Dealing with celestial scrap
Removing space junk
Plans to clean up orbits around Earth are being hatched
Jan 12th 2021 |
scrap n.小片，小塊; 碎屑; 廢品，廢棄材料; scraps [複數]吃剩的東西，殘羹剩飯; 〔消息、事實等的〕一點點，點滴; 【非正式】 爭吵，吵架; 打架; v. 〔因不切實際而〕放棄，拋棄〔計劃、體系〕; 把〔舊機器、舊汽車等〕當作廢料處理，報廢
hatch v.〔蛋〕孵化; 孵出; hatch out〔幼禽等〕破殼而出; 孵出; hatch a plot/plan/deal etc 密謀/秘密計劃/秘密策劃交易等; n.〔船、飛機上的〕艙口; 艙門, escape hatch 逃逸艙口，應急離機口
HUMAN BEINGS are messy. They tend to leave rubbish behind them wherever they go—and to expect someone else to clear that rubbish up. This is true even in outer space. The problem of orbiting debris, and the concomitant risk of it colliding with and damaging an active and probably expensive satellite, has been around for a while. But it is rapidly getting worse. There may now be as many as 1m bits of debris measuring 1cm or more across in orbit. Of larger objects, more than 20,000 are being actively tracked from Earth. And, according to Daniel Oltrogge, an expert who advises the Space Data Association, an industry body, on such matters, the past three years have seen a doubling of the number of times that bits of junk have almost hit operating satellites.
In the short term, satellite owners can, literally, dodge the problem—as long as their craft are fitted with appropriate thrusters. Mr Oltrogge’s day job is to arrange for that to happen, for he also works for AGI, an American firm that develops (among other things) software which helps satellite operators sidestep such collisions. In the longer term, however, more radical action will be needed.
dodge v. 〔快速〕躲開，避開，閃開; 〔故意〕避開，避免〔談到或做某事〕; SYN evade, duck;
這裡出現的短語 dodge the problem 逃避/避開問題可以借鑑在寫作中
thruster n.助力器；（尤指太空飛行器的）推進器，加速器
sidestep v.
sidestep 1. sidestep a problem/issue/question 迴避問題: 2. 橫跨一步躲過，側移一步閃開
Part of the problem is the growing number of launches taking place. On January 17th, for example, Virgin Orbit, a new entrant to the market that is part of Richard Branson’s Virgin Group, plans to launch ten satellites into orbit using a rocket released from a modified Boeing 747-400. Another part, though, is that, every year, a dozen or so sizeable chunks of debris orbiting Earth break up. Around half of these explosions are caused by things like the ignition of leftover rocket fuel and the bursting of old batteries and pressurised tanks. The rest are the result of collisions.
entrant n.參賽者; 【尤英】 大學新生; 新職員
sizeable a.相當大量的，SYN considerable
ignition n.〔汽車引擎的〕點火裝置 ; 【正式】 著火，起火燃燒; 點火
pressurise v.使（潛艇、飛機等內）保持正常氣壓 ; 逼迫；使迫不得已 pressurize~ sb (into sth/into doing sth) ,相當於force；
The upshot is a chain reaction of impacts in orbit. Unlike the fictional version of such a chain-reaction, which inconvenienced Sandra Bullock’s character in 「Gravity」, a film released in 2013, this real one is accelerating only slowly, so there is still time to curtail it. But if action is not taken soon, insurance premiums for satellites will rise, spending on tracking and collision-avoidance systems will have to increase, and certain orbits eventually risk becoming unusable.
