On Rlaan and a Zippo

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On Rlaan and a Zippo

Post by guest »

I may not understand a lot about chemistry, but a question is making me wonder for a while: what happens if I light a match on a Rlaan planet? I guess either nothing would happen, because of the absence of oxygen, or, if there's some way combustion can occur without O2 or O2 is present in some way, the whole planet would go BBQ, since methane is combustible. Any of those would mean the Rlaan civilization has developed without any contact with fire. Is that right or am I missing something?
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Post by pincushionman »

The stoichiometric formula for methane combustion is as follows:

CH4 (methane) + 2O2 (diatomic oxygen) -> CO2 (carbon dioxide) + 2H2O (water vapor)

That's only important if you wanted to learn something today. But as you can see, the reaction favors oxygen (by mole, 2:1, but by mass, it's more like 4:1). In an oxygen-rich atmosphere such as ours, that's not a big issue. But since we've already agreed that Rlaan live on methane-rich worlds, we can assume that there is very little oxygen, and the amount therof becomes the limiting factor in combustion; the Rlaan would treat oxygen as the "fuel" to be brought to the reactions, treating it as we do hydrocarbons here on Earth.

And looking at the stoichiometry, we see that you'd need to bring 4 kg of oxygen (32 amu per molecule) into a methane planet to get the same amount of fire as bringing only 1 kg of methane (16 amu per molecule) to an oxygen planet.

So unless the methane-heavy wolrds are also rich in oxygen, and I shall assume they are not, we can infer that the Rlaan are pretty safe from being toasted. Perhaps, even safer than we are.

Class dismissed!

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Post by dfryer »

Hmm, what is the Rlaan metabolic cycle based on? We humans "burn" (oxidize) sugars, correct?
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Post by jackS »

dfryer wrote:Hmm, what is the Rlaan metabolic cycle based on? We humans "burn" (oxidize) sugars, correct?
for a fun investigation of various possible metabolisms and related "xeno-biology" http://www.freelancetraveller.com/featu ... xbio2.html

(and related pages)

in particular:
See Above Link wrote: Hypothetical central metabolic pathways take the following general form:

'biomolecule' + 'reactant' <-> 'breakdown products' + energy
Reactant ('inhaled') Breakdown Product of Reactant ('exhaled')
Oxygen Carbon dioxide and water
Nitrogen Ammonia or urea (NH2 - CO - NH2)
Sulphur Hydrogen sulphide
Hydrogen peroxide Water
Chlorine Chlorides
Methane Carbon dioxide
Phosgene Carbon dioxide
Hydrogen Methane
Ammonia Nitric acid
Hydrogen sulphide Sulphuric acid


Substance melting point boiling point
Oxygen -219 -183
Carbon dioxide -57* -78
Water 0 100
Nitrogen -210 -196
Ammonia -78 -33
Urea 132.7 150 (decomposes)
Nitrates ** **
Sulphur 119 445 (monoclinic)
Hydrogen sulphide -83 -62
Hydrogen peroxide -0.4 -158
Chlorine -101 -35
Chlorides ** **
Methane -183 -162
Hydrocarbons *** ***
Phosgene -104 8
Hydrogen -259 -253
Nitric acid -47 86
Sulphuric acid 10 340 (decomposes)

Melting and boiling points are in degrees Celsius at one atmosphere ambient pressure, unless otherwise stated.

* Carbon dioxide sublimes, turning directly from solid to gas at one atmosphere pressure. The melting point given is under multiple atmospheres pressure (about 4).

** These compounds are very stable, having melting and boiling points in the hundreds of degrees.

*** melting and boiling points increase with increasing chain length. Compounds less than 5 carbons long are gases at 15 °C ; compounds less than 16 carbons long are liquids at this temperature.

The choice of available compounds for surface life's metabolism will be limited by temperature and surface gravity, as discussed in Part 1. Worlds with hydrogen atmospheres will be gas or sub-giants or far flung outer zone bodies.

