A huge water geyser on Saturn’s moon helps make the rings, and a bonus eclipse from Mars

September 17, 2012 • 7:58 am

The site i109, which describes this phenomenon in a short paragraph, calls the photo “space porn.” But on his NPR website (via North Country Public Radio), Robert Krulwich goes into more detail with the tersely titled post, “Volcano shoots geyser of water into space.

First, though, a short astronomy fact: Saturn in fact has 62 moons, and 53 of them have been officially named. (As Johnny Carson would have said, “I did not know that.”) Here’s a figure from NASA’s Cassini Solstice Mission to Saturn:

Have a look at Enceladus, top center, and then at the picture below. This is fantastic:

Enceladus, the sixth-largest moon of Saturn, seen shooting geysers water into space from its south polar region in this mosaic composite photograph. Photo by Michael Benson.

Krulwich explains what’s going on:

What we have here is a moon — a small one (slightly wider than the state of Arizona) — circling Saturn.

If you look closely, you will see a small splay of light at its top, looking like a circular fountain.

That’s because it is a fountain — of sorts. A bunch of volcano-like jets are sending fantastically high geysers of water vapor up into the sky, so high that you can see them in this remarkable print by Michael Benson, back lit by light bouncing off of Saturn.

It turns out this moon, called Enceladus, is a snowball containing what may be a sea of liquid water, warmed by the squishes and stretches of Saturn and other moons that pass nearby (plus it may have a hot, rocky core.) All that gravity pushing and pulling on this little ball squeezes the liquid inside so it shoots up through some fissures at the top.

Nobody knew these fountains were there until the Cassini spacecraft flew near enough to Enceladus to find them. But now comes the amazing part.

Some of that water vapor turns into ice and the crystals fall like snow back onto the moon at a rate of 0.02 inches a year; but some ice is thrown so high, it joins a ring around Saturn, one of the outer rings, labeled “E.”

Take a look at this image of the same moon, Enceladus — it’s the dark spot inside the bright flare — getting real close to the E ring. According to Sascha Kempf of the Max Planck Institute for Nuclear Physics in Heidelberg, this moon is “feeding” water crystals into Saturn’s ring.

Enceladus making Saturn’s E ring. Photo by Michael Benson from a digital transmission sent by the Cassini probe. It appears in Benson’s about-to-be published book Planetfall: New Solar System Visions.

Krulwich continues:

Who knew that a moon could spray ice onto a planetary ring? Before these photos were taken, scientists thought teeny meteorites, called micrometeoroids, would slam into Saturn’s moons kicking up dust (adding to dust from a long exploded moon) and that’s how the rings were formed.

Nobody imagined that the rings would be fed by geysers.

But that seems to be what’s happening to the E ring. According to Kempf, the ring will carry those ice nuggets around Saturn for an orbit or two, until they meet the moon again and are recaptured. But some crystals just keep circling and circling for 50, maybe 400 years.

The E ring is astonishingly thin. Its debris is thousands of miles across, but often only 3 meters (about 9.3 feet) high. A giraffe traveling on this ring would poke out like a giant.

Yes, who knew? Damn, but science is just a constant feed of cool new facts and theories. Theology doesn’t come close.

And, as lagniappe, reader Sigmund sent me a photo this morning taken by the Mars rover; it appeared on the Curiosity’s Twitpic feed. This is a partial solar eclipse occurring when the Martian moon Phobos passed in front of the Sun. Curiosity took it looking up from the surface of Mars.

Curiosity tweets, anthropomorphically, “Phobos takes a bite out of the sun: My week included taking pics of a Martian lunar transit. How ’bout you?”

h/t: Matthew Cobb, Sigmund

27 thoughts on “A huge water geyser on Saturn’s moon helps make the rings, and a bonus eclipse from Mars

  1. As a biologist with an interest in biochemical evolution, I do wonder about the likelihood of life on other solar system bodies. Enceladus seems like one of the most promising candidates – particularly in light of the fact that we may not need to drill through kilometers of ice to sample some of the interior water. And if we could capture some emitting from one of these ice geysers, we may not even need to land!

    1. I used to think that the likelihood for an Enceladus’ biosphere was pretty low. Cassini’s mass spectrometer has low resolution but the peaks are all consistent with cometary pristine material.

      But now they have a much better handle on the existence and characteristics of the inner ocean and:

      1) The jetted water is probably mostly remelted pristine ice, consistent with observations.

      2) The ocean is at least 100 Ma from the vented ice thickness, enough time for abiogenesis through hydrothermal vent action.

      3) The ocean has contact with the core, supplying the necessary minerals.

      So there is a good likelihood that extant or extinct life could show up as traces in the jets.

      Cassini’s lead, Caroline Porco, has been on record for wanting a lander sampling the outfall from the jets and the ice deposits with direct analysis. Collecting the jets indirectly would preserve everything from ice structure and up, and presumably having in situ analysis cuts the mission time and direct cost.*

      Still, even with gravitational braking around Saturn and its moons, the craft would need to be slightly less massive than Cassini. It would take the medium type of mission I hope (and as I’m typing this I have forgotten its name), making it somewhat less than a pipe dream.

