Redefining the TU

[jwdh71]

Silent, that is exactly what I did for my latest campaign. I generated the systems, and the ones that didn't have a habitable planets, or that didn't have resources, didn't get populated. This made for long distances between settled systems, and I made a tech change to adjust for it. Jump fuel usage in my campaign was only 1% per jump number, not 10%. I also used standard designs,which made normal ships capable of 10 jumps before needing to fully refuel. It made things interesting, as there were plenty of empty systems for those ethically challenged merchants to hang out in, hoping to spot some unwary prey...

 

[aramis]

I'm starting (I've two Traveller projects on my table, an MT-Mayday hybrid and a setting) to work on a redefined settinng, using 3d mapping.

I'm using 8x8x8 subsectors
16x16x16 sectors, (8 SS)
32x32x32 domains
and 64x64x64 for "known space"...

Each sector can then use a 000-FFF location code... hehehe.

I'm also redefining atmo codes to be nothing but pressure. I'll add a Br code for breathable atmosphere, Ta for tainted but breathable. That way I can get CO2 and Amonia atmospheres in a range of pressures, and even on small worlds. (That, to my mind, is the big problem with Traveller system generation.)

I may add a breathability UPP...
2d6-7+AtmPres
0 - 3 non-oxydizing (3 is O2 extractable)
4-5 Insufficient Oxygen (compressor needed)
6-8 good oxygen
9-A Excessive oxygen (Reducer needed to avoid oygen toxicity)
B Mild Corrosive (Ammonia)
C Strong Corrosive (Acid)
D Reducing (Strong Acid or high heat)
E Insidious (Strong Acid AND High heat)
F Torturous (Strong Acid and very high heat. Venus, for example)

I'm thinking that Oygen atmospheres need to be fairly rare, and typically on earthlike worlds...

 

[mike wightman]

The presence of oxygen in a world's atmosphere is a likely indicator of native life - or terraforming
Methane, Ammonia, Fluorine amd Chlorine based atmosphere's could also harbour native lifeforms - very different to life as we know it. And as to how you could end up with a CL or F based atmosphere...
time to ask Malenfant

 

[Malenfant]

Actually, I think a F or Cl based atmosphere would be pretty much impossible in reality. For starters, they've incredibly reactive gases, and they'd all react with the surface material or other gases and disappear - unless they're being replenished somehow. But there aren't any natural mechanisms that pump out Cl and F gas in significant amounts (unless the entire planet has an incredibly weird geochemistry). HCl and HF can be found in volanic eruptions, but they're very small amounts and are again very reactive.

The other thing is that Cl and F are actually very rare elements in the universe - there isn't an awful lot of those gases around, so planets only get a tiny amount of them when they accrete.

CH4 and NH3 are ridiculously common atmospheric gases though, moreso in the outer zone.

 

[mike wightman]

You're looking for a form of life that takes in Cl and F containing compounds and breaks them down to store energy in the new products, much like some weird form of photosynthesis. The Cl or F would then be released to the atmosphere and begin to concentrate, providing the oxidising agent to release the stored energy within the organism.
So the presence of F or Cl in large concentrations in an exotic atmosphere would probably be an indicator of very exotic life.

 

[aramis]

It's probably too early scientifically to rule out reducing atmospheres as harbouring life.

In fact, it's quite probable that much life in the universe will be based upon the same amino acids, but that does not, of need, require oxygen metabolism.

Likewise, chlorophil/oxygen cycles could be replaced with a wide number of other combinations, and some of those are not inherently inimical to the amino acids known. (Also: not all the known amino acids are used in our mamalian biochemistry!)

Life requires, by definition, an energy cycle, resource intake and utilization, self-replication, and the ability to spread (by locomotion or growth). Other than that, it's a vague definition. (The classic definition was Consume, Replicate, Excrete, and Respirate, with animals adding locomote...)

Take Hemoglobin: there are at least two versions; the iron based red one, and another one used by some deep ocean invertibrates... ISTR it is copper based... they work in different regimes.

Life also does not require light, a recent (last 20 years) revelation of deep ocean exploration and geology. Chemosynthesis can, in fact, replace photosynthesis. Microbes can and do actually use chemosythesis within continental rock layers, and in the deep ocean vents. Both have an energy cycle, both conume raw materials. Both spread, and both form

We have an oxygenated atmosphere because our native life broke down CO2 and concentrated "Waste" O2; later life adapted to metabolize it, and O2 leaks less than the rate at which its released by geological processes.

Oh, and someone was commenting on a recent program that some of the deep ocean microbes seem to use a hydrogen sulfide biochemistry.

 

[Malenfant]

Originally posted by Sigg Oddra:
[QB] You're looking for a form of life that takes in Cl and F containing compounds and breaks them down to store energy in the new products, much like some weird form of photosynthesis. The Cl or F would then be released to the atmosphere and begin to concentrate, providing the oxidising agent to release the stored energy within the organism.

