評論
打印
Science and technology
科學技術
Stopping asteroid strikes
阻止小行星撞擊地球
Defenders of the Earth
地球的守護者
The cosmic near-miss in February has boosted research on space rocks
二月一顆小行星掠過地球，促進了對太空巖石的研究
ON JUNE 24th NASA, America's space agency, announced it had discovered the 10,000th Near Earth Object,
6月24日，美國宇航局NASA宣布已發現第10000顆近地天體。
the rather dry name given to asteroids and comets that orbit the sun in the vicinity of Earth and which might, therefore, one day smash into it.
這個頗為平淡的名稱指的是在地球鄰近區域圍繞太陽運動的小行星和彗星，它們可能說不定哪天就撞向地球。
Ten thousand potentially dangerous objects sounds a lot, but NASA reckons there could be ten times as many still waiting to be found.
一萬顆潛在危險物體聽起來很多，但NASA認為尚待發現的NEO數量，可能是這個數字的10倍。
A week earlier, on June 18th, the agency therefore launched a Grand Challenge intended to recruit and co-ordinate help from industry, academia and anyone else who is interested for a project to detect any asteroid that could threaten Earth.
一星期前的6月18日，NASA因此發布了一項大挑戰，為一個探測可能威脅地球的小行星的工程，向企業界和學術界求助，意圖從中招募人才和協調力量，任何對此有興趣的個人也可以參與進來。
All ideas are welcome.
NASA對各方建議一概歡迎。
NASA's bosses are also thinking of allocating extra time on the ground-based telescopes they control to the search for such threats.
NASA的領導們也在考慮將旗下的地面望遠鏡更多地用于搜索此類威脅。
They have plans, too, to revive a mothballed space telescope called the Wide-field Infrared Survey Explorer to aid in the hunt.
同時，他們還打算喚醒一臺休眠中的太空望遠鏡—廣域紅外巡天探測者—來協助搜尋工作。
And Lori Garver, the agency's deputy administrator, has asked for the budget of a programme to find 90% of NEOs with a diameter above 140 metres to be doubled.
NASA還有一個項目，旨在找出90%的直徑在140米以上的NEO，NASA副署長洛瑞-伽爾瓦已申請將該項目的預算加倍。
So far, NASA reckons it has a quarter of these in the bag, but finishing the job at the present rate of discovery will take decades.
目前，NASA估算自己已確認了這些NEO中的四分之一，但按照目前的探測進度計算，完成這項工作還需要幾十年時間。
Nor is this renewed effort all NASA's.
在這股NEO探測復興中努力的不只有NASA一家。
The European Space Agency is chipping in, too.
歐洲航天局也參與其中，
In May it opened a NEO Co-ordination Centre, to help scientists organise their work and share data.
5月開放了一個NEO協調中心，該中心能幫助眾科學家組織工作和分享數據。
And the B612 Foundation, a charity which hopes to build and launch an asteroid-hunting space telescope called Sentinel, has also reported a substantial rise in donations.
此外還有一個叫做B612基金會的慈善組織，希望建造和發射一臺名為哨兵的太空望遠鏡，用于小行星搜尋。該基金會報告稱其獲得捐款數顯著上升。
The reason for all this activity is the events of February 15th, when an asteroid a mere 15-20 metres across exploded with the force of a medium-sized atom bomb over Chelyabinsk, in Russia, and another, much larger one buzzed Earth a few hours later.
上述所有行動，都是因為2月15日發生了一些事情，一顆半徑只有15-20米的小行星在俄羅斯車里亞賓斯克州上空爆炸，威力相當于中等大小的原子彈；就在數小時之后，又有一顆比這大得多的小行星掠過地球。
What had been regarded as the stuff of science-fiction novels suddenly became a clear and present danger—but one that, unlike earthquakes, volcanic eruptions, tsunamis and hurricanes, might actually be prevented by timely human action.
原先認為是科幻小說里的情節，突然變成了實實在在的危險—但與地震、火山噴發、海嘯和颶風等災難不同的是，人類可以采取及時的行動阻止小行星撞擊地球。
NEOShield, a research project involving several European Union countries, as well as Russia and the United States, is looking at three main ways of diverting incoming asteroids.
近地軌道防護盾是幾個歐盟國家與俄羅斯美國合作開展的研究項目，研究讓來襲的小行星改變方向的三個主要辦法。
One is to use a kinetic impactor—in effect employing a heavy, fast-moving spacecraft as the cue ball in a game of interplanetary billiards.
一種辦法是使用動能沖擊飛船—就好像把一種重型快速移動的飛船當做白球，在太空打臺球一樣。
The second is a gravity tractor.
第二種是重力牽引飛船，
This is a spacecraft parked near an asteroid, so that its minute gravitational pull will slowly tug the rock into a safer orbit.
這種航天器會靠在小行星旁邊，利用微小的引力效應，慢慢把巖石牽引到安全的軌道。
And if an incoming object is particularly large, or is detected particularly late, the third course of action would be to blast it into a new orbit with nuclear weapons.
如果來襲的物體特別大，或者偵測得特別晚，就輪到第三種應對措施了—使用核武器把它炸到新的軌道上。
If all else fails, or if a threat is spotted too late to deflect, there is also the option of evacuation.
如果所有手段失敗的話，或者威脅發現得太晚以至于無法讓它轉向，我們還有疏散的選擇。
In 2008, for example, a small asteroid was detected 20 hours before it hit Earth. The world's astronomers scrambled, and its likely point of impact was calculated with what turned out to be reasonable accuracy.
舉例來說，2008年，一顆小行星在撞擊地球前的20小時才偵測到。全世界的天文學家急忙開始行動，結果證明，計算撞擊點的精確度還是不錯的。
It blew up over the Nubian Desert, in Sudan, and no one was injured.
這顆小行星在蘇丹的努比亞沙漠上空爆炸，無人受傷。
But this incident showed that a properly organised early-warning system might pay dividends if ground zero turned out to be a populated area.
但這個事件說明，如果地面零點是居住區域的話，組織恰當的預警系統就能顯示出它的價值了。
John Tonry, of the University of Hawaii, hopes to provide one.
夏威夷大學的約翰-通瑞希望自己能提供一個預警系統。
He is working on an eight-telescope system called ATLAS.
他正在開發一個8臺望遠鏡組成的系統，名為ATLAS。
It is designed to scan the whole sky twice a night, looking for fast-moving objects.
根據設計，該系統每晚會對天空全面掃描兩次，搜尋快速移動的物體。
Unlike most astronomers, Dr Tonry presumably hopes he will not find what he is looking for.
與大多數天文學家不同的是，通瑞博士可能不太希望找到他要找的東西。
But if he does, many people who would not otherwise have lived to tell the tale may thank him.
但如果他找到了，會有許多人感謝他的—否則他們都無法幸存下來，向他人訴說這次慘遇。
