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UNIVERSE TODAY
Feb 24, 2004 -- NASA's Spirit rover has discovered an unusual patch of sand in a hollow on its journey to the crater "Bonneville". An unusual pattern of irregular lines and polygons in the soil could indicate the presence of a salty brine. This could mean there's liquid water right below the surface of Mars, which could harbour life - microbes thrive in similar environments on Earth. The rover dug a trench and examined the spot with its array of instruments, which scientists will study intensely back on Earth.
Opportunity has been getting the lion's share of the attention in recent weeks, because its twin sister Spirit has been engaged mostly in long-distance driving. But it may be about to steal the spotlight. For several sols, Spirit has been working its way towards nearby Bonneville crater. But even before it gets there, the mobile robot may make a critical discovery. It may find evidence of liquid water on Mars.
Well, not exactly liquid water. Liquid brine, actually. Brine is water that contains dissolved salts. The salts lower the melting temperature of the mixture so that it remains liquid well below the freezing point of pure water. (That's why road crews "salt" roadways to melt ice in the winter.) Scientists have long speculated that brines, or super brines - a super brine contains high concentrations of dissolved salts - may exist in the martian subsurface.
Spirit's discovery of patterns in the surface soil at Gusev Crater is what led scientists to believe that there may be subsurface brines there. As of sol 45 (Tuesday, February 17), Spirit had traveled to Laguna Hollow, a small depression located about halfway between Spirit's landing site and Bonneville crater. In the fine-grained surface material inside the hollow, scientists can see irregular patterns of lines and polygons.
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