Mars Photos Seem to Show Recent Water Flows

Scientists launched new fantasies of life on Mars Wednesday when they revealed remarkable new findings that suggest water may still be flowing on the alluring Red Planet.

The results came to light through an analysis of photographs taken by an orbiting space probe. Pictures of gullies on the sides of Martian craters taken by the Mars Global Surveyor several years ago, and then again more recently, revealed differences.

The newer photos showed light-colored deposits that appear to be dried-up salt or frost left by water which first flowed, then evaporated. The deposits were not in the earlier images.

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"It's exciting. It greatly magnifies [the chances] of life as we know it on Mars," Neil DeGrasse Tyson, an astrophysicist with the American Museum of Natural History in New York City, told "If it's still oozing out in liquid form, this reaffirms Mars as an interesting destination to look for life there today."

Tyson said the Martian life that could exist in light of the new findings, simultaneously published online Wednesday in the journal Science, is likely microbial — not the little green creatures with antennae that have made their way into countless science fiction stories.

"We're talking bacteria and other single-cell life forms, which are very hardy — more hardy than we are," said Tyson, the director of the American Museum's Hayden Planetarium. "We're not talking about alligators."

Water and a stable heat source are considered keys for life to emerge, or at least survive.

"This is a squirting gun for water on Mars," said Kenneth Edgett, a scientist at San Diego-based Malin Space Science Systems, which operates a camera on the Global Surveyor, at a press conference held by NASA Wednesday afternoon in Washington, D.C.

Mars was likely once warm and wet, with a radiation-deflecting magnetic field like Earth, but dried up billions of years ago. Any life that evolved might still exist as hardy microbes living underground, able to tolerate extreme cold and radiation.

"No one denies that liquid water once flowed heavily on the Martian surface," Tyson told "There's tremendous surface evidence: river beds, flood plains, lake beds. The question is, where did all the water go? It's widely believed that it went below the surface and froze there."

Scientists have long noted Martian features that appear to have been scoured by water or look like shorelines. Ice has already been found at the Martian north pole.

"This underscores the importance of searching for life on Mars, either present or past," said Bruce Jakosky, an astrobiologist at the University of Colorado at Boulder, who had no role in the study. "It's one more reason to think that life could be there."

Tyson said the just-released study about water flowing on Mars adds new impetus to human-run missions to the Red Planet and means the equipment sent there will need to be upgraded so it can drill below the Martian surface.

"You don't want to go to Mars knowing this without being able to do experiments related to it. That would just be embarrassing," he said. "You want to make sure what you take there — rovers, astronauts — are ready to probe in just the ways you would need to learn about the liquid water."

The latest findings point to the possibility that Mars can sustain liquid water, which the majority of scientists hadn't previously thought to be the case, according to Tyson.

"Most sensible scientists presume that the water was frozen," he said. "It's very cold in the Martian environment. We lost the water on the surface for reasons not yet understood ... This new result says not all of it is frozen, and we can ask what melted it."

Oded Aharonson, an assistant professor of planetary science at the California Institute of Technology, said that while the interpretation of recent water activity on Mars was "compelling," it's just one possible explanation.

Aharonson said further study is needed to determine whether the deposit could have been left there by the flow of dust rather than water.

The latest research emerged when the Global Surveyor spotted gullies and trenches that scientists believed were geologically young and carved by fast-moving water coursing down cliffs and steep crater walls.

Scientists at Malin Space Science Systems decided to retake photos of thousands of gullies in search of evidence of recent water activity.

Two gullies that were originally photographed in 1999 and 2001 and reimaged in 2004 and 2005 showed changes consistent with water flowing down the crater walls, according to the study.

In both cases, scientists found bright, light-colored deposits in the gullies that weren't present in the original photos.

They concluded the deposits — possibly mud, salt or frost — were left there when about 10 swimming pools' worth of water recently cascaded through the channels.

Some researchers were skeptical that liquid water was responsible for the surface feature changes seen by the spacecraft. They said other materials such as sand or dust can flow like a liquid and produce similar results.

"Nothing in the images, no matter how cool they are, proves that the flows were wet, or that they were anything more exciting than avalanches of sand and dust," Allan Treiman, a geologist at the Lunar and Planetary Institute in Houston, said in an e-mail.

Edgett, however, said a combination of factors, including the shape and color of the deposits, led the team to believe it was recent water action and not dust that slipped down the slope. He said dust would leave dark deposits.

Water cannot remain a liquid on the surface of Mars for long because of subzero surface temperatures and low atmospheric pressure that would turn water into ice or gas.

But scientists theorize that liquid water is being shot up to the surface from an underground source, like geysers. Subterranean icy mud may also be being thawed by sunlight periodically hitting the normally dark walls of craters.

The Global Surveyor, managed by NASA's Jet Propulsion Laboratory, abruptly lost radio contact with Earth last month. Attempts to locate the spacecraft, which has mapped Mars since 1996, have failed and scientists fear it is unusable.

NASA's durable Mars rovers have sent scientists strong evidence that the planet once had liquid water at or near the surface, based on observations of alterations in ancient rocks.

"Every place where we find liquid water, we find life," Tyson said.

FOX News' Catherine Donaldson-Evans and The Associated Press contributed to this report.