Europa is an icy ocean world—and NASA is finally going to explore it

Will Clipper drill beneath Europa’s crust?

Sadly, the spacecraft can’t land and take samples, but many scientists are hoping to spot geysers spouting from Europa’s surface. Hubble images from around a decade ago hinted that such plumes could be erupting. But “all the detections have been at the detection limits,” says planetary scientist Francis Nimmo of the University of California, Santa Cruz. “If [the plumes] exist, then they’re pretty intermittent, and they may not actually be there at all.”

Clipper should hopefully clear up this conundrum, either by taking direct photos of a geyser or finding evidence of a recent deposit on the surface. If the plumes exist, they would be a major boon because mission directors might be able to fly Clipper through a spout, tasting and analyzing material from within or below the ice sheet.

(Explore Europa’s icy ocean through this interactive graphic.)

What’s going on in Europa’s depths?

No one is quite sure how geologically active the rocky surface at the bottom of Europa’s ocean is. Some suspect that hot, smoking hydrothermal vents could be present there, the same as those that exist in the depths of Earth’s oceans, providing warm and energetic habitats to microbes, crabs, and worms. But recent models splashed cold water on this idea: Based on the strength of the rocky crust and low tectonic activity of our own similarly-sized moon, some researchers questioned whether Europa’s seafloor might actually just be super low energy. 

“If we’re right, it’s not going to be the kinds of hydrothermal systems that we might be familiar with on Earth, with those big worms and those really hot black and white smokers,” says Paul Byrne, a planetary scientist at Washington University in St. Louis who helped devise the new models.