The problem with liquid water isn’t so much the temperature as the vapor pressure. Liquid water would evaporate away at the Martian atmospheric pressure. There is vapor pressure depression in pores, so there could be pore water even at low pressure.

Many salts effloresce, that is change into powder on loss of water. A layer of such a salt a few microns thick would scatter more light as a powder than it would as a denser solid. The apparent motion of the â??flowsâ? could be related to the presence of different mineral species at those regions which are relics of actual flows a long time ago.

That many of the pictures seem to show changes in light scattering in places without access to ground water flows. If that change is due to hydration changes, the water likely comes from the atmosphere.

Magnesium perchlorate is a likely candidate.

http://adsabs.harvard.edu/abs/2010DPS….42.5103G

I wonder why the claim of ‘briny water’ – is the rock known to have large amounts of salt?

Because it’s too cold for liquid fresh water. If it is liquid water, it must be briny in order to be liquid at those temperatures.

As for humans on Mars … AAAHAHAHAHAHAHAHAHAHAHAHAHAHA! Human corpses maybe – even for a short trip to Mars (only a few months) making a large enough vehicle with enough supplies is quite a challenge – and that’s not even considering a return trip. However, the dangers are no hindrance – there are enough people on the planet who would gladly go knowing they’ll never make it back alive.