Wednesday, 6 December 2006
Water Flowing on Mars: NASA

Water flows on Mars.

In one image, a shining snake of light flows from a hidden spring into a crater's depression, an orbiting camera aboard NASA's Mars Global Surveyor catching sunlight reflected by the evaporating liquid. In another, a smear of ice grows mysteriously over a period of years, expanding like a slow-motion inkblot over the red planet's parched landscape.

"If this was coming down the slope [toward you], you'd want to get out of the way," said NASA's Kenneth Edgett, a scientist with Malin Space Science Systems. "This is the squirting gun for water on Mars."

"We've found it," said Michael Meyer, NASA's lead scientist on their Mars Exploration Program. "Water seems to have flowed on the surface of today's Mars." Philip Christensen, a professor from Arizona State University in Tempe, added that the discovery would change NASA's plans for Mars exploration, not to mention our understanding of the desert world itself.

Mars Global Surveyor, whose extended mission came to an end last month following a power failure, captured the images while tracking changes in geography over a period of years. Dry gulleys, previously through to have held water no more recently than millions of years ago, were found to have filled between observations.

Certain tasks remain, according to the panelists. For example, a spectrographic analysis of the "white stuff," to prove that it is definitely water. These might be carried out by the Mars Reconnaissance orbiter, recently arrived in order to replace the aging Global Surveyor.

"These things appearing bright is extremely unusual," said to NASA panelist Michael Malin, explaining why NASA believes the apparitions are water, not mere avalanches of dust. "In the past, the things we've seen are very dark ... this requires some kind of fluidizing agent."

Subsurface aquifers or melting ground ice were floated as possible sources of the water. One of the springs even appears at a fault line, according to Malin, just as they often do on Earth.

The shortness of the gulleys, which seem to flow for but a few hundred yards, might be accounted for by a process similar to a volcano's eruption on Earth, with water instead of magma building up underground, and ice, instead of fire, characterizing the resulting flow.

"When it reaches the surface, the water freezes and creates a dam that blocks up the water behind it," Edgett said. "Eventually the water breaks, causing an outflow of the dam ice, and the water comes bursting out."

Edgett warned against likening it to Earth-bound processes, however, as the geology is dissimilar. "It's more akin to a flash flood. ... Those mudflows are probably very similar to what this would look like in terms of the body of the flow."

Liquid water is a necessary precondition for life, so the new findings will renew interest among scientists searching for microbial life on Mars. If subterranean aquifers exist, it could boost long-term plans to build a research base on the distant world--and even make it more viable than a facility on the moon, where frozen ice, deposited by meteorites and comets, is the only known source of water.

While Mars' atmosphere is so thin that liquid water evaporates or freezes quickly on the surface, it appears to last long enough to carve snaking gulleys across the planet. Nasa has counted tens of thousands.

At the conference, NASA also revealed observations of ongoing cratering on the planet's surface, including a recent impact that released power equivalent to a 100 kiloton nuclear explosion, five times more powerful than the atomic bombs detonated over Hiroshima and Nagasaki during WWII.

Source: http://blog.wired.com/gadgets/2006/12/f … ter_o.html