Planet Pailly

I have decided, reluctantly, that I need to take some time off of regular blogging. There’s just too much work I need to do with my manuscript.  But I promise I will be back as soon as I can.  There is, after all, some exciting Mars news that just came out, and I’m eager to dig into the research behind the headlines.

Today’s post is part of a bi-weekly series here on Planet Pailly called Molecular Mondays, where we take a closer look at the atoms and molecules that make up our physical universe, both in reality and in science fiction.

Imagine you’re a traveler in space, living in a time two or three centuries hence, engaging in the trade of resources between Earth, the Moon, Mars, and the asteroid belt.  What is the rarest and most precious resource necessary for your survival out there?

You might think it’s oxygen, or perhaps water.  Those are difficult resources to find in space, but not that difficult.  A surprising number of asteroids do, in fact, have a surprising amount of frozen water on them or inside them.  And if you can get water, you can easily split water molecules into hydrogen and oxygen through the magic of electrolysis.

No, of all the resources you absolutely must have to stay alive, the hardest one to find out there may actually be nitrogen.  I first read about this nitrogen problem in a book called Asteroid Mining 101: Wealth for the New Space Economy, which says:

Nitrogen presents a more significant problem [than other essential resources]. Because of the great stability and high volatility of molecular nitrogen, it is poorly retained by solid minerals and poorly represented in meteorites.

Volatility, in this context, refers to the tendency of a chemical substance to turn itself into a gas. Planets and moons and asteroids (especially asteroids) have a really tough time holding onto volatile chemicals, also referred to as “volatiles.”  And the closer a celestial body happens to be to the Sun, the more likely it is to lose its volatiles to the solar wind.

Your best bet for finding nitrogen in space would be the carbonaceous asteroids that tend to be found in the outer reaches of the asteroid belt.  They’re a little bit farther from the Sun, and therefore have held on to their volatiles a little bit better.  These carbonaceous asteroids are also one of the best places to go looking for water.

But according to Asteroid Mining 101, nitrogen has been found to make up only about 0.25% of the mass of carbonaceous meteorites, mostly in the form of organic polymers.  “The figure of 0.25% is not very impressive […],” the book goes on to say (what an understatement of the problem!), but if you manage to capture a large enough carbonaceous asteroid, you could still potentially harvest a fair amount of nitrogen from it.

Of course if we were to imagine ourselves living in the even more distant future, in an era when humanity has expanded well beyond the asteroid belt, perhaps making it all the way out to the Kuiper belt, then nitrogen might not be such a ridiculously scarce resource. Based on what we’ve learned about Pluto and other Kuiper belt objects, it seems frozen nitrogen is a whole lot more common out there.

Welcome to another episode of Molecular Mondays, a special bi-weekly series here on Planet Pailly about chemistry.  Every other Monday, we take a closer look at the atoms and molecules that—

Turns out my muse won’t let me write when I’m sick.  I’ve come down with a really bad cold, or maybe it’s the flu.  I don’t really know, but I should be well enough to write again in time for Sciency Words on Friday.

In the meantime, I’ll do my best to get better, with a little help from this chemical and this chemical and this chemical.

So the cartoon… I mean, the highly technical diagram in yesterday’s post implied that being in space wouldn’t be much of a thrill for fish. I mean, they swim up, they swim down… they swim in whatever direction they want, right?

But then I found a video showing a side-by-side comparison of the fish tank aboard the International Space Station and an identical fish tank down here on Earth, and it looks like I was very, very wrong. Fish do change their swimming behavior in microgravity. It’s really pretty, actually, watching them spin and twirl about.

Today’s post is part of a bi-weekly series here on Planet Pailly called Molecular Mondays, where we take a closer look at the atoms and molecules that make up our physical universe.

Okay, I know I said March would be Mars Month here on Planet Pailly, but for today’s episode of Molecular Mondays, we really must talk about the latest news from Venus. Our best lead for finding life on Venus has just dried up.

The idea of life on Venus has always been a long shot, but for the last few decades planetary scientists have been puzzled by a mysterious something in the Venusian atmosphere. A something that absorbs large quantities of light in the ultraviolet and near-ultraviolet part of the spectrum. This unknown UV absorbing substance has come to be known as the “unknown absorber.”

In his book Venus Revealed, planetary scientist David Grinspoon hypothesizes that the unknown absorber could perhaps maybe possibly be a “photosynthetic pigment” similar to chlorophyll. If so, that would mean there are little, photosynthetic microorganisms swarming about in Venus’s atmosphere, gobbling up UV radiation and converting it into usable energy. This hypothesis is extremely unlikely—Grinspoon makes that abundantly clear—but we could never rule the idea out entirely.

Except, unfortunately, we can now rule this idea out entirely. The unknown absorber has been identified. It’s not a photosynthetic molecule. It’s not even a particularly complicated molecule. It’s just a simple sulfur/oxygen compound called disulfur dioxide.

The story goes like this: sulfur monoxide (SO), which is fairly common in Venus’s atmosphere, combines with itself to form disulfur dioxide (S₂O₂). Specifically, it creates two different versions (or isomers) of disulfur dioxide called cis-OSSO (which has its oxygen atoms oriented in the same direction, as pictured above) and trans-OSSO (which has its oxygen atoms oriented in opposite directions). Then when cis- and trans-OSSO absorb ultraviolet light, they break back down into sulfur monoxide, and the cycle begins anew.

So our best hope for finding life on Venus appears to be gone. Oh well. It was a long shot anyway. I still have high hopes for finding life (probably fossilized life) on Mars.