本期Nature Communications介紹了遠(yuǎn)古水在其從太空飛馳而過的一個(gè)隕石中蒸發(fā)過程的最后時(shí)刻,。這些發(fā)現(xiàn)支持以下觀點(diǎn)：地球的水來自太空,。
隕石是較大小行星的碎塊,，自太陽系在距今46億年前形成以來一直在太空中漂浮,。它們是從第一批宇宙顆粒形成的,，也許含有可用來確定地球上水和生命起源的關(guān)鍵信息,。Yuki Kimura及同事研究了2000年在加拿大掉到地球上的一個(gè)隕石中的微小晶體的磁性,，以揭示曾經(jīng)在太空中存在的遠(yuǎn)古水的特征,。該研究小組發(fā)現(xiàn),，微小磁鐵礦顆粒的磁性是這樣的：這些晶體只有在最后的水滴干了之后才能形成，留下一個(gè)幾十億年之后將被發(fā)現(xiàn)的獨(dú)特水印,。（生物谷Bioon.com）
生物谷推薦的英文摘要
Nature Communications doi:10.1038/ncomms3649
Vortex magnetic structure in framboidal magnetite reveals existence of water droplets in an ancient asteroid
Yuki Kimura,，Takeshi Sato，Norihiro Nakamura,，Jun Nozawa,，Tomoki Nakamura，Katsuo Tsukamoto& Kazuo Yamamoto
The majority of water has vanished from modern meteorites， yet there remain signatures of water on ancient asteroids. How and when water disappeared from the asteroids is important,， because the final fluid-concentrated chemical species played critical roles in the early evolution of organics and in the final minerals in meteorites. Here we show evidence of vestigial traces of water based on a nanometre-scale palaeomagnetic method,， applying electron holography to the framboids in the Tagish Lake meteorite. The framboids are colloidal crystals composed of three-dimensionally ordered magnetite nanoparticles and therefore are only able to form against the repulsive force induced by the surface charge of the magnetite as a water droplet parches in microgravity. We demonstrate that the magnetites have a flux closure vortex structure， a unique magnetic configuration in nature that permits the formation of colloidal crystals just before exhaustion of water from a local system within a hydrous asteroid.
