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Life Without Water

By | August 2013
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When astronomers search for life outside of our solar system, they look right past the gas giants like Saturn and Jupiter, past the torrid, rocky planets like Mercury and Venus, and past the dwarf planets like Pluto. They stop when they find an exoplanet like Gliese 581d. Gliese 581d is about 50 percent larger than Earth, and like Earth, it orbits in what's known as astar's habitable zone, the stellar sweet spot where a planet is capable of having liquid water. And where there's water, there might, just possibly, be life. What makes scientists think that water is better at sustaining life than every other substance? Part of the reason is that we've never discovered an organism that's proven otherwise. While some organisms need less than others -- the cyanobacteriaChroococcidiopsis, for instance, needs so little water that biologists think it may be able to survive on the arid surface of Mars -- every organism we know of needs water to survive. In fact, without water, life on Earth would have never begun. Acting as a medium in which organic compounds could mix with one another, water facilitated the formation of the planet's first life forms, possibly even protecting them from the sun's radiation. From those simple starter organisms to the most complex plants and animals, water has played a critical role in survival ever since. In humans, it acts as both a solvent and a delivery mechanism, dissolving essential vitamins and nutrients from food and delivering them to cells. Our bodies also use water to flush out toxins, regulate body temperature and aid our metabolism. No wonder, then, that water makes up nearly 60 percent of our bodies or that we can't go for more than a few days without it. Besides being essential for our bodies to function, water also promotes life in numerous other ways. Without it, we couldn't grow crops, keep livestock or wash our food (or our bodies, for that matter). Water has also advanced civilization, providing a means for travel for...

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