As I understand it the probe can only establish...

As I understand it the probe can only establish if there is any unfrozen water in the soil (down to incredibly small amounts). But what we seem to have is frozen ground where all pore water (if indeed there is any) has turned to ice. Any exchange of H20 between air and ground and back again is limited to sublimation - no liquid phase. That would fit with the apparent lack of hydration shattering in the rocks around Phoenix.

But it is also a thermal probe? So do they use heat transfer to determine the thermal conductivity of the regolith and does this enable them to measure any liquid water film resulting in the frozen ground? I mean, does the result also indicate that there is no ice content in the regolith? More information please Leslie; what is the thermal inertia characteristic of the regolith, is it possibly hydrophobic? It must be a superb insulator.

I mentioned before Winston that I put my hopes on the ice/regolith boundary layer, but from the probe results I'm not holding my breath. I don't know what the sub surface temperature is, but it must be very low since we have well bonded permafrost that slowly sublimates when exposed, despite the fact that it is expected to be salty with significant freezing point suppression.

Hmm an exposed water ice source next to the lander. I wonder if that is the source of the humidity changes? Is it a local effect - did we have the same effect during the few windy days?