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\n NASA\u2019s Phoenix Lander\u2019s solar panel and robotic arm with a sample in the scoop<\/p>\n NASA\/JPL-Caltech\/University of Arizona\/Texas A&M University<\/p>\n<\/div>\n<\/figcaption><\/figure>\n<\/p>\n Mars may have a network of liquid water flowing through the frozen ground. All buried permafrost, on Earth and beyond, is expected to host narrow veins of liquid, and new calculations show on Mars, they could be big enough to support living organisms.<\/p>\n \u201cFor Mars we always live on the edge of maybe habitable, maybe not, so I set out to do this research thinking maybe I can close this loop and say that it\u2019s very unlikely to have enough water and have it be arranged so that it\u2019s habitable for microbes,\u201d says Hanna Sizemore at the Planetary Science Institute in Arizona. \u201cI proved myself wrong.\u201d<\/p>\n <\/p>\n She and her colleagues used measurements of the soil composition on Mars to calculate how much of the icy soil could actually be liquid water and the size of the channels that water would run through. It is tricky to keep water liquid on Mars, because temperatures can get as low as -150\u00b0C (-240\u00b0F) on the planet. While pure water freezes at 0\u00b0C, the abundant salts on Mars can dissolve in the water there and lower its freezing point significantly.<\/p>\n The researchers found that it was \u201csurprisingly easy\u201d to get soil with more than 5 per cent liquid, running through channels at least 5 microns in diameter \u2013 the requirements they set for the veins to be considered habitable. \u201cThe largest veins we\u2019re talking about are 10 times narrower than very fine human hair,\u201d says Sizemore. \u201cBut it\u2019s a large enough environment to submerge a microbe, and [they are] connected enough to move food and waste through the environment.\u201d<\/p>\n Based on soil measurements from NASA\u2019s Phoenix spacecraft, which landed on Mars in 2008, these networks of channels could be abundant at latitudes higher than 50 degrees. If there is life on Mars, the liquid veins would be the easiest place to look for it, says Sizemore: \u201cThis is an environment where we can land and dig down like 30 centimetres and sample this.\u201d<\/p>\n The main potential problem with these veins as habitable environments is their temperature, which can be much colder than most known lifeforms can tolerate. \u201cWe have to be careful, though, about using the limits in which terrestrial life can grow and metabolise, as they do not necessarily represent the limits in which any life, anywhere, could function,\u201d says Bruce Jakosky at the University of Colorado Boulder. \u201cThe bottom line is that, based on this and related work in particular, it\u2019s not impossible that life could exist in the Martian near surface.\u201d<\/p>\n Topics:<\/p>\n