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Exoplanet Design Factchecking: Making The World (Not) Burn

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bibliophile20 bibliophile20's picture
Exoplanet Design Factchecking: Making The World (Not) Burn
So, I'm solidly in the midst of my Gatecrashing campaign (I just got my first PC fatality last session! Whoo! And it was hilarious.) and I'm in the process of designing my next scenario to put my PCs through. And, thanks to being a detail-oriented, fastidious GM, I'm currently stuck on an aspect of my next planet design: Oxygen. Specifically, how much oxygen is too much oxygen? If the atmospheric pressure is in the range of 3 bar, with a carbon-based biosphere on a habitable moon, at what point does the atmosphere itself become a spontaneous combustion risk, from lightning strikes, if nothing else? And would it be breathable by any sort of biomorph at those pressures?

"Democracy is two wolves and a lamb voting on what to have for lunch. Liberty is a well-armed lamb contesting the vote." -Benjamin Franklin

bibliophile20 bibliophile20's picture
Found my answer!
Found my answer! Stoichiometry to the rescue!
"Democracy is two wolves and a lamb voting on what to have for lunch. Liberty is a well-armed lamb contesting the vote." -Benjamin Franklin
nerdnumber1 nerdnumber1's picture
Do try to take into account
Do try to take into account the stability of the atmosphere. One would assume that this planet existed for quite some time before trans-humanity found it and that any local life and phenomenon would have ignited the atmosphere accidentally at some point if that was a serious likelihood. Also, I'm not sure how easy it would be to keep a high-oxygen atmosphere up, considering how reactive oxygen is (we have plants to actively produce oxygen, but they require significant CO2 levels to survive. It sounds like the intervention of another species might be needed to make a biosphere that could avoid sparking a conflagration accidentally through static discharge. Maybe the species found high O2 concentrations to be beneficial to their physiology so optimized the biosphere to create/maintain such levels and even guard against, or recover from, "accidents". Occasional mass conflagrations might be an important part of the life cycle...
bibliophile20 bibliophile20's picture
Yep. Smallish moon (5k km
Yep. Smallish moon (5k km diameter; 0.29 g) of a warm Jovian. 19 day orbital period. Heavily intense ecosystem, with regular mass wildfires moving through the plant growth; between the wildfires and volcanism from tidal heating, the atmosphere is ~1% CO2, which helps fuel massive plant growth, resulting in Carboniferous-like oxygen content. One of the major challenges for the exoplanetary colony has been finding a place to settle down that won't be A) overgrown, B) burned down, C) invaded by giant eusocial arthropods looking for dinner, D) invaded by giant eusocial arthropods looking for a safe place to hide from the giant eusocial arthropods looking for dinner or E) all of the above.
Spoiler: Highlight to view
My PCs are going to be responding for a call for help from the colony; a number of their colonists have disappeared lately under mysterious circumstances; it could be the giant insects being clever again, but it could also be the "next door" Planetary Consortium colony that was recently linked to, so the colonial autonomists want investigators to help dig up what happened... and help defend the colony, if necessary. Their paranoia is half right... the threat did originate on that neighboring colony, but wasn't the PC that ordered the attacks. So, when they eventually go to investigate, they find a deserted colony base on a Mars-like world... and, if I time it right, I can have my campaign's first encounter with exsurgents the week of Halloween. :D

"Democracy is two wolves and a lamb voting on what to have for lunch. Liberty is a well-armed lamb contesting the vote." -Benjamin Franklin

nerdnumber1 nerdnumber1's picture
bibliophile20 wrote:Yep.
bibliophile20 wrote:
Yep. Smallish moon (5k km diameter; 0.29 g) of a warm Jovian. 19 day orbital period. Heavily intense ecosystem, with regular mass wildfires moving through the plant growth; between the wildfires and volcanism from tidal heating, the atmosphere is ~1% CO2, which helps fuel massive plant growth, resulting in Carboniferous-like oxygen content. One of the major challenges for the exoplanetary colony has been finding a place to settle down that won't be A) overgrown, B) burned down, C) invaded by giant eusocial arthropods looking for dinner, D) invaded by giant eusocial arthropods looking for a safe place to hide from the giant eusocial arthropods looking for dinner or E) all of the above.
