i got this from www.space.com,
it looked so intresting i thought i'd share it with you.
Squeezed out of the soil
In perusing rover imagery, Levin reports there is clear
evidence for liquid water existing under Martian environmental conditions. "The images should be reviewed against the background of surface temperatures as varying from below to above freezing reported by both Spirit and Opportunity," he explained.
Levin points to the potential for mud puddles on Mars, showing an image of clearly disturbed martian soil after rover airbags bounced across Mars’ surface. Possible standing water and sinkholes can also be seen in rover imagery, according to his analysis. In some pictures, the often-discussed "blueberries, " tiny spheres of material, disappear as if submerged underneath mud-like surroundings, he added.
Then there are tracks left by the machines as they roll across the martian terrain. Self-taken shots by the robots show what Levin said appears to be water squeezed out of the soil which then freezes into a whitish residue left in embedded tread marks.
Similarly, Levin added, are images taken by Opportunity of the results from an operation of the robot’s Rock Abrasion Tool, or RAT. The center of that particular RAT hole is largely white, possibly indicating the formation of frost since the hole was drilled, he noted.
Organisms there now?
"The evidence presented strongly indicates the presence of liquid water or moisture at the Mars Exploration Rover sites," Levin reported at the SPIE meeting. "Mars today could support many forms of terrestrial microbial life."
Other scientists are cautious to point out that the presence of water does not guarantee life. Rather, it means one crucial ingredient exists.
There is clear evidence for frost or ice on Mars, the former Viking experimenter stated. At some point of the day -- when temperatures climb above freezing -- there’s going to be moisture…"and that’s enough to support microorganisms," he said.
None of the many new findings about Mars revealed by Spirit and Opportunity, Levin concluded, conflict with, or render untenable, his long-held belief that the Viking Labeled Release experiment in 1976 detected living microorganisms in the soil of Mars.
"I contend that today you could take a great many Earth microorganisms, put them on Mars, and they’d grow," Levin said. "And I think there are organisms there now. They may have come from Earth. They may have originated on Mars. They may have come from a third place that populated both Mars and Earth."
Rocks can be kicked up from one planet by an asteroid impact, drift through space for eons, then land on the other. Other studies have shown that these rocks could potentially transport life, in a dormant phase, from one planet to the other.
Levin said that he thinks the "greatest speculation" would be to say there can be no life on Mars.