight that addressed the responsibility of the growing commercial space sector to participate actively in practices that mitigate space debris.这类举措的范例包括在由威尔顿公园国际(Wilton Park International)讨论论坛举办的题为“新兴空间经济体:走向繁荣的下一些步骤”的一次讲习班上所作的发言和专题介绍。
SWF staff participated in the 3rd European Workshop on Space Debris Modelling and Remediation, held in Paris from 16 to 18 June 2014.该论坛是外交关系理事会主持的关于推动空间安全和可持续性的一个圆桌会议,此外还在有关载人和商业航天飞行的国际专题讨论会上作了公开讲演,其中谈及日益增强的商业空间部门在积极参加减缓空间碎片实务上所负责任的问题。
SWF participation included co-chairing the first ever session on the legal, policy and other non-technical challenges related to space debris remediation, and a presentation on a draft protocol for determining how to ask permission to interact with a space object for remediation.世界安全基金会工作人员参加了2014年6月16日至18日在巴黎举行的空间碎片建模和修复问题的第三期欧洲讲习班。
The protocol uses the principles established in the existing outer space treaties to create a list of steps a State can take for determining which State has jurisdiction and control over a space object.世界安全基金会的参与包括联合主持讨论空间碎片修复相关法律、政策及其他非技术性挑战的首次会议,并且就确定如何要求允许为修复目的而同空间物体互动的议定书草案作专门介绍。
In cases where the determination cannot be made, the protocol suggests steps that can be taken to notify the world community of its intent to remediate a space object in a safe and responsible manner.该议定书使用了现有外层空间各项条约就列举一国为确定究竟哪一个国家对空间物体享有管辖权和控制权而可采取的各种步骤所确立的原则。
As part of its efforts to facilitate cooperative discussions, SWF has cooperated with the Maui Economic Development Board and the Japan Space Forum (JSF) to hold two Advanced Maui Optical Space Surveillance (AMOS) dialogues.对于无法加以确定的情况,该议定书就为让国际社会了解其以安全负责的方式修复空间物体的意图而可采取的步骤提出了建议。
The purpose of the dialogues was to foster discussion on policy issues related to space situational awareness cooperation and data-sharing.作为其为便利展开合作型讨论所作努力的一部分,世界安全基金会与毛伊岛经济发展局和日本空间论坛合作举行了有关毛伊岛先进的光学与空间监视技术的两次对话。
The first dialogue was held in Tokyo on 26 February 2014 just prior to the third JSF International Symposium on Sustainable Space Development and Utilization for Humankind.这些对话的目的是,推动有关空间态势认知合作和数据共享政策问题的讨论。
The second dialogue was held on the island of Maui, United States, on 11 September 2014 during the 2014 AMOS conference.第一次对话就在为造福人类而实现可持续空间发展和利用的第三次日本空间论坛国际专题讨论会召开之前而于2014年2月26日在东京举行。
Both dialogues brought together Government and private sector representatives from multiple countries to discuss ways to improve space situational awareness data-sharing and cooperation.第二次对话是在2014年有关毛伊岛先进的光学与空间监视技术的会议举行期间于2014年9月11日在美国毛伊岛举行的。
Finally, as part of its general outreach efforts on the issue, SWF once again featured space debris prominently in its publication entitled “Space sustainability: a practical guide”, which had been updated and republished this year.这两次对话都聚集了多个国家的政府和私营部门的代表,目的是共商如何改进关于空间态势认知数据的共享与合作。
That document can be downloaded free of charge from the SWF website at www.swfound.org/media/121399/swf_space_sustainability-a_practical_guide_2014__1_.pdf.最后,作为其有关该问题一般性推介活动的一部分,世界安全基金会在其题为“空间可持续性:实务指南”的一份出版物中将空间碎片放在了突出的位置,该出版物今年已得到更新和补充,可从世界安全基金会的网址www.swfound.org/ media/121399/swf_space_sustainability-a_practical_guide_2014__1_.pdf上免费下载。
Space Generation Advisory Council航天新一代咨询理事会
[Original: English][原件:英文]
