July 17, 2008
New Findings Show Diverse, Wet Environments on Ancient Mars
New findings show diverse, wet environments on ancient Mars
WASHINGTON, July 16 (Xinhua) -- Mars once hosted vast lakes, flowing rivers and a variety of other wet environments that had the potential to support life, according to two new studies based on data from instruments on board NASA's Mars Reconnaissance Orbiter (MRO).By combining data from these high-tech instruments, scientists have identified three principal classes of water-related minerals dating to the early history of Mars. The variations in the minerals suggest that different processes, or different types of watery environments, created them.
"The big surprise from these new results is how pervasive and long-lasting Mars' water was, and how diverse the wet environments were," says Scott Murchie, principal investigator of the MRO's Compact Reconnaissance Imaging Spectrometer for Mars (CRISM).
One study, published in the July 17 issue of Nature, shows that vast regions of the ancient highlands of Mars -- which cover about half the planet -- contain clay minerals, which can form only in the presence of water. Volcanic lavas buried the clay-rich regions during subsequent, drier periods of the planet's history, but impact craters later exposed them at thousands of locations across the planet.
The clay-like minerals, called phyllosilicates, preserve a record of the interaction of water with rocks dating back to what is called the Noachian period of Mars' history, about 4.6 to 3.8 billion years ago.
A companion study, published in the recent issue of Nature Geosciences, finds that the wet conditions persisted for a long time. Thousands to millions of years after the clays were formed, a system of river channels eroded them out of the highlands and concentrated them in a delta where the river emptied into a crater lake.
"The distribution of clays inside the ancient lakebed shows that standing water must have persisted for thousands of years," says Bethany Ehlmann, another member of the CRISM team and lead author of the study of the ancient lakebed. "Clays are wonderful at trapping and preserving organic matter, so if life ever existed in this region, there's a chance of its chemistry being preserved in the delta."
"Our whole team is turning our findings into a list of sites where future missions could land to look for organic chemistry and perhaps determine whether life ever existed on Mars," says Murchie.
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