A Fizzy Ocean May Lie Beneath Enceladus' Icy Crust

The Cassini spacecraft spotted icy plumes jetting from Saturn's moon Enceladus in 2005. Now researchers say a carbonated ocean may fuel the plumes. Science News reporter Ron Cowen talks about this and other news from a meeting of the American Astronomical Society's Division for Planetary Sciences.

IRA FLATOW, host:

This is SCIENCE FRIDAY. I'm Ira Flatow.

All week long, scientists have been swapping stories about our solar system, talking about the winds and sulfurous clouds on Venus, the icy volcanoes and dunes on Titan, Saturn's largest moon; and debating how the planets and their moons and rings formed - still a bit of a mystery.

All that took place at the American Astronomical Society's meeting out there in Pasadena, California. My next guest joins us now with a few stories from that meeting.

Ron Cowen is the astronomy writer for Science News in Washington. Welcome back to SCIENCE FRIDAY

Mr. RON COWEN (Astronomy Writer, Science News): Thanks, Ira.

FLATOW: And you can read about Ron's articles in sciencenews.org. And Ron, I've got to start off with this great line that you have in that article, on that page, it's called "It's Only a Seltzer Moon."

(Soundbite of laughter)

Mr. COWEN: Right.

FLATOW: Tell us what that refers to.

Mr. COWEN: Okay, well, it refers to the fact that inside this moon of Saturn called Enceladus, where we think there is an ocean there, and we think there's an ocean there because we know that there are plumes of water vapor that erupt from its south polar surface.

There's a model now that says that this ocean is carbonated like Perrier inside that moon, and the carbonation, actually the bubbles in that seawater would actually help the water rise to near the surface and get through cracks in the ice and actually help fill the chambers right next to the icy surface, where these geysers actually erupt.

And without the bubbles, without the Perrier, this according to these researchers, the water really wouldn't get out. So it's actually carbonated.

FLATOW: So it's like if you took the top off a seltzer bottle, it's spraying out through these volcanoes.

Mr. COWEN: That's right. That's right. Yeah, that's what they think, yeah.

FLATOW: That's a great story. Do we have any idea how all that carbonation got into the ocean in the first place?

Mr. COWEN: Yeah because the core of this it is an icy moon, but the core of it is believed to be rocky, and there are carbon compounds, organic compounds believed to be in the rock and that the ocean - apparently not recently, but way but several billion years ago - soaked up some of the carbon from the rock in the middle of Enceladus, the rocky core, and got the carbonation.

FLATOW: As intriguing and as sort of funny as this moon is, there's a really other interesting presentation on the possibility of the building blocks of life that could be formed on Saturn's Titan. Is that right? Wow.

Mr. COWEN: That's right. That's Saturn's largest moon, Titan. And Titan has this really thick atmosphere of nitrogen, methane, ethane and other organic compounds.

And people have speculated for a while, that when sunlight hits the top of this atmosphere, it can trigger all kinds of chemical reactions. In fact, the Cassini spacecraft, which is visiting Saturn and its moons, has seen very massive, large chains of chemicals that they haven't been able to identify.

So what this group did, is they - back on Earth - they simulated the chemical composition of Titan, all these the methane and nitrogen - and then instead of sort of using ultraviolet light from the sun, they used radio waves to try to spark a reaction.

And when they did this - and they didn't need water, and they didn't need lightning like in some other classic experiments - they produced nucleotide bases, which make up DNA and RNA, and they also found amino acids.

And what they're thinking - they dont know - is that these large compounds that have not been identified on Titan, may be these amino acids and these nucleotide bases.

They now have to go back with another spacecraft that can really that's what they want to do, go back and really identify and see for sure. But what's really neat is that this is saying perhaps that life - not just at Titan, maybe life throughout the solar system - really began up in the air, up in the sky, even on Earth.

Maybe we didn't need liquid pools of water on the ground. Maybe the first reaction that gave compounds that supported life, was in the atmosphere, not on the ground in water.

FLATOW: Is there any water in the Titan atmosphere?

Mr. COWEN: There wouldn't be Titan is frozen. If there is any water, it would have frozen. And what they say is that the methane on Titan is what water is on Earth. So no, there wouldn't be much water, and it would be all frozen out.

FLATOW: So this shows you that you don't need to have water to create those building blocks of life.

Mr. COWEN: That's right. That's what this seems to say. So that's really, really exciting.

FLATOW: Wow, and we always said about Titan, that this was a place to go visit more.

Mr. COWEN: That's right.

FLATOW: And study, right?

Mr. COWEN: Exactly, right.

FLATOW: And here's a new reason.

Mr. COWEN: Exactly. It's really, I mean, what they say is that Titan could be like a frozen snapshot of what the Earth was like when it was very, very young. And Titan sort of stayed frozen in time. So, yeah.

FLATOW: Interesting. And the last story we'll pick up from you is you had a story on Mars and why its size is the way it is.

Mr. COWEN: Right, right. So it's always been a mystery why Mars, at least compared to Earth and Venus, which are of course also in the inner solar system, is relatively svelte. It's a lot lighter.

And it's always been a puzzle, because when you want to explain how the planets form, people believe - and actually have found evidence for - that there's a swirling disk of gas and dust and ice around very young stars.

And within that disk, stuff coalesces to form the planets. You know, you form little boulders and house-sized bodies, and finally planets. And in the inner solar system, there's just a lot of material. And it would seem that Mars ought to be five to 10 times heavier than it really is.

And in this one model that two teams have proposed, they believe for various reasons, that there's a gap in the disk near where Mars formed. And I can explain why there might be a gap in a minute, but it just turns out that basically Mars would get pushed to a certain point, and then it would reach this gap, and it just there's nothing there. So it just can't pack on more material.

And one reason why there might be a gap is that there's reason to believe that Jupiter might have come barreling in - to the inner solar system - and then been tugged back by its big neighbor, Saturn.

And in going in and going out, this is like the first 10 million years of the solar system's Earth, it could have created that gap. And so what I say, is there's a whole lot there was a whole lot of moving and shaking going on in the early solar system, especially the inner part, that we might not have known about.

FLATOW: But this is just, of course, just speculation.

Mr. COWEN: It is true. It is true. I mean, there's some predictions that these models make about the composition of the asteroid belt, for example, which is the belt that begins just after Mars' orbit. But yeah, it's speculation. And they're working on refining thing.

FLATOW: Great stuff, Run. Thanks for coming on.

Mr. COWEN: Thank you.

FLATOW: And we'll see you next month.

Mr. COWEN: Thanks so much, okay.

FLATOW: You're welcome. Ron Cowen is the astronomy writer for Science News in Washington, and if you want to follow what we're talking about and get more details, you can go to his articles at sciencenews.org.

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