Flatulence in Space (II)

A few months ago, from Astromol’s facebook, we posed a challenge: if we could reach four hundred followers, we would write more reports on stinky gases in the universe. And we got over them. In fact, since the publication of “Flatulence in Space (I)“, we have exceeded eight hundred. So here’s the second part of “spatial flatulence,” dedicated, this time, to carbonyl sulfide.

“Nature never ceases to amaze us.” As if it were the script of a documentary, I see myself pronouncing this phrase as I choose the title of this report. I know it’s a little scatological, but it’s totally true: let’s talk about some of the gases that are in our flatulence. Watch out, in our flatulence there’s not just gas, there are more things, but we’re not going to talk about those. The compounds that give farts that smell (not all smell the same, it will all depend on what we have ingested) are well known. And some of them are also in space. Now you’ll understand why I, who usually talk about Astrophysics and Astrochemistry, get into these issues.

After talking about hydrogen sulfide (H2S) in “Flatulences in Space (I)“, today we will focus on carbonyl sulfide (OCS) which, although having a very nice name, does not fall short in terms of danger compared to the previous compound.

On our planet, carbonyl sulfide, a colorless gas, is produced in swamps, inside volcanoes, in the oceans, in hydrothermal sources and, pay attention, in fertilized soils (manure) and other environments. It is present in some grains and seeds, and in some cheeses and prepared cabbage.

Humans release carbonyl sulfide to the environment after certain processes (no, we don’t yet talk about farts), for example, combustion, when we use the car, in coal-fired power plants, when processing fish (all this is said by Wikipedia and I believe it), in the manufacture of some products, but in all these cases they are a result, an impurity generated after a process (what is called a by-product).

It is known that inhaling it in high concentrations for a short time can cause narcotic effects in humans and can irritate eyes and skin. But if we stay too long, it can cause seizures and lead to collapse and death from respiratory paralysis. This happens because, as with hydrogen sulfide, it affects our nervous system, nullifying our olfactory capabilities and leaving us exposed to danger. So you know, if you detect something smelly, walk away just in case.

Another danger is its combustion capacity: it is a highly flammable gas [1]. And according to this company in Canada, under pressure it’s corrosive.

Finally, as you already knew, this sulfur compound is found in flatulence, albeit in a very low proportion. In fact, its presence in the environment is generally quite low, although it stinks of rotten eggs.

Apparently, this that smells so bad can be related to… (we know we repeat this a lot in astrochemistry and astrobiology, but it is simply the truth) the origin of life!

Carbonyl Sulfide in Space

It was 1971 [2] when Jefferts and his team detected the presence of OCS in the interstellar medium, specifically Sagittarius B2 (Sgr B2), one of the largest molecular clouds in our galaxy (its total mass is three million times the mass of the Sun and its size about 150 light years). Again, as with hydrogen sulfide, Penzias and Wilson, Nobel laureates thanks to their discovery of the cosmic microwave background, signed the article describing this finding along with P.M Solomon, astronomer at Columbia and California universities (remember that Jefferts, Penzias and Wilson worked for Bell Telephone Laboratories). [2]

In 1995 Mauersberger et al. reported on the first detection of carbonyl sulfide in an extragalactic source: the Silver Coin Galaxy or NGC253, a very bright galaxy that is nearly 13 million light-years from us.

The same year, the OCS molecule was also detected in ice mantles covering interstellar dust grains, near the W33A protostar.

Paradoxically, it took time to confirm its presence in our Solar System. In 1997 L.M. Woodney led the team that found this molecule on Comet Hyakutake. (As you may recall, in “Spatial Flatulences I”, we also talked about comets and the importance of detecting these compounds in these objects.)

But today we are going to focus on the detection of OCS in the atmosphere of the planet Venus, carried out in 1990. Studies suggest that, due to the difficulty of carbonyl sulfide to be produced inorganically, and since, on Earth, the presence of this gas is considered an indicator of biological activity, it would be interesting to review the atmospheric chemistry of the planet. But what happens, does anyone suggest there’s life on Venus?

Not exactly, but apparently in Venus’ atmosphere, about 50 km from the surface, lies the only place (after Earth) of the Solar System with an atmospheric pressure of almost one bar, temperatures that would allow the existence of liquid water (0 to 100 °C ), energy provided by the Sun and life-critical elements such as carbon , oxygen, nitrogen and hydrogen.

So far, missions launched to Venus have not detected microbial life. What has been done has been to confirm the distribution of OCS in the Venusian atmosphere thanks to ESA’s Venus Express mission and VIRTIS instrument, aboard the satellite. The data confirmed in 2008 that there is more carbonyl sulfide in equatorial regions than in high latitudes.

So, if we go to Venus, we should be prepared to smell what will surely not be a dish of taste because there smells like flatulence too. Although no, it’s not our last word.  

To be continued…


[1] Air flammability limits (under standard temperature and pressure conditions): 12.0-28.5 vol%

[2] Ten years later, in 1981, there were already ten interstellar and circumstellar sources in which the presence of SCO had been detected.


Space-filling 3D model of carbonyl sulfide. Ball-and-stick model of the carbon disulfide molecule, OCS. C=S bond length of 1.5601 Å; C=O bond length of 1.1578 Å. Data from CRC Handbook of Chemistry and Physics, 88th edition. Credits: Ben Mills. Wikipedia.


Data about OCS ant its discovery in different environments in www.astrochymist.org.

New Jersey Department of Health: hazardous substance fact sheet for Carbonyl Sulfide https://nj.gov/health/eoh/rtkweb/documents/fs/0349.pdf

Originally published in Spanish on the Naukas website:  Flatulencias espaciales (II) (2016/01/13).

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