January 11, 2010 | David F. Coppedge

Computer Keeps Enceladus Old

There’s a new theory for how Enceladus can be so active but still be 4.5 billion years old.  It erupts only every billion years or so.  This was explained on PhysOrg.  Heat builds up slowly then is “released as one catastrophic event around every billion years or so.”
    The scientists already knew that “Enceladus was an enigma.”  They said, “Somehow it seems to be pumping out more energy than it gets, which would violate the laws of thermodynamics.”  But that’s only if it is really as old as claimed.  Their conclusion was based on a computer simulation.  It showed that “The ice sheets would flow like glaciers, the heat causing geysers to pop up all over the active surface.”
    A press release from Jet Propulsion Laboratory filled in more details of the model.  The authors claim that the active periods last 10 million years, and quiet periods last 10 to 200 times longer.  For evidence, the authors only appealed to current features of the surface and assumptions of age based on crater counts.  Then they modeled what they assume is the strength of the surface ice and core, although those features are not observable, if heat rolls around in the interior.  A remaining question, though, is why this activity happens on Enceladus and not the other moons of Saturn.  JPL also mentioned that the geysers are actively expelling argon, which only comes from radioactive decay, and that the geysers emit 6 gigawatts, “the equivalent of at least a dozen electric power plants.  This is at least three times as much heat as an average region of Earth of similar area would produce, despite Enceladus’ small size.”
    For more on the Enceladus geysers, see 12/18/2008 bullet 2, 06/19/2008, 03/26/2008, 03/10/2008, 02/09/2008, 08/04/2007 bullet 3, and 03/13/2007.  For more on using computer models to simulate prehistory, see 09/08/2008.

Well, isn’t that convenient.  Starting with the assumption that Enceladus is old, and programming that assumption into a computer, you reach a conclusion that supports your belief system: Enceladus can stay old, yet be active.  “Their model suggests the active periods have occurred only 1 to 10 percent of the time that Enceladus has existed,” the press release said.  Did you catch that?  The length of time Enceladus “has existed” (the assumed age of the solar system, 4.5 billion years), was never called into question.  The crater count dates are similarly married to assumed 4.5-billion-year age (for problems with crater counts, see 03/25/2008 and embedded links).  What would happen if that parameter were not fixed in advance by decree?  Why not free it up and follow the evidence where it leads?
    And my, aren’t we humans lucky to be observing Enceladus during the current eruptive episode when we have the technology to fly a spacecraft there.  The last eruptions wouldn’t have been noticed by the little microbes swimming around earth’s oceans a billion years ago.  Planetary scientists used to lecture us that we should avoid presuming that humans are observing the solar system at a special time.
    They should call this “selective catastrophism.”  Let’s try it.  Water under earth’s crust builds up pressure and erupts once every 10,000 years, spewing water all over the earth (see CSC).

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Categories: Solar System

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