August 17, 2013 | David F. Coppedge

Scientists Dodge Youthfulness of Saturn Moon Titan

Like Enceladus, Saturn’s moon Titan shows multiple signs of being far less than 4.5 billion years old – yet the press releases are strangely silent about the implications.

As we showed recently with Enceladus (8/7/13), planetary scientists become oddly silent about evidences that conflict with their old-age assumptions.  Another case is Titan, Saturn’s largest moon.

Case of the disappearing methane:  Titan’s methane may dry up, a surprise announcement said on, where Megan Gannon wrote, “the compound doesn’t seem to be getting replenished fast enough on Titan’s surface to keep the methane cycle sustainable, scientists say.”  She was referring to a JPL press release (echoed on NASA Astrobiology Magazine) that asked if the methane is “going, going, soon to be gone” (cf. 4/16/13).  The articles acknowledged the ongoing photodissociation of methane by the solar wind, hinting that ethane should accumulate on the surface – but the observed lakes present far less than previously calculated (scientists had expected to find a global ocean of methane and ethane about half a kilometer deep).   Icarus said that over half the surface liquid should be ethane, presumably from the solar wind breakdown.   Christophe Sotin thinks the methane disappearance may be tens of millions of years in the future, but readers should ponder that ten million years is 1/450th the assumed age of Titan.  To rescue the assumption that Titan is billions of years old, the press release posited an unobservable, ad hoc event: “The team suggests that the current load of methane at Titan may have come from some kind of gigantic outburst from the interior eons ago possibly after a huge impact.”  It’s not known, though, whether a reservoir of methane exists under Titan’s surface that could be excavated by an impact.

Case of the flat surface:  No such huge impact is evident, however.  Science Now told about Titan’s remarkably flat surface, joking that hiking and biking would be easy.  The highest point is only half a kilometer above the mean; the lowest, 1.7 km.  On earth, the highest mountains are 9 km above sea level.  Why is this?  “…perhaps because Titan’s crust isn’t strong enough to support tall mountains or because its thick atmosphere unleashes methane rains that erode them away.”  This seems unlikely, however.  Jupiter’s Io (smaller than Titan) supports high mountains despite global volcanism; and Ganymede, slightly larger than Titan, is loaded with craters and complex terrains.

Case of the windless lakes:  Now that a global ocean on Titan has been debunked, planetologists are trying to understand the scattered lakes at the poles.  (Even if they were deep lakes, the amount of methane and ethane in them is far, far less than predicted in the 1990s.)  Now, it appears the lakes might be little more than shallow mudflats.  “The missing waves on Titan” (Astrobiology Magazine) grapples with why waves have not been detected on the surface of the lakes.  “We know there is wind on Titan,” Alex Hayes (Cassini radar scientist) said. “The moon’s magnificent sand dunes [prove] it”  (cf. 1/18/13) Why, then, no waves?  Cassini has not found any, not even at the millimeter scale (see video clip in the article).  Hayes suggests the surface might be thick, like tar, but he prefers his theory that the wind is seasonally low.  If so, it should pick up in the next few years.  Maybe, however, there is just not be that much liquid present.

Saturn, too:  “Saturn’s youthful appearance” was in a headline on Science Daily.  Scientists have come up with an idea to rescue the planet’s presumed old age, even though its atmosphere looks young.  “As planets age they become darker and cooler. Saturn however is much brighter than expected for a planet of its age — a question that has puzzled scientists since the late sixties.”  The rescue comes in the form of an ad hoc scenario: “layers of gas, generated by physical instability deep within the giant planet, prevent heat from escaping and have resulted in Saturn failing to cool down at the expected rate.”  But did they apply this to the other gas giants, or only to Saturn?  One can always escape by saying the answer is too complex: “These findings suggest that the interior structure, composition and thermal evolution of giant planets in our Solar System, and beyond, may be much more complex than previously thought.

The whole darn solar system:  Alan Boss, planet formation theorist, is concerned that data don’t fit the standard model of accretion into planetesimals.  Meteorites and comets, particularly, pose problems due to the presence of compounds that only could have formed at high temperatures.  In “Solar System’s Youth Gives Clues to Planet Search,” Science Daily gave air to Boss’s ad hoc scenario that puts it all together:

Boss’ new model demonstrates how a phase of marginal gravitational instability in the gas disk surrounding a proto-sun, leading to an outburst phase, can explain all of these findings. The results are applicable to stars with a variety of masses and disk sizes. According to the model, the instability can cause a relatively rapid transportation of matter between the star and the gas disk, where matter is moved both inward and outward. This accounts for the presence of heat-formed crystalline particles in comets from the solar system’s outer reaches.

Nobody was around, of course, to see any of this.

Planetary scientists are fully capable of inventing scenarios to keep Titan old, but that’s the point: the data require a story to fit a belief.  Titan looks young.  Based on processes we observe in operation, assuming they have been in steady state, we can set upper limits on Titan’s age.  Those limits (though theoretically in the millions of years) are far, far less than the assumed age of billions of years.  The implications are enormous.  Unless scientists can argue that Titan appeared in the relatively recent past, it should not look like it does.  Where did it come from?  Where did Saturn come from?   Where did the solar system come from?  Why are they stuck on billions of years?  Even Alan Boss believes in a “relatively rapid transportation of matter” from a disk instability that would have happened quickly.  Billions of years are not needed!  But without billions of years, the grand Darwin myth goes into the trash.

We repeat a maxim from many times before: planetary scientists are excellent at observing, measuring, and describing the present, but they have been miserable failures at predicting the worlds revealed by the space program.  Virtually every object in the solar system, from meteorites to giant planets, has turned out to be far different than expected.  We need these people for accurate scientific description of the observable present, but when it comes to origins, if they were this wrong at any other job, they would have been fired long ago.  Lesson: don’t trust their stories.

Richard Kerr in Science reminded us that Pluto will be “the last planetary first” when the New Horizons spacecraft arrives for its brief flyby on July 14, 2015.  Someone take note of scientists’ predictions now.  Let’s see if they get this one right for once.  Actually, they’ve left themselves a lot of fudging room: it could be active, it could be dead; it could be complex, it could be simple.  “We can expect the unexpected,” Paul Schenk said.  “We are going to be captivated; we are going to be befuddled.”  History proves him right.  Incidentally, the article describes the active, youthful surface of Neptune’s moon Triton – a reminder of how totally wrong scientists were about that world when Voyager 2 flew by in 1989.  Pluto could well be the next Triton.  As if remembering past mistakes, John Spencer allowed that “It [Pluto] could be just as wonderful and exotic as Triton’s surface.”



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  • lux113 says:

    Hm. Scientists aren’t very scientific..

    If Titan has signs it’s young, the solar system has signs it’s young, Saturn has signs it’s young – if everything we take a look at ends up having signs they are young… as much as you might hate the implication… guess what?

    And “scientists” could we please stop using “outbursts” and random ‘collisions” as ad hoc explanations for everything that runs contrary to your wishes? It ain’t very scientific.. and it’s getting really predictable.

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