| Mars may have been wet for a billion years longer than previously thought, new water-related opal evidence from NASA's Mars Reconnaissance Orbiter suggests. The findings have implications for the possibility that Mars once supported life. |
從美國(guó)國(guó)家航空航天管理局的火星偵探衛(wèi)星獲得了跟水相關(guān)的蛋白石新證據(jù)，證據(jù)表明：火星的濕潤(rùn)階段可能比以前所認(rèn)為的要長(zhǎng)10億年。這個(gè)發(fā)現(xiàn)意味著，火星可能一度支持生命的存在。 |
| Scientists have known for some time that the 4.5 billion-year-old planet once harbored liquid water because of the many features on its surface that were likely created by flowing water. Hydrated, or water-containing, mineral deposits also provide telltale signs of where and when water was present on ancient Mars. |
科學(xué)家們已經(jīng)了解到，這個(gè)45億歲的行星上有一段時(shí)間曾經(jīng)擁有水，因?yàn)槠浔砻嫔显S多地貌特征好象是由于流水造成的。含水沉積層也提供了明確的跡象，可以說明古代火星曾經(jīng)在何時(shí)何地出現(xiàn)過水。 |
| Until now, only two major groups of hydrated minerals, phyllosilicates and hydrated sulfates, have been observed by spacecraft orbiting the red planet. (The clay-like phyllosilicates formed more than 3.5 billion years ago where igneous rock encountered water. Hydrated sulfates formed until about 3 billion years ago from the evaporation of salty and sometimes acidic water.) |
此前，環(huán)繞這顆紅色星球的太空船觀察過兩種主要的含水礦物——層狀硅酸鹽和含水硫酸鹽。35億多年以前，粘土狀的層狀硅酸鹽形成于火成巖遇到水的地方；直到大約30億年前，由于含有鹽分的、有時(shí)呈酸性的水蒸發(fā)而形成了含水硫酸鹽。 |
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But a new hydrate mineral has now entered the picture: hydrated silica, commonly known as opal. These opaline silicates were detected by MRO's Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) and are the youngest of the three types of hydrated minerals. They formed where liquid water altered materials created by volcanic activity or meteorite impacts on the Martian surface. |
但是，現(xiàn)在一種新的水合礦物進(jìn)入了視野：水合二氧化硅，俗稱蛋白石。這些蛋白石硅酸鹽是由火星偵探衛(wèi)星上搭載的專用小型偵察影像頻譜儀（CRISM）發(fā)現(xiàn)的，是三種含水礦物中最年輕的一種?；鹕交顒?dòng)或隕星在火星表面的撞擊所產(chǎn)生的物質(zhì)，被液態(tài)水改變之后就形成了蛋白石硅酸鹽。 |
| "This is an exciting discovery because it extends the time range for liquid water on Mars, and the places where it might have supported life," said CRISM principal investigator Scott Murchie of the Johns Hopkins Applied Physics Laboratory in Laurel, Md. "The identification of opaline silica tells us that water may have existed as recently as 2 billion years ago." |
“這是個(gè)令人興奮的發(fā)現(xiàn)，因?yàn)樵摪l(fā)現(xiàn)延長(zhǎng)了水在火星上的存在時(shí)間，也擴(kuò)大了可能支持生命存在的范圍，”專用小型偵察影像頻譜儀的主要研究人員、馬里蘭州勞瑞爾市約翰霍普金斯應(yīng)用物理實(shí)驗(yàn)室的斯科特·默基說，“蛋白石硅酸鹽的發(fā)現(xiàn)使我們可以斷定：僅僅20億年前，火星上仍有水存在?！?/SPAN> |
| Some of the opaline deposits were also associated with iron sulfates, which study team member Ralph Milliken of NASA's Jet Propulsion Laboratory in Pasadena, Calif., said is "the exact sort of minerals you would expect to see if you had really acidic water." |
一些蛋白石沉積層也跟硫酸鐵和硫酸亞鐵有關(guān)。研究小組成員、加州帕薩迪納市美國(guó)國(guó)家航空航天管理局空氣推進(jìn)實(shí)驗(yàn)室的拉爾夫·米利肯說：“這些硫酸鹽跟存在酸性水的情況下你所期望看到的那種礦物一模一樣。” |
| And not only do the deposits indicate the past presence of liquid water, but that the water "was there long enough to alter some of the rocks," Milliken told SPACE.com. "It wasn't an overnight process." |
米利肯告訴《太空網(wǎng)》：“這些沉積層不但證說明了過去存在液態(tài)水，而且還說明液態(tài)水存在的時(shí)間很長(zhǎng)，足以使某些巖石發(fā)生改變。這個(gè)改變過程不是一夜之間所能完成的?！?/SPAN> |
| One particular location where the opaline silicates were found was the large canyon system Valles Marineris. "We see numerous outcrops of opal-like minerals, commonly in thin layers extending for very long distances around the rim of Valles Marineris and sometimes within the canyon system itself," Milliken said. |
發(fā)現(xiàn)蛋白石硅酸鹽的一個(gè)特殊地點(diǎn)是大型山谷系統(tǒng)——水手谷?！拔覀兛吹搅嗽S多路出地面的蛋白石狀礦物層，通常呈薄層狀，在水手谷周圍的凸緣上延伸出很遠(yuǎn)的距離，有時(shí)也在該山谷系統(tǒng)之內(nèi)延伸，”米利肯說。 |
| The minerals were also recently found in Gusev Crater by NASA's Mars rover Spirit. |
美國(guó)國(guó)家航空航天管理局的“勇氣”號(hào)火星探測(cè)器最近在古瑟夫環(huán)形山中也發(fā)現(xiàn)了這種礦物。 |
| Another recent study, which Milliken co-authored, looked at images of the same deposits taken by MRO's HiRISE camera. |
不久前，由米利肯跟其他研究人員共同發(fā)起的另外一項(xiàng)研究，在圖像中觀察到了同樣的沉積層。這些圖像是由火星偵探衛(wèi)星上搭載的高分辨率科學(xué)實(shí)驗(yàn)成像儀（HiRISE）拍攝的。 |
| The new study, detailed in the November issue of the journal Geology, reveals that opaline silicates are widespread and occur in relatively young terrain. |
這項(xiàng)新研究詳細(xì)地記錄在11月份出版的《地質(zhì)學(xué)》雜志上。該研究顯示：蛋白石硅酸鹽分布廣泛，并出現(xiàn)在相對(duì)年輕的巖體中。 |
| "What's important is that the longer liquid water existed on Mars, the longer the window during which Mars may have supported life," Milliken said. "The opaline silica deposits would be good places to explore to assess the potential for habitability on Mars, especially in these younger terrains." |
“重要的是，液態(tài)水在火星上存在的時(shí)間越長(zhǎng)，火星可能適合生命存在的時(shí)間也就越長(zhǎng)，”米利肯說，“若要評(píng)估火星上潛在的可居住性，這些蛋白石硅酸鹽沉積層，特別是較為年輕巖體中的沉積層，將會(huì)是理想的研究地點(diǎn)。” |
