Set against the backdrop of Jupiter’s dramatic, swirling atmosphere, Europa may look a bit drab at first glance — its gray-white surface might even resemble well-worn billiard balls in a run-down pool hall — but upon closer inspection, the Jovian system’s fourth-largest moon emits a mesmerizing glow from deep within.
As far as we know, Europa’s icy outer layer hides a vast ocean containing twice as much water as Earth. This, plus signs of geophysical activity such as rust streaks across its surface and complex chemical reactions, are why Europa has long intrigued astronomers searching for habitable worlds beyond our pale blue dot. So, are conditions on Europa that could support life? The answer remains to be seen.
In October, NASA will launch the $5 billion Europa Clipper probe, which will probe Europa’s geology and chemistry and, with luck, identify telltale signs of habitability. The mission has been decades in the making, and builds on previous explorations that have provided tantalizing clues about what lies within Europa’s frozen shell—and why questions persist.
Clipper promises answers. The probe will explore the moon’s surface and the ocean hidden beneath it in more detail than ever before. It may even sample water, as we suspect, in the plumes of steam spewing from Europa’s surface. And while the probe isn’t designed to find direct evidence of life, such as bacterial cells, recent developments suggest there’s a small chance it could do just that. “Europa Clipper will really allow us to…