[7 November 2014][2014年11月7日]
The space debris situation空间碎片情况 自从1957年发射第一颗卫星以来,地球轨道已日渐拥挤。 许多国家和商业企业均已将各自的航天器发射到地球周围的轨道上,其中许多航天器目前仍在轨道上。 在空间物体中,仅有6%的物体仍在运行,而近60%属于由爆炸和碰撞所产生的碎片。 这些失去控制的碎片以及空间碎片的其他断片,例如被废弃的火箭壳体和已经退役的卫星,均能彼此碰撞并从而产生更多碎片。 俗称为凯斯勒综合症的这种周而复始的现象,导致随着时间的推移轨道碎片急剧增加,并从而对轨道上的作业机体构成日益严重的威胁。 空间碎片按照纬度情况的分布情况显示,1,000公里纬度的空间碎片数量从2007年年初到2012年4月间增加了两倍多。 由中国在2007年发射的拦截卫星的试验以及2009年铱星33号(Iridium 33)和宇宙2251号(Cosmos 2251)之间的碰撞所产生的碎片是造成空间碎片数量剧增的主要原因。 铱星号卫星和宇宙号卫星之间的碰撞等事故显示了碎片间碰撞在改变空间碎片环境上所可发挥的重要作用。 低地轨道的碎片场目前并不稳定。 模拟情况表明,即便今后不再有任何发射,碎片场都将缓慢扩展。 然而,这是一种乐观的并且不切实际的设想,因为空间发射预期绝不会马上停止。
Ever since the first satellite was launched in 1957, Earth’s orbit has become more crowded.由于发射比率是固定的,并且又没有缓减措施,在轨碎片的数量可能会急剧增加。
Many nations and commercial enterprises have launched their own spacecraft into orbit around Earth, and many of those craft are still in orbit.500个质量最大的空间碎片物体的分布,使得经由审视现有低地球轨道火箭壳体和质量最大并且碰撞可能性最高的产品的航天器之间在远地点和近地点纬度与倾角分布上的关系,即可确定其中究竟哪些物体的碰撞风险高。
Of the objects in space only 6 per cent are still operational, while almost 60 per cent are fragments produced by explosions and collisions.这些物体最有可能造成灾难性碰撞,从而增加低地轨道空间碎片的数目,这种情况此前已见于铱星号卫星和宇宙号卫星之间的碰撞。
These uncontrolled fragments, along with other pieces of space debris such as discarded rocket bodies and retired satellites, can collide with each other and generate yet more debris.携带核动力技术的航天器
This cycle, popularly known as the Kessler syndrome, results in an exponential growth of orbital debris as time progresses, and hence in an ever-increasing risk to operational bodies in orbit.在有关核动力航天器方面有三种一般设想值得考虑:
The distribution of space debris according to altitude shows that the amount of space debris at an altitude of 1,000 km more than doubled between the beginning of 2007 and April 2012.设想1:航天器配备了用作机载电源和仪器加热(例如深空探测器)的放射性同位素热电发生器(RTG);
Fragments generated by the anti-satellite test conducted by China in 2007 and the collision between the Iridium 33 and Cosmos 2251 satellites in 2009 were major factors in the jump in the amount of space debris.设想2:航天器以核为动力源,并且使用由此产生的动力来驱动航天器,包括在发射阶段(例如漫游者(Rover)项目)和火箭飞行器用核引擎方案(NERVA));
Incidents such as the Iridium-Cosmos collision show the important role that debris-debris collision can have in changing the space debris environment.设想3:航天器的设计是为了将核技术用于驱动而非发射。
Currently the debris field in low-Earth orbit is not stable.只有当航天器在轨时方可使用核推进。 设想2和3的根本区别在于发射阶段,对此将在以下章节中加以考虑。
Simulations have shown that, even without any future launches, the debris field will slowly grow.设想1最为常见,多数用于深空飞行任务。 太阳阵列从太阳光中得到的能源按照平方反比定律递减:随着同太阳的距离的增加,利用太阳能的航天器所可利用的能源将会减少。
However, this is an optimistic and unrealistic scenario, since space launches are not expected to stop any time soon.一旦超过太阳阵列因为所有实际目的而失去效力之点,核技术即可为航天器系统提供一种可靠的热量和能源来源。 RTG基本上利用了塞贝克效应,将放射性材料(通常是钚-238)的自然衰化所释放的热量转换为电能。
With regular launch rates and no mitigation measures, the quantity of debris in orbit is likely to grow exponentially.应当指出的是,这并非裂变反应。 火星科学实验室这类飞行任务(把好奇号探测器着陆在火星)及旅行者1和2号与先驱者10和11号之类太阳系探测器均利用RTG开展可靠的动力和热管理。 以往报告了涉及核动力源航天器的某些事故。 首次事故发生于1964年,当时TRANSIT 5BN-3导航卫星在硬件发生故障后无控再入地球大气层。 该卫星按照原先的设计在大气层上层完全烧毁,但其对人群的长期影响难以确定。 这类再进入导致放射性核素在大气层上层的负荷增加,并且放射性核素随着时间的推移将急剧沉降到海平面。 由于RTG材料的半衰期通常很长(数千年),因而有可能对公众和环境造成危害。 涉及核动力源航天器的其他两个广为人知的事故涉及到阿波罗13号飞行任务,该飞行任务是使用功能无损的机载RTG和宇宙-954号雷达海洋侦察卫星(RORSAT)再入大气层的,该卫星无控再入大气层,坠毁在加拿大西北地区的无人居住区。 RORSAT原本计划再入时烧毁,但却未能如愿,致使大量核材料落到地球上。 阿波罗13号飞行任务的RTG坠落南太平洋,并且至今仍在太平洋底。
