Dust rocks martian river theory

[DC09]

Gullies on Mars that appear to have been carved by flowing water could instead have been created by landslides of dry powdery material, scientists have found.

Troy Shinbrot and colleagues of Rutgers University in New Jersey say that Mars's smaller gravity, which is 38% weaker than Earth's, would allow rockfalls to last longer than they do on Earth. This means landslides could cause the kind of geological features usually only associated with running water.

The researchers doubt that all martian "rivers" can be explained away like this, but the theory could account for some of the most puzzling and provocative examples.

Spacecraft in the 1970s were the first to see Martian geological features that resembled dried-up riverbeds. This helped establish the theory that the surface of Mars once held rivers, lakes and even oceans.

NASA's Mars Rover missions, which touched down on the red planet in January, uncovered geological evidence that there was indeed liquid water on Mars, a very long time ago. That confirmed what many already believed.

But four years ago, the Mars Global Surveyor spacecraft astonished planetary scientists by taking pictures of gullies and channels that seemed to have been formed in the relatively recent past: a few million years ago, or even less.

Those pictures have led some researchers to propose that Mars might still experience outbursts of liquid water today, perhaps by the sudden venting of underground reservoirs. Yet perplexingly, these young gullies are found in regions of the planet that are always very cold.

Now Shinbrot and colleagues say the more recent features might not be sculpted by water at all, but could be the result of flows of dry mineral grains, like slumping sand.

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[Athlon64]

Mars' gravity is 38% that of Earth, not 38% weaker.

[poleshift]

Can this theory explain the blue berries?