本帖最后由 人与自然 于 2012-12-1 00:22 编辑
http://www.dailymail.co.uk/sciencetech/article-2240702/Ice-Mercury-Nasa-probe-reveals-planet-frozen-organic-materials-north-pole.html
Burning hot Mercury has ice and frozen organic materials inside permanently shadowed craters in its north pole, Nasa scientists said today.
Earth-based telescopes have been compiling evidence for ice on the planet closest to the sun for 20 years, but researchers were left surprised after finding of organics.
Nasa's MESSENGER spacecraft, the first probe to orbit Mercury, has revealed the materials are similar to tar or coal. They are believed to have been delivered millions of years ago by comets and asteroids crashing into the planet.
简单翻译一下：
NASAD的科学家今天说，炙热的水星在其北极地区永久背阴处的陨石坑中有冰和冷冻的有机物。20年来，科学家一直在搜集整理这个距离太阳最近的星球存在有水的证据，但是发现冰冻有机物，仍然令科学家们惊异不已。
Radar image: The red shows areas of Mercury's north polar region that are in shadow in all images acquired by MESSENGER to date. They are believed to contain ice 红色区域显示为水星北极地区，在信使号水星探测器拍摄的所有图片中，这些地区处于阴影般隐蔽之处，因此科学家认为这些地区有冰
A radar image of Mercury's north polar region. Yellow areas denote regions of high radar reflectivity. Since their discovery in 1992, these polar deposits have been hypothesised to consist of water ice trapped in permanently shadowed areas 水星北极地区的雷达图，黄色区域具有很高的雷达反射率，自从1992年这些处于阴暗处的环形山陨石坑被发现以来，这些区域已被假设存在有水冰。
'It's not something we expected to see, but then of course you realise it kind of makes sense because we see this in other places,' such as icy bodies in the outer solar system and in the nuclei of comets, planetary scientist David Paige, with the University of California, Los Angeles, said.
Unlike Nasa's Mars rover Curiosity, which will be sampling rocks and soils to look for organic materials directly, the MESSENGER probe bounces laser beams, counts particles, measures gamma rays and collects other data remotely from orbit.
The discoveries of ice and organics, painstakingly pieced together for more than a year, are based on computer models, laboratory experiments and deduction, not direct analysis.
'The explanation that seems to fit all the data is that it's organic material,' said lead MESSENGER scientist Sean Solomon, with Columbia University in New York.
Added Paige, 'It's not just a crazy hypothesis. No one has got anything else that seems to fit all the observations better.'
Scientists believe the organic material, which is about twice as dark as most of Mercury's surface, was mixed in with comet- or asteroid-delivered ice eons ago.
The ice vaporised, then re-solidified where it was colder, leaving dark deposits on the surface. Radar imagery shows the dark patches subside at the coldest parts of the crater, where ice can exist on the surface.
A 68-mile-diameter crater in the north polar region of Mercury which has been shown to harbour water ice, thanks to measurements by the Messenger spacecraft 按照信使号探测器的的数据和图片，北极地区这个直径达68英里的环形山，一直显示出有水冰的迹象
Scientists working with Nasa's MESSENGER spacecraft program explain the new findings during a press conference at Nasa headquarters in Washington, DC 华盛顿DC的NASA总部，科学家团队在解释水星的水冰和冰冻有机物问题
(Left to right) Sean Solomon, David Lawrence, Gregory Neumann and David Paige revealed recent studies performed by the spacecraft indicate support for the theory Mercury planet harbours abundant water ice and other frozen materials 科学家们宣读了他们的研究报告，这些报告的工作由自信使号探测器完成，证明了水星有水和冰冻有机物
The areas where the dark patches are seen are not cold enough for surface ice without the overlying layer of what is believed to be organics.
So remote was the idea of organics on Mercury that MESSENGER got a relatively easy pass by Nasa's planetary protection protocols that were established to minimize the chance of contaminating any indigenous life-potential material with hitchhiking microbes from Earth.
Scientists don't believe Mercury is or was suitable for ancient life, but the discovery of organics on an inner planet of the solar system may shed light on how life got started on Earth and how life may evolve on planets beyond the solar system.
'Finding a place in the inner solar system where some of these same ingredients that may have led to life on Earth are preserved for us is really exciting,' Paige said.
MESSENGER, which stands for Mercury Surface, Space Environment, Geochemistry and Ranging, is due to complete its two-year mission at Mercury in March.
Scientists are seeking Nasa funding to continue operations for at least part of a third year. The probe will remain in Mercury's orbit until the planet's gravity eventually causes it to crash onto the surface.
Whether the discovery of organics now prompts Nasa to select a crash zone rather than leave it up to chance remains to be seen. Microbes that may have hitched a ride on MESSENGER likely have been killed off by the harsh radiation environment at Mercury.
The research is published in this week's edition of the journal Science.
Read more: http://www.dailymail.co.uk/sciencetech/article-2240702/Ice-Mercury-Nasa-probe-reveals-planet-frozen-organic-materials-north-pole.html#ixzz2Dit4oS7O
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