Eve's oceans (again)

[NichG]

So I decided to look for non-extreme things Eve's oceans could be made of that are actually consistent with the surface temperature range (-50C to 150C) and pressure (5atm). A few random shots in the dark and I found a possible contender: Toluene boils at something like 160C at 5atm, and melts at -95C.

So the question would be, what natural processes might produce toluene oceans? Its basically carbon, hydrogen, and a tiny bit of oxygen, but its a fairly large molecule compared to the usual ocean-forming stuff (methane, ammonia, etc). Wikipedia says it forms at some fraction in crude oil, so perhaps Eve was once a lush world covered with biomass, which then got broken down due to high temperatures in a runaway greenhouse process and slowly degraded into a number of large organic molecules, out of which leaked all the stuff which happened to be liquid over the entire range of Eve's day-night cycle. The stuff that straddles the cycle (and there's a lot of it) would form some sort of very complex daily pattern of evaporation and condensation that I don't really know how to think about. I guess it would probably end up creating density bands in the atmosphere, staying just high enough that the local pressure means that it remains in vapor phase, like you'd get in fractional distillation. Alternately, it might create mid-atmosphere rain storms where something hits a combination of temperature and pressure sufficient to condense high in the atmosphere and then rains down to an area of the atmosphere where it reverts to vapor phase as the temperature increases.

Anyone have a handy dandy atmosphere calculator we can put the components of crude oil into and see what we get?

[Polstar]

Also on wikipedia - "Like other solvents, toluene is sometimes also used as an inhalant drug for its intoxicating properties; however, inhaling toluene has potential to cause severe neurological harm." - thats why kerbals have that daft grin all the time

[cantab]

Is it ever -50 at sea level? If not, the possible liquids are more varied. The wiki mentions even water is possible, thanks to the high atmospheric pressure.

[problemecium]

When would a Kerbal ever inhale something PURPLE on purpose? Now if we were talking about intoxicating chemicals in Jool's atmosphere...

[jwenting]

Is it ever -50 at sea level? If not, the possible liquids are more varied. The wiki mentions even water is possible, thanks to the high atmospheric pressure.

haven't done many temperature readings at Eve, but all of those indicate temperatures on the surface (day and night) in of several hundred degrees.

Would have to do the math, but it's quite possible water isn't liquid at that temperature even at the higher pressures encountered at Eve.

[MalfunctionM1Ke]

I though we all came to the conclusion that Eve's Oceans are mode of Nukelar Rock-it Propellant

[jwenting]

that was a semi-serious comment by a dev in response to the speculation on the forums. The KSP wiki doesn't state what they're made of, just that joke as a possibility.

[lajoswinkler]

This was discussed many times. It can be water, because water is liquid at such conditions. Also, it's the simplest explanation. There is a myriad of compounds out there which would fit the description, but water is very abundant.

If only Eve had dense clouds...

[NichG]

Water wouldn't work at -50C though, even at 5atm. But if its never that cold on the ground then that changes a lot. At that point, it could be pretty much anything whose 1atm boiling point is somewhere around/above 110C I think, since the boiling point vs pressure adds from 40-90C to the boiling point going from 1atm to 5atm for the usual small molecule culprits (e.g. things with a small enthalpy of vaporization). For the more tightly-bound options (8-carbon stuff, liquid metals, things that form highly charged ions, etc) you get to add about 30C to the boiling point, so you'd want to look around 130C for those.

Water is interesting because its just barely at the boiling point at 5atm (152C). That would suggest that the temperature and pressure at the surface of Eve would be very strongly buffered if it had water oceans, because not only is the heat capacity of the water resisting temperature variation but it also boils off as needed (resisting both pressure variation and also adding the enthalpy of vaporization to the energy budget to resist a temperature change). So this might mean that the day-night cycle would be very muted as far as temperature swings.

I guess the other possible thing to look at would be temperature at the poles versus temperature at the equator, and the distribution of ocean over the surface. It seems like I'm going to need to send a number of probes now (unless due to biomes for Eve not being in yet, the temperature readings are the same everywhere on the surface?)

Edit: Surface temperature of Eve in game is 150C regardless of time of day or location I think; at least, a sample at the equator and at 70S both gave the same result.

Edited March 28, 2014 by NichG

[lajoswinkler]

Occasional (permanent for me) low temperatures on Eve are a buggy issue because the temperature measurement in KSP doesn't work properly. It's generally accepted that Eve is very hot all the time.