The distribution of the 500 largest space debris objects makes it possible to identify a high collision risk by looking at the relationship between the apogee and perigee altitudes versus inclination distributions of the existing low-Earth orbit rocket bodies and spacecraft that have the highest mass and collision probability products.它虽历经再入和撞击但仍完好无损,未检测到有任何辐射的释放。 这些事故导致空间系统所用核动力系统设计的改变。
These objects are the most likely to cause catastrophic collisions that can increase the amount of space debris in low-Earth orbit, as previously seen in the Iridium-Cosmos collision.这些核动力系统如今的设计是为了抵御再入和撞击的影响,从而能够在到达地面时完好无损。
Spacecraft carrying nuclear power technology并且最为重要的是,不释放任何放射性材料。 阿波罗13号RTG的设计已证明了这种做法的有效性。 发射
There are three general scenarios to consider with respect to nuclear-powered spacecraft:发射被视为涉及核动力源航天器飞行任务的最关键阶段,并且也是最有可能威胁到普通人群的飞行任务阶段。 目前推出“关键性”的概念也很重要。 关键性基本上是指核芯启动裂变并且副产品开始积累之点。 在关键性以前,核燃料中并无任何副产品。 该燃料相对于副产品危害不大,因为它通常属于α-辐射体,只是在被吸收之时方对人的健康构成重大危害。 然而,一旦关键性得以实现,裂变副产品将开始在系统中积累。
Scenario 1: The spacecraft is equipped with a radioisotope thermal generator (RTG) for on-board power and instrument heating (e.g. deep space probes);这就对人的健康构成更大危害,因为这些副产品中相当一部分属于β和γ辐射体,仅由于外部接触即可对人造成伤害。
Scenario 2: The spacecraft is nuclear-powered and uses the energy generated to power the spacecraft, including at the launch phase (e.g. Project Rover and the Nuclear Engine for Rocket Vehicle Applications programme (NERVA));设想2要求在发射前实现关键性,并且利用核反应产生的热量来驱动该航天器的上升。
Scenario 3: The spacecraft is designed to use nuclear technology for propulsion, but not for its launch.20世纪中叶在Rover-NERVA的方案中对此展开了调查和测试。
Nuclear propulsion will only be used once the spacecraft is in orbit.然而,根据这一设想,火箭发生的任何故障均有可能导致裂变副产品的释放。
Scenarios 2 and 3 basically differ in the launch phase and are considered in the following section.相形之下,设想3的假设是,使用常规推进方法将航天器射入轨道。
Scenario 1 is the most common and has been used mostly for deep-space missions.显然,任何核材料的释放均不可取,而不论是在实现关键性之前或之后实现。
The energy that solar arrays can derive from sunlight decreases in accordance with the inverse square law: as the distance from the Sun increases, the power available to a spacecraft using solar power diminishes.然而,为了限制任何潜在后果的严重性,最好在核反应堆安全进入轨道之后实现关键性。
Nuclear technology provides a reliable source of heat and energy for spacecraft systems once they are beyond the point where solar arrays, for all practical purposes, become ineffective.地球轨道飞行任务及碎片撞击风险
An RTG basically converts the heat released by the natural decay of radioactive material (usually Pu-238) into electrical power, using the Seebeck effect.鉴于涉及到大量能源,作为最坏的设想,必须把涉及空间碎片的撞击视之为灾难性撞击。
It should be noted that this is not a fission reaction.而且,最坏情况的实例是核芯容器受损,导致裂变产品被释放到太空中。
Missions such as the Mars Science Laboratory (which landed the Curiosity rover on Mars) and solar system probes, such as Voyager 1 and 2, and Pioneer 10 and 11, have utilized RTGs for reliable power and thermal management.对于RTG的情况,所作的假设是,碰撞造成RTG被毁,致使其作为颗粒物质四处散落。