The forward (left -> right) reaction is equivalent to the breakdown of glucose; the reverse, photosynthesis.

In general terms, reactions analogous to glucose breakdown should:

* cause the 'biomolecule' to lose electrons (oxidation)
* cause the 'reactant' to gain electrons (reduction)
* lead to the release of energy from bond rearrangements.

The ammonia -> nitric acid and hydrogen sulphide -> sulphuric acid systems do not fulfil the criteria above, in that the reactant substances are oxidised, not reduced; but energy production is reasonable. Exotic or corrosive atmosphere worlds could be populated with organisms that run on such systems.
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Post by DrTiger »

Me finds it strange to have an atmosphere consisting of a flammable (though not very reactive) gas. Especially since you need to reduce the methane with something like oxygen, and any "breather" (as opposed to those creating methane, since organic structures won't appear out of nothing and dominate an atmosphere) will have to get quite a lot of it - both Oxygen and Methane.
Now take a second look. The energy-rich substance we use for generating our chemical energy (ATP/ADP) are sugars, actually something like methane, just more complex. To prevent an explosion this process is slowed down somewhat by enzymatic processes generating the ATP (if I'm correct... at this point of my studies I don't bother much about biochemistry yet).
A key point is: There's a big need for sugar and a big need for methane respectively. Now, sugar is brought to the ribosomes in a solvation. Oxygen too, though they are transported via a Iron-based complex named Haemoglobyne (ok forgive my primitive measures to translate it to English language), but it travels by diffusion to it's end destination.
Ok you know the primary difference between solid mass and gas? Yes... Volume. Given a specific temperature and pressure, any gas will have the same volume e.g. 24l / mol. Oxygen will take the exactly same amount.
I think for an organism to provide the same functionality like a human, will need to breath like a jet turbine.
Another problem with methane is, that methane easily substitutes Hydrogen with something else, given the circumstances. Halogenids for example. And if not methane itself, these compounds quickly become a problem because of the reactivity with a wide range of metals...
Also You need to find a solvant for methane and something containing oxygen.
I think without a solid understanding of biochemistry one should not try and develop a race based on anything but the solid Carbon/Hydrogen/Oxygen basis.
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Post by jackS »

DrTiger wrote:Especially since you need to reduce the methane with something like oxygen, and any "breather" (as opposed to those creating methane, since organic structures won't appear out of nothing and dominate an atmosphere)
quick notes: you got reduction and oxidation backwards there (methane is fully reduced)
There was never an assumption that atmosphere would be primarily methane. Rather, the assumption was that methane was the second most common gas, after nitrogen. As for organics appearing without life - Titan, for instance, has a ~95% N2 ~5% CH4 atmosphere without any evidence of active life.

As for how the Rlaan metabolic pathway works, I haven't completely figured it out ;-)
Back when I decided to go with methane breathers, I'd seen the term often enough in sci-fi literature that I'd assumed it would be easy to find decent documentation on how such worked. I assumed incorrectly. My best current guesses rather marginalize the role of methane actually, being much more centered around compounds associated with the ammonia solvent (actually, it's looking progressively more likely that it would be an ammonia-water solution as the solvent, which would necessitate somewhat warmer climes than I'd previously assumed)

Currently, I'm looking towards something along the lines of

4(NH4NO3) + CH4 --> 4N2 + 10H20 + CO2

as the backbone of the metabolic process, but this is not without a score of issues, not the least of which being my lack of biochemistry knowledge in judging which guesses are worth pondering ;-) (especially with regard to what's likely to happen given a particular solvent and temperature - I'm not going to worry too much about what the catalysts are). Nitrogen fixing is very expensive, so it would be interesting to explain why the reversal of this reaction is the preferred photosynthetic analog (albeit, expenses aside, in a situation with negligible free oxygen, using nitrates as oxygen storage does have its benefits). Also, methane, in this case, plays a fairly inconsequential role, especially as there are other ammonium nitrate decompositions which would not have any use for the molecule at all.

