News &Highlights
枫叶正红Space Trash Removal
Chris Palmer
Senior Technology Writer
March 2019saw the culmination of the RemoveDEBRIS satellite mission,which demonstrated a t of technologies that could one day help address the problem of space trash.This burgeoning collection of
debris in low Earth orbit is inching toward a crisis that threatens to make the region of space within 2000km of the Earth’s surface very difficult to u.
The US Department of Defen estimates that there are some 500000pieces of debris,or space trash,in low Earth orbit,includ-ing about 23000objects larger than a grapefruit that the agency tracks with ground-bad instruments [1].As rocket launches continue and the number of satellites placed in orbit grows,the chance that the objects could collide—and thereby create even more debris in a dangerous cascade effect known as the Kessler syndrome [2]—is putting current,new,and replacement satellite deployments at risk.
The world’s major space agencies agree that orbital debris is a rious issue.Studies by the Inter-Agency Space Debris Coordina-tion Committee indicate that mitigating the creation of new debris is critical to the future of orbital missions,as is debris already in place [3].Another study by Aeronautics and Space Administration (NASA)to ten of the largest debris objects—dead satellites from a refrigerator to a city bus—would have to be year just to stabilize the
growth in space debris However,only a small number of pieces of
been removed from orbit,due to challenges economic in nature.‘‘There’s actually a handful of n f
or how to go up and remove space interest to date in funding missions,said Brian tor of program planning for the Secure World Broomfield,Colorado-bad organization focud peaceful and sustainable us of outer space.
The European Space Agency (ESA)has put the developing and testing active debris removal of a larger program called Clean Space that the sion has funded since 2012.‘‘Europe is a little more ing on the sorts of environmental issues,”RemoveDEBRIS was sponsored by the and is its most notable active debris removal active removal technologies being evaluated by satellite bearing a robotic arm that can grab onto it into a lower orbit where it will burn up in the a satellite-mounted conical net that opens up on derelict satellites [5,6].Other space agencies are exploring the u of ground-bad lars to ablate the leading edges of defunct satellites and other debris,causing the objects to slow down and re-enter the atmosphere [7].
The RemoveDEBRIS spacecraft was designed and built by an international consortium of aerospace companies and rearch institutions,including Airbus,Surrey Satellite Technology,Ltd.,CSEM (Switzerland),Inria (France),ISIS (the Netherlands),Stellen-bosch University (South Africa),and the Surrey Space Centre at the University of Surrey (United Kingdom),which led the project.Fer-ried to the International Space Station (ISS)aboard a SpaceX Falcon 9rocket in April 2018,the 100-kilogram
RemoveDEBRIS experiment platform (Fig.1)was designed to test four decidedly nautical-sounding debris-removal technologies:a net,a navigation system,a harpoon,and a drag sail [8].
In June 2018,the Canadarm2robotic arm on the ISS positioned the RemoveDEBRIS mission into orbit.Three months later,RemoveDEBRIS relead a shoebox-sized satellite.This ‘‘cubesat”1.The RemoveDEBRIS satellite,the largest ever deployed from the ISS,moved into an airlock by NASA astronaut Ricky Arnold.The satellite successfully completed three out of its four missions to test technologies for removing debris from orbit.Credit:NASA/NanoRacks.
RemoveDEBRIS then relead another cubesat in December 2018and cloly tracked the spinning object through space with an onboard,vision-bad navigation system consisting of a t of two-dimensional cameras and three-dimensional lidar technology [10].This test demonstrated that the navigation system could be ud in future missions to track debris in space in order to target it for removal.
For the third stage of its mission,which occurred in February 2019,RemoveDEBRIS relead a ping-pong paddle-sized aluminum target supported by a carbon-fiber boom deployed by the satellite. The satellite thenfired a pen-sized titanium harpoon into the tar-get at20mÁsÀ1and reeled it back in(Fig.2)[10].
One month later,the RemoveDEBRIS spacecraft deployed its paper-thin,polyester sheet drag sail[10].The hypothesis was that the10m2sail would catch residual air molecules at the satellite’s 400km altitude,ultimately slowing the satellite down and acceler-ating its descent into the Earth’s atmosphere.Due to design con-straints,the sail was unfurled on the one side of the spacecraft that was out of view of its onboard cameras.Obrvations from the ground indicate that the spacecraft’s orbital trajectory has not changed significantly,and its solar panels are still receiving full sunlight,suggesting that the sail likely did not fully deploy.So,for now,the result of the last experiment remains uncertain.
