Jupiter's Icy Moon Europa: Best Bet for Alien Life

Under a thick crust of ice, Europa might have an ocean warmed by tidal interactions with Jupiter. 

This tidal flexing could also produce a geologically active core that might in turn create hydrothermal vents on the ocean floor.

Credit: NASA/JPL/Ted Stryk

Jupiter's moon Europa doesn't look like a particularly inviting place for life to thrive; the icy satellite is nearly 500 million miles (800 million kilometers) from the sun, on average.

But beneath its icy crust lies a liquid ocean with more water than Earth contains. This ocean is shielded from harmful radiation, making Europa one of the solar system's best bets to host alien life.

That's one of the reasons Europa is so alluring to scientists. It has all the elements thought to be key for the origin of life: water, energy, and organic chemicals, the carbon-containing building blocks of life, scientists said at an event called "The Lure of Europa," held here last month.

"All the ingredients are there to make us think Europa is the next place to go," NASA Chief Scientist Ellen Stofan said at the event, which was organized by the Planetary Society, a nonprofit organization headed by scientist and TV host Bill Nye.



Just as a layer of ice over a pond allows the water beneath it to stay liquid through the freezing winter, Europa's icy crust shields its enormous ocean despite the moon's great distance from the sun.

As Europa travels around Jupiter, the massive planet bends and flexes the satellite, generating interior heat that keeps its water from freezing completely.

Beneath Europa's surface, active volcanoes may also heat the water, providing vents where bacterial life may thrive as it does on Earth.

"With that combination of volcanism and water, good things are going to happen," Stofan said.