But, that's what I'm working with at the moment until I find out it's untennable and go back to the drawing boards again.

I have no interest in abandoning carbon based life, nor the important roles of CHON (& Cl, P, S, etc.) - but given the persistence of anerobic life and extremophiles on this oxygen rich planet - it seems somewhat "oxygen chauvinistic" to assume that all complex life must be dependent on gaseous oxygen, even if the only anaerobic life we're familiar with is limited in complexity and suffers from a significant inefficiency factor relative to oxygen breathers.
Even if the cards are somewhat stacked against the ammonia users of the universe, I think it's still worth it to see if we can't come up with at least a reasonable system for them to work within.
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methane breathers

Post by Fart_Plume »

given the temperatures given lets say a methane breather is a cold bodied gill using species. If methane is a liquid then it would stand to reason as with gasoline its not flammable as a liquide only when it becomes vapor ,so with that in mind with methane liquide between the temps of -183 to -162 O2 dissolved in the methane much like fish in water, the Rlaan can utilize it for their controled metabolizim as any other does. we O2 breathers inhale traces amounts of all kinds of combusible gases, such as hydrogen, the high nitrogen content in our atmosphere helps in keeping the whole planet from burning to a crisp. incontrast the rlaan 's atomspere would have a low dissolved O2 or any other catalytic conent how ever their food sources would contain those elements for the biological process to take place. just suffice it to say their enviroment is totally reversed from that of an O2 breather.,their plant life could store O2 in a trapped form providing their equivalate to sugars.
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Post by tripintraveler »

so if im reading this right, the rlaan and aera cant breath on our planets, .. and we cant breath in Their planets Correct?
..... and if so, Why the hell are we at war with a race that cant land and walk around, .... just a curiosity, that will probably be answered in some page somewhere of somethign i probably should have already read but didnt lol
take care,
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Post by jackS »

tripintraveler wrote:so if im reading this right, the rlaan and aera cant breath on our planets, .. and we cant breath in Their planets Correct?

Actually, not correct. Humans, Aera, Uln, and other species associated with the former are all accustomed to oxygen-nitrogen+etc. atmospheres (so, comfort levels aside, each can, for a sufficiently loose definition, breathe each other's atmosphere). Only the Rlaan and one of their client species require methane-nitrogen+etc. type atmospheres.
tripintraveler wrote: ..... and if so, Why the hell are we at war with a race that cant land and walk around, .... just a curiosity, that will probably be answered in some page somewhere of somethign i probably should have already read but didnt lol
take care,
Tripintraveler
So the current hostilities between Aera and Humans are between two species quite capable of enjoying each other's planets. However, the conflict is not about current resources, but about future resources. The jump network thins out progressively in the rimward direction (the Aera being rimward of everyone else) and, more importantly, there appears to be no way to get from the Aeran space to the rest of the galaxy using the jump network without going through either Human or Rlaan space. Thus the Humans and Rlaan have a stranglehold on all potential Aera expansion, while each is free to continue their own expansion. Thus, if nothing is done, the Aera will eventually be relegated to being a backwater no longer in control of their own fate, having been outstripped by their expanding neighbors while they are consigned to the territory they have.

This is listed in some other documents actually...
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Post by tripintraveler »

ahhh ok, thanks JackS, ..... i guess i got confussed on what was breathable and what wasnt breathable atmosphere wise between the races. as to my comment on why the war, i blamne that on waiting for spec drive to get me anywhere and playing VS for 10+ hours straight trying to gain enough money to do anything with (see my other post about contract amount and actual pay out on completion) lol
but anyway, thanks :)
..... on a side note to JackS or whoever, do ya still need people to play test stuff? im not a programmer, but a growingly avid player, that would like to help out if i can.
thanks
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