火星大气中消失的碳-凯发k8官网

火星大气中消失的碳
文章来源:未知 文章作者:enread 发布时间:2015-11-26 05:58 字体: [ ] 
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mars is blanketed by a thin, mostly carbon dioxide atmosphere--one that is far too thin to prevent large amounts of water on the surface of the planet from 1 or evaporating. but many researchers have suggested that the planet was once 2 in an atmosphere many times thicker than earth's. for decades that left the question, "where did all the carbon go?" now a team of scientists from caltech and jpl thinks they have a possible answer. the researchers suggest that 3.8 billion years ago, mars might have had only a moderately 3 atmosphere. they have identified a photochemical process that could have helped such an early atmosphere evolve into the current thin one without creating the problem of "missing" carbon and in a way that is consistent with existing carbon 4 measurements.
 
the scientists describe their findings in a paper that appears in the november 24 issue of the journal nature communications.
 
"with this new 5, everything that we know about the martian atmosphere can now be pieced together into a consistent picture of its evolution," says renyu hu, a postdoctoral scholar at jpl, a visitor in planetary science at caltech, and lead author on the paper.
 
when considering how the early martian atmosphere might have transitioned to its current state, there are two possible 6 for the removal of excess carbon dioxide (co2). either the co2 was incorporated into minerals in rocks called carbonates or it was lost to space.
 
a separate recent study coauthored by bethany ehlmann, assistant professor of planetary science and a research scientist at jpl, used data from several mars-orbiting satellites to 7 carbonate rocks, showing that there are not enough carbonates in the upper kilometer of crust to contain the missing carbon from a very thick early atmosphere that might have existed about 3.8 billion years ago.


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1 e3d2069e66638a9348977c28d0b227f1     
伟大的( sublime的现在分词 ); 令人赞叹的; 极端的; 不顾后果的
参考例句:
2 6b3958ee6e7b263c722c8b117143345f     
v.隐瞒( shroud的过去式和过去分词 );保密
参考例句:
  • the hills were shrouded in mist . 这些小山被笼罩在薄雾之中。
  • the towers were shrouded in mist. 城楼被蒙上薄雾。 来自《简明英汉词典》
3 aonzx     
a.密集的,稠密的,浓密的;密度大的
参考例句:
  • the general ambushed his troops in the dense woods. 将军把部队埋伏在浓密的树林里。
  • the path was completely covered by the dense foliage. 小路被树叶厚厚地盖了一层。
4 7ad2ece915960e8c295e01a4d04cc192     
adj.同位素的,合痕的
参考例句:
  • the isotopic signatures of most ancient limestones indicated the same process. 大多数古代石灰岩的同位素特征说明了同样的过程。 来自辞典例句
  • isotopic discrimination is not likely. 同位素甄别是不可能的。 来自辞典例句
5 zcwxr     
n.机械装置;机构,结构
参考例句:
  • the bones and muscles are parts of the mechanism of the body.骨骼和肌肉是人体的组成部件。
  • the mechanism of the machine is very complicated.这台机器的结构是非常复杂的。
6 d0db71d70348ef1c49f05f59097917b8     
n.机械( mechanism的名词复数 );机械装置;[生物学] 机制;机械作用
参考例句:
  • the research will provide direct insight into molecular mechanisms. 这项研究将使人能够直接地了解分子的机理。 来自《简明英汉词典》
  • he explained how the two mechanisms worked. 他解释这两台机械装置是如何工作的。 来自《简明英汉词典》
7 04xx7     
n.详细目录,存货清单
参考例句:
  • some stores inventory their stock once a week.有些商店每周清点存货一次。
  • we will need to call on our supplier to get more inventory.我们必须请供应商送来更多存货。
tag标签: planet carbon mars
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