Let’s Be Pedantic.

I hate to be a pedantic bore (no, actually I love it) but it is theoretically possible to set up life based on carbon, hydrogen, and oxygen, but where liquid methane substitutes for water.

M in the comments

M’s survival instincts are misfiring.

Let’s be pedantic. We haven’t told you anything except that there is methane and electrified sand, and the carbon-based life is not welcome. M has no idea if there is silicon based life thriving on this planet or if a planet-wide energy based sapient bioweb encircles it, projecting its consciousness into space, or what have you, because we haven’t told you anything about it. Yet M took the time to correct us and he relished it. He really loves being a pedant.

I was going to let all those comments quietly disappear, but this one got me, because I can’t let this misunderstanding of chemistry go. I am going to assume that M is basing that weirdo statement above on Titan of our lovely solar system, which has methane and nitrogen atmosphere and liquid methane seas.

For life as we know it to exist even in its most primitive form, there must be a membrane, a boundary that defines the inner space of the organism and separates it from the environment. Here it is, courtesy of Encyclopedia Britannica.

The cell membrane has two functions: to protect things inside and to allow nutrients to enter and waste products to exit. Our membranes are made mostly of phospholipids and sterols (mostly cholesterol.)

Do you see that O in the formula? That’s oxygen. The P stand for phosphorus, also a very helpful element. The lipid molecules are polarized, which is what makes them “stick” together.

What does that mean? Imagine a sewing pin.

This is our phospholipid molecule. We’ve discussed before that water is sticky because its molecule is polarized. The head of the our “pin” is also sticky. It’s polar and likes water. The long end (there are 2 of them per each head) is hydrophobic and doesn’t like water.

If you drop oil into water, it will quickly form a round drop. These guys function the same way. You drop them in water and they right away will arrange themselves into a sphere with the heads pointing toward water and tails pointing inside our little ball. And because we still have water inside the ball, they make a second layer that’s a mirror of the first one. This forms a barrier that’s surprisingly resilient and flexible.

M, for the record, the planet is not Titan, but if it were Titan with its liquid methane seas, we would still need this lipid membrane. However, there is a big problem with that.

Phosphorus and oxygen, found in Earth cell membranes, don’t exist in Titan’s frigid methane oceans, so any cell-like membranes would have to be based on nitrogen, hydrogen and carbon, all of which are abundant on Titan.

NASA

NASA stipulated that life on Titan, if it were to exist, is methane-based and oxygen-free. It would be based on nitrogen, hydrogen, and carbon, because there is no oxygen or phosphorus in Titan’s methane seas. There might be water under the liquid methane, but that’s a whole different story.

So, no, you can’t “set up life based on carbon, hydrogen, and oxygen, but where liquid methane substitutes for water.” Because there is no phosphorus or oxygen, you can’t have a lipid membrane.

But what if there is magic oxygen that we miraculously pulled out of our butt and stuck into other elements available on Titan?

Okay, if you have carbon, hydrogen, and oxygen, and you wanted to make a lipid molecule, you could make a fatty acid. It’s nonpolar, so it won’t work. You could make cholesterol, which is again largely nonpolar. (No, we are not going to be discussing hydroxyl groups. We are keeping it simple.) You need phosphorus-oxygen combo for that polarity.

Even if you somehow – and I don’t know how – made a magically polar lipid molecule out of carbon, hydrogen, and oxygen, it still wouldn’t work. Why? Because methane liquefies at -260°F. The surface of Titan is a brisk -292 degrees Fahrenheit.

However, the phospholipid membranes, which are so strong and elastic in water, do not perform as well in liquid methane. The nonpolar tails of phospholipids would seem to be compatible with nonpolar liquid methane, and the polar heads with each other; does this suggest that an inverse membrane to those formed in water could exist in methane? Unfortunately not; this phospholipid hypothesis neglects the fact that the tails of phospholipids are long-chain hydrocarbons, which will be rigid at cryogenic temperatures. Furthermore, the phospholipid head component atoms, oxygen and phosphorus, are not available in any form in the methane seas of Titan and presumably not in any similar liquid methane environment. Inverted-phase liposomes are therefore not a viable option. The idea of using polarity to prevent dissolution, however, is valid if any suitable materials exist.

Membrane alternatives in worlds without oxygen: Creation of an azotosome

Translation: it is too cold. The membrane has to be flexible and at this temperature our poor lipids float there, stiff as a nail, and refuse to stick together. So our trio of C, H, and O is right out.

We have to search for alternatives to lipids. You can theoretically set up a life-enabling membrane based on vinyl cyanide, which looks like this.

It is theorized that vinyl cyanide could form a spherical membrane in a methane sea. We don’t know if it happens. We only know that it could happen.

Now then, we posted a teaser for Innkeeper, and ModR had to trash 10 comments. We haven’t even started. There is literally no fiction up. I am sure that M was excited to share his understanding of methane-based life, but by comment #10, I am done.

Our blog policy is that any person who offers corrections without listing their credentials will have said corrections removed without explanation. If you are correcting something we wrote about Houston, you should live there. If you are correcting something a Mancunian says, you better be one. If you are not an expert, please cite your references. Otherwise, you are spreading misinformation, which we have to refute or which will create a long comment thread and lead to fights. If you see something in error of fact (not a typo) in the narrative, please email us using the contact form.

Most of BDH really enjoyed the teaser, so this bottom part is addressed to those who, like M, relish being pedantic and decided to nitpick 3 sentences (WTF) in the previous post. You have to decide if you are going to be “helpful” or if you want to read Innkeeper in a serial form. No person alive can write in a toxic atmosphere – and it’s not methane this time – that so many “helpful corrections” create. Especially since half of the time, as M’s comment above demonstrates, they are in error.

Gordon has not seen this post yet, because his fuse is short when it comes to Innkeeper corrections. He is not a fan of serialization, because some people tend to get obsessive and abusive. I hope that by the end of August we will all be on the same page regarding Innkeeper’s availability.

Please do not trash each other in the comments. I have an ER scene to write in Ruby Fever because important people are very hurt, and I have told Mod R to exercise extreme prejudice. 😀