Drop shots
Stopping this orbital-junk-generating chain reaction means casting part of the superfluous tonnage in space down into Earth’s atmosphere, where the frictional heat of re-entry will burn it up. A clean sweep is not necessary.
drop shot 〔網球等的〕網前球，短吊，短球
superfluous a.【正式】 多餘的，過剩的，不必要的; SYN unnecessary
tonnage n.〔以噸計的〕總重量，總噸數
Removing a handful of the larger derelicts every year would be enough. Exactly how many is debated. Yamamoto Toru of Japan’s space agency, JAXA, estimates somewhere between three and seven. Ted Muelhaupt of America’s Aerospace Corporation, a taxpayer-funded research centre, reckons a dozen. But even that sounds doable. Except that no one knows how to do it.
derelict a.〔建築物或土地〕破舊的，棄置的; n. 無家可歸者，社會棄兒〔含貶義〕
reckon v. 認為，相當於believe， think
doable a.【口，非正式】 可做的，可行的
People are, though, planning to practice. One such rehearsal, scheduled for lift-off in March, is led by Astroscale, a firm based in Tokyo. Astroscale proposes to launch, from Baikonur Cosmodrome in Kazakhstan, a mission dubbed ELSA-d. This consists of a 175kg mother ship called a servicer, and a 17kg pod fitted with a ferrous docking plate that will act as a dummy target. If all goes well, the servicer will eject and recover the pod three times, in successively harder trial runs, before thrusters push the whole kaboodle to fiery doom in the atmosphere below.
dub v.把…稱為，給…起綽號， SYN label , name：be dubbed sth, 被稱為…. ；為〔電影或電視節目〕配音
servicer n. 燃料加注車,(飛彈發射)服務車
pod n.〔太空船的〕可分離艙; 〔尤指飛機翼下的〕吊艙; 豆莢, 詞組like two peas in a pod 【非正式】 〔容貌、行為等〕一模一樣的
ferrous a.【術語】含鐵的; 鐵的
kaboodle n. 群；捆（等於caboodle）
fiery a.火紅的; 火一般的; 易怒的，暴躁的; 怒氣衝衝的; 充滿激情的〔食物或飲料〕辣的
In the first test, the servicer will use springs to push the pod out and then, once it is ten metres away, will approach it again, lock onto the docking plate using an arm fitted with a magnetic head, retract the arm and pull it back to the servicer. For the second test, it will push the pod at least 100 metres away before its starts approaching it. A reaction wheel and a set of magnetic torque-generators will then put the pod into a tumble involving all three axes of motion, at a speed of half a degree a second.
retract v.（使）縮回，（使）縮入; 收回，撤回〔已說的話或已答應的事〕; SYN withdraw;
reaction wheel 反動式葉輪 （A reaction wheel is a type of flywheel used primarily by spacecraft to change their angular momentum without using fuel for rockets or other reaction devices.）
torque n. (尤指機器的)扭轉力;轉(力)矩
torque-generator 扭矩發電機
This is, as it were, an important twist—for chunks of orbiting debris typically spin in this fashion. A real deorbiting mission will therefore have to deal with such spinning objects. Markings on the pod will help the servicer work out its prey’s motion. Using eight thrusters, it will manoeuvre itself until those markings appear, to its sensors, to be stationary. This will mean its motion exactly matches that of the tumbling pod, and that the magnetic head can therefore be extended to do its job.
manoeuvre v.巧妙地移動[轉動]〔尤指大而重的物件〕；策劃; 誘使； n.熟練[謹慎]的動作; 策略，巧計，花招; manoeuvres [複數] 軍事演習; room for manoeuvre/freedom of manoeuvre 迴旋的餘地
stationary a.不（移）動的; 靜止的; 形近詞語 stationery 〔一般指有信封配套的〕信紙，信箋; 文具
For the third capture test, the servicer will first use its thrusters to back off several kilometres from the pod, putting the pod beyond sensor range. Then it will search for it, as would need to be the case if it were hunting for a real derelict spacecraft.
For all the technological prowess these tests will require, however, real derelicts pose a greater challenge than dummy ones. For one thing, unlike Astroscale’s pod, few spacecraft have been designed to expedite their own removal. Also, those objects which most need removing are dangerously heavy. A spacecraft that miscalculates while attempting to capture a massive piece of tumbling debris could be smashed to smithereens, thus contributing to the problem it was supposed to be solving.