Regardless,Guglielmo Aglietti,director of the Surrey Space Cen-tre,said the mission was successful on multiple fronts.‘‘As for the technical aspects,we have demonstrated that the methods can work in space,”he said.‘‘The behavior of anything in space is a bit different from what you get on the ground,so for us to e
how certain things actually behaved in orbit was an important learning exerci and will contribute to designing the next missions.”
Another accomplishment of the mission was incread public awareness of the space debris issue.‘‘
灰兔子
This is important,”Aglietti said,‘‘becau at the end of the day if missions to clean space are to be funded through governments or national space agencies,hav-ing favorable public opinion clearly will help.”
And while most of the RemoveDEBRIS demonstrations worked, they were somewhat limited,Weeden said.‘‘There is still quite a long way to go,”he said.‘‘I would hope that other governments—China,Japan,Russia,and the United States—will fund their own technology demonstrations to further this sort of rearch.”
There also remains the possibility that the space debris problem could be tackled—perhaps in part—commercially.Some of the RemoveDEBRIS industrial partners are looking into making a busi-ness out of this,Aglietti said.
‘‘Airbus is examining options relating to active debris removal, including techniques in addition to tho proven in the Remove-DEBRIS project,”said Alexander Hall,a mission systems engineer for Airbus,in an e-mail.‘‘A decision is currently being made as to whether active debris removal is a viable commercial business model,specifically in relation to the increasing number of mega constellations entering into rvice.”
Meanwhile,with the outcome of the drag sail experiment pend-ing,RemoveDEBRIS has ironically become—at least for the time being—another piece of space trash.References
[1]Garcia M,ed.Space debris and human spacecraft[Internet].Washington,DC:
National Aeronautics and Space Administration;2013Sep27[updated2017 Aug7;cited2019May13].Available from:v/ mission_pages/station/news/orbital_debris.html.
[2]Kessler DJ,Johnson NL,Liou JC,Matney M.The Kessler syndrome:implications
to future space operations.Adv Astronaut Sci2010;137(8):2010.
[3]Inter-Agency Space Debris Coordination Committee.IADC space debris
mitigation guidelines.Vienna:United Nations Office for Outer Space Affairs;
2007.
[4]Liou JC.NASA’s long-term debris environment and active debris removal
modeling activities[prentation].In:International Conference on Orbital Debris Removal;2009Dec8–10;Chantilly,VA,USA;2009.
[5]From active debris removal to in-orbit rvicing:the new trajectory of
e.Deorbit,part two[Internet].Paris:European Space Agency;2018Dec18
[cited2019May29].Available from:blogs.esa.int/cleanspace/2018/12/ 18/from-active-debris-removal-to-in-orbit-rvicing-the-new-trajectory-of-e-deorbit-part-two/.
[6]Perrin S.How a startup plans to clean up space[Internet].Lausanne:Ecole
Polytechnique Fédérale de Lausanne;2019Apr5[cited2019May29].
Available from:actu.epfl.ch/news/how-a-startup-plans-to-clean-up-space/.
[7]Phipps C,Baker KL,Libby SB,Liedahl DA,Olivier SS,Pleasance LD,et al.
关于礼仪的作文
Removing orbital debris with puld lars.AIP Conf Proc2012;1464: 468–80.
[8]Forshaw J,Aglietti GS,Navarathinam N,Kadhem H,Salmon T,Pisloup A,et al.
RemoveDEBRIS:an in-orbit active debris removal demonstration mission.Acta Astronaut2016;127:448–63.
[9]Amos J.RemoveDEBRIS:UK satellite nets‘‘space junk”[Internet].London:BBC;
2018Sep19[cited2019May13].Available from:/ news/science-environment-45565815.
[10]Amos J.Space harpoon skewers‘‘orbital debris”[Internet].London:BBC;2019
Feb15[cited2019May13].Available from:/ news/science-environment-47252304
.
Fig.2.The RemoveDEBRIS satellite’s‘‘space harpoon”was designed to skewer and reel in pieces of orbiting space junk.Here,during a ground-bad test,the harpoon’s design was tested on an aluminum ping-pong paddle-like panel similar to the one ud in the orbital test mission.Credit:Airbus/The RemoveDEBRIS Consortium.
