Solar panel and robotic arm of NASA's Phoenix lander with sample in scoop
NASA/JPL-Caltech/University of Arizona/Texas A&M University
Mars may have a network of liquid water flowing through the frozen ground. All buried permafrost on Earth and beyond is expected to contain narrow veins of liquid, and new calculations suggest that on Mars they could be large enough to support living organisms.
“With Mars, we're always living on the edge of maybe being habitable, maybe not, so I decided to do this research thinking maybe I could close that loop and say it's unlikely to have enough water on it and make it habitable for microbes,” says Hannah Sizemore at the Planetary Science Institute in Arizona. “I proved myself wrong.”
She and her colleagues used measurements of soil composition on Mars to calculate how much of the icy soil might actually be liquid water, as well as the size of the channels through which water would flow. It is difficult to keep water liquid on Mars, as temperatures on the planet can drop to -150°C (-240°F). While pure water freezes at 0°C, there is plenty of salts on Mars can dissolve in water and significantly reduce its freezing point.
The researchers found that it was “surprisingly easy” to get soil with a liquid content of more than 5 percent flowing through channels at least 5 microns in diameter – the requirement they place on the veins to be considered habitable. “The largest veins we're talking about are 10 times narrower than very fine human hair,” says Sizemore. “But this is a medium large enough to immerse a microbe in it, and [they are] connected enough to move food and waste through the environment.”
These channel networks may be abundant at latitudes above 50 degrees, according to soil measurements from NASA's Phoenix spacecraft, which landed on Mars in 2008. If there is life on Mars, liquid veins would be the easiest place to look for it, says Sizemore: “This is an environment where we can land, dig down to about 30 centimeters and take samples.”
The main potential problem with these veins as habitable environments is their temperature, which can be much lower than most famous life forms I can stand it. “However, we must be careful when using the limits within which terrestrial life can grow and metabolize, since they do not necessarily represent the limits within which any life anywhere can function,” says Bruce Jakoski at the University of Colorado Boulder. “The bottom line is that, based on this and related work in particular, it is possible that life could exist in the near-surface layer of Mars.”
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