There aren't an awful lot of compounds that contain Cl or F that are available to break down - the only ones that are even remotely commonplace that I can think of are evaporites like NaCl (salt) and to a much lesser extent CaF2 (fluorite).

What you're envisaging is a lifeform whose metabolism can break down NaCl and then release the Cl2 gas into the air. I'd imagine such a lifeform would have to be sitting on a lot of NaCl if that's its main energy source (and I don't have a clue about biochemistry, so I don't even know if this reaction is viable from that point of view). It could instead break down fluorite, but that's a fairly uncommon mineral.


I don't think this would work. However, I do have a book that may provide a possibly viable environment...

Digging out my Worldbuilding book (by Stephen Gillet), he does mention these worlds. And he does mention that:

(a) Fluorine is very rare in the universe- about 15,000 times rarer than Oxygen!
(b) It's stupidly reactive.

He rules Fluorine breathers out because of this.

Chlorine is also out as the primary constinuent of an atmosphere for similar reasons. (life would get much more energy doing reactions with oxygen than chlorine). Plus you wouldn't have Cl2 over HCl oceans either, because pure HCl is only liquid at very low temperatures - lower than Cl2 is a gas (the HCl acid you see in chemistry labs is a mix of HCl and H20).


He does, however cite a "Chlorox" as a possibly realistic example. There's a lot of Cl on Earth in the oceans - in fact, that's where most of it is, in the form of the Cl- (chloride) ion. He proposes that it may be possible for plants to produce Cl gas as a defence mechanism by stripping off the electron using energy derived from a normal oxygen metabolism. They might release this gas as a defence mechanism against predators, which would result in a tiny amount of free Chlorine in the atmosphere, maintained by the plants that produce it.

So you basically have an earthlike N2/O2 world with a small amount of Chlorine in the air (probably means it'd be a tainted atmosphere). Even in such very small amounts, this changes quite a few things. First, it'll give a greenish/yellow tinge to the air. It's also photodissociated by wavelengths of light that are shorter than about 490 nm (deep blue) - that might be a problem on worlds that orbit A/F/G V stars which put out more of that wavelength, because that splits the Cl2 atom into free chlorine which is very reactive, and very good at destroying ozone that protects against UV light. That said, the Cl2 is itself absorbing UV light as it's being broken up, so that may counter the effect of losing the ozone.

The Cl2 will also react with other things in the atmosphere (N2, O2, CO2, whatever else is there) so you'll get a bit of HCl and possibly traces of nasty organic chlorine compounds like Phosgene (COCl2), which is very toxic.

And also, Cl2 settles into lowlands and caves, because it's even heavier than CO2. This could kill lifeforms on the planet, since they can only tolerate a certain amount of Cl2, and they don't actually breathe it.

The biggest problem is that the Cl2 reacts with any H2O to form HCl and HClO. The HCl dissolved in water solution is hydrochloric acid, and HClO is hypochlorous acid (which happens to be a disinfectant). So the rivers and oceans would basically be a dilute acid and bleach solution... which is rather reactive.

Life may be possible on such a world, but it'd have a rather different biochemistry in order to be resistant to the acid and Cl2 gas. Essentially, you're looking at lifeforms with skins and armour made from natural plastics! (and there'd be no carbonates or anything that would react with the Cl2).

 

[mike wightman]

Silicates are acid proof too

Thanks for the info Mal.

Oh, and by the way, there are a few more Cl and F bearing minerals than you know.
Look here and click on Cl or F (or anything else for that matter ).

 

[Malenfant]

Yeah, but the only really common Cl-bearing minerals are NaCl and KCl (the latter - Sylvite - I did forget about, it also forms in evaporite deposits). And Fluorite is by far the most commonly found Fluorine-bearing mineral.

Silicates can still be broken down by acids - pretty much the only common mineral that would survive unscathed would be Quartz, everything else will be broken down to form clays.

 

[aramis]

Mal: you forget one small issue: Minimum retained molecular weight.

Molecular Oygen (and many useful oxygen light compounds) are low weight, and could be non-retained easier than flourine/Flouride and Clorine/Cloride compounds, on lower gravity worlds.

Also, para-oxidant reactions (IE, oygen-like reactions) do not require molecular forms, but may use other forms.

Likewise, Oygen is NOT the primary constituent of our atmosphere... Nitrogen is. In fact, the nitrogen content being molecular nitrogen seems a possible result of life, as well, rather than being locked into methane, ammonia, nitrtrides and nitrates. Some scientists are convinced, others are merely indifferent.

