Bound water on Mars Options

[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

[slinted]

Although I'm not sure this is what Mike was referring to, some of the materials exposed at the Tyrone site did undergo a gradual color change from yellow to white after being exposed to the atmosphere.

from Salty Soils at Gusev Crater as Revealed by Mars Exploration Rover Spirit:

...the “yellowish” soils appear to become more spectrally similar to the “whiteish” soils since the time of their exposure to Martian surface conditions. This observation supports our model of the layered structure of salty soils at Tyrone. Indeed, we hypothesize that the “yellowish” soils were originally not in equilibrium with surface conditions because they were buried deeper. Over time, the equilibrium has been developing thus the “yellowish” soils are becoming similar to "whiteish” soils, which were more or less in equilibrium with surface conditions because of their originally much shallower burial depth.