May 11, 2015 | David F. Coppedge

It's Curtains for Enceladus

The geysers of Saturn’s little moon are like sheets instead of jets, spelling trouble for theories of its ancient age and possible life.

Enceladus has been in the news lately. Astrobiology Magazine (a NASA public outlet) is one of several news sources that reported on a new interpretation of the little moon’s south-pole geysers. New analysis of the plumes suggests that the eruptions come out in sheets or curtains, rather than individual jets. “Many features that appear to be individual jets of material erupting along the length of prominent fractures in the moon’s south polar region might be phantoms created by an optical illusion, according to the new study.”

Although the paper in Nature does not explicitly say so, the appearance of “broad vertical curtains extending over many kilometres of fracture” would seem to imply a greater volume of expelled material than previously thought. If so, this would require accounting for the mass loss over time.

The extent of mass loss from Enceladus is visible in new pictures from a distance, showing icy tendrils emerging from the plumes and feeding Saturn’s E ring (Astrobiology Magazine).  For the first time, planetary scientists were able to trace the tendrils down to the plumes on the surface. Cassini scientists also observed changes in the tendrils over the time, which they believe is associated with changes in tidal flexing from Saturn’s gravity.

There is even more that can be extracted from the images, the scientists say. “As the supply lanes for Saturn’s E ring, the tendrils give us a way to ascertain how much mass is leaving Enceladus and making its way into Saturn orbit,” said Carolyn Porco, team leader for the imaging experiment and a coauthor on the paper. “So, another important step is to determine how much mass is involved, and thus estimate how much longer the moon’s sub-surface ocean may last.” An estimate of the lifetime of the ocean is important in understanding the evolution of Enceladus over long timescales.

No estimates were given in the articles, but certainly this rate of mass loss has a time limit. Space.com didn’t address this question either.

A recent paper in Icarus says that the vents must be large to account for the size and quantity of micron-size grains that are condensing in the vents before being expelled at escape velocity into space.

Life?

A dubious press release from Carnegie Science claims that “Geochemical processes on Saturn’s moon linked to life’s origin.” No life has been found, obviously – not even close. What they’re referring to is the pH of the water in the subsurface ocean. Surprisingly, that pH is highly alkaline:

The team’s model, constrained by observational data from two Cassini teams, including one led by coauthor Waite, shows that the plume, and by inference the ocean, is salty with an alkaline pH of about 11 or 12, which is similar to that of glass-cleaning solutions of ammonia. It contains the same sodium chloride (NaCl) salt as our oceans here on Earth. Its additional substantial sodium carbonate (Na2CO3) makes the ocean more similar to our planet’s soda lakes such as Mono Lake in California or Lake Magadi in Kenya. The scientists refer to it as a “soda ocean.”

So what does that have to do with life? The authors admit that the chemical process producing these observations is most likely serpentinization at depth, a process wherein fluids interact with ultramafic (magnesium-rich) lava. The fluid becomes strongly alkaline in that process. The implications for life seem stretched:

“Why is serpentinization of such great interest? Because the reaction between the metallic rocks and the ocean water also produces molecular hydrogen (H2), which provides a source of chemical energy that is essential for supporting a deep biosphere in the absence of sunlight inside moons and planets,” Glein said. “This process is central to the emerging science of astrobiology, because molecular hydrogen can both drive the formation of organic compounds like amino acids that may lead to the origin of life, and serve as food for microbial life such as methane-producing organisms. As such, serpentinization provides a link between geological processes and biological processes. The discovery of serpentinization makes Enceladus an even more promising candidate for a separate genesis of life.

If hydrogen justifies a springboard to speculations about life, one might as well look for life in the interiors of stars, where hydrogen is plentiful. As for life in soda lakes on Earth like Mono Lake, nobody believes that the brine flies, seagulls and other organisms in that body’s rich ecology emerged from the alkaline waters of the lake; rather, pre-existing life forms colonized the lake and became adapted to its alkalinity as water levels declined in geologically recent times.

Europa

It’s curtain’s for Europa, too. “Europa’s Elusive Water Plume Paints Grim Picture For Life,” Elizabeth Howell writes for Space.com. That’s because the elusive plume was probably a rare occurrence coming from a meteorite strike. Howell explains why this is a downer for astrobiologists:

Europa would need to have fissures in its surface to allow for contact between its underground ocean and the combined effects of the magnetosphere and solar input on its surface. The energy input would include gravitational flexing by Jupiter in addition to the sun and magnetosphere. If Europa’s plume is a rare event, this means there are likely few or no cracks in the surface. Europa might be a socked-in icy ball with a barren ocean below.

Conclusion: if the output from the surface is small, “this would have grim implications for the prospect of life on Europa.” For years, Europa has been one of the leading candidates for bodies in our solar system likely to harbor life beyond the Earth.

Ceres

Speaking of eruptions, cross off activity on Ceres. New images from the DAWN spacecraft show the bright spots to be highly reflective material on the surface, possibly ice, shining brightly at certain angles to the sun, not signs of active vents (JPL and BBC News). The mission is just beginning its scientific observations of the largest asteroid.

Certainly, the mass loss rate on Enceladus (or any active body) is linked to the possibility of life. If Enceladus is young, Darwinism is dead. Charlie counted on vast ages for his miracles of emergence to occur; that’s why he could hide his miracles in the mists of an unobservable prehistory.

It’s uncanny how non-specific the reporters and scientists are about the mass loss rate. The moyboys must know that that it’s a huge challenge to their views. If Enceladus has been erupting material at this prodigious rate for billions of years, it would be long gone by now. There is also no mechanism for generating that kind of interior heat for vast ages.

It will be interesting to see what’s going on at Pluto this July.

 

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