Tuesday, December 6, 2016

Tracking The Watery Past of The Planet Mars


A possible water-carved channel on the surface of a region ('Arabia Terra') north of Mars equator.

As those of us following the NatGeo 'Mars' miniseries (by Ron Howard) are aware, the first explorers have finally "lucked out" in managing to find a deep pit laden with frozen water. This will now be able to furnish them water to drink - via melting- but also oxygen to breathe via electrolysis. Now, they basically have to just figure out how to furnish their new digs.

Whether there is still any water on Mars, even in deep caves, remains to be seen or found out. However, it appears that Mars had a relatively warm, wet climate in the distant past- the remains of which appear to be visible today. (See e.g. the image shown above of a water-carved channel north of the Martian equator.)

Now, new research by Sharon A. Wilson et al, published in The Journal of Geophysical Research, Planets e.g.

http://onlinelibrary.wiley.com/doi/10.1002/2016JE005052/abstract


suggests that flowing water, possibly from snow melt, formed mid-latitude valleys between 2 billion and 3 billion years ago. This would be near the transition between Mars' Hesperian and Amazonian periods. (Mars has geological periods or epochs similar to Earth's, i.e. the Jurassic period)

The findings arose from the team's efforts to uncover the history of distinctive, water -carved features known as fresh shallow valleys, found across Mars' mid-latitude areas. These formations are narrower, shallower and less degraded than other ancient valleys, indicating they may also be younger.

Wilson's team used high resolution images and topographic data collected by satellites to examine the size, shape, age and distribution of fresh shallow valleys in Arabia Terra, a large region just north of the Martian equator. (See one such valley in the image shown)  They also used a computer model to simulate water flow and re-create rivers and lakes that may have existed in Mars' past.

Their results suggest that fresh shallow valleys in Arabia Terra formed between the late Hesperian period, which ended 3 billion years ago, and the mid-Amazonian about 2 billion years ago. The shape and shallow depth of the valleys indicate they were likely less active for a geologically short period of time and probably carved by seasonal melting of snow that formed across the surface.

Other researchers have conjectured that the relatively young Martian valleys may have been formed by volcanic activity or asteroid impacts but these hypotheses are inconsistent with the authors' findings. The latter, citing the wide distribution north of the Martian equator, are much more supportive of a cooler, wetter Mars climate in its distant past.

Clearly, what we need is future Mars probes to finally settle the matter, particularly probes with the capability of launching their own data recording drones to fly over significant distances in order to map these shallow valleys..


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