Some accidents involving nuclear-powered spacecraft have been reported in the past.取决于碰撞在轨道何处发生,这不一定构成公众或对地球的环境所担心的问题,因为只要大气阻力并非是造成这种现象的一个原因,而且轨道可被视为是稳定的,则通常可假设,核材料将仍在上面。
The first occurred in 1964, when the TRANSIT 5BN-3 navigational satellite performed an uncontrolled re-entry into the Earth’s atmosphere after a hardware malfunction.然而,这类碰撞也可能会对某些碎片产生足够的能量,能够将其推至大气阻力不致构成阻碍的轨道,这既可能是由于初始撞击,也可能是由于稍后随之发生的间接撞击。
The satellite completely burned up in the upper atmosphere as it was designed to, but the long-term effects on the human population are hard to determine.鉴于对轨道碎片如何扩散至轨道纬度上轨道中心周围的壳的了解,这一模式将有效导致在某一轨道纬度上出现辐射带。
Re-entries of this kind result in an increased loading of radionuclides in the upper atmosphere, which can in time spiral down to sea level.这将不会对航天员或航天器构成直接的重大威胁,但在相关纬度开展舱外活动的人的健康都将直接受到危害。
As the half-life of the RTG material is typically long (thousands of years), it is possible that harm was caused to the public and the environment.因此,导致核材料释放至轨道的碰撞将会对所能开展的舱外活动构成限制。
Two other well-known incidents involving nuclear-powered spacecraft were related to the Apollo 13 mission, which re-entered the atmosphere with a fully functional RTG on board, and the Cosmos-954 radar ocean reconnaissance satellite (RORSAT), which made an uncontrolled re-entry and crashed into an unpopulated area of the Northwest Territories of Canada.然而,也需要考虑对声誉的影响问题,因为普通公众通常不信任核技术。
RORSAT was designed to burn up upon re-entry but failed to do so, and a significant amount of nuclear material reached Earth.这类性质的事故实际上将会导致现有和未来核航天器方案过早终结。
The RTG from the Apollo 13 mission plunged into the South Pacific, where it remains to date.因此,这类事故的后果将是严重的,即便并不立即构成任何健康危害。
It survived the re-entry and impact, and no release of radiation has been detected.还需要评估与碎片发生碰撞的可能性。
These incidents have led to changes in the design of nuclear power systems for use in space systems.已经开展了评估在轨碎片面积和数量的研究,在此基础上建立碎片撞击可能性的模型比较容易。
Those nuclear power systems are now being designed to withstand re-entry and impact so that they reach the ground intact and, most importantly, without releasing any radioactive material.总体可能性普遍不高(在每年10-5之间)。
The RTG from Apollo 13 had already been designed in such a way, which demonstrates the validity of this approach.然而,如果辅之以上文提及的严重后果,总体风险排序可被视为不低,应当推动在任何工程方案中列入重要保障措施,以便防止在发生碰撞时放射性核素的释放。
Launch处置
Launch is considered the most critical phase of a mission involving a nuclear-powered spacecraft, and also the mission phase with the highest potential threat to the general population.还需要考虑到航天器在完成飞行任务后的处置。
At this point it is also important to introduce the concept of “criticality”.关键核心会发生何种情况?
Essentially criticality refers to the point where fission is initiated in a nuclear core and by-products will start to accumulate.最简单的回答是,将航天器移至安全的墓地轨道并将它留在那里。
Prior to criticality there are no by-products present in the nuclear fuel.这将导致在轨空间碎片物体数目的进一步增加,并从而导致空间碎片对未来飞行任务的影响的增加。
The fuel is relatively benign in comparison to the by-products, as it is typically an alpha-radiation emitter and poses a significant risk to human health only if ingested.而且,与寿命终了的核动力空间系统发生碰撞可能会产生其他后果,例如放射性材料泄露到太空。
However, once criticality is achieved, fission by-products start to accumulate in the system.较长期可持续解决办法是空间系统的有控再入。
