Rough Cut (no reporter narration)<br/> <br />NASA's Mars rover, Curiosity, dispatched to learn if the most Earth-like planet in the solar system was suitable for microbial life, has found clear evidence its landing site was once awash in water, a key ingredient for life, scientists said on Thursday (September 27).<br/> <br />Curiosity, a roving chemistry laboratory the size of a small car, touched down on Aug. 6 inside a giant impact basin near the planet's equator. The primary target for the two-year mission is a three-mile (five-km) -high mound of layered rock rising from the floor of Gale Crater.<br/> <br />Scientists suspect the mound, known as Mount Sharp, is the remains of sediment that once completely filled the crater. Analysis of a slab of rock located between the crater's north rim and the base of Mount Sharp indicate a fast-moving stream of water once flowed there.<br/> <br />Images taken by Curiosity and released on Thursday show rounded stones cemented into the rock, which rises like a piece of jack-hammered sidewalk from the planet's surface.<br/> <br />The stones inside the rock are too big to have been moved by wind, Curiosity scientist Rebecca Williams, with the Planetary Science Institute in Tucson, Arizona, told reporters on a conference call.<br/> <br />"The consensus of the science team is that these are water-transported gravel in a vigorous stream," she said.<br/> <br />The rock is believed to be from the floor of an ancient stream which was once between ankle- and knee-deep.<br/> <br />The analysis is based on telephoto images taken by the rover, which is en route to a patch of land named Glenelg where three different types of rock intersect.<br/> <br />Scientists have not yet decided if the slab of rock warrants a chemical analysis, or if there are better targets for Curiosity to look for the building blocks of life and the minerals to preserve it.<br/> <br />"The question about habitability goes beyond the simple observation of water on Mars," said lead scientist John Grotzinger at the California Institute of Technology.<br/> <br />"Certainly flowing water is a place where microorganisms could have lived. This particular kind of rock may or may not be a good place to preserve those components that we associate with a habitable environment," he said.<br/> <br />The $2.5 billion Mars Science Laboratory Curiosity mission is NASA's first astrobiology mission since the 1970s-era Viking probes.
