評論
打印
Narrator:Listen to part of a lecture in an Astronomy Class
獨(dú)白:聽下面一部分的天文學(xué)課程
Professor:Last week, we covered some arguments against going back to the Moon.
教授:上周，我們談到了反駁回到月球的一些觀點(diǎn)。
But there are compelling reasons in favor of another Moon landing too,
而這節(jié)課我們要談到的是支持登月的幾個(gè)充分原因。
um… not the least of which is trying to pinpoint the moon's age.
我們這樣做絕不是試圖得出月球的確切壽命。
We could do this in theory by studying an enormous impact crater, known as the South Pole-Aitken Basin.
理論上，我們可以通過研究一個(gè)名為南極艾特肯盆地的巨大撞擊坑來得出結(jié)論。
Um…it's located in the moon's South Polar Region.
嗯，它位于月球的南極區(qū)。
But, since it's on the far side of the moon, it can only be seen from space.
但是，由于它位于距地球很遠(yuǎn)的一邊，我們只能在太空中才能看到它，
Here is an image of…
我這里有一張圖片。
we'll call it the SPA Basin.
我們將其命名為 SPA 盆地。
This color-coated image of the SPA Basin, those aren't its actual colors obviously,
可以看到盆地上一層著色的圖層，很明顯這不是真實(shí)的顏色。
this image is from the mid 90s, from the American spacecraft called Clementine.
這張圖拍攝于九十年代中期，來自名為克萊門的美國宇宙飛船。
Um… unlike earlier lunar missions, Clementine didn't orbit only around the moon's equator.
不像早些時(shí)候的月球探測，嗯，克萊門飛船并沒有僅僅沿著月球的軌道。
Its orbits enable it to send back data to create this topographical map of …
這種特殊的飛行使得飛船能夠發(fā)送數(shù)據(jù)回地球，從而得出這張地形圖。
well, the grey and white area towards the bottom is the South Pole,
延伸至底部的灰白區(qū)域是南極，
the purples and blues in the middle correspond to low elevations,
中間紫色和藍(lán)色的部分是海拔較低的地帶，
the SPA Basin itself, the oranges and reds around it are higher elevations.
而橙紅色地帶的SPA 盆地海拔較高。
The basin measures an amazing 2,500 km in diameter, and its average depth is 12 km.
盆地直徑達(dá)到驚人的 2500 千米，平均深度達(dá)到 12 千米。
That makes it the biggest known crater in our solar system and it may well be the oldest.
這使得它成為了太陽系中已知的最大撞擊坑，很可能也是年代最久遠(yuǎn)的。
You know planetary researchers love studying deep craters until learn about the impacts that created them, how they redistributed pieces of a planet's crust and in this case,
我們知道，在知道行星形成的原因之前，行星研究人員喜歡研究撞擊深坑，它們?nèi)绾沃匦路峙湫行堑耐鈿の镔|(zhì)。
we especially want to know if any of the mantle, the layer beneath the crust, was exposed by the impact.
我們特別想知道在外殼下層中是否存在某些金屬因撞擊而受到影響。
Not everyone agrees,
不是所有人都同意這樣的說法，
but some experts are convinced that whatever created the SPA Basin did penetrate the Moon's mantle.
但是某些專家堅(jiān)信不管何種物質(zhì)使 SPA 盆地形成，它都會(huì)滲透過月球的金屬層。
And we need to find out, because much more than the crust, the mantle contains information about a planet's or Moon's total composition.
而由于金屬層包含信息比外殼要多得多，我們必須找到一個(gè)行星或是月球的整體構(gòu)成要素。
And that's key to understanding planet formation. Um… Dian?
這是了解行星構(gòu)成的關(guān)鍵所在。迪安有問題嗎？
Dian:So, the only way to know the basin's age is to study its rocks directly?
迪安:那么知道盆地形成時(shí)間的唯一途徑就是對其巖石進(jìn)行直接的研究？
Professor:well, from radio survey data, we know that the basin contains lots of smaller craters.
教授:嗯，輻射調(diào)查的數(shù)據(jù)顯示，我們知道盆地里有很多更小的火山口。
So it must be really old, about 4 billion years, give or take a few hundred million years.
因此應(yīng)該有一定歷史了，大概 40 億年，允許有一億年左右的誤差。
But that's not very precise.