That poses a much greater hazard to human health, as a significant part of those by-products are beta and gamma emitters, which may cause damage to humans from external exposure alone.这就要求航天器特别是其核部件的设计能够抵御再入进程的高温、压力和撞击载荷。
Scenario 2 requires criticality to be achieved before launch and uses the heat derived from a nuclear reaction to power the ascent of the spacecraft.行星探索所用RTG系统以前采取了这种做法,但这可能提高航天器的成本。
This was investigated and tested in the mid-twentieth century in the Rover-NERVA programme.在活性核反应堆(及其裂变副产品)的情况下,任务更具挑战性,其原因是,最终能否制造能够抵御再进入风险的反应堆尚不清楚。
However, under this scenario any failure of the rocket could potentially result in the release of fission by-products.考虑到今后发生碰撞的可能性不高,将已用过的核芯移至为处置核驱动航天器而专门选定的墓地轨道相关风险将低于同其再进入有关的风险。
In comparison, scenario 3 assumes that the spacecraft is launched into orbit using conventional propulsion methods.这类墓地轨道的选择需要以尽量减少空间碎片碰撞并降低未来风险为目的。
It is obvious that the release of any nuclear material, either before or after criticality is achieved, is undesirable.深空探索飞行任务
However, in order to limit the severity of any potential consequences, ideally a nuclear reactor should not achieve criticality until it is safely in orbit.利用核驱动航天器进行深空探索较之于地球轨道飞行任务更能让人接受。
Earth orbit missions and the debris impact hazard随着同太阳之间的距离增加,RTG比太阳阵列的效率更高,从而更加有助于核动力的使用。
An impact involving space debris must be considered catastrophic as a worst-case scenario, given the significant energies involved.虽然深空飞行任务在发射时的风险相同,但邻近地球时所费时间较少。
Furthermore, the worst-case example would be a breach of core containment, resulting in fission products being released into space.因此,与深空飞行任务有关的空间碎片撞击风险较低。
In the case of an RTG, it is assumed the collision results in the RTG being destroyed and scattered as particulate matter.然而,实情是否如此取决于飞行任务的概况。
This is not necessarily a concern for the public or Earth’s environment, depending on where in orbit the collision occurs, because as long as atmospheric drag is not a factor and the orbit can be considered stable, it can generally be assumed that the nuclear material will stay aloft.如果航天器在前往其目的地的直接转移轨道上偏离地球(这种情况很少发生),并且发生了事故,随之产生的放射性碎片将停留在轨道上,而这最终将与地球轨道交叉,从而最终导致放射性碎片进入地球邻近地带。
However, it is also possible that such a collision will impart sufficient energy to some debris to move it into an orbit where atmospheric drag does become a factor, either from the initial impact or from the resultant secondary impacts occurring at a later time.结论
Given what is known about how orbital debris spreads into a shell around the orbital focus at the orbit’s altitude, this model would effectively result in a band of radiation at a certain orbital altitude.将核动力源用于航天器使得以往几次重要的飞行任务成为可能(尤其是深空探索飞行任务),并且只要采取必要的安全措施,则将继续如此。
This would not pose a significant direct threat to astronauts or spacecraft, although anyone carrying out an extravehicular activity at the altitude in question may face direct health hazards.航天新一代咨询理事会就此建议:
Therefore it is likely that a collision resulting in nuclear material being released into orbit would lead to restrictions on where extravehicular activities can be carried out.(a) 如果航天器使用核芯,则应当将该核芯带入轨道,并且只在轨道上开启裂变反应,而不是将核推进用作抵达轨道的一种手段;
However, reputational issues also need to be considered, as the general public tends to distrust nuclear technology.(b) 对于使用核动力的所有航天器,应当特别强调核动力系统的坚固和牢靠。
