Titan, awash in oceans of liquid methane and full of azotosomes?
March 1, 2015 7:29 PM   Subscribe

"A press release from Cornell explains how the researchers used some creative chemical modeling to construct a hypothetical, methane-based cell that's stable in Titan's sub-zero oceans. They call their alien life form an "azotosome.""

It order search for this hypothetical life form, we'll need a submarine.
posted by Brandon Blatcher (24 comments total) 15 users marked this as a favorite
 
There's a lot more to a living cell than just a cell membrane, which is all they've actually described. There needs to be an information storage and duplication system and some way of using that information to build copies of the cell.

In other words, they need an equivalent of DNA and an equivalent of amino acids and proteins. Absent those things, this is just a curiousity.
posted by Chocolate Pickle at 7:34 PM on March 1, 2015 [2 favorites]


Don't the lakes of Titan completely evaporate and switch hemispheres every year? Seems like a prohibitive environment for azotosomic life.
posted by Renoroc at 7:36 PM on March 1, 2015 [1 favorite]


Don't the lakes of Titan completely evaporate and switch hemispheres every year?

Maybe that's just the azotosomal geese migrating.
posted by Sys Rq at 8:13 PM on March 1, 2015 [4 favorites]


I kind of sort of suspect life on Titan is a real possibility, and this modeling exercise demonstrates that such an idea isn't outside the realm of possibility. It's important to realize that this model is extremely hypothetical and very much incomplete, but it goes quite a ways towards demonstrating that life on Titan isn't necessary a pipe dream and that it is at least worth talking about.
posted by surazal at 8:27 PM on March 1, 2015 [3 favorites]


There's a lot more to a living cell than just a cell membrane, which is all they've actually described. There needs to be an information storage and duplication system and some way of using that information to build copies of the cell.

In other words, they need an equivalent of DNA and an equivalent of amino acids and proteins. Absent those things, this is just a curiousity.


Dang, I guess you're right, they didn't literally create life from scratch. What a fucking disappointment these scientists are
posted by Greg Nog at 8:28 PM on March 1, 2015 [37 favorites]


Well they do work at an upstate New York ag college, so what do you expect?
posted by Eyebrows McGee at 8:42 PM on March 1, 2015 [5 favorites]


I read a book about mechanical life on Titan, Code of the Lifemaker. It has its moments.

Even absent finding life, mechanical or otherwise, I'm incredibly excited about a mission to Titan. To be honest, when I was 10 I figured we'd already have a moon base by now. The fact that it wasn't even seriously considered worries me.
posted by ob1quixote at 9:00 PM on March 1, 2015


DNA is probably a very complex evolutionary endpoint, being so fragile. We don't begin to know what is needed for life in environments we know little about, let alone know what we will find here. Clays, RNAs, arsenic-based life chemistries, etc. Let's go explore before we open our mouths to shoot down imaginative ideas.
posted by a lungful of dragon at 9:29 PM on March 1, 2015


Chocolate Pickle: There's a lot more to a living cell than just a cell membrane, which is all they've actually described. There needs to be an information storage and duplication system and some way of using that information to build copies of the cell.

The Earth-like equivalent, liposomes, can spontaneously form out of a phospholipid/water mixture. They can “eat” new phospholipids to grow larger, and when they get too big they divide into daughter liposomes. I'm not saying they're alive, but they exhibit several forms of life-like behavior, and they provide a separation between “interior” and “exterior” that can establish the strong differences in chemical environments that is probably necessary for recognizably alive biochemical reaction systems. These discoveries led scientists to recognize a third category in the age-old debate of metabolism-first versus (R)NA-first as for how life first evolved: membrane-first.

(I used to study this stuff before changing life paths.)

After Earth had liquid water on its surface, but before life, the oceans were covered with an oily scum of whatever substances weren't water-soluble but were less dense than water. Not much is known about it, but I've read estimates of anywhere from a few molecules thick to a centimeter thick. Every time a wave splashed, it created droplets and micelles and liposome-like things. They had a literal sea of organic pre-life molecules to react with chemically. One of the intriguing things about this scenario is that it establishes the conditions for evolution before life emerges: all you need is behavior that acts like growth, reproduction, and differential survivability; you get evolution whether what's doing those things are computer programs or crystals or liposomes with random chemicals inside them. And if evolution is kick-started before actual life, it's possible that things like metabolisms and RNA evolved into existence and those liposomes just gradually crept across the nonliving/living boundary.