Spoiler: Highlight to view
My PCs are going to be responding for a call for help from the colony; a number of their colonists have disappeared lately under mysterious circumstances; it could be the giant insects being clever again, but it could also be the "next door" Planetary Consortium colony that was recently linked to, so the colonial autonomists want investigators to help dig up what happened... and help defend the colony, if necessary. Their paranoia is half right... the threat did originate on that neighboring colony, but wasn't the PC that ordered the attacks. So, when they eventually go to investigate, they find a deserted colony base on a Mars-like world... and, if I time it right, I can have my campaign's first encounter with exsurgents the week of Halloween. :D
So the PCs have to fight swarms of giant bugs when the use of most advanced weaponry (beam, seeker, shock and kinetic weapons to name a few) risks killing everyone instantly? You sadistic bastard. Then again, since there are coronal morphs like the surya (which I understand don't work in normal environments), I wonder how fireproof they could make a specialized morph. They might even make a pod version of one of the local arthropod-analogues, like they did with the scurrier morph (if enough resources and time were devoted to such a project). I really like how well thought out this world is, like how high oxygen concentrations cause fires, which kills excess vegetation, releasing CO2 and nutrients through burning, allowing for quick regrowth, until the oxygen levels get to the point that the cycle restarts. Also how the high oxygen concentrations allow for larger arthropods, despite a less efficient respiratory system (though they might still have a little more complex a respiratory system. Arthropods' hardy exterior and resistance to high infant mortality would also be beneficial in such an environment. Out of curiosity, how giant are the bugs? Like dog-sized giant, human-sized, truck-sized, and building+ sized? With eusocial creatures, you don't have to be TOO big to be terrifying in large numbers, but it doesn't hurt.
Arenamontanus Arenamontanus's picture
bibliophile20 wrote
bibliophile20 wrote:
Specifically, how much oxygen is too much oxygen? If the atmospheric pressure is in the range of 3 bar, with a carbon-based biosphere on a habitable moon, at what point does the atmosphere itself become a spontaneous combustion risk, from lightning strikes, if nothing else? And would it be breathable by any sort of biomorph at those pressures?
This is a fun topic. I am working on my own compendium of how to calculate relevant stuff for exoplanets. Here is from my section on atmosphere breathability: • Oxygen must be between 400mm and 50mm of mercury partial pressure. Above 400 and oxygen becomes toxic, below 50 and anoxia sets in. Beyond 190 mmHg fire hazard becomes large. • Carbon dioxide becomes toxic above 5mm partial pressure. • Nitrogen narcosis begins at 2400-3700 mm (mild impairment, mistakes, well-being) becoming serious at 4000-6000 (confusion, hallucinations, slow reactions, memory loss) and severe beyond 6000 mmHg. ”Martini’s law” states that the effect is like one martini for every 620 mm beyond 1230mm. • Other gases like xenon, krypton, argon and hydrogen can also be narcotic at high partial pressures. The partial pressure is (atmospheric pressure)*(fraction of the gas). If you measure pressure in atmospheres, the formula is 760*(pressure)*(fraction) mmHg. When the government is open again, check out http://msis.jsc.nasa.gov/sections/section05.htm I think you will have a slightly too high CO2 content for comfort. Check out https://en.wikipedia.org/wiki/Hypercapnia - might be fun! The global fire hazard is something I didn't think too much about, but it is a pretty important factor. Apparently 35% is the upper limit on Earth: http://www.pnas.org/content/103/29/10861.full "Experimental data (6–10) provide the following observations about O2 levels and fire in the fossil record: At levels <13%, except under exceptional circumstances, wildfires will not ignite and spread irrespective of moisture content (7). Between 13% and 16% fires would be rare and would only burn very dry plant material. Ecologically, only vegetation growing in environments liable to drying would burn. Between 18% and 23% fire occurrences would be similar to those under the PAL of 21%, where plant matter (fuel) must have low moisture content; dry seasons help to effect this decline in fuel moisture and permit the rapid spread of the flame front and fire propagation (11). At >25% fires would become widespread, especially in wetter climatic areas, because of the prevalence of lightning strikes. At levels >30% fire activity would be globally distributed. However, at levels >35% plants have been predicted to burn irrespective of drying, resulting in an upper limit of O2 beyond which fires could not be extinguished" Lower pressure would presumably increase the window, although I have not yet found a formula.