An incident of this nature could effectively lead to the premature termination of current and future nuclear spacecraft programmes.应当对其加以保护,以免受到碎片撞击、再进入压力和极端气温的影响;
Thus, the consequences of such an incident would be severe, even if they did not pose any immediate health hazard.(c) 携带核动力系统的深空飞行任务应当凡有可能则使用非直接转移轨道;
The likelihood of a collision with debris also needs to be assessed.(d) 在到达其寿命终了时,都应当以有控方式再进入使用RTG系统的低地轨道上所有航天器,以确保核动力系统完好无损地存活下去;
Studies have been carried out to assess the size and quantity of debris in orbit, and it is relatively easy to model the probability of a debris impact on this basis.(e) 在到达其寿命终了时,地球同步轨道上使用核反应堆或使用RTG的所有航天器都应当被转移到墓地轨道。
The overall probability is generally low (in the order of 10-5 per year).该墓地轨道的选择应当确保核燃料半衰期期间的稳定(例如不致衰化,也不知构成碰撞风险),或直到所造成的辐射不再对人群构成危害;
However, when paired with the severe consequences mentioned above, the overall risk ranking can be considered high and should drive any engineering programme towards including significant safeguards to prevent a release of radionuclides, should a collision occur.(f) 对于考虑使用核动力的每一个飞行任务,都应当有一个独立的核安全专门小组(类似于美利坚合众国机构间核安全审查专门小组),以确保所有安全程序均得到遵行;
Disposal(g) 安全工作应当侧重于规划和预防,而不是对事故的调查。
The disposal of a spacecraft after mission completion also needs to be taken into account.关于航天新一代咨询理事会
What happens to the critical core?航天新一代咨询理事会是一个专注于空间部门学生和年轻专业人员的国际非盈利性组织。
The simplest answer is to move the spacecraft into a safe graveyard orbit and leave it there.它代表了下一代空间领导者在相关联合国机构及其他空间组织所发表的看法。
This would lead to a further increase in the number of space debris objects in orbit and, consequently, increase the risk of space debris impact to future missions. Moreover, collisions with an end-of-life nuclear-powered space system can have other consequences, such as a leak of radioactive material into space. A longer-term sustainable solution is controlled re-entry of the space system. This would require the spacecraft, and particularly its nuclear components, to be designed to withstand the high temperatures, stresses and impact loads of the re-entry process. This has been done previously with RTG systems used in planetary exploration, but it might drive up the costs of the spacecraft. The case of active nuclear reactors (and their fission by-products) presents a much more challenging task, as it is still not clear whether a reactor capable of withstanding re-entry can actually be manufactured. The risk associated with moving used cores into a graveyard orbit selected specifically for the disposal of nuclear-powered spacecraft taking into account the low probability of future collisions would be lower than that associated with their re-entry. Such a graveyard orbit needs to be selected with the aim of minimizing space debris collisions and reducing future hazards. Deep-space exploration missions The use of nuclear-powered spacecraft for deep-space exploration is somewhat more acceptable than for Earth-orbit missions. The increased efficiency of RTGs over solar arrays as the distance from the Sun increases supports the use of nuclear power. While deep-space missions pose the same hazard on launch, they