北京時間8月11日消息，據(jù)美國《連線》雜志報道,，科學(xué)家通過對火星勘探衛(wèi)星獲得的數(shù)據(jù)進(jìn)行了分析表明,，原始火星上的環(huán)境與原始地球類似，或許火星當(dāng)時的環(huán)境也適合生命的形成,。相關(guān)成果發(fā)表在《自然》（Nature）雜志上,，這或許是一系列火星發(fā)現(xiàn)中最令人興奮的一項(xiàng)。
地質(zhì)專家吉姆·貝爾(Jim Bell)并沒有參與此項(xiàng)研究,，但他表示：“火星的環(huán)境很有可能適合生命存在,。如果有某種生命形式，它們會生活在一個有益于它們存在的環(huán)境中,，甚至?xí)且环鷻C(jī)勃勃的景象,。”6月，火星不斷蒸發(fā)的冰層時間推移圖驗(yàn)證了長期被懷疑是否存在的火星水,。很快,，科學(xué)家發(fā)表報告稱，火星曾經(jīng)遍布著水，在該行星的發(fā)展史上扮演過重要角色,。這周早些時候,，美國航空航天局宣布發(fā)現(xiàn)了高氯酸鹽，一種一些地球上的細(xì)菌新陳代謝產(chǎn)物,。
這份研究報告描繪的火星上馬沃斯山谷(Mawrth Vallis),，該山谷是由火星上的水流流經(jīng)火星南半球的諾亞高地(Noachian highlands)形成的。地質(zhì)學(xué)家發(fā)現(xiàn)了廣泛存在的一種鐵元素沉積層,，至少在地球上,，這種沉積層是由火山巖風(fēng)化形成的，該沉積層可以支持細(xì)菌生命存在,。生物谷
研究報告聯(lián)合撰稿人美國布朗大學(xué)地質(zhì)學(xué)家約翰·馬斯特德(John Mustard)說：“在地球上,，如果周圍存在這種鐵元素，就會被細(xì)菌所利用,。”更讓人感到驚奇的是,，馬斯特德的小組發(fā)現(xiàn)了粘土礦物層，有可能是由長期水滲透過鐵元素沉積層形成的,。馬斯特德說：“幾何關(guān)系表明火星曾存在大量水,。貝爾說：“火星上有可能存在降雨現(xiàn)象，這種現(xiàn)象表明當(dāng)時的環(huán)境提供了較高溫度,。與今天相比,，過去火星上的環(huán)境與地球要相似的多。我們不知道它是否曾有生命存在,，但上面曾有湖泊,，池塘，河流,，降雪和冰川,。”
兩位研究人員均謹(jǐn)慎地指出，這種沉積層有可能是一種地質(zhì)巧合,，但也認(rèn)為火星上曾存在水是解釋這種現(xiàn)象的一個答案,。除了水，溫暖的氣候以及基本礦物,，生命存在最后的一個條件就是含有碳元素的有機(jī)分子,。馬斯特德說，那些碳分子很容易通過火星早期落到上面的隕石沉積獲得,?？茖W(xué)家認(rèn)為隕石也將開啟生命的分子送到了地球，馬斯特德指出,，馬沃斯山谷的粘土有可能很容易與有機(jī)物結(jié)合,，創(chuàng)造出肥沃的生命成分。貝爾說,，主要的問題是,，這些條件是否足夠長期存在，直到生命的出現(xiàn),。
他說：“如果只是曇花一現(xiàn),，火星不可能為復(fù)雜的化學(xué)成分提供足夠時間產(chǎn)生生命并進(jìn)行進(jìn)化。但如果持續(xù)十億年,，或僅僅數(shù)億年,，火星或許會形成地球曾經(jīng)的環(huán)境，一旦形成了與地球相似的環(huán)境,，生命會迅速萌發(fā),。”（生物谷Bioon.com）
生物谷推薦原始出處：
Nature，doi:10.1038/nature07097,，John F. Mustard, T. Titus & M. Wolff
Hydrated silicate minerals on Mars observed by the Mars Reconnaissance Orbiter CRISM instrument
John F. Mustard1, S. L. Murchie2, S. M. Pelkey1, B. L. Ehlmann1, R. E. Milliken3, J. A. Grant4, J.-P. Bibring5, F. Poulet5, J. Bishop6, E. Noe Dobrea3, L. Roach1, F. Seelos2, R. E. Arvidson7, S. Wiseman7, R. Green3, C. Hash8, D. Humm2, E. Malaret8, J. A. McGovern2, K. Seelos2, T. Clancy9, R. Clark10, D. D. Marais6, N. Izenberg2, A. Knudson7, Y. Langevin5, T. Martin3, P. McGuire7, R. Morris11, M. Robinson12, T. Roush6, M. Smith13, G. Swayze9, H. Taylor2, T. Titus14 & M. Wolff9Bioon
Department of Geological Sciences, Brown University, Providence, Rhode Island 02912, USA
Johns Hopkins University/Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, Maryland 20723, USA
Jet Propulsion Laboratory, California Institute of Technology, Mail Stop 183-301, 4800 Oak Grove Drive, Pasadena, California 91109, USA
Center for Earth and Planetary Studies, National Air and Space Museum, Smithsonian Institution, Independence Avenue at 6th Street SW, Washington, DC 20560, USA
Institut d'Astrophysique Spatiale, Université Paris Sud 11, 91405 Orsay, France
National Aeronautics and Space Administration, Ames Research Center, 515 N. Whisman Road, Mountain View, California 94043, USA