Grasping the matter
The Commercial Removal of Debris Demonstration, a plan by JAXA to deorbit a discarded Japanese rocket stage, highlights these difficulties. Before a spacecraft can be designed to capture whichever derelict Japan’s space agency selects as the experiment’s target, a reconnaissance mission must first be launched to study it up close. JAXA has awarded the contract for this part of the demonstration to Astroscale, which plans to do it using a craft, called ADRAS-J, that will be launched in two years』 time. To measure the motion and features of a rocket part which might weigh tonnes, ADRAS-J will approach within mere metres. Once it collects the necessary data, another spacecraft can be designed to seize the junk on a subsequent mission.
In this case, magnets will not be used to grapple with the target, for normal spacecraft have no iron in them. Using a harpoon to capture such an object might be feasible, though. In a test conducted in 2019, Airbus, a European aerospace giant, successfully shot a harpoon from a satellite into a piece of panelling 1½ metres away. However, that panelling was attached to a boom extending from the satellite, so this was but the most preliminary of experiments. Also, a harpoon can miss, ricochet or—worse—break off parts of the target which will then contribute yet more objects to the celestial junkyard.
harpoon n. 捕鯨叉
feasible a.可行的，行得通的
panelling n. 〔用於裝飾牆壁的〕嵌板，鑲板
boom n. 帆桁，帆杆; 〔起重機的〕吊杆，起重臂; 〔橫攔於河面或港灣以阻止物件漂走的〕擋柵，水柵; 〔生意〕繁榮，興旺，激增;OPP slump
this was but 僅僅，只，不過是
ricochet v.〔子彈、石塊等運動物體〕回跳，反彈 ; n.彈飛的物體
Another option is to shoot a net. Airbus tested this idea in 2018. That test successfully enveloped a small 「cubesat」 which had been pushed seven metres away from the net-throwing craft—though this net was not tethered to the mother ship, which would therefore have been unable to deorbit its target. Tethers are hard to manage in the weightlessness of orbit, which is why Airbus chose not to use one in this preliminary net-tossing experiment. That leads some to doubt whether such cosmic retiarii are a sensible idea at all. Chris Blackerby, Astroscale’s chief operations officer, expects the best approach will be to design robotic arms to clench the target vehicle’s fairing-connector ring (the shallow cylinder that links a rocket’s upper stage to the covering of its payload), if this proves still to be intact.
envelop v.【正式】 覆蓋；包住
tether v.拴住，系住〔牲畜〕; n. 拴牲畜用的〕繫繩，拴鏈; be at the end of your tether to be so worried, tired etc that you feel you can no longer deal with a difficult or upsetting situation 無計可施; 走投無路; 一籌莫展
weightlessness n. 失重狀態 weightless a.失重的
clench v.緊握; 緊咬； 〔因憤怒或下決心而〕握緊拳頭/咬緊牙關等
fairing n. a member or structure whose primary function is to produce a smooth outline and to reduce drag (as on an airplane)
cylinder n.圓柱體; 圓筒; 〔發動機的〕汽缸: a four-cylinder engine 四汽缸引擎; be firing/running on all cylinders 【非正式】 竭盡全力，開足馬力
payload n.運輸工具的〕最大載荷，有效載荷; 〔運輸工具的〕裝載貨物;
intact a.完好無損的，未受損傷的
If all that works, JAXA’s debris-removal demonstration will face a final challenge. This is to execute a safe re-entry. Many pieces of the re-entering complex of captor and captive will survive frictional melting and slam, at speed, into Earth’s surface. Were re-entry to occur at a random spot, the probability of a human casualty would now exceed the threshold of one in 10,000 that NASA, America’s space agency, set as an acceptable level of risk in 1995, and which was adopted by Japan and other countries thereafter. The complex will therefore need to be put into a steep descent aimed at an uninhabited area—probably part of the Pacific Ocean.