Nitrogen Sulfide (along with Hydrogen Sulfide, Sulfur dioxide (SO2), CO2, and several others) are all products of vulcanism. Nitrogen Sulfide and the resultant life-form freed nitrogen and sulfur could result in an exotic atmosphere with large amounts of sulfur and sulfuric compounds. These all react with oygen, but if a planet has a minimum retained molecular weight above 16, molecular oxygen is NOT going to stick around, nor will water. SO2 has a molecular weight of ~32, Ozone (O3) of 24... but ozone is unstable, prefering to break 2(O3) +2N-> 2(N20) + O2... and so the Oxygen can (slowly) leak out even when MMWR is in the high teens and low 20s (18-22). Since MMWR is a function of gravity... smaller worlds are more likely to have strange atmospheres. (2300 uses the MMWR method for atmosphereic gasses.)

 

[Malenfant]

Dude. If there's one thing I NEVER forget, it's MMW . I've got tables and calculations all over the place at the moment for that...

You're wrong on several counts though, which may explain some of your odd results.


First, you have your MW completely wrong - you seem to be using the atomic number, instead of the atomic weight, which you should be using. So O2 has a molecular weight (MW) of 32, CL2 has an MW of 71, and F2 has an MW of 38, O3 has a molecular weight of 48, not 24 (each oxygen atom has MW 16). And SO2 has MW of 64.1. So your planet needs an MMW of more than 32 for it to lose oxygen.

O2 would be lost to space more easily than F2, and much more easily than Cl2. I don't know how that's particularly relevant though, because if the world can retain N2 and O2 (which the "Chlorox" example I summarised does), then it can retain F2 or Cl2.


N2 isn't a result of life - Titan has a thick atm that is at least 90% N2 and it's way too cold for life. Most of the N2 in the atmosphere comes from volcanic/primordial sources, not life (think about it - Life breathes in O2 and expels CO2. The N2 is just there as an inert buffer gas, or for fixing into the soil).

Nitrogen Sulfide is not found in volcanic gases (I worked in a volcanology dept for seven years, and I sure never heard anyone talking about it). HYDROGEN sulfide is pretty commonly found in volcanic gas though.

 

[aramis]

Yes, i confused Atomic weights and Atomic numbers... I forgot to double check. Net realtionship, however, for "nominal" forms is similar.

The important thing is that smaller worlds will be able to retain Cl and F, and S, wile losing oxygen to space; Ozone retention is meaningless due to the N2 interaction at upper atmosphere layers; If there is an oygen freeing process, it will result in O2 loss on smaller worlds.

And as for titan being too cold, well, NASA doesn't think so. Too cold for O2 breathing warm-bloods, sure. Too cold for life, no. (life exists at EVERY terrestrial surface location we've checked on earth. Life appears to have existed on Mars. Venus might harbor life; we can't keep probes there long enough to check, and we have developed bacteria that can live in more hostile regimes. Any life on venus is unlikely to be compatible with our life... but it isn't an outright impossibility.

Nitrogen, in other atmospheres, is typically registered as part of compounds. As a gas, it is relatively inert, but in compounds, relatively active IN TERRAN THERMAL REGIMES.

 

[Malenfant]

Originally posted by Aramis:
[QB]The important thing is that smaller worlds will be able to retain Cl and F, and S, wile losing oxygen to space

That doesn't really help you though. Without the oxygen, you don't get anything producing the Cl (forget F. It's not going to work, it's too rare and too reactive). And once Cl stops being produced, it'll react with whatever is around and disappear from the atmosphere.

Ozone retention is meaningless due to the N2 interaction at upper atmosphere layers; If there is an oygen freeing process, it will result in O2 loss on smaller worlds.

I'm not that up on my atmospheric chemistry, so I don't follow what you're getting at here.

And as for titan being too cold, well, NASA doesn't think so.

There might be life in the oceans below the ice shell, but not on the surface - the temperature there is about 96 Kelvin - far below any location on Earth. Plus there's no oxygen or other reactive gas. AFAIK NASA haven't claimed or suggested that there is life on Titan's surface.

Life appears to have existed on Mars.

That is by no means definite. There is currently circumstantial evidence that there might be life there due to the methane signature in the atmosphere detected by Mars Express, but that could equally be explained by volcanic activity. The jury is still very much out on this, never mind wishful thinking from the astrobiologists.

Venus might harbor life; we can't keep probes there long enough to check, and we have developed bacteria that can live in more hostile regimes. Any life on venus is unlikely to be compatible with our life... but it isn't an outright impossibility.

It's not, and there have been suggestions that bacteria could survive in the upper cloud layers. But again, the jury is out on that. And remember, just because something may be possible doesn't necessarily mean that it does happen.

Nitrogen, in other atmospheres, is typically registered as part of compounds.

Nitrogen mostly exists in the solar system either in its molecular form (N2) or Ammonia (NH3). Other Nitrogen compounds are pretty darn rare here (there are a few other complex Ammonium compounds in the gas giants, and traces of NO2 and NO in the terrestrial planets' atmospheres, but that's about it).