[KerikBalm]

... crude oil, so perhaps Eve was once a lush world covered with biomass, which then got broken down due to high temperatures in a runaway greenhouse process and slowly degraded into a number of large organic molecules,

I am unconvinced(and there is scientific dissent) that the oil on Earth is actually all a result of "fossil fuel", especially if we are talking multicellular life.

Titan shows us strong evidence that small hydrocarbons can exist abiotically.

We already know the heat and pressure of Earth's core can form carbon into very large covalently linked molecules (indeed, a diamond is a single molecule).

I see no reason to think that primordial hydrocarbons could not be turned into larger hydrocarbons abiotically.

Sure, rapid forrestation, and then burying of forrests, as in the carboniferous, would lead to large concentrations of buried carbon, and could result in more being formed.

Also, microbes deep underground could synthesize larger compounds to accelerate the process.

- But I doubt lush forrests, or even life at all, is required to make various heavy hydrocarbons - ie "oil"

A "curiosity" type mission to Titan would be very interesting, as would a submersible on Titan.

[NichG]

Yeah, mostly I suggest the biomass thing because it's pretty evocative. A secondary reason is, whatever you have oceans of, you need some process pervasive and thorough enough to produce oceans of that material at the surface (either through generating it within the planet and then migrating it preferentially to the surface, or generating it at the surface, or having it come in via impact events). For large hydrocarbons its kind of a delicate balance to get them via chemical equilibrium, since at high temperatures its preferable to have many smaller molecules rather than one big one (pressure goes the opposite way, which is what's going on with diamond), but at low temperatures its hard to get over the energy barrier to form covalent bonds. Maybe something like a 'cold' (e.g. significantly less than 500C), high-radiation environment would be ideal for that kind of process? E.g. something that creates a lot of chemically active things that can drive condensation reactions, but which doesn't create an environment where cracking of large hydrocarbons occurs naturally. This kind of chemistry is getting far outside of my realm of comfortable speculation though.

[lajoswinkler]

I am unconvinced(and there is scientific dissent) that the oil on Earth is actually all a result of "fossil fuel", especially if we are talking multicellular life.

Titan shows us strong evidence that small hydrocarbons can exist abiotically.

We already know the heat and pressure of Earth's core can form carbon into very large covalently linked molecules (indeed, a diamond is a single molecule).

I see no reason to think that primordial hydrocarbons could not be turned into larger hydrocarbons abiotically.

Sure, rapid forrestation, and then burying of forrests, as in the carboniferous, would lead to large concentrations of buried carbon, and could result in more being formed.

Also, microbes deep underground could synthesize larger compounds to accelerate the process.

- But I doubt lush forrests, or even life at all, is required to make various heavy hydrocarbons - ie "oil"

A "curiosity" type mission to Titan would be very interesting, as would a submersible on Titan.

There is no scientific dissent, only fringe stuff. The chemical composition of the oil clearly suggests it was made by living beings. Crude oil does not contain only simple aliphatic hydrocarbons. There are very complex compounds (heterocyclic, among others) that must be the result of degradation of even more complex biochemicals. Such diversity and complexity of chemicals in it is impossible to occur in sterile conditions, and microbes can't exist in conditions in which oil is formed. The temperature and the pressure is too high.

By the way, forests are mainly responsible for coal. Oil was made by plankton deposits.

[vger]

When would a Kerbal ever inhale something PURPLE on purpose? Now if we were talking about intoxicating chemicals in Jool's atmosphere...

If you turn your back on them during a Minmus EVA for more than 5 seconds, they'll try to eat it. When WOULDN'T a Kerbal inhale something purple on purpose?

[KerikBalm]

There is no scientific dissent, only fringe stuff. The chemical composition of the oil clearly suggests it was made by living beings. Crude oil does not contain only simple aliphatic hydrocarbons. There are very complex compounds (heterocyclic, among others) that must be the result of degradation of even more complex biochemicals.

For sure, most of those hydrocarbons involved biological processes. Hence the key word "all". The question is if you can get relatively long chain hydrocarbons abiotically, and if any such abiotic hydrocarbons are still present on Earth.