608 C.Palmer/Engineering5(2019)607–608
Engineering 2 (2016) xxx–xxx
News & Highlights
清除太空垃圾
Chris Palmer
Senior Technology Writer
2019年3月，“清除碎片”（RemoveDEBRIS ）卫星任务圆满完成，该任务展示了一系列有朝一日可能有助于解决太空垃圾问题的技术。这种在近地轨道上迅速增长的碎片收集正慢慢走向一场危机，这场危机有可能使距离地球表面2000 km 以内的太空区域变得难以使用。
美国国防部估计，在近地轨道上有大约500 000块碎片或空间垃圾，其中，大约23 000个物体比该机构用地面仪器追踪的葡萄柚还大[1]。随着火箭发射的继续和卫星进入轨道的数量的增加，这些物体可能会相撞——从而产生更多的碎片，形成一种危险的级联效应，被称为凯斯勒综合征[2]——正在使现有的、新的和替代的卫星部署处于危险之中。
世界上主要的航天机构都认为轨道碎片是一个严重的问题。机构间空间碎片协调委员会的研究表明，减少新碎片的产生对于轨道飞行任务的未来至关重要，清除现有的碎片也是如此[3]。美国国家航空航天局（NASA ）的另一项研究得出的结论是，为了稳定太空碎片的增长，每年必须清除5～10个最大的碎片物体——从冰箱到城市公交车大小不等的报废卫星[4]。
然而，由于技术和经济方面的挑战，只有少数碎片从轨道上被移走。Brian Weeden 说：“实际上有一些想法对如何上去清除空间碎片是有意义的。”但到目前为止他对资助太空任务的兴趣不大。Brian Weeden 是世界安全基金会的项目规划主任，该基金会是一家位于科罗拉多州布鲁姆菲尔德的组织，
致力于促进外层空间的和平和可持续利用。
作为欧盟委员会自2012年以来资助的一个名为“清
洁空间”（Clean Space ）的更大项目的一部分，欧洲航天局（ESA ）投入了最大的精力来开发和测试主动清除碎片的技术。Weeden 说：“欧洲在这类环境问题上更有前瞻性。”
小学语文一年级下册RemoveDEBRIS 由欧盟委员会赞助，是迄今为止最受关注的活跃碎片清除项目。ESA 正在评估的其他主动清除技术包括：一颗带有机械臂的卫星，该卫星的机械臂可以抓住碎片并将其拖到较低的轨道上，碎片会在大气中燃烧；一种安装在卫星上的锥形网，可以打开并夹住废弃的卫星[5,6]。其他航天机构正在探索使用地面激光烧蚀废弃的卫星和其他碎片的前缘，使这些物体减速并重新进入大气层[7]。
RemoveDEBRIS 航天器由航空航天公司和研究机构组成的国际财团设计和建造，包括空中客车公司（Airbus ）、萨里卫星技术有限公司、瑞士电子与微技术中心（CSEM ）、法国国家信息与自动化研究所（INRIA ）、荷兰小卫星公司（ISIS ）、斯泰伦博斯大学（南非），以及萨里大学（英国）的萨里航天中心共同领导该项目。2018年4月，重100 kg 的RemoveDEBRIS 实验平台（图1）搭载SpaceX 猎鹰9号火箭前往国际空间站（ISS ），以测试四种明显具有航空探测能力的碎片清除技术：网、导航系统、鱼叉和拖帆[8]。
2018年6月，ISS 上的Canadarm2机械臂将Remove-DEBRIS 任务定位到轨道上。三个月后，RemoveDE-BRIS 发射了一颗鞋盒大小的卫星。这颗立方体卫星向外漂移了7 m ，并将一组帆充气，使其整体尺寸增加到1 m 宽。然后发射出一个直径为5 m
的网，将立方体卫星
Contents lists available at ScienceDirect
Engineering
2Author name et al. / Engineering 2(2016) xxx–xxx
包裹起来[9]。在接下来的几个月里，网慢慢地增加了
立方体卫星的阻力，将它扔进地球大气层，并于2019年
3月烧毁。
RemoveDEBRIS随后于2018年12月发射了另一颗立
方体卫星，利用机载的视觉导航系统，包括一组二维摄
怎么做寿司像头和三维激光雷达技术，在太空中密切跟踪旋转的物
体[10]。这项试验表明，导航系统可以在未来的任务中用于跟踪空间碎片，以将其作为目标进行清除。
在其任务的第三阶段，即2019年2月，RemoveDE-BRIS发射了一个乒乓球拍大小的铝靶，由卫星部署的碳纤维吊杆支撑。然后，卫星以20 m·s–1的速度向目标发射了一支钢笔大小的钛鱼叉，并将其卷起（图2）[10]。
一个月后，RemoveDEBRIS太空船部署了薄纸般的聚酯板拖帆[10]。假设10 m2的帆在卫星400 km的高度捕获剩余空气分子，最终使卫星减速并加速降落到地球大气中。由于设计上的限制，在飞船的一侧展开了帆，而飞船的车载摄像头看不到它。地面观测表明，航天器的轨道没有明显改变，其太阳能电池板仍能接收到充足的阳光，这表明该帆可能没有完全展开。因此，目前为止，最后一次实验的结果还不确定。
不管怎样，萨里空间中心主任Guglielmo Aglietti说，这次任务在多个方面都取得了成功。“在技术方面，我们已经证明这些方法可以在太空中工作，”他说，“太空中任何物体的行为都与地面上的有所不同，所以对我们来说，了解某些物体在轨道上的实际行为是一项重要的学习活动，将有助于设计下一个任务。”
该任务的另一项成就是提高了公众对空间碎片问题的认识。“这很重要，”Aglietti说，“因为如果清洁空间的任务最终要由政府或国家航天机构资助，拥有良好的公众舆论显然会有所帮助。”
尽管大多数的RemoveDEBRIS演示都有效，但它们还是有一定的局限性。“还有很长的路要走，”Weeden说，“我希望其他政府——中国、日本、俄罗斯和美国的政府将资助他们自己的示范技术，以进一步开展此类研究。”
太空碎片问题仍有可能得到解决——或许在一定程度上从商业上解决。Aglietti说，RemoveDEBRIS的一些工业合作伙伴正在考虑利用这一点开展业务。
