Craft reveals Martian site of ancient water.The distribution of materials in this composite image of the Nili Fossae region of Mars tells scientists that water resided there no more recently than nearly 4 billion years ago. Green indicates clay minerals Clay minerals are hydrous aluminium phyllosilicates, sometimes with variable amounts of iron, magnesium, alkali metals, alkaline earths and other cations. Clays have structures similar to the micas and therefore form flat hexagonal sheets. that formed in a wet environment. Red depicts the mineral olivine olivine (ŏlĭv`ēn), an iron-magnesium silicate mineral, (Mg,Fe)2SiO4, crystallizing in the orthorhombic system. , which formed about 3.8 billion years ago, according to according to prep. 1. As stated or indicated by; on the authority of: according to historians. 2. In keeping with: according to instructions. 3. the region's cratering record. Earlier data showed the clays, but a spectrometer and a high-resolution camera on NASA's Mars Reconnaissance Orbiter now reveal that the olivine is in sand dunes and that the clays are in exposed bedrock. That juxtaposition indicates that the clay was laid down first, says Jack Mustard of Brown University in Providence, R.I. He unveiled the image Dec. 13 at a meeting of the American Geophysical Union The American Geophysical Union (or AGU) is a nonprofit organization of geophysicists, consisting of over 50,000 members from over 140 countries. AGU's activities are focused on the organization and dissemination of scientific information in the interdisciplinary and in San Francisco. |
|
||||||||||||||||
Printer friendly
Cite/link
Email
Feedback
Reader Opinion