For example:

http://www.osti.gov/scitech/biblio/7052010

According to one hypothesis, methane from the mantle is continuously injected into the deep crust at lithospheric plate boundaries, ancient suture zones, and other areas of crustal weakness such as large meteorite impact sites. Where introduced beneath sedimentary basins this methane could accumulate in the conventional structural and stratigraphic traps in which we find petroleum. Geochemical evidence strongly argues that crude oil is of sedimentary (biogenic) origin, but the origins of natural gas are more complex and the proportion that may be derived from mantle (that is, abiogenic) sources is unknown. Using a geometric mean of 3x10[sup 6] for the molar CH[sub 4]/[sup 3]He ratio in uncontaminated, mantle-derived fluids from spreading ridges, mantle plumes and summit fumaroles of arc volcanoes, the median abiogenic methane content of commercial gases is estimated to be less than 200 ppm by volume (range=0 to 12,000 ppm). While admittedly a rough estimate, this calculation suggests that little confidence should be placed in the resource potential of abiogenic natural gas. In rift or convergent margin basins, hot magmatic fluids can strip methane and other volatiles from metamorphic basement and overlying sedimentary rocks, however, and commercial accumulations of this type of gas may be present.

There are abiotic hydrocarbons on Earth - in the specific case above, that abiotic methane is only 0.02%... but it is there.

I will agree the consensus is that a biological origin is the predominant origin.

But on a lifeless world, where the much faster biotic process is absent, could an abiotic process still produce significant amounts of high MW hydrocarbons?

As I said, Titan may be a nice test case to see what sort of complexity you can get in hydrocarbons without biological processes.

Of course,

#1) It will be very hard to see anything that is not on the surface or just a short distance below it

#2) Due to its lower mass, the pressures will not be as great

#3) Its much lower temperatures will also affect this.

#4) There's a chance that biological processes are at work on Titan, and that would be so cool that nobody should mind that our test case is inapplicable

Such diversity and complexity of chemicals in it is impossible to occur in sterile conditions, and microbes can't exist in conditions in which oil is formed. The temperature and the pressure is too high.

By the way, forests are mainly responsible for coal. Oil was made by plankton deposits.

Yea, I was being too imprecise, I'm mainly just talking about generic "hydrocarbons"

microbes can't exist in conditions in which oil is formed.

Well, I'm not sure why you mention this.

#1, I didn't mean to imply that the microbes would be synthesizing compounds at the same place that the petrol is being formed. I shouldn't have specified deep underground at all - however, in the case of a "lush world" bs a world where the surface is sterile (as is likely the case on mars), you could have a deep biosphere responsible for the presence of the petrol, but the world would be far from "lush"

#2, cyanobacteria, and not forrests may concentrate and synthesize the hydrocarbons - so accepting a biological origin, hydrocarbon deposits do not mean a world once covered in forrests, it could be "slime" covered. (again, a not so "lush" world)

#3, the abiotic origin hypothesese have the petroleum form, then migrate upward, where bacteria then feed on it and alter it. Its then a question if the hydrocarbon originated from within the earth, or from buried biomass. No bacteria would be involved at the origin.

Additionally:

http://www.pnas.org/content/99/17/10976.full

Experiments to demonstrate the high-pressure genesis of petroleum hydrocarbons have been carried out using only 99.9% pure solid iron oxide, FeO, and marble, CaCO3, wet with triple-distilled water. There were no biotic compounds or hydrocarbons admitted to the reaction chamber.

...

At pressures below 10 kbar, no hydrocarbons heavier than methane were present. Hydrocarbon molecules began to evolve above 30 kbar. At 50 kbar and at the temperature of 1,500°C, the system spontaneously evolved methane, ethane, n-propane, 2-methylpropane, 2,2-dimethylpropane, n-butane, 2-methylbutane, n-pentane, 2-methylpentane, n-hexane, and n-alkanes through C10H22, ethene, n-propene, n-butene, and n-pentene in distributions characteristic of natural petroleum. The cumulative abundances of the subset of evolved hydrocarbons consisting of methane and n-alkanes through n-C6H14 are shown in Fig. 3 as functions of temperature.

...

the theoretical results must be considered as the determination of minimum boundary conditions for the genesis of hydrocarbons. In short, the genesis of natural petroleum must occur at depths not less than ≈100 km, well into the mantle of the Earth.

Clearly

a) Abiotic hydrocarbons exist (Methane, Ethane, as on titan)

At sufficient pressure, abiotic hydrocarbons can form alkanes up to at least decane, and also forms alkenes and various other variations.