Extropian
Arenamontanus Arenamontanus's picture
Update on the pressure: the
Update on the pressure: the lower flammability limit of various air-fuel mixtures does not seem to be strongly affected by pressure all the way down to ~50 mmHg - even a low pressure world will be able to sustain forest fires. Incidentally, a smallish planet with lower gravity will have another property in regards to fire: convection is weaker. The force exerted by a buoyant parcel of hot air is proportional to gravity, so in low gravity flames and smoke will not rise as straight and well as on Earth, and oxygen inflow will often be worse. So expect more smoky, smoldering fires than on Earth. Wind can however feed them just fine.
Extropian
nerdnumber1 nerdnumber1's picture
I wonder how difficult it
I wonder how difficult it would be to modify a morph for oxygen toxicity immunity, so that they survive/thrive in high O2 environments. Would it be easier or harder than ruster respiration?
Arenamontanus Arenamontanus's picture
It would likely be easier.
It would likely be easier. You need to make the lungs less permeable to oxygen (or, better solution: make permeability go down in high oxygen environments), or add safeguards to the bloodstream like modified respirocytes replacing the red blood cells. Hmm, the later solution is nice, but will make everybody look like a vampire unless the respirocytes are colored :-)
Extropian
thezombiekat thezombiekat's picture
The problem with reducing O2
The problem with reducing O2 permeability in the lungs is the morph becomes dependant on high O2. If you installed a pulmonary bypass with variable flow so in high O2 conditions not all the blood would pass through the lungs the rest of the body would be protected. The lung tissue itself is still being exposed so it would need to be producing high quantities of antioxidants.
bibliophile20 bibliophile20's picture
Alright, here's what I've got
Alright, here's what I've got so far regarding constructing this particular exomoon. Vicorica Statistical Data
Spoiler: Highlight to view
Type: Terrestrial Jovian Moon Gravity: 0.29 g Diameter: 5000 km Atmospheric Pressure: 3.12 atm Atmospheric Composition: 64.3% Nitrogen, 31.4% Oxygen, 1.9% Argon, 1.1% CO2, 0.4% Xenon, 0.9% various trace gases Hydrosphere: 75% Surface Temperature (Min/Mean/Max): -4 C / 26 C / 47 C Day Length: 472.1 hours (Tidally locked to planet) Satellite Of: Bluebell System Primary: Class K2V; Designation: Turq Colony Established: 7 AF Colony Size: 2,720 egos Affiliation: Autonomist Alliance (Argonaut/Anarchist)
Overview:
Spoiler: Highlight to view
A small moon with a dense atmosphere, orbiting a warm Jovian class planet, which in turn orbits an orange dwarf. Situated somewhat beyond the extreme outer edge of the primary's habitable zone, Vicorica is kept warm by an extremely high carbon dioxide content in its thick atmosphere. Due to tidal heating, the moon has considerable volcanism, with at least four presently active volcanoes contributing to the CO2 content of the atmosphere. The carbon dioxide, in turn, helps fuel an extremely intense ecology. Due to the low gravity and high CO2 content, Vicorica's forests grow fast and intense, with a dozen species competing for light and height; in some places, the latticework of tree-like organisms rises over a kilometer off of the surface of the moon. However, these areas rarely last for extended lengths of time; due to the high oxygen content, large wildfires are commonplace, with at least one large region of the moon in flames at any given time, adding additional CO2 to the atmosphere. Numerous species depend on the fires to clear away old growth and open up new areas for colonization. The wildfires themselves are widespread, with typically 3,000-10,000 square kilometers of the moon's roughly 19,600,000 square kilometers of terrestrial surface area on fire at any given time. However, as convection currents are a function of gravity and density, Vicorica's forest fires do not have the same intense convection currents that fueled Earth's forest fires to such great intensities during the century before the Fall. Quite simply, the convection winds are just not as intense, even accounting for the moon's greater atmospheric density. A raging crown fire will still burn a forest down to the soil level, but the conditions to create such a massive clearing are not as common as one would think. Thanks to the low gravity, high atmospheric density and high oxygen content, flight