Europa: secret lakes could fuel life on Jupiter moon
New research suggests that lakes of liquid water could be buried in the icy crust of Europa, a moon of Jupiter. The processes that create the lakes could also provide nutrients crucial for life on Europa, the scientists say.
Mysterious depressions and domes on Jupiter's ice-encrusted moon Europa may signal the presence of subsurface lakes, at least one of which holds enough water to fill the American Great Lakes.Skip to next paragraph
The finding, if confirmed, could be a boost for those who speculate that simple forms of life could exist on the moon.
For several decades, scientists have known that an ocean of liquid water exists beneath Europa's crust of ice. But some research suggests that Europa's ice shell could be miles thick. The subsurface lakes described by NASA scientists Wednesday, however, appear to exist within that icy mantle, meaning they would be at a far shallower depth than the underlying ocean.
Moreover, the lakes could be part of a planetary dumb-waiter system that transfers potential nutrients from the surface to the subsurface ocean, the team suggests. That transfer of nutrients could be crucial to any potential life on Europa.
With liquid water, Europa already has one necessary ingredient for life. That has made it "a compelling object for study for decades," says Tori Hoehler, an astrobiologist at NASA's Ames Research Center in Moffett Field, Calif., who was not part of the research team.
But another requirement for life, he adds, is a source of energy, a.k.a. food. The moon's upper crust is rich in compounds that could be a food source, but the potential nutrients would need a system to deliver them to the ocean deep below.
The mechanism that forms the subsurface lakes – involving rising plumes of heat – could provide that service, the team suggests.
If the team is right, "you've moved from a system that checks [off] one of the requirements for life to a system that checks two requirements for life," Dr. Hoehler says.
The results, set for publication in Thursday's issue of the journal Nature, grew out of an attempt to explain two different areas within Europa's "chaos terrain" – a landscape of jumbled surface features visible in images from the Voyager and Galileo spacecraft.
The two areas that have puzzled scientists cover significant large patches of the moon's surface and host icebergs with ground-up ices filling the channels in between – much as jumbled ice chunks fill gaps between icebergs as they calve from ice shelves in polar regions on Earth.
One of the two areas appeared as a depression in the surface. The other appeared as a dome.
"Why are these two features so similar but so different?" says Britney Schmidt, a planetary scientist at the University of Texas at Austin who led the research team.
In trying to solve the puzzle, the team was struck by parallels on Earth. Similar features are apparent in ice that forms above under-ice volcanoes, as well as at ice shelves where warm sea water is thought to be thinning the ice from underneath.