智利阿塔卡马沙漠：在地球最干燥之地寻找生命极限
Stretching across northern Chile, the Atacama Desert is not merely the driest nonpolar expanse on Earth; it is a geological mirror of Mars, its parched soils and salt-encrusted basins offering a natural laboratory for one of science's most audacious questions: where does life end, and how might it begin elsewhere? Here, a small but determined cohort of astrobiologists has spent years cataloguing extremophiles—microorganisms that thrive in conditions that would sterilise most terrestrial habitats—probing the boundary between the viable and the barren.
Recent field campaigns, led by an interdisciplinary consortium from South American and European universities, have focused on hyperarid zones that receive rainfall only once per decade. Using sterile coring tools and portable sequencing machines, researchers extract samples from centimetres beneath the salt crust, where traces of deliquescent moisture allow cryptic microbial communities to persist. These organisms, predominantly archaea and certain bacterial lineages, metabolise by harvesting energy from trace atmospheric hydrogen or by oxidising minerals in the soil—an existence so tenuous that their cellular activity is measurable only with sensitive isotopic tracers.
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