captor n. 捕捉者
captive n.被捕捉的…； 囚徒，戰俘，俘虜；be captive to sth 受某物禁錮，受某物影響而無法擺脫: Our communities should not be captive to the mistakes of the past. 我們的社會不應受制於過去犯下的錯誤。
descent n.& v.【正式】 下降，降落; 出身，血統; 淪落，墮落: descent into alcoholism/chaos/madness etc; 【英】 〔不受歡迎的〕突然到訪; 突襲
As to the first clearance of actual orbiting debris, that is likely to be a European affair, for, in 2019, the European Space Agency awarded a contract to ClearSpace, a Swiss firm, to grab a 100kg piece of rocket debris that has been looping Earth since 2013. This mission is scheduled for 2025.
ClearSpace plans to use a capture craft fitted with four robotic arms. Unlike harpoons or net tosses, this strategy permits repeated attempts at recovery to be made. Even so, Luc Piguet, ClearSpace’s boss, expects his spacecraft will spend at least nine months in trials near the target before it secures the derelict and decelerates sufficiently to descend.
Pay up!
An era of serious cleanup in space is still some way off. Besides the technological obstacles, removing junk will be expensive. The controlled re-entry of an object requires fuel, big thrusters and close attention from a ground controller. These things can tack millions of dollars—perhaps more than $20m—onto a deorbiting operation’s price tag. ClearSpace’s mission, for example, may cost as much as €100m ($122m), though Mr Piguet hopes subsequent jobs will be cheaper.
pay up : to pay money that you owe, especially when you do not want to or you are late
tack v.〔用圖釘〕把…釘上: tack sth to sth; 〔船〕搶風航行; 〔大針腳〕暫縫，粗縫 n. 平頭釘，大頭釘; 【美】圖釘，按釘;SYN thumbtack; SYN drawing pin BrE 【英】 ;方針; 方法; 思路; 【術語】 馬具，鞍轡 ; 【英】 〔難看而廉價的〕小裝飾品
tack sth. on: 〔尤指畫蛇添足地〕增補，附加
Cheaper or not, the question remains, 「who will pay」? The littering of space is a textbook example of the tragedy of the commons, in which it is in everyone’s interest for a problem to be solved, but no one’s to be the lone individual who takes on the burden of solving it.
The solutions to tragedies of the commons usually have to be imposed from outside, often by governments. One idea is a special launch tax, with the proceeds hypothecated to pay for cleanup operations. A more creative proposal is what Mr Muelhaupt calls 「a bottle-deposit system」. Spacefarers would pay a deposit for each craft they lofted into orbit. If owners then failed to deorbit their equipment after its mission was over, the job could be done by someone else, who would collect the deposit instead. That would encourage people to build deorbiting capabilities into satellites from the start, so the celestial dustmen would eventually no longer be needed. A third suggestion, proposed by Akhil Rao of Middlebury College, in Vermont, is to charge rent, known as orbital-use fees, for every commercial satellite in orbit. That would have the same effect.
Support for such schemes is growing, though they would require both international agreements between countries with launch facilities and an enforcement mechanism to stop outsiders with laxer rules from undercutting the arrangement.
There is also one other point. As Jean-Daniel Testé, once head of the French air force’s joint space command, notes, equipment developed for orbital cleanup could be used to disable satellites, too. Mr Testé says advances in orbital robotics made by France’s adversaries, not to mention the lack of any international 「space gendarmerie」, are leading his country to plan spacecraft to defend its military and intelligence satellites.
Mr Testé is coy on specifics. But France’s armed-forces minister, Florence Parly, has revealed more about her country’s plans than have her equivalents in other powers, America included. She foresees France launching special 「lookout」 and 「active defence」 spacecraft, to protect its assets in space. The latter are likely to be armed with powerful lasers. As Ms Parly has put it, 「we intend to blind」 threatening spacecraft. Preferably without disintegrating them.■