Just a mile or so beneath the surface, near the south pole of Mars, there is a reservoir of briny water sloshing and churning below layers of ice and rock.
This subglacial lake, discovered by a ground-penetrating radar on the Mars Express spacecraft, is about 20 kilometers (12.4 miles) wide and perhaps no more than a meter deep. Its discovery is the latest piece of evidence that suggests water was not only present on Mars in the past but is still flowing in some capacity today. The findings, if confirmed by future observations, would be the most significant discovery of liquid water on Mars to date.
Scientists already had little doubt that there was, at one point, liquid water on Mars, thanks to tiny spherical deposits discovered by the Opportunity rover in 2004 and the comprehensive mineralogy studies conducted by the Curiosity rover. The evidence suggests that vast lakes and rivers dominated the surface of Mars billions of years ago. What’s more, tantalizing clues have continued to imply the existence of liquid water on Mars today. Condensation was measured on the Phoenix lander in 2009, and dark streaks spotted on Martian dunes may be evidence of briny water (although more recent examination suggests they could be avalanches of dry sand).
This new discovery of a subterranean water deposit, outlined in a new paper in Science,suggests water is indeed underneath the red sands of Mars. Perhaps the Red Planet even has entire subsurface lake systems like those beneath Antarctica.
A Breakthrough 15 Years in the Making
Mars Express is a European Space Agency probe that has been orbiting the fourth planet from the sun since December 2003. A year and a half after it arrived, the craft deployed two 20-meter radar booms, forming a 40-meter antenna. The Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) instrument came online. Since then, MARSIS has been studying Mars with radar signals to learn more about the planet’s interior structure and composition.
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