News media are jumping over an announcement that Saturn’s moon Enceladus may have a large body of water under its icy crust, but what does it mean?
Cassini scientists, publishing in Science Magazine, announced indirect evidence (via Doppler measurements of gravity anomalies during flybys) that Saturn’s little geysering moon Enceladus probably has a sub-surface ocean of liquid. The data cannot resolve whether the ocean is regional or global, but is probably regional: “Although the gravity data cannot rule out a global ocean, a regional sea is consistent with the gravity, topography, and high local heat fluxes and does not suffer from the thermal problems that a global ocean encounters,” they said. That’s because keeping water liquid requires a suitable heat source – the more water, the more heat required:
The endogenic (nonsolar) power emitted from the south-polar region, derived from Cassini Composite Infrared Spectrometer data, is 15.8 GW [gigawatts], with a 20% formal uncertainty. This is equivalent to an average surface heat flux of ~20 mW/m2 and is an order of magnitude larger than conventional estimates of tidal heating if Enceladus’ current orbital eccentricity represents a so-called “equilibrium” resonant state with other satellites. It indicates time-variability in its internal properties, in a resonant state with other nearby moons, or in the rate of heat transport. In any or all of these cases, a plausible internal structure is that of a liquid water ocean overlain by a (thermally conductive) crust.
It indicates those options, however, only if Enceladus is 4.5 billion years old, as assumed for solar system bodies. The BBC News coverage mentions that the ocean could only last for tens of millions of years, “maybe 100 million years,” in steady state, unless some unknown cycles, like episodes of higher eccentricity, intervene.
Science journalist Richard A. Kerr, commenting on the paper in the same issue of Science, did not pay much attention to the time problem of maintaining heat for billions of years, other than to speculate, “The presence of liquid water remains unexplained, but Saturn’s powerful gravity probably played a role, by tidally kneading the moon and heating its interior.” Yet the scientists themselves had stated in their paper that the measured heat flux is “an order of magnitude larger than conventional estimates of tidal heating”.
Rather than deal with that, Kerr focused on a different subject: “Suspicions that Saturn’s icy moon Enceladus harbors an internal ocean—one that could host life—have hardened into near certainty with exquisitely precise observations from the Cassini spacecraft,” he began. His ending mentioned life twice: “Such strong support for a sea beneath the spouting plumes of Enceladus should encourage scientists, mostly Cassini team members, who want NASA to send a new mission to Enceladus to explore for life,” he stated, also speaking of the possibility of “life-laden waters” under Enceladus.
The popular media, predictably, focused on life:
- “The findings … will boost the view that the 500km-wide moon would be one of the best places beyond Earth to go look for the existence of microbial life.” (BBC News)
- “Saturn Moon Harbors Ocean, Raising Possibility of Life.” (National Geographic)
- “New gravity readings suggest it hosts a subsurface sea the size of Lake Superior at its south pole — and that this liquid water is in direct contact with the moon’s core, which is rich in nutrients. Both findings boost hopes that the sea hosts life.” (New Scientist)
- “Will Ocean Discovery On Enceladus Spur Life-Hunting Missions to Icy Moons of Saturn, Jupiter?” (Space.com – Mike Wall uses word “life” six times)
Astrobiology Magazine, naturally, mentioned it, since astro-“biology” is their business: “Even if the reservoir is relatively young on the scale of geologic time, there’s still a chance for life,” the article said (oddly pointing out the possibility that the ocean is young; a young ocean would seem to require believing in life on the fast track). But once the idea of rapid life enters the imagination, why stop there? “This unexpected finding of an ocean on a small moon so far from the Sun raises a distinct possibility: that there are more oceans on more moons, each with a chance for life.” A possible pool of liquid water suddenly became evidence for life all over the solar system!
The original paper is more reserved in its claims, as befits scientific modesty: “The interpretation of Enceladus gravity presents a greater difficulty and uncertainty than usual, given the strikingly different appearances of the northern and southern hemisphere and the apparent confinement of endogenic activity to the high southern latitudes,” it cautions. “Still, the deviation of J2/C22 from 10/3 (the value for a laterally homogeneous body) is modest (of order 5%) and the non–degree-2 gravity is small (of order 2% relative to J2), suggesting that there is some prospect of useful inferences.”
Science Daily, echoing a press release from Caltech, did not mention life at all. To its credit, this report was also very modest in its claims, mentioning that a sub-surface ocean is only a reasonable possibility:
The suspicion is that the fractures—in some way that is not yet fully understood—connect down to a part of the moon that is being tidally heated by the globe’s repeated flexing as it traces its eccentric orbit. “Presumably the tidal heating is also replenishing the ocean,” Stevenson says, “so it is possible that some of that water is making its way up through the tiger stripes.”
JPL’s press release, however, mentioned the L-word life three times (Cassini is an international mission managed by JPL). Cassini project scientist Linda Spilker likely fueled the speculations of the popular media: “Material from Enceladus’ south polar jets contains salty water and organic molecules, the basic chemical ingredients for life,” she said. “Their discovery expanded our view of the ‘habitable zone’ within our solar system and in planetary systems of other stars.” Data: gravitational anomalies on a tiny moon. Conclusion: life abundant in the universe.
It would be hard to find a more clear example of hydrobioscopy in action. Give evolutionists an inch and they take a light year. They have even less time to play with, using “chemical ingredients” they cannot see, employing processes that are not well understood, but then they turn around and extrapolate their imaginary microbes evolving around the whole universe! Spilker, of all people, should know better. She claims to be a Christian but repeats the water-equals-life mantra in a way that would make atheists applaud. Doesn’t she know that naturalistic origin-of-life theories are in crisis? (Survey our Origin of Life category for abundant evidence.)
But why stop with microbial life? Since speculation is OK in science now, let’s dream of underwater cities under Enceladus, inhabited by mermaids and mermen. They can’t see Earth, but they speculate that if such a place exists, it can’t possibly be an abode for intelligent life. Perhaps they’re right.