![]() ![]() "We know that there are large lakes of liquid methane and ethane on Titan," one of the moons of Saturn, McKay told Live Science in an email. Unlike water, however, methane becomes liquid only at very cold temperatures - at a frigid minus 296 degrees Fahrenheit (minus 182 degrees Celsius). ![]() ![]() Methane isn't polar, but it can dissolve many other substances. Ammonia, like water, is a polar molecule that is relatively abundant in the universe, but scientists haven't found any large bodies of ammonia anywhere in the solar system, McKay said. Some of the top contenders are ammonia and methane, said Chris McKay, an astrobiologist at the NASA Ames Research Center in Moffett Field, California. Scientists are also looking at other liquids that could play a similar role as universal solvent and transport medium. Of course, while water is crucial to life on our home planet, there could be life-forms that don't conform to the Earthling playbook. "One possibility is that because the building blocks are frozen within the water, it has this protective mantle around it that could be delivered," Kaiser told Live Science. However, in its solid form, water could have provided a way to shield those molecules from radiation, Kasier speculated. But traveling through space is a harsh journey, with punishing levels of radiation that would normally degrade those delicate molecules, Kaiser said. One theory for how life on Earth emerged, called panspermia, posits that icy comets smashed into Earth, bearing tiny organic molecules that formed the precursors to life. Water may be more than a fluid to help facilitate life's essential processes - it may also have been the protective cradle that carried the building blocks of life to Earth, said Ralf Kaiser, a physical experimental chemist at the University of Hawaii at Manoa, who has research experience in astrochemistry. "All three available on our planet creates this really neat variety of habitats and microclimates," Glazer said.įor instance, frozen ice can be found in glaciers that carve through mountains, whereas water vapor helps warm the atmosphere, Glazer said. The fact that water can be in all three phases in a relatively tight range of pressures creates many opportunities for life to flourish, he added. "Water really is at that sweet spot," Glazer said. Other molecules that have been identified as good candidates for supporting life tend to be liquid at temperatures or pressures that would be inhospitable for most known life-forms, Glazer said. Water, with its amazing dissolving properties, is the perfect medium for transmitting substances, such as phosphates or calcium ions, into and out of a cell.Īnother feature of water is that it can act as a solid, liquid and gas within the range of temperatures that occur on Earth. The positive hydrogen end tends to attract negative ions (or atoms with an extra electron in the outer shell), while the negative region lures in positive ions (which have had one of their electrons stripped off). That's because the molecule has polarity, meaning the hydrogen atoms tend to bunch on one side of the molecule, creating a positive region, while the oxygen end has a negative charge. "The way they're bonded together makes water this wonderful universal solvent," meaning that almost every substance can dissolve in water, Glazer told Live Science. The humble water molecule is made up of two hydrogen atoms bonded to an oxygen atom. ![]() By contrast, deriving energy from a solid is a much tougher prospect (though there are microbes that eat rock), Glazer said.īut the other part of the equation - that water can carry things into and out of the cell - has to do with water's unique chemical configuration. Because it flows, water provides an efficient way to transfer substances from a cell to the cell's environment. In this regard, water is essential simply because it's a liquid at Earth-like temperatures. To stay alive, the organism takes in important materials for making energy, while shuttling out toxic substances such as waste products. Not only can water dissolve nearly anything, but it is also one of only a few materials that can exist as solid, liquid and gas within a relatively narrow range of temperatures.Īt heart, all life on Earth uses a membrane that separates the organism from its environment. It turns out that several chemical properties of water make it indispensable for living creatures. ![]()
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