for National Geographic News
Stunning color pictures from Mars offer new evidence that plentiful groundwater once percolated through Martian bedrock.
The new images, taken by NASA's Mars Reconnaissance Orbiter, reveal a terrain of banded rocks similar to that found in the southwestern U.S., said Chris Okubo, a postdoctoral researcher at the University of Arizona's Lunar and Planetary Laboratory.
The new pictures show that Martian rocks in this sandy landscape are riddled with small cracks.
These cracks bear telltale signs that fluid—probably water—seeped through them hundreds of millions of years ago.
Prominent riblike structures along the cracks, for instance, suggest that running water dissolved minerals in the Martian soil, forming a kind of cement.
The water also dissolved dark minerals out of the rocks, leaving light-colored "halos" around the cracks.
These findings are exciting, because they suggest that similar water-filled fractures might still exist beneath the Martian surface, scientists said.
"What we see at the surface today are glimpses of what used to be underground," Okubo said.
Okubo presented the new images at a press conference today in San Francisco, California. His team's findings will appear in tomorrow's issue of the journal Science.
Search for Life May Shift
Water is a key component of life as we know it, so the new discovery will be useful in helping scientists hone the search for possible life on Mars, researchers at the conference said.
There is already abundant evidence that early Mars was once water rich, said Stephen Clifford, a Mars hydrologist from the Lunar and Planetary Institute in Houston, Texas.
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