spend less time in Earth’s vicinity. Consequently the space debris impact hazard associated with deep-space missions is lower. However, whether this is indeed the case depends upon the mission profile. If the spacecraft were to depart from Earth on a direct transfer orbit to its destination (which is rarely the case) and an accident were to occur, the resultant radioactive debris would remain on an orbit that could eventually intersect the Earth’s orbit, ultimately resulting in radioactive debris entering Earth’s vicinity. Conclusion The use of nuclear power for spacecraft has made several important missions possible in the past (particularly deep-space exploration missions) and can continue to do so as long as the necessary safety measures are undertaken. In this connection the Space Generation Advisory Council recommends that: (a) If a spacecraft uses a nuclear core, it should carry that core into orbit and start the fission reaction only in orbit, as opposed to using nuclear propulsion as a means to reach orbit; (b) For all spacecraft using nuclear power, special emphasis should be placed on the robustness and sturdiness of the nuclear power system. It should be protected against debris impacts, re-entry stresses and extreme temperatures; (c) Deep-space missions carrying nuclear power systems should use non-direct transfer orbits if possible; (d) Upon reaching their end of life, all spacecraft in low-Earth orbit using an RTG system should be re-entered in a controlled manner that ensures the intact survival of the nuclear power system; (e) Upon reaching their end of life, all spacecraft using nuclear reactors or using an RTG in geosynchronous orbit should be transferred to a graveyard orbit. That graveyard orbit should be selected in such a way as to assure stability, i.e. it should not decay or present a collision hazard, for the duration of the nuclear fuel’s half-life or until the radiation emitted no longer poses a hazard to human populations; (f) For every mission for which the use of nuclear power is considered there should be an independent nuclear safety panel (similar to the Interagency Nuclear Safety Review Panel in the United States of America) to assure that all safety procedures are followed; (g) Safety efforts should focus on planning and prevention rather than investigation of accidents. About the Space Generation Advisory Council The Space Generation Advisory Council is an international non-profit organization dedicated to students and young professionals in the space sector. It represents the views of the next generation of space leaders before relevant United Nations bodies and other space organizations. Having been created in the United Nations environment (namely the Third United Nations Conference on the Exploration and Peaceful Uses of Outer Space), the Council’s work with the United Nations, particularly the Committee on the Peaceful Uses of Outer Space, is of central importance to its mission.由于创建于联合国环境(即第三次联合国探索及和平利用外层空间会议),该理事会与联合国特别是与和平利用外层空间委员会携手合作对其任务至关重要。
The Council gives regular input to the Committee and acts as a conduit for the opinions of its members.理事会定期向委员会提供咨询,并且成为传递其成员意见的管道。