
Welcome to a special A to Z Challenge edition of Sciency Words! Sciency Words is an ongoing series here on Planet Pailly about the definitions and etymologies of science or science-related terms. In today’s post, J is for:
JUICE
Speaking as a space enthusiast and a citizen of the United States, I have to confess I’m a bit disappointed with the status of the American space program. While there have been some success stories—New Horizons, Curiosity, Scott Kelly’s year in space—I can’t help but feel like NASA has spent the last decade or so floundering.
However, it’s encouraging to see that so many other space agencies around the world are starting to pick up the slack. My favorite example of this is the JUICE mission, a project of the European Space Agency (E.S.A.).
Astrobiologists have taken a keen interest in the icy moons of Jupiter. There’s compelling evidence that one of those moons (Europa) has an ocean of liquid water beneath its surface. There’s also a growing suspicion that two more of those moons (Ganymede and Callisto) may have subsurface oceans as well.
The original plan was for NASA and the E.S.A. to pool their resources for one big, giant mission to the Jupiter system. But then the 2008 financial crisis hit. The U.S. Congress was loath to spend money on anything—especially space stuff. “Due to the unavailability of the proposed international partnerships […]”—that’s how this E.S.A. report describes the matter.
So the E.S.A. decided to go it alone. Personally, I think this was a very brave move. E.S.A. has never done a mission to the outer Solar System before, not without NASA’s help. But there has to be a first time for everything, right? And so JUICE—the JUpiter ICy moons Explorer—began. It’s not my favorite acronym, but it works.

According to E.S.A.’s website, JUICE will conduct multiple flybys of Europa and Callisto before settling into orbit around Ganymede. You may be wondering why JUICE won’t be orbiting Europa. This is in large part because of the radiation environment around Jupiter. Europa may be more exciting to astrobiologists, but Ganymede is a safer place to park your spacecraft.
Meanwhile, NASA has recovered much of the funding it lost after the 2008 financial crisis, and they’re once again planning to send their own mission to the Jupiter system. So maybe NASA and E.S.A. will get to explore those icy moons together after all! Or maybe not. According to this article from the Planetary Society, NASA’s budget is under threat once again.
I guess we’ll have to wait and see, but no matter what happens to NASA’s budget, E.S.A. seems fully committed to JUICE. So speaking as a space enthusiast, at least I have that to look forward to.
Next time on Sciency Words A to Z, how do you measure the size of an alien civilization?