A new study published in the journal Nature explains that there is likely more water beneath the Earth's crust than on top of it — and that below-crust water may contain life.
Researchers from the University of Toronto looked at data from 19 mine sites in Canada, South Africa, and Scandinavia, and found 2.5 cubic miles of water. The water had reacted with billions-of-years-old Precambrian rocks to produce hydrogen, the BBC reports, which could be a food source for potential life. The researchers also estimate that their findings double the amount of hydrogen believed to be on Earth.
The production of hydrogen suggests that "complex microbial communities" could be just below Earth's crust, according to the researchers. The ancient water's chemistry is similar to that of the water found near Earth's deep sea vents.
Mars also has billions-of-years-old rocks with the potential to produce hydrogen, so the discovery could have "ramifications for astrobiology" if similar processes are found occurring there. First, though, scientists are going to look for more evidence closer to home.