对火星甲烷的研究,增强火星存在生命的猜想-凯发k8官网

对火星甲烷的研究,增强火星存在生命的猜想
文章来源:未知 文章作者:meng 发布时间:2009-12-09 00:57 字体: [ ] 
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scientists have ruled out the possibility that排除……可能性 1甲烷 is delivered to mars by meteorites陨星, raising fresh hopes that the gas might be generated by life on the red planet, in research published tomorrow (wednesday 9 december 2009) in earth and planetary science letters. methane has a short lifetime of just a few hundred years on mars because it is constantly being depleted消耗的,枯竭的 by a chemical reaction in the planet's atmosphere, caused by sunlight. scientists analysing data from telescopic observations and unmanned space missions have discovered that methane on mars is being constantly 6充满的 by an unknown source and they are keen to uncover how the levels of methane are being topped up.

researchers had thought that 3 might be responsible for martian methane levels because when the rocks enter the planet's atmosphere they are subjected to intense heat, causing a chemical reaction that releases methane and other gases into the atmosphere.

however, the new study, by researchers from imperial college london, shows that the volumes of methane that could be released by the meteorites entering mars's atmosphere are too low to maintain the current 7 levels of methane. previous studies have also ruled out the possibility that the methane is delivered through 8 activity火山活动.

this leaves only two plausible似真实的,似合理的 theories to explain the gas's presence, according to the researchers behind today's findings. either there are microorganisms微生物 living in the martian soil that are producing methane gas as a 10副产品 of their 11 processes代谢过程, or methane is being produced as a by-product of reactions between volcanic rock and water.

co-author of the study, dr richard court, department of earth science and engineering at imperial college london, says: "our experiments are 12 to solve the mystery of methane on mars. meteorites vaporising in the atmosphere are a proposed methane source but when we recreate their 13 entry in the laboratory we get only small amounts of the gas. for mars, meteorites fail the methane test."

the team say their study will help nasa and esa scientists who are planning a 14 mission to the red planet in 2018 to search for the source of methane. the researchers say now that they have discovered that meteorites are not a source of methane on mars, esa and nasa scientists can focus their attention on the two last remaining options.

co-author, professor mark sephton, department of earth science and engineering at imperial college london, adds: "this work is a big step forward. as sherlock holmes said, eliminate all other factors and the one that 15 must be the truth. the list of possible sources of methane gas is getting smaller and excitingly, extraterrestrial life地外生命 still remains an option. ultimately the final test may have to be on mars."

the team used a technique called quantitive pyrolysis-fourier transform 16 spectroscopy光谱学 to reproduce the same searing灼热的 conditions experienced by meteorites as they enter the martian atmosphere. the team heated the 2 fragments碎片 to 1000 degrees 17 and measured the gases that were released using an infrared beam红外光束.

when quantities of gas released by the laboratory experiments were combined with published calculations of meteorite in-fall rates on mars, the scientists calculated that only 10 kilograms of meteorite methane was produced each year, far below the 100 to 300 tonnes required to 5 methane levels in the martian atmosphere.