As abiogenesis theories go it's not without its problems, and the big question is what sort of geochemical environment there actually was floating on the ocean back then—were there actual phospholipids? PAHs? Something else? But that background shows how much of a big deal this could be: up to now there's been lots of speculation but little more about possible biologies in non-Earthlike environments. If liposomes really were all that when it came to the origin of life here, azotosomes could very well be just as important elsewhere, especially since the components of these azotosomes occur already on Titan. I would absolutely love to see someone recreate Titan-like conditions in the lab and see if they couldn't show azotosomes spontaneously assembling.
posted by traveler_ at 9:39 PM on March 1, 2015 [26 favorites]


A problem with this is that the rates of the root chemical reactions are likely all dependent on temperature, as the Arhennius equation suggests. So if there's some absolute floor to the number of reactions needed to arrivee at life (by some definition we can agree on), life must then take N times longer to arise on Titan than on Venus. I'm guessing. Is there something wrong with my reasoning on this?
posted by newdaddy at 9:48 PM on March 1, 2015


If we can seed the moon/planet with the basic building blocks for life, why not? It at least gets our technology out there.
posted by five fresh fish at 10:33 PM on March 1, 2015


I say technology because I'm skeptical we'll be able to make distant space travel a reality. We'll be sending technology in our place.
posted by five fresh fish at 10:51 PM on March 1, 2015


Well one reason why not is you almost gave me a heart attack! More seriously, the big reason why not is that up until now everything we know about the origin of life and the possibilities of biochemistry have a sample size of 1. If there's any chance at all that Titan already has life, destroying that second biosphere with an intentional infection of artificial life would be a literally priceless catastrophe. I mean how do you quantify the loss? And that's even coldly ignoring the philosophical question of the inherent right of that second biosphere to exist.

And the problem is we almost can't know that there isn't actually life there, anywhere that life is possible. There's even speculation about an unknown “shadow biosphere” here on Earth that uses a biochemistry different enough from our recognized methods that we can't tell it's here—that could describe something as exotic as a mineral-based form of life deep underground, or something that looks and acts like an ordinary bacterium but, if we were to ever figure it out, came from a separate evolutionary path and doesn't use the same DNA systems or enzymes as the rest of Earth life.

So as long as we don't provably know that Titan (or anywhere else) is sterile, inoculating it with anything would be a tragedy.
posted by traveler_ at 11:17 PM on March 1, 2015 [5 favorites]


On the other hand, I wouldn't worry too hard that something whipped up by scientists in a lab on Earth is going to outcompete to extinction something that has evolved to live on Titan for as much as four billion years.
posted by Mitrovarr at 11:36 PM on March 1, 2015 [2 favorites]


Do I have bad news for you traveler_.
posted by lenny70 at 11:49 PM on March 1, 2015


If we can seed the moon/planet with the basic building blocks for life, why not? It at least gets our technology out there.

Vonnegut's way ahead of you.
posted by George_Spiggott at 12:02 AM on March 2, 2015 [1 favorite]


We might oughta be careful about sending anything up there to Titan, it could be considered an act of war. Lord knows we just discovered Ceres keeping it's eyes on us. I can't say I blame them for not trusting us much, the way we've been littering up the Moon and Mars of late. And recently, even a comet.
posted by scottymac at 1:03 AM on March 2, 2015


What a fucking disappointment these scientists are

They didn't even throw their heads back and cry "It's alive! Aliiive!" I understand scientific restraint, but what can I say?; I'm a traditionalist.
posted by GenjiandProust at 3:19 AM on March 2, 2015 [1 favorite]


If there's any chance at all that Titan already has life, destroying that second biosphere with an intentional infection of artificial life would be a literally priceless catastrophe.

Yeah but if you bother to check for life and you send a team down it turns out to be Ceti Alpha Five instead of Ceti Alpha Six like you thought and then you're truly screwed.
posted by freecellwizard at 5:57 AM on March 2, 2015


But what if cells weren’t based on water, but on methane, which has a much lower freezing point?

What if jet engines weren't made out of metal, but out of cheese? I've developed a computer model that shows a turbine-shaped block of Havarti can sort of spin if it's mounted on a toothpick shaft. I'm pretty sure it could function like a jet engine. Engineer? No, I'm a chef. That means I can approach the problem from a new perspective.
posted by dephlogisticated at 7:49 AM on March 2, 2015


So, there is a future for lunar green cheese farming? Havarti at it!
posted by Oyéah at 10:07 AM on March 2, 2015


Are they actually working on the Methane consuming life form, for here?
posted by Oyéah at 10:09 AM on March 2, 2015


I think we're cool so long as we don't try seeding Europa.
posted by straight at 10:25 AM on March 2, 2015


As an aside, the paper is published in Science Advances, an open access journal that the AAAS is trying out in parallel to their flagship, Science. Full paper text.

If you want to just look at one thing, check out Figure 3: (A) Azotosome. Interlocking nitrogen and hydrogen atoms reinforce the structure. (B) Solid. Adjacent nitrogen atoms create some unfavorable repulsion. (C) Micelle. Adjacent nitrogen atoms make this highly unfavorable. (D) Azotosome vesicle of diameter 90 Å, the size of a small virus particle.

They're showing that you can get small virus-particle sized vesicles out of this structure, which is pretty freaking awesome: the first truly plausible structures for a methane-based biology.

Oddly enough, we were just discussing the paper at Science Coffee this morning with Jonathan, the astronomer co-author: Yes, he agrees that they did not show yet whether such structures could spontaneously self-assemble, and that's one of the key outstanding questions. He was one of the prime movers for the Titan Mare Explorer (declined in favor of Mars), so you can hardly blame him for not trying hard enough to get ground truth data...
posted by RedOrGreen at 11:02 AM on March 2, 2015 [1 favorite]


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