In 2005, NASA's Cassini-Huygens spacecraft found evidence of water — in the form of ice — on Saturn's moon Enceladus. That was cool, but earlier this month, a paper published in the science journal Icarus confirmed the existence of an entire liquid-water ocean beneath that ice. And that has led to speculation about alien space fish.
How do we know there's liquid water on a moon with little-to-no atmosphere, where the average temperature is a rather nippy -324 degrees Fahrenheit? The paper's authors studied the way Enceladus moves along its orbit. Measuring the moon's precise movements, they found that Enceladus experiences librations — known as wobbliness to non-astronomers — that are too large to be explained by ice resting on a rocky surface. They can, however, be explained by tides created by Saturn's gravity; Enceladus's ice has melted underneath the surface, and it's sloshing back and forth as the moon moves around the planet.
"We've suspected Enceladus may have liquid water for a while — because we have seen active geysers, and in fact have already sampled them," Barbara Cohen, a planetary scientist at NASA Marshall Space Flight Center, told VICE News. Those samples are courtesy of Cassini, which flew through a volcano-propelled geyser of water spouting out of the 310-mile diameter moon in 2011.
And, says Jonathan Lunine, director of Cornell's Center for Astrophysics and Planetary Science, "other Cassini data tell us [the ocean] is very likely habitable."
Everywhere there's liquid water on Earth, there's life — even at the bottom of the deepest ocean trenches and in volcanic vents. So it makes sense that if there is a liquid-water ocean on Enceladus, there may also be life there. Arthur C. Clarke's novel 2010: Odyssey Two postulated the existence of alien space fish and other creatures living around volcanic vents on the floor of the ocean underneath the crust of Jupiter's icy moon, Europa. And NASA is currently looking into sending a mission to Europa to search for life.
One serious supporter of a life-seeking mission to Europa is Congressman John Culberson, the new chairman of the House Subcommittee on Commerce, Justice, and Science, which has jurisdiction over NASA. His congressional site notes that he is "so enthusiastic about this mission because [he] truly believe[s] that when we first find life on another world, it will be in the immense ocean of Europa."
Dr. Carolyn Porco, the scientist who leads the imaging team for the Cassini mission, says that Enceladus is an even better candidate for a scientific search for life. Porco is part of a team proposing a Discovery-class mission to the moon to answer big questions. Whether there will actually be funding for a mission like that in the next decade, however, is another story.
If we find alien space fish — even alien space plankton — what do we do about it? Before we think about returning it to Earth, Porco explained, "NASA has to update the requirements for planetary quarantine. Right now, it seems the very mechanisms we would be required to use to ensure no out-of-control contamination of Earth by alien microbes would destroy the very material we want to retrieve."
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The quarantine Porco mentioned is a real-life version of the Andromeda Strain problem: We don't want to bring back bacteria that causes some sort of horrific space plague here on Earth. The flip side of the Andromeda Strain problem is Star Trek's "Prime Directive," wherein we Earthlings try to avoid contaminating another world's natural development with our alien selves (or our bacteria). Either way, it can be difficult to do the right thing.
"The simple truth of it is that nothing could be more exciting and scientifically [significant] than having a sample of another life form — one that originated on another body in an extraterrestrial environment — to examine, study, and compare with terrestrial life," Porco said. "And I do very much hope I live to see that day."
Follow Bart Leahy on Twitter: @SciCheerGopher
Photo via NASA