Mars was, in its ancient days, a wet place, at least at times. It is believed that lakes existed on the planet, and that water flowed in various places. How that was possible, though, has researchers baffled, at least according to NASA. As it turns out, ancient Mars wasn’t as hot as it is today, and according to current estimations, it seems ancient Mars would have been too cold for the water to be in a liquid state. Even the possibility of warmth from greenhouse gases is problematic.