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1 t1eyx     
n.甲烷,沼气
参考例句:
  • the blast was caused by pockets of methane gas that ignited.爆炸是由数袋甲烷气体着火引起的。
  • methane may have extraterrestrial significance.甲烷具有星际意义。
2 2wny1     
n.陨石;流星
参考例句:
  • the meteorite in jilin exhibition hall is believed to be the largest in the world.吉林展览馆的陨石被认为是世界上最大的。
  • the famous murchison meteorite smashed into the australian ground in 1969.1969年著名的默奇森陨石轰然坠落在澳大利亚。
3 12efd1ed528a28fe1f7cb667a7fbc1e0     
n.陨星( meteorite的名词复数 )
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》
  • one theory about the existence of extraterrestrial life rests on the presence of carbon compounds in meteorites. 地球外存在生命的理论是基于陨星上存在碳化合物质这一事实的。 来自《简明英汉词典》
4 31d93165da679292f22e5e2e5aa49a03     
adj. 枯竭的, 废弃的 动词deplete的过去式和过去分词
参考例句:
  • food supplies were severely depleted. 食物供应已严重不足。
  • both teams were severely depleted by injuries. 两个队都因队员受伤而实力大减。
5 kcayv     
vt.补充;(把…)装满;(再)填满
参考例句:
  • i always replenish my food supply before it is depleted.我总是在我的食物吃完之前加以补充。
  • we have to import an extra 4 million tons of wheat to replenish our reserves.我们不得不额外进口四百万吨小麦以补充我们的储备。
6 9f0ecb49d62f04f91bf08c0cab1081e5     
补充( replenish的过去式和过去分词 ); 重新装满
参考例句:
  • she replenished her wardrobe. 她添置了衣服。
  • she has replenished a leather [fur] coat recently. 她最近添置了一件皮袄。
7 6eayr     
adj.大气的,空气的;大气层的;大气所引起的
参考例句:
  • sea surface temperatures and atmospheric circulation are strongly coupled.海洋表面温度与大气环流是密切相关的。
  • clouds return radiant energy to the surface primarily via the atmospheric window.云主要通过大气窗区向地表辐射能量。
8 blgzq     
adj.火山的;象火山的;由火山引起的
参考例句:
  • there have been several volcanic eruptions this year.今年火山爆发了好几次。
  • volcanic activity has created thermal springs and boiling mud pools.火山活动产生了温泉和沸腾的泥浆池。
9 hbcyy     
adj.似真实的,似乎有理的,似乎可信的
参考例句:
  • his story sounded plausible.他说的那番话似乎是真实的。
  • her story sounded perfectly plausible.她的说辞听起来言之有理。
10 nsayp     
n.副产品,附带产生的结果
参考例句:
  • freedom is the by-product of economic surplus.自由是经济盈余的副产品。
  • the raw material for the tyre is a by-product of petrol refining.制造轮胎的原材料是提炼汽油时产生的一种副产品。
11 2r4z1     
adj.新陈代谢的
参考例句:
  • impressive metabolic alternations have been undergone during embryogenesis.在胚胎发生期间经历了深刻的代谢变化。
  • a number of intoxicants are associated with metabolic acidosis.许多毒性物质可引起代谢性酸中毒。
12 2rgzdc     
n.食物的一份&adj.帮助人的,辅助的
参考例句:
  • the poor children regularly pony up for a second helping of my hamburger. 那些可怜的孩子们总是要求我把我的汉堡包再给他们一份。
  • by doing this, they may at times be helping to restore competition. 这样一来, 他在某些时候,有助于竞争的加强。
13 eleye     
adj.燃烧着的,火红的;暴躁的;激烈的
参考例句:
  • she has fiery red hair.她有一头火红的头发。
  • his fiery speech agitated the crowd.他热情洋溢的讲话激动了群众。
14 m3lx4     
adj.联合的,共同的;n.关节,接合处;v.连接,贴合
参考例句:
  • i had a bad fall,which put my shoulder out of joint.我重重地摔了一跤,肩膀脫臼了。
  • we wrote a letter in joint names.我们联名写了封信。
15 1kmzty     
n.剩余物,残留物;遗体,遗迹
参考例句:
  • he ate the remains of food hungrily.他狼吞虎咽地吃剩余的食物。
  • the remains of the meal were fed to the dog.残羹剩饭喂狗了。
16 dx0yp     
adj./n.红外线(的)
参考例句:
  • infrared is widely used in industry and medical science.红外线广泛应用于工业和医学科学。
  • infrared radiation has wavelengths longer than those of visible light.红外辐射的波长比可见光的波长长。
17 axrzl     
adj.摄氏温度计的,摄氏的
参考例句:
  • the temperature tonight will fall to seven degrees celsius.今晚气温将下降到七摄氏度。
  • the maximum temperature in july may be 36 degrees celsius.七月份最高温度可能达到36摄氏度。
tag标签: mars methane meteorite
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