The probability of life on Jupiter’s moon Europa just got a lot higher

Human beings have long looked to the stars and hoped that alien life might look back at us. Yet the truth is that the first extraterrestrial life we discover is far more likely to be microbial — a prospect less romantic perhaps than the idea of bipedal aliens shaking hands with humans after landing on Earth. 

Such microbial life has been theorized to have existed in the early days of Mars, before its water dried up, though we still don’t know for certain. Now, astrobiologists are turning their gaze towards another nearby neighbor, Europa — an icy gray moon of Jupiter — as a suddenly much more alluring candidate for simple life. 

Renewed interest in Europa’s potential to harbor life stems from a new study about the peculiar moon. The subject of curiosity is the giant ridges that criss-cross the planet’s surface like scratches on a cue ball. Underneath those ridges, explain the authors of a new paper in the journal Nature Communications, there may be pools of salty, liquid water. And since those ridges are ubiquitous, that means the pools could also be commonplace.

Of course, early microbial life on Earth evolved in the liquid salt water environment of our oceans — which is what makes the hint of salt water on Europa so tantalizing. The unique geography of Europa also happens to very much resemble Northwest Greenland, which is the other half of what the study concerns.

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“Here we present the discovery and analysis of a double ridge in Northwest Greenland with the same gravity-scaled geometry as those found on Europa,” the authors explained. “Using surface elevation and radar sounding data, we show that this double ridge was formed by successive refreezing, pressurization, and fracture of a shallow water sill within the ice sheet. If the same process is responsible for Europa’s double ridges, our results suggest that shallow liquid water is [ubiquitous] across Europa’s ice shell.”

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Europa is not a particularly large world; a mere 2,000 miles in diameter, it is not even as large as Earth’s own moon. Yet Europa’s surface is unique, festooned in giant double ridges that can tower as high up as 1,000 feet into the air.

When a team of scientists at Stanford University learned about Europa’s double ridges, they decided to study smaller geological structures in Greenland’s northwest. More specifically, they studied the little double ridge feature in Greenland and learned how it was formed. It turned out that they came into existence because shallow pools of water beneath the surface first froze and then wound up breaking through on multiple occasions. This repeatedly pushed up the twin ridges.If the analogous ridges on Europa were formed the same way, as seems probable, the constant churning could have helped bring about the chemical reactions necessary to create life….