Thursday, December 7, 2006

Recent Water Flows on Mars?

New observations just came in from NASA’s Mars Global Surveyor, areas imaged in 1999 and 2000 were recently re imaged. Comparing the two sets of images revealed new features in the more recent set of images hinting strongly at the presence of liquid water on the red planet. This is not the only data indicating the possible presence of subsurface water on Mars. But as it was said at the press conference held at JPL, “There are basically several lines of evidence. The first is the.morphology of the features that we see suggests that they were emplaced by a afluidized material, as opposed to a liquid material, something that was dirt mixed in with something that gave it mobility. The attributes that we see, it moved very slowly on a steep slope, which means that it was changing its properties as it was moving down slope. But it’s easily diverted around very, very subtle topography and it has very long, finger-like terminations at the ends of these flows. Those are all attributes of something that has liquid water in it.”

Scientists hypothesize that the water is coming from deep in the ground. “It’s warmed as it gets closer to the center of Mars. The outer parts of Mars are really, really quite cold, but the inner part is probably still warm, just as the Earth’s interior is warm. As the water came up, it reached the surface and initially froze at the surface. But as more and more water came up, it would build pressure behind the frozen water in front of it and eventually it would break out of behind that barrier and flow down the surface. So we think there’s an ice dam that is holding back water for some period of time, and then that dam breaks, and water comes out, and as it comes out, and as the dam breaks, it consists of rock debris from the rock around that water, it includes ice fragments from the dam and it includes liquid water.” Once on the surface it flows down these very steep slopes, 20, 30 degree slopes and picks up rock debris and spreads out and forms the deposit that is seen in the picture below. It is possible that there’s a trickle of water initially just sort of building up pressure behind the ice dam. After a certain period of time eventually there’s a rapid release of many thousands of cubic meters of water, like swimming pools amounts of waters come rushing out of the ground in a very short, brief event and then the surface refreezes. As more water builds up over time it eventually breaks again.

Subsurface water on Mars would mean a difference for any future exploration or even colonization of Mars, a good read on this topic is Zubrin and Wagner’s book “The Case for Mars“. More recent articles are available here.

Water Gullies on Mars

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