Evidence for a biological origin does not exclude a parallel abiotic process. The biological process may be much faster and dominate, and it may also "reprocess" the abiotically produced hydrocarbons, obscuring the origin.

The biomarkers are clear, but abiotic origins are still plausible, and thus for the purposes of this discussion, if Eve had hydrocarbon lakes, we could not conclude a history of life (particularly given that Eve's gravity would result in even higher subsurface pressures)

Edited March 30, 2014 by KerikBalm

[lajoswinkler]

There is no doubt that some of the low hydrocarbons on Earth are abiotic, but I don't think it's much because Earth is too close to the Sun and most of the stuff has evaporated long time ago. Also, rotting and turning to oil has released copious amounts of methane into the underground deposits.

It's also possible that abiogenic catalysis can clip together low hydrocarbons into a bit heavier, but such "oil" is a lot more different than crude oil and would resemble a purified fraction of it. Crude oil is a rich mixture of various compounds. Not just carbon. Lots of sulfur compounds there.

Edited March 30, 2014 by lajoswinkler

[NERVAfan]

I haven't been to Eve yet, but the pictures I've seen make the oceans look more silvery than water. They could be water with something else dissolved in it, though.

I think getting oceans of hydrocarbons on a 'warm' world is kind of a stretch. Titan kept a lot of primordial volatiles that inner-solar-system worlds lost. The amount of crude oil on Earth (even before we started burning it) doesn't even get close to making an ocean.

I'd suggest mercury because of the silvery appearance (and it's liquid at the right temperature... freezing point is -38.83 C, boiling 356.73 C according to wikipedia) but that's a heavy element and I can't see any way to get it in that amounts, that concentrated... heavy elements are pretty rare in the universe.

Oceans are probably going to be made out of "common" substances nearly everywhere, stuff like H/C/N/O compounds (water, ammonia, methane, ethane, liquid nitrogen...) or maybe silicates on really hot worlds (much hotter than Venus or Mercury, more like some of those practically sun-grazing exoplanets).

[NichG]

It seems like the smallest compounds of abundant things are either solid or gaseous at the relevant temperatures. It'd be interesting to e.g. search a chemical database for all compounds of C,H,O,N,Si,S, Fe, Mg, (Ne, He - yeah right) containing no more than 5 atoms, to see if any of them would actually be liquid in the conditions on Eve's surface (water would be, just barely). I've been poking around a bit in searchable databases, but I haven't found something that quite lets me specify that particular search yet.

I'm curious what the distribution of melting and boiling temperatures (at 5atm or 1atm or whatever) would look like, and if there'd be some obvious gaps or structure; it might let one make a sort of HR-diagram-equivalent for planetary oceans (e.g. if you plot temperature and pressure, plausible oceans only form over certain regions of the entire diagram).

How about Cyanamide? It decomposes at 260C, but at Eve surface conditions the boiling point is pretty close to 150C. It's also a somewhat smaller molecule than other proposals so far, so abundance-wise it's probably more reasonable. Producing it looks hard though - requires 2000C processes industrially. Sulfuric acid could work too (bp of ~300C) I guess.

Edited March 31, 2014 by NichG
Found another possible compound.

[lajoswinkler]

I haven't been to Eve yet, but the pictures I've seen make the oceans look more silvery than water. They could be water with something else dissolved in it, though.

I think getting oceans of hydrocarbons on a 'warm' world is kind of a stretch. Titan kept a lot of primordial volatiles that inner-solar-system worlds lost. The amount of crude oil on Earth (even before we started burning it) doesn't even get close to making an ocean.

I'd suggest mercury because of the silvery appearance (and it's liquid at the right temperature... freezing point is -38.83 C, boiling 356.73 C according to wikipedia) but that's a heavy element and I can't see any way to get it in that amounts, that concentrated... heavy elements are pretty rare in the universe.

Oceans are probably going to be made out of "common" substances nearly everywhere, stuff like H/C/N/O compounds (water, ammonia, methane, ethane, liquid nitrogen...) or maybe silicates on really hot worlds (much hotter than Venus or Mercury, more like some of those practically sun-grazing exoplanets).

Mercury would never not pool in surface lakes. It's way too heavy and it sinks through the ground cracks. In nature, it's found in both elemental and bonded states. When elemental, it's disperged in little droplets among the rocks containing its compounds.