      * My own idea was repeated aerogel sampling after a Titan aerobrake for Saturn orbit insert (since we know now its atmosphere), and then sample return for best analysis.

      Alas, the planetary mission specialists have different ideas.

      1. Like sending people to Mars. That’s a worthwhile eventual endeavor but very wasteful at this time. Much better to do robots until the technology allows for the real possibility of establishing a permanent presence. Otherwise, its just an athletic performance for bragging rights and very expensive, when robots can be used so much more effectively and efficiently at this stage of exploration.

        1. Sophisticated space exploration is only expensive in the context of current budgets. It’s dirt cheap compared to certain other very popular endeavors, such as killing brown people.


    2. Best would be not some life form comparable to here on Earth, but some primordial molecules such as Jack Szostak works on/contemplates, that would give further direction to work on abiogenic origins.

      But even before that, OK, there’s water, but what are the levels of carbon, nitrogen and phosphorous?

  2. Great post! And as Sigmund says, in that fountain there may be amino acids and signs of life – Enceladus, along with Europa, is one of the main options for finding water-based life (the only kind we know). They should send a probe through that spray and analyse it!

    And if there’s anything big in that ocean, it will have the shape of a fish or a dolphin or an icthyosaur, not because of any spooky convergence, but because of physics and the importance of Reynolds numbers in determining movement in a fluid. Reynolds, as everyone knows, was Professor of Engineering at the University of Manchester.

    1. Actually both Porco, the Cassini lead, and Mendez, the Habitable Exoplanet Catalog lead, classify Enceladus as the prime target. Porco because it is readily available, Mendez because models of the ocean makes it at least as habitable as our own oceans:

      “The Standard Microbial Habitability index rates worlds on a scale of 0 to 1 as to how suitable they are for microscopic life-forms like those on Earth.

      “What’s good for [microorganisms] is good for life in general,” said research leader Abel Mendez, of the University of Puerto Rico at Arecibo.

      Enceladus scored 0.4–the same as Earth.”

      And of course the Enceladus Focus Group likes to think it is best:

      “Saturn’s icy moon Enceladus is emerging as the most habitable spot beyond Earth in the Solar System for life as we know it, scientists said last week at a meeting of the Enceladus Focus Group at the SETI Institute in Mountain View, California.”

      The absence of an oxygenated biosphere speaks against “anything big” tough.

  3. That is the best image of Enceladus I’ve seen yet. And I’ve collected quite a few over the course of the Cassini mission. Wonder how I missed that one.

  4. Some other of Saturn’s rings are caused by micrometeorite bombardment of the inner moons: Janus & Epimetheus, Pan and Pallene have faint dust rings in their orbits, and Anthe and Methone have dust arcs. The G Ring also has a tiny moon (Agaeon) inside of its densest region. We also see this at Uranus and Jupiter.

    Tiny moons (the size of cities, rather than the size of Western US states) are the best for making these impact dust ringlets. Enceladus has too much gravity: most of the material in the plumes falls back to the surface. It’s just that the plumes make a lot more material than impacts do, so even the tiny amount that escapes builds up to the E Ring.

    1. The Cassini mass spectrometer is a small low resolution (~ 1 amu) < 100 amu instrument, I think. They didn't expect to observe organics.

      If there is no confusion it should be able to resolve glycine (~ 57 amu) and perhaps some others. I haven't heard of any such detection.

  5. Thank you! I had forgotten that they started in on norse mythology on naming Saturn’s moons, and I didn’t know about the Inuit group of moons at all.

    Though I must say that the norse ice giants and other giants (jötnar/jötunn; sw: jättar/jätten) – Ymir, Surtr, Skaði, Fornjót, Nǫrfi, the giant Fenrisúlfr wolf, et cetera, et cetera – have been short changed.

    Oh, and nice pics!

  6. OMFG! Yes, as you said, theology has nothing to compare to the majesty of this! This post, on the large(r) scale structure of features of our universe (and nowhere NEAR the largest), together with your posts on tiny features such as the legs of horseshoe crabs (nowhere near the tiniest!), illustrate so clearly to me the wonder of science taken without supernatural intervention! Awesome! Magical, in the naturalistic sense of that word!

  7. Excellent post, thanks.

    I have previously mentioned how informative and sassy #ScienceSunday is at G+: https://plus.google.com/u/0/+sciencesunday/posts Many of the contributors have religious beliefs, but none of them sacrifice science. It is a nice collaborative effort. It is established enough after a year where a posse is summoned to take care of creationist trolls, if required. I highly recommend it.

    The same folks curate #ScienceEveryday: https://plus.google.com/u/0/s/%23ScienceEveryday This hashtag has humour connected with science also–it’s a great stream.

    Jerry, you have an inactive G+ page (I have circled you), and it’s a shame that your science stuff does not get put on your stream. If you want to do that and use these two hashtags to draw readers, please let Rajini Rao, one of the curators, know. She will assist you and tell her I sent you. 🙂 You can contact her on G+ by sharing a post just with her (You have to circle her first).

    1. I tried emailing you privately but the address you gave wasn’t valid (or at least my email was bounced back). Could you email me and let me know how I contact Ms. Rao, and whether she or I decide which posts go up?

      And how is deo88xxx?

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