wishful thinking also an isotope in the sand would have allowed water to stay flowing at the below freezing temperatures that mars has, so if you were grasping

wishful thinking also an isotope in the sand would have allowed water to stay flowing at the below freezing temperatures that mars has, so if you were grasping for straws at why there would be water, this would support it, but if you weren't wishing there was water there as the presupposition then this new answer would have been more immediately obvious