Monday, February 6, 2012

Short Sharp Science - Martian real estate, windy and cratered but isolated

Andrew Purcell, online producer
(Image: ESA/DLR/FU Berlin (G. Neukum))

Now in the ninth year of its mission, the European Space Agency's Mars Express orbiter has sent back images of the Red Planet's mysterious Syrtis Major region - once thought to be a shallow sea.
Syrtis Major was first discovered in 1659 by physicist and astronomer Christaan Huygens, who used its appearance during the planet's rotation to help calculate the length of a day on Mars.
We now know that it is not water, but sand and dust which cause the region's shape to change over time. The dispersal patterns of the lighter-toned dust and darker-toned sand in the image show the prevailing direction of the wind.
The region is also now known to have volcanic origins, with lava flows and partly-filled impact craters visible in the image. The number and size of these impact craters has enabled scientists to calculate that the Syrtis Major region is approximately 3 billion years old.
Despite notions of present-day oceans on Mars having long been dismissed, Mars Express has also recently added to the evidence suggesting that there may indeed have once been oceans on the Red Planet. Features resembling ancient shorelines have previously been identified in images from several spacecraft and Mars Express has now used radar to detect sediments reminiscent of an ocean floor within the boundaries of these previously identified ancient shorelines.
"It is a strong new indication that there was once an ocean here," says Jérémie Mouginot of the Grenoble Institute of Planetology and Astrophysics (IPAG) and the University of California, Irvine.
Mouginot says an ocean first existed 4 billion years ago, when warmer conditions prevailed on Mars. A second ocean may have formed a billion years later when subsurface ice melted following a large impact, creating outflow channels that drained the water into areas of low elevation. The search for life, meanwhile, goes on.

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