[X] My Assistant

[alan]

Physicists at the University of Guelph have detected the first "on-the-spot" evidence of significant amounts of water still existing on Mars.

Rather than existing in pools, the water is trapped in sub-surface soil on the red planet, most likely the remnants of oceans or pools that evaporated, according to lead researcher Iain Campbell.

"Our work is the first in situ evidence for total bound water in the Martian subsurface,” said Campbell,

An X-ray spectrometer called an APXS on the rover's arm captured the data about the trapped water. "Other instruments suggest the possibility — the APXs lets us determine the actual amount," said Campbell,

The water appears to be contained in mineral compounds in sulphur-rich soil just beneath the planet's surface, Campbell said. The distinctive bright white material was churned up by the rover's wheels as it moved across the soft red surface in the Columbia Hills region of the planet

In a paper that is in the final stage of review by the Journal of Geophysical Research: Planets, the team says the bright, sulphur-rich material contains up to 16 per cent water.

http://www.uoguelph.ca/news/2007/10/u_of_g_scientis_1.html

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I'm anxious to see the actual paper as well, since some of the previous work trying to identify the exact sulfates has been contradictory (or at least muddled). Coming up with an fit that is consistent with the measurements of Pancam, miniTES, Mossbauer and APXS seems to be no easy task. ( see Identifying the Phosphate and Ferric Sulfate Minerals in the Paso Robles Soils (Gusev Crater, Mars) Using an Integrated Spectral Approach

HDP Don: Although I completely agree that this finding isn't Mars-shattering in its conclusion, I do find it interesting that we now have ground truth for some of the previously assumed forms of stored (in this case bound) water on Mars. We, through the rovers, may have actually touched the last gasp of surface water. Finding samples this pure helps to make sense of the GRS findings for equatorial water.
Also, although most of the sulfates could have gone through many cycles of dehydration and rehydration, I did find one paper from the 2005 LPSC that states that some of the ferric sulfates in particular may not be able to rehydrate (The Hydration and Dehydration of Hydrous Ferric Iron Sulfates). This may help put constraints on the atmospheric conditions when/if last these deposits were exposed to the surface.

Then again, I may just find this stuff interesting because it makes for such pretty pictures