Creation Moment 4/6/2016 - Saturn's Modern Adornments

"Elizabeth Howell printed the shocking headline on Space.com: “Saturn’s Moons and Rings May Be Younger Than the Dinosaurs,” based on modeling done by the SETI Institute. David Rothery on The Conversation echoed the refrain, adding, “So could life really exist there?” His answer is maybe; more about this below.

Really, though, why the change in thinking? The SETI Institute press release explains:

New research suggests that some of Saturn’s icy moons, as well as its famous rings, might be modern adornments.  Their dramatic birth may have taken place a mere hundred million years ago, more recent than the reign of many dinosaurs.

“Moons are always changing their orbits.  That’s inevitable,” says Matija Cuk, principal investigator at the SETI Institute.  “But that fact allows us to use computer simulations to tease out the history of Saturn’s inner moons.  Doing so, we find that they were most likely born during the most recent two percent of the planet’s history.”

While Saturn’s rings have been known since the 1600s, there’s still debate about their age.  The straightforward assumption is that they are primordial – as old as the planet itself, which is more than four billion years.  However, in 2012, French astronomers found that tidal effects – the gravitational interaction of the inner moons with fluids deep in Saturn’s interior – are causing them to spiral to larger orbital radii comparatively quickly.  The implication, given their present positions, is that these moons, and presumably the rings, are recent phenomena.

The new estimates do not apply to the more distant moons like Titan and Iapetus. But to keep the inner moons so close to Saturn, especially the smaller ones and the rings, they can’t have survived tidal effects and resonances since the assumed age of Saturn (4.5 billion years).  The results are published in the Astrophysical Journal. The press release explains the assumptions behind the model:

To get a more specific value for the ages of these moons, Cuk used ice geysers on Saturn’s moon Enceladus. The researchers assumed that the energy powering those geysers comes from tidal interactions with Saturn and that the level of geothermal activity on Enceladus has been constant, and from there, inferred the strength of the tidal forces from Saturn.

Using the computer simulations, the researchers concluded that Enceladus would have moved from its original orbital position to its current one in just 100 million years — meaning it likely formed during the Cretaceous period. The larger implication is that the inner moons of Saturn and its gorgeous rings are all relatively young.

That’s one way to explain the Enceladus geysers; reduce their age. The authors seem to realize that Enceladus couldn’t be blowing chunks for billions of years. But how are they going to keep the rest of the Saturn system old? Here’s where a little imagination works wonders:

“So the question arises, what caused the recent birth of the inner moons?” asks Cuk.  “Our best guess is that Saturn had a similar collection of moons before, but their orbits were disturbed by a special kind of orbital resonance involving Saturn’s motion around the Sun.  Eventually, the orbits of neighboring moons crossed, and these objects collided.  From this rubble, the present set of moons and rings formed.”

If this result is correct, Saturn’s bright rings may be younger than the heyday of the dinosaurs, and we are fortunate to witness them today.

Others aren’t so willing to invoke ad hoc circumstances to make Enceladus young. Edwin Kite and Allan Rubin published a new theory in PNAS about tidal resonances keeping the cracks open down to the moon’s presumed subsurface ocean. Science Daily describes how Kite and Rubin claim to have found the “sweet spot” between tidal forces:

“It’s a puzzle to explain why the fissure system doesn’t clog up with its own frost,” Kite said. “And it’s a puzzle to explain why the energy removed from the water table by evaporative cooling doesn’t just ice things over.”

What’s needed is an energy source to balance the evaporative cooling. “We think the energy source is a new mechanism of tidal dissipation that had not been previously considered,” Kite said.

It’s a finely balanced Goldilocks situation, Elizabeth Howell writes for Space.com:

The new model suggests that deep vertical “slots” may be located between the icy surface of Enceladus and the water below. If the slots were wide, the eruptions would happen very soon after the tidal force goes into effect, the researchers say. If the slots were narrow, the tidal forcing would take longer. The observed delay of 5 hours comes from a size of slot that is somewhere in between, the scientists said.

“In between, there’s a sweet spot,” Kite said.

The paper claims this could keep the geysers going over “geological timescales.” Atheist imaging scientist and ring expert Carolyn Porco seems to like this theory, according to NASA’s Astrobiology Magazine. But when you read the paper looking for how long those timescales are, they only mention “million-year timescales,” not billions. A million years is only 1/4,500th the assumed age of the solar system. None of them explain that. They do, however, want to keep Enceladus active long enough to give life a chance:

The sustainability of water eruptions on Enceladus affects the moon’s habitability (e.g., ref. 16), as well as astrobiology (follow-up missions to Enceladus could be stymied if the plumes shut down).

David Rothery’s worldview is showing on The Conversation in his reaction to the youth of Saturn’s moons. If Enceladus is so young, he speculates, would there be time for life to evolve there?

Titan has been in the news a lot recently. We’ll report on the latest findings in a coming post.

The answer to “Are Saturn’s Moons Younger than the Dinosaurs?” is no; they’re both the same age, because they were created not that long ago. The dinosaurs just kicked the bucket sooner. Saturn’s moons cannot last billions of years, or even millions; in time, they will go extinct, too." CEH

  .....by whom also he made the worlds;
Hebrews 1:2