Department of Earth and Planetary Sciences, Washington University, St Louis, Missouri 63130, USA
Applied Coherent Technology, 112 Elden Street Suite K, Herndon, Virginia 22070, USA
Space Science Institute, 4750 Walnut Street, Suite 205, Boulder, Colorado 80301, USA
US Geological Survey, MS 964 Box 25046, Denver Federal Center, Denver, Colorado 80225, USA
ARES Code KR, National Aeronautics and Space Administration, Johnson Space Center, 2101 NASA Parkway, Houston, Texas 77058, USA
School of Earth and Space Exploration. Box 871404, Arizona State University, Tempe, Arizona 85287-1404, USA
National Aeronautics and Space Administration, Goddard Space Flight Center, Code 693.0, Greenbelt, Maryland 20771, USA
US Geological Survey, 2255 N. Gemini Drive, Flagstaff, Arizona, 86001, USA
Correspondence to: John F. Mustard1 Correspondence and requests for materials should be addressed to J.F.M. (Email: [email protected]).
Phyllosilicates, a class of hydrous mineral first definitively identified on Mars by the OMEGA (Observatoire pour la Mineralogie, L'Eau, les Glaces et l'Activitié) instrument1, 2, preserve a record of the interaction of water with rocks on Mars. Global mapping showed that phyllosilicates are widespread but are apparently restricted to ancient terrains and a relatively narrow range of mineralogy (Fe/Mg and Al smectite clays). This was interpreted to indicate that phyllosilicate formation occurred during the Noachian (the earliest geological era of Mars), and that the conditions necessary for phyllosilicate formation (moderate to high pH and high water activity3) were specific to surface environments during the earliest era of Mars's history4. Here we report results from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM)4 of phyllosilicate-rich regions. We expand the diversity of phyllosilicate mineralogy with the identification of kaolinite, chlorite and illite or muscovite, and a new class of hydrated silicate (hydrated silica). We observe diverse Fe/Mg-OH phyllosilicates and find that smectites such as nontronite and saponite are the most common, but chlorites are also present in some locations. Stratigraphic relationships in the Nili Fossae region show olivine-rich materials overlying phyllosilicate-bearing units, indicating the cessation of aqueous alteration before emplacement of the olivine-bearing unit. Hundreds of detections of Fe/Mg phyllosilicate in rims, ejecta and central peaks of craters in the southern highland Noachian cratered terrain indicate excavation of altered crust from depth. We also find phyllosilicate in sedimentary deposits clearly laid by water. These results point to a rich diversity of Noachian environments conducive to habitability.
