It’ll be a fine day for Poland Spring, when Mars is finally colonized: bottled’s the only option, when you’re living on a planet whose last substantial traces of flowing liquid water disappeared a few billion years ago. That ancient water has occasioned much study and debate, and provided the name for at least one French-Candian psych rock band. The fact that it existed, at one point, is a large part of why dreams of annexing Mars have flourished. But where did it go, exactly? By what majestic geological processes do massive bodies of space-liquid just disappear? For this week’s Giz Asks, we talked to a number of Mars experts to find out.To read more, click here.