Hi Winston,
Since the flocculose soil appears to be magnetic I would punt on Maghemite, or at least a significant maghemite component. Can I justify that other than on extremely general terms - no. Am I right - probably not. Just one of those hunches that feels good.
The thing is that your suggestion would require that there would be, in the regolith, 'something, chemical or otherwise that traps water from the atmosphere' and then freely releases it as a function of the daily temperature cycle, with no free molecules. That is a pretty weird and complex scenario. Dr Zent has not come out and clarified his statement related to H20 vapour concentrations in terms of absolute humidity. So I wonder exactly how much water vapour delta we are talking about when frost and clouds are considered.
Barsoomer, The subsurface ice is evident North and South of 60 degrees latitudes. They were expecting to find ice within the limited depth capability of the phoenix scoop. Not a feature of tropocal/equatorial regions.