Airbus的任务系统工程师Alexander Hall在一封电子邮件中说：“空客正在研究与主动清除碎片有关的方案，包括已在RemoveDEBRIS项目中证明的技术之外的其他技术。”“目前我们正在决定，积极清除碎片是否是个可行的商业模式，特别是考虑到越来越多的巨型星座投入使用。”
与此同时，随着阻力帆实验的结果悬而未决，具有讽刺意味的是，至少在目前，RemoveDEBRIS已经成为另一块太空垃圾。References
[1] Garcia M, ed. Space debris and human spacecraft [Internet]. Washington, DC:
National Aeronautics and Space Administration; 2013 Sep 27 [updated 2017 Aug 7; cited 2019 May
13]. Available from: v/ mission_ pages/station/news/orbital_debris.html.
[2] Kessler DJ, Johnson NL, Liou JC, Matney M. The Kessler syndrome: implications
to future space operations. Adv Astronaut Sci 2010;137(8):2010.
清澈反义词
[3]Inter-Agency Space Debris Coordination Committee. IADC space debris孤儿英语
图1. RemoveDEBRIS卫星是国际空间站上部署的最大的卫星，由
NASA宇航员Ricky Arnold送入气闸中。该卫星成功地完成了四个任
务中的三个，以测试从轨道上清除碎片的技术。图片来源：NASA/
NanoRacks 。
图2. RemoveDEBRIS卫星的“太空鱼叉”设计用于碾碎和卷绕轨道
上的太空垃圾。在地面测试中，鱼叉的设计是在类似于轨道测试任
务中使用的铝制乒乓球拍板上进行测试的。图片来源：Airbus/The
RemoveDEBRIS Consortium。
3 Author name et al. / Engineering 2(2016) xxx–xxx
mitigation guidelines. Vienna: United Nations Office for Outer Space Affairs;
2007.
[4] Liou JC. NASA’s long-term debris environment and active debris removal
modeling activities [prentation]. In: International Conference on Orbital Debris Removal; 2009 Dec 8–10; Chantilly, VA, USA; 2009.
[5] From active debris removal to in-orbit rvicing: the new trajectory of
e.Deorbit, part two [Internet]. Paris: European Space Agency; 2018 Dec 18
[cited 2019 May 29]. Available from: blogs.esa.int/cleanspace/2018/12/ 18/from-active-debris-removal-to-in-orbit-rvicing-the-new-trajectory-ofe- deorbit-part-two/.
[6] Perrin S. How a startup plans to clean up space [Internet]. Lausanne: Ecole
Polytechnique Fédérale de Lausanne; 2019 Apr 5 [cited 2019 May 29].羊肉火锅底料配方
Available from: actu.epfl.ch/news/how-a-startup-plans-to-clean-
upspace/.
[7] Phipps C, Baker KL, Libby SB, Liedahl DA, Olivier SS, Pleasance LD, et al.
Removing orbital debris with puld lars. AIP Conf Proc 2012;1464: 468–
80.
[8] Forshaw J, Aglietti GS, Navarathinam N, Kadhem H, Salmon T, Pisloup A, et
al. RemoveDEBRIS: an in-orbit active debris removal demonstration mission.
Acta Astronaut 2016;127:448–63.
[9] Amos J. RemoveDEBRIS: UK satellite nets ‘‘space junk” [Internet]. London:
BBC; 2018 Sep 19 [cited 2019 May 13]. Available from: / news/science-environment-45565815.
[10] Amos J. Space harpoon skewers ‘‘orbital debris” [Internet]. London: BBC; 2019
Feb 15 [cited 2019 May 13]. Available from: / news/ science-environment-47252304.
