Lying about 1.9 miles (3 kilometers) from the surface, the ice-trapped lake may represent the newest potentially habitable environment in the solar system—and one of the best prospects for the search for life beyond Earth.
"For decades scientists have thought Jupiter's moon Europa was a likely place for life, but now we have specific, exciting regions on the icy moon to focus our future studies," Don Blankenship, senior research scientist at the University of Texas at Austin's Institute for Geophysics, told National Geographic News.
(Related: "Could Jupiter Moon Harbor Fish-Size Life?")
Europa's "Chaotic Terrains" Explained
Similar in size to Earth's moon, Europa is already thought to house a global, salty ocean beneath its 62-mile-thick (100-kilometer-thick) ice shell. NASA's Galileo spacecraft, which orbited Jupiter and its moons from 1995 to 2003, first discovered evidence of the ocean.
In a new study, Blankenship and his team located the lake by specifically focusing on two circular, bumpy features in decade-old Galileo images of the moon's surface. These so-called chaos terrains are a traffic jam of floating icebergs and colliding ice flows—collapsing parts of the moon's global ice shelf.
The team was able to infer the presence of Europa's lake by making a connection between processes seen on Europa and Earth. The team drew upon both observations of Antarctica's floating ice shelves and ground-penetrating radar that can peer through thick layers of ice sheets. This technology has already located dozens of subglacial lakes in Antarctica, for example.
"It's only been in recent years [that] we have been able to witness and study the breakup of ice shelves with satellites on our planet," said Blankenship, whose study appears tomorrow in the journal Nature.
"So now we are using the Earth['s] perspective to take a new look at explaining some of the paradoxes found in the Galileo data," he said.
An orbiting spacecraft equipped with ice-penetrating radar is needed to confirm and map Europa's lake in detail. NASA is currently considering such a flagship mission for launch sometime before 2022.
Renewed Search for Europa Life?
There probably are many more lakes under Europa's ice, Blankenship added.
Likewise, the prospects for searching for life on Europa could improve dramatically, as research suggests some of these icy lids covering the lakes may be much thinner than thought. (Read "Searching for New Earths" in National Geographic magazine.)
"It's possible for lake water to be only a few tens of meters of depth [under the moon's surface], meaning that there may be great opportunities to land and sample remnants of the salty ocean with relative ease," he said.
"We aren't talking of drilling tens of kilometers anymore—I think this will naturally create more enthusiasm for a future landing on Europa."