Earth-like Mars dealt a fatal blow- but life still worrisome problem
Congratulations on putting an end to the watery Mars/ Earth-like Mars model,
but my gut estimate (and it is nothing more) is that there is still enough water on Mars at high enough temperatures to allow the growth of potentially nasty microbes
Take an enviornment such as say in the layers beneath the surface of a shattered quartz, or perhaps even in the layers of some kind the crystals of one type of slat or another -
So what you have is not enough water to be useful for man, but enough water so that the biohazard of back contamination remains -
now to get on with the business at hand, which is finding the next asteroid or comet before it hits -
ep