但也不是很精確。
If we had rock samples to study, we'd know whether the small craters were formed by impacts during the final stages of planetary formation,
如果我們研究巖石樣本，我們就知道小火山口是不是在行星形成的最后階段影響而形成的，
or if they resulted from later meteor showers.
或者是否由于最近的流星雨造成的。
Dian:But if we know around how old the Basin is, I'm not sure that's reason enough to go to the Moon again.
迪安:但如果我們知道了盆地的大概年齡，我不敢確定這是否足以成為我們再次登月的理由。
Professor:No…, but such crude estimates…um…we can do better than that.
教授:不。。這只是粗略的估計(jì)，嗯，我們能得到更為準(zhǔn)確的數(shù)字。
Besides, there are other things worth investigating, like is there water ice on the moon?
此外，還有其他東西值得。研究，比如月球上有水冰資源嗎？
Clementine's data indicated that the wall of the south-polar crater was more reflective than expected.
克萊門的數(shù)據(jù)顯示南極撞擊坑比人們預(yù)期的要更具有反射效果，
So some experts think there's probably ice there.
因此某些專家認(rèn)為那里很可能有冰的存在。
Also, data from a later mission indicates significant concentrations of hydrogen and by inference water less than a meter underground at both poles.
同樣，最近的一項(xiàng)月球探測任務(wù)數(shù)據(jù)顯示，那里氫氣高度密集，據(jù)推測，兩級(jí)的水就在地下不到一米處。
Student:Well if there's water, how did it get there?
學(xué)生:嗯，如果有的話，水是怎么到達(dá)的呢？
Underground rivers?
地下河？
Professor:We think meteors that crashed into the moon or tails of passing comets may have introduced water molecules.
教授:我們認(rèn)為撞擊月球的流星或經(jīng)過的彗星尾巴留下一些水分子。
Any water molecules that found their way to the floors of craters near the moon's poles, that water would be perpetually frozen, because the floors of those craters are always in shadow.
水分子會(huì)沿路到達(dá)月磁極旁的火山口地上，由于這些火山口的地面總是處在陰影中，水分子會(huì)永遠(yuǎn)凍結(jié)。
Um…furthermore, if the water ice was mixed in with rock and dust, it would be protected from evaporation.
嗯，還有，如果在水冰中混雜石頭和灰塵，便不會(huì)容易蒸發(fā)掉。
Dian:So are you saying there might be primitive life on the moon?
迪安:那么你是不是說月球上可能有原始生物？
Professor:that's not my point at all. Um… o.k., say there is water ice on the moon.
教授:我不是這個(gè)意思。嗯，好吧，假設(shè)月球上有水冰。
That would be a very practical value for a future moon base for astronauts.
這對未來在月球上駐地的宇航員們而言將會(huì)有非常實(shí)際的價(jià)值。
Water ice could be melted and purified for drinking.
水冰可以融化過濾，供人飲用。
It could also be broken down into its component parts-oxygen and hydrogen.
同時(shí)也可以分解成氧和氫兩種元素。
Oxygen could be used to breathe, and hydrogen could be turned into fuel, rocket fuel.
氧氣供人呼吸，而氫氣可以轉(zhuǎn)化成燃料，特別是火箭燃料。
So water ice could enable the creation of a self-sustaining moon base someday, a mining camp perhaps or a departure point for further space exploration.
因此，未來自給自足的月球基地將成為可能，也許一個(gè)采礦營或者是未來太空探索的出發(fā)點(diǎn)。
Student:But holding tons of equipment to the moon to make fuel and build a life support system for a moon base, wouldn't that be too expensive?
學(xué)生:但是帶著噸重的裝備到月球去制造燃料，給月球研究基地提供生命支持系統(tǒng)，代價(jià)不會(huì)太高了嗎？
Professor:Permanent base, maybe a way's off, but we shouldn't have to wait for that.
教授:永久基地，也許是一種解決方式，但我們不需要等那么久。
The dust at the bottom of the SPA Basin really does have a fascinating story to tell.
SPA 盆地底部的灰塵蘊(yùn)藏著非常有趣的故事。
I wouldn't give for a few samples of it.
我不會(huì)錯(cuò)失一些樣本的。