Take a look at the NASA Planetary Fact Sheets if you don't believe me.

As a gas, it is relatively inert, but in compounds, relatively active IN TERRAN THERMAL REGIMES.

From what little chemistry I know, I can believe that Nitrogen would be more active gas in hotter environments (like the atmospheres of worlds in the inner zone). But its compounds don't usually last long in Earth's environment.

 

[aramis]

There is a recurrant Ozone reaction whcih maintainns the Ozone Layer; Ozone and Nitrogen react to make nitrous oxide and O2; solar radiation (UV, IIRC) creates free atomic oxygen, which reacts with the NO2 to reform into O3 and N2.

If the world is smaller (small enough that O2 is non-retained), that reaction gets disrupted, as much more of the atomic O2 escapes, and the O2 stage also escapes more readily. Thus oxygen presence is VERY much a size/gravity factor. Far too many small worlds have way too muh O2 in the OTU. Which leaves the way clear for other, heavier, reactives.

On to nitrogen: Funny, only earth has more than 10% Nitrogen atmospherically. (Same said fact sheets.)

Nitrogen is used by the life forms, and the proportions in the GG's are all in Amonia. Interesting. Where does all the abundant free nitrogen come from on earth?

 

[Malenfant]

Originally posted by Aramis:
[QB]If the world is smaller (small enough that O2 is non-retained), that reaction gets disrupted, as much more of the atomic O2 escapes, and the O2 stage also escapes more readily.

You mean "lost" - not "non-retained"

.

You may have a point there, assuming the atomic O is actually being lost. We keep it here on Earth because our MMW is about 5. If the planet's MMW is above 16 then it could well lose the atomic O. Interesting...

Which leaves the way clear for other, heavier, reactives.

Or no reactives at all. They aren't necessary in an atmosphere.

On to nitrogen: Funny, only earth has more than 10% Nitrogen atmospherically. (Same said fact sheets.)

Oops. I forgot Titan didn't have its own fact sheet. Have a look at this - Titan has a greater percentage of N2 in its atmosphere than Earth.

Nitrogen is used by the life forms, and the proportions in the GG's are all in Amonia.

I found this website that explained a bit more about nitrogen fixation too.

Interesting. Where does all the abundant free nitrogen come from on earth?

Here's an explanation, and another interesting article

Mostly it's leftover from Earth's formation, and is recycled by volcanoes. Because N2 doesn't react with much, it just keeps building up.

 

[mike wightman]

N2 isn't very water soluble either, so it won't be removed from the atmosphere as other gases are.

 

[Malenfant]

Another thing to keep in mind is that the MMW numbers show what gases can be retained over a timescale of billions of years. (it's also complicated by the fact that the presence of O2 actually causes gas to be lost faster because oxygen generates more energy when hit by UV light - effectively it heats up the exobase of the atmosphere and raises the MMW of the planet as a result)

Anyway, even if a planet has an MMW of say 16-20, atomic oxygen is still going to hang around for millions of years. The loss will be very gradual. The MMW has to be much higher to lose it rapidly (ie on the timescale of millennia or less)

 

[Malenfant]

You may have a point there, assuming the atomic O is actually being lost. We keep it here on Earth because our MMW is about 5. If the planet's MMW is above 16 then it could well lose the atomic O. Interesting...

Hrm. So it looks like if a world has a MMW of about 25, then atomic O (and therefore all the O2 and O3) can be lost in a timescale of a few 100,000 years (geologically rapidly). If the MMW is about 20 then atomic O (and O2 and O3) is lost over a timescale of a few millions years. If the MMW is 16 or less, then the planet can retain the atomic O over a timescale of billions of years (essentially it won't lose any significant amount of it).

That means that the smallest world with a density the same as Earth that can retain oxygen in its atmosphere in the habitable zone is size 5. A size 4 world with earth density would lose its oxygen over a timescale of about few hundred thousands to a couple of million years (which means that the only way it could have oxygen was if the Ancients had terraformed such a world and we're seeing the vestiges of its O2 today. If that's not the case, then it's lost its natural O2 if it had any). Anything smaller would have lost its O2.

So assuming they have a density the same as the Earth, you can't have breathable atmospheres on worlds of size 1,2,3, and very probably 4. But you can have breathable atmosphere on larger worlds... .

Interesting.

 

[Krikkitone]

Necroing a little bit here but retaining O2 (or O) is not the problem. It’s retaining the H2O vapor, which gets lost regardless of any process making oxygen if the MMW is ~18-20, without H2O you don’t have any life that is even vaguely familiar. Which means Size 0-3 (probably 4) if in Hab zone should have 0 hyd and either 0,1… or possibly A atm (ie lots of N2 and CO/CO2 for the A)