US spacecraft set for Moon crash 美宇宙飞船将坠落月球
文章来源:未知 文章作者:meng 发布时间:2009-10-09 05:12 字体: [ ]  进入论坛
(单词翻译:双击或拖选)

Nasa is set to crash two unmanned spacecraft into the Moon in a bid to detect the presence of water-ice.

美国航空航天局将向月球坠落两艘无人宇宙飞船以探测冰水是否存在。

The "shepherding spacecraft" will analyse the impact <a href=debris1" width="466" border="0" src="/upimg/091009/4_053118_1.jpg" />
The "shepherding spacecraft" will analyse the impact debris

A 2,200kg rocket stage will be first to collide, hurling2 debris(碎片,残骇) high above the lunar surface.

A second spacecraft packed with science instruments will analyse the contents of this dusty cloud before meeting a similar fate.

The identification of water-ice in the impact plume3(羽流) would be a major discovery, scientists say.

Not least because a supply of water on the Moon would be a vital resource for future human exploration.

The existence of water-ice in permanently4 shadowed craters6(弹坑,火山口) at the lunar poles had previously7 been postulated8(要求,假定) by scientists, but never confirmed.

The $79m (£49m; 53m euro) mission is called LCROSS (the Lunar Crater5 Observation and Sensing Satellite).

There are two main components9: the large Centaur10 rocket upper stage and a smaller "shepherding spacecraft".

These have been connected since they were launched from Cape11 Canaveral, Florida, in June.

The shepherding spacecraft is designed to guide the rocket to its target at the Moon's south pole, a shaded 98m-wide depression called Cabeus crater.

Rocket separation

In the early hours of Friday morning (BST), the Centaur and shepherding spacecraft will separate.

At a scheduled time of 1231 BST (0731 EDT), the rocket stage will hit the Moon's south pole at roughly twice the speed of a bullet, throwing an estimated 350 metric tonnes(公吨) of debris to altitudes(高度) of 10km (6.2 mile) or more.

With an energy equivalent to one-and-a-half tonnes of TNT, the collision will carve out a crater some 20m (66ft) wide and about 4m (13ft) deep.

The shepherding spacecraft will follow in the Centaur's wake, descending12 through the debris plume to hit the lunar surface four minutes after the initial impact.

It will use onboard spectrometers(光谱仪) to look for signs of water, hydroxyl compounds(羟基化合物) (OH), salts, clays(黏土,陶土), hydrated(含水的) minerals and organic molecules13 in the sun-lit plume.

The spacecraft will collect data continuously until it too slams(砰然,猛击) into the Moon, generating a second, smaller debris cloud.

Permanently shadowed craters are very cold, receiving heat only from space and from the Moon's interior (which is geologically dead).

Here in the lunar "shadowlands", ice - perhaps delivered by cometary(彗星似的) impacts - is protected from the Sun's rays and could remain stable over geological timescales.

In September, analyses of data from three spacecraft revealed that very fine films of water coat the particles which make up the lunar soil.

This water might also migrate to darkened craters, sublimating14(升华) during the lunar day and condensing once it reached the cooler poles.



点击收听单词发音收听单词发音  

1 debris debris     
n.瓦砾堆,废墟,碎片
参考例句:
  • After the bombing there was a lot of debris everywhere.轰炸之后到处瓦砾成堆。
  • Bacteria sticks to food debris in the teeth,causing decay.细菌附着在牙缝中的食物残渣上,导致蛀牙。
2 hurling bd3cda2040d4df0d320fd392f72b7dc3     
n.爱尔兰式曲棍球v.猛投,用力掷( hurl的现在分词 );大声叫骂
参考例句:
  • The boat rocked wildly, hurling him into the water. 这艘船剧烈地晃动,把他甩到水中。 来自《简明英汉词典》
  • Fancy hurling away a good chance like that, the silly girl! 想想她竟然把这样一个好机会白白丢掉了,真是个傻姑娘! 来自《简明英汉词典》
3 plume H2SzM     
n.羽毛;v.整理羽毛,骚首弄姿,用羽毛装饰
参考例句:
  • Her hat was adorned with a plume.她帽子上饰着羽毛。
  • He does not plume himself on these achievements.他并不因这些成就而自夸。
4 permanently KluzuU     
adv.永恒地,永久地,固定不变地
参考例句:
  • The accident left him permanently scarred.那次事故给他留下了永久的伤疤。
  • The ship is now permanently moored on the Thames in London.该船现在永久地停泊在伦敦泰晤士河边。
5 crater WofzH     
n.火山口,弹坑
参考例句:
  • With a telescope you can see the huge crater of Ve-suvius.用望远镜你能看到巨大的维苏威火山口。
  • They came to the lip of a dead crater.他们来到了一个死火山口。
6 craters 1f8461e3895b38f51c992255a1c86823     
n.火山口( crater的名词复数 );弹坑等
参考例句:
  • Small meteorites have left impact craters all over the planet's surface. 这个行星的表面布满了小块陨石留下的撞击坑。 来自《简明英汉词典》
  • The battlefield was full of craters made by exploding shells. 战场上布满弹坑。 来自《现代英汉综合大词典》
7 previously bkzzzC     
adv.以前,先前(地)
参考例句:
  • The bicycle tyre blew out at a previously damaged point.自行车胎在以前损坏过的地方又爆开了。
  • Let me digress for a moment and explain what had happened previously.让我岔开一会儿,解释原先发生了什么。
8 postulated 28ea70fa3a37cd78c20423a907408aaa     
v.假定,假设( postulate的过去式和过去分词 )
参考例句:
  • They postulated a 500-year lifespan for a plastic container. 他们假定塑料容器的寿命为500年。
  • Freud postulated that we all have a death instinct as well as a life instinct. 弗洛伊德曾假定我们所有人都有生存本能和死亡本能。 来自辞典例句
9 components 4725dcf446a342f1473a8228e42dfa48     
(机器、设备等的)构成要素,零件,成分; 成分( component的名词复数 ); [物理化学]组分; [数学]分量; (混合物的)组成部分
参考例句:
  • the components of a machine 机器部件
  • Our chemistry teacher often reduces a compound to its components in lab. 在实验室中化学老师常把化合物分解为各种成分。
10 centaur zraz4     
n.人首马身的怪物
参考例句:
  • His face reminded me somehow of a centaur.他的脸使我想起半人半马的怪物。
  • No wonder he had soon been hustled away to centaur school.也难怪父母匆匆忙忙就把他送到了半人马学校。
11 cape ITEy6     
n.海角,岬;披肩,短披风
参考例句:
  • I long for a trip to the Cape of Good Hope.我渴望到好望角去旅行。
  • She was wearing a cape over her dress.她在外套上披着一件披肩。
12 descending descending     
n. 下行 adj. 下降的
参考例句:
  • The results are expressed in descending numerical order . 结果按数字降序列出。
  • The climbers stopped to orient themselves before descending the mountain. 登山者先停下来确定所在的位置,然后再下山。
13 molecules 187c25e49d45ad10b2f266c1fa7a8d49     
分子( molecule的名词复数 )
参考例句:
  • The structure of molecules can be seen under an electron microscope. 分子的结构可在电子显微镜下观察到。
  • Inside the reactor the large molecules are cracked into smaller molecules. 在反应堆里,大分子裂变为小分子。
14 sublimating 84ca21689d111a764454df17cfd1c9b5     
v.(使某物质)升华( sublimate的现在分词 );使净化;纯化
参考例句:
发表评论
请自觉遵守互联网相关的政策法规,严禁发布色情、暴力、反动的言论。
评价:
表情:
验证码:点击我更换图片