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Space scientists from the University of New Hampshire and multi-institutional colleagues report they have quantified levels of radiation on the moon's surface from galactic cosmic ray (GCR) bombardment(轰炸,炮击) that over time causes chemical changes in water ice and can create complex carbon chains similar to those that help form the foundations of biological structures. In addition, the radiation process causes the lunar soil, or regolith(风化层) , to darken over time, which is important in understanding the geologic1 history of the moon. The scientists present their findings in a paper published online in the American Geophysical Union's Journal of Geophysical Research (JGR). The paper, titled "Lunar Radiation Environment and Space Weathering from the Cosmic Ray Telescope for the Effects of Radiation (CRaTER2)," is based on measurements made by the CRaTER instrument onboard NASA's Lunar Reconnaissance Orbiter (LRO) mission. The paper's lead author is Nathan Schwadron, an associate professor of physics at the UNH Space Science Center within the Institute for the Study of Earth, Oceans, and Space (EOS). Co-author Harlan Spence is the director of EOS and lead scientist for the CRaTER instrument.

The telescope provides the fundamental measurements needed to test our understanding of the lunar radiation environment and shows that "space weathering" of the lunar surface by energetic radiation is an important agent for chemical alteration3. CRaTER measures material interactions of GCRs and solar energetic particles (SEPs), both of which present formidable hazards for human exploration and spacecraft operations. CRaTER characterizes the global lunar radiation environment and its biological impacts by measuring radiation behind a "human tissue-equivalent" plastic.

Serendipitously4, the LRO mission made measurements during a period when GCR fluxes6 remained at the highest levels ever observed in the space age due to the sun's abnormally extended quiet cycle. During this quiescent7 period, the diminished power, pressure, flux5 and magnetic flux of the solar wind allowed GCRs and SEPs to more readily interact with objects they encountered -- particularly bodies such as our moon, which has no atmosphere to shield the blow.

"This has provided us with a unique opportunity because we've never made these types of measurements before over an extended period of time, which means we've never been able to validate8 our models," notes Schwadron. "Now we can put this whole modeling field on more solid footing and project GCR dose rates from the present period back through time when different interplanetary conditions prevailed." This projection9 will provide a clearer picture of the effects of GCRs on airless bodies through the history of the solar system.

Moreover, CRaTER's recent findings also provide further insight into radiation as a double-edge sword. That is, while cosmic radiation does pose risks to astronauts and even spacecraft, it may have been a fundamental agent of change on celestial10 bodies by irradiating water ice and causing chemical alterations11. Specifically, the process releases oxygen atoms from water ice, which are then free to bind12 with carbon to form large molecules13 that are "prebiotic(生命起源以前的) " organic molecules.


1 geologic dg3x9     
  • The Red Sea is a geologic continuation of the valley.红海就是一个峡谷在地质上的继续发展。
  • Delineation of channels is the first step of geologic evaluation.勾划河道的轮廓是地质解译的第一步。
2 crater WofzH     
  • 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。
3 alteration rxPzO     
  • The shirt needs alteration.这件衬衣需要改一改。
  • He easily perceived there was an alteration in my countenance.他立刻看出我的脸色和往常有些不同。
4 serendipitously f55aa1079a29c693ef902a1807d36530     
  • There was a serendipitous second advantage working with a library of equations. 利用方程库有个意外收获的附带好处。
  • Strategic networking prepares us for serendipitous moments. 战略性人际交往让我们为不时之需做好准备。
5 flux sg4zJ     
  • The market is in a constant state of flux.市场行情在不断变化。
  • In most reactors,there is a significant flux of fast neutrons.在大部分反应堆中都有一定强度的快中子流。
6 fluxes fe973c05de3ff6dd2396188728b29a39     
连续的改变( flux的名词复数 ); 不稳定的状态; 不停的变化; 通量
  • In general, fluxes and forces may have different tensorial characters. 一般说来,力和通量可以具有不同的张量特征标。
  • The parameterized eddy fluxes simulatedthe seasonal and latitudinal variations reasonably well. 模拟出涡动通量的空间分布和时间变化。
7 quiescent A0EzR     
  • It is unlikely that such an extremist organization will remain quiescent for long.这种过激的组织是不太可能长期沉默的。
  • Great distance in either time or space has wonderful power to lull and render quiescent the human mind.时间和空间上的远距离有一种奇妙的力量,可以使人的心灵平静。
8 validate Jiewm     
  • You need an official signature to validate the order.你要有正式的签字,这张汇票才能生效。
  • In order to validate the agreement,both parties sign it.为使协议有效,双方在上面签了字。
9 projection 9Rzxu     
  • Projection takes place with a minimum of awareness or conscious control.投射在最少的知觉或意识控制下发生。
  • The projection of increases in number of house-holds is correct.对户数增加的推算是正确的。
10 celestial 4rUz8     
  • The rosy light yet beamed like a celestial dawn.玫瑰色的红光依然象天上的朝霞一样绚丽。
  • Gravity governs the motions of celestial bodies.万有引力控制着天体的运动。
11 alterations c8302d4e0b3c212bc802c7294057f1cb     
n.改动( alteration的名词复数 );更改;变化;改变
  • Any alterations should be written in neatly to the left side. 改动部分应书写清晰,插在正文的左侧。 来自《简明英汉词典》
  • Gene mutations are alterations in the DNA code. 基因突变是指DNA 密码的改变。 来自《简明英汉词典》
12 bind Vt8zi     
  • I will let the waiter bind up the parcel for you.我让服务生帮你把包裹包起来。
  • He wants a shirt that does not bind him.他要一件不使他觉得过紧的衬衫。
13 molecules 187c25e49d45ad10b2f266c1fa7a8d49     
分子( molecule的名词复数 )
  • 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。
TAG标签: moon space radiation