The Search for Life Beneath Europa’s Ice

Europa has captured our interest in a way that is almost unyielding. Astronomers, science fiction authors, and astrobiologists have been returning to this tiny, brilliant moon of Jupiter for decades, as though it held the answer to a question we were still unsure how to pose. Perhaps the most significant discovery in human history lies somewhere beneath a frozen shell and a salty ocean. At least that was the dream.

The reality of this dream is now colder than the surface of Europa. According to a recent study headed by Paul Byrne of Washington University in St. Louis and published in Nature Communications in January, the seafloor beneath all that ice might not be particularly noteworthy. Hydrothermal vents are not boiling. not ruptured by tectonic movements. Simply silent. Be calm. chilly. And most likely dead, today at least.

Today, that word is important. Byrne and his associates are not arguing that life could not have existed on Europa in some far-off geological past or that it was always this way. After calculating the internal structure of Europa and the gravitational pull it experiences from Jupiter, they conclude that the engine appears to have stopped. Simply put, not enough heat is produced to maintain the seafloor’s level of activity compared to Earth’s deep oceans. And those hydrothermal vents, which Robert Ballard’s team found in 1977, are exactly where life on Earth flourishes in the absence of sunlight. The most likely source of energy for anything swimming in Europa’s darkness is eliminated when the vents are removed.

It’s difficult to avoid getting a little stung by this. A generation of scientists grew up picturing tiny submarines drifting into a black, alien sea after breaking through the ice. For the task, engineers at NASA’s Jet Propulsion Laboratory have actually designed submersibles the size of two soda cans. Mars, with its parched riverbeds and dusty plains, has never quite matched its romantic quality. The more thrilling wager was meant to be Europa.

Additionally, the wager is not completely lost. Launched in late 2024, NASA’s Europa Clipper is still en route and is expected to begin detailed flybys in 2031. The spacecraft may discover things that the models failed to predict because it will measure the ice shell with far greater accuracy than anything that has come before it. Byrne himself seems less disappointed and more inquisitive. Whatever the seafloor turns out to be, he wants to see it. He notes that while the ocean has received a lot of attention, the rock at its bottom has received very little.

Additionally, there is something worthwhile to consider regarding the advancement of science. Europa has been the most promising place to find life outside of Earth for fifty years. The public’s perception of that hasn’t altered, and it might not even now. However, the case is faltering, and seeing it falter is like witnessing a long-held conviction put to the test in real time. The ocean may be dead. Perhaps Clipper discovers something unexpected. In any case, the search itself continues, in part because it’s our job and in part because, in Byrne’s words, we explore to see what’s out there. even though there may be nothing at all out there.