is a common means of mobility for the local animal species, with an entire aerial ecology in place, consisting of plankton-analogues floating on internal bladders and streamers, and a number of airborne herbivorous species that feed on them. At the peak of many of the local food chains are an order of eusocial arthropods, which utilize social intelligence to great effect and lethality. Interactions with these eusocial species are presently the number one cause of transhuman death and injury on the exomoon. The Vicorica Gate is located underground, in an extensive limestone cave system, approximately 40 km from the location of the primary settlement (atop and into a local mountain that is mostly clear of the moon's heavy plant growth). Many side chambers of the cave system have been colonized by eusocial arthropod hives, rendering exploration extremely risky. The local colony is presently at a population of nearly 3,000 individuals, a little under half sleeved in variant biomorphs adapted for the local environment (Exalts with Enhanced Respiration (Planet Specific), Medichines, Enhanced Vision and Radiation Tolerance). Most of the population (roughly 1,800 individuals) resides in a single habitat, called Raqiya, built onto and into a local mountain peak (summit 12 km above local sea level, with the external structure of the habitat itself extending an additional kilometer above that) approximately 40 km from the Pandora Gate. The remaining population is spread out across various smaller bases, mostly on the same hemisphere as the main habitat. Most of these smaller bases are ecological research stations, but there are also a fair number of geological research stations and resource extraction locations, as well as one site atop a distant mountain range that is being used as a drydock for constructing aerostats. That last site is currently under construction itself, and is projected to be finished and then commence with aerostat construction in the next 8-11 months. The colony is presently nearly 3 years old, with Raqiya being finished to its current state last year. The Raqiya habitat structure, extending a kilometer above the summit of the mountain that it is built into, and more than four kilometers into the mountain itself, has space and support capacity for over 150,000 biomorphs, and has an extensive exo-womb plant deep within the structure producing nearly 10 Vicorica exalts per day, with more capacity coming on line over the course of the next year; the recent disappearances have made a considerable dent in their mature morph stocks. (There are still sufficient morphs, however, to allow for resleeving PCs or NPC losses, including many other morphs "traded in" by the locals in exchange for the Vicorica exalts, meaning that any losses are not limited to resleeving in Vicorican Exalts). The present plan was to finish resleeving as much of the current population in Vicorican Exalts as desired, produce additional morphs beyond that point, and then open mass immigration for infomorphs from the Sol system over the next year, in blocks of 500 egos, as the morphs became available. The colony produces many commodities for export to other colonies in trade, including oxygen and other gases, various foodstuffs made from local materials, and extraneous morphs no longer in use by locals who have resleeved in the Vicorican Exalt variant. Vicorica itself is the largest moon of a Warm Jovian-class gas giant in orbit around an K2V star; there are five other planets in the system, and 16 other moons around the gas giant.
Known species:
Spoiler: Highlight to view
Flora:
  • Zen Pools; Tree-like plant; creates large networks of forest that mutually supports themselves as they grow in height; can create large networks of woody regions that reach nearly a kilometer in height and hundreds of square kilometers in extent; rather than pump water up from their roots, they create large pools up at the canopy level to capture rainwater.
  • Balloon Bombs; disaster flora; colonizes an area very quickly after a fire. Propagates by creating a floating seed pod filled with hydrogen, which pop quickly in the presence of heat, scattering the seeds on the fresh ashes.
  • Aerial plankton: an umbrella term for thousands of plant and animal species that stay aloft on winds and using air bladders. All of the species are highly mobile, and use various strategies to use the storms and fires to their benefit.
  • Fire Caps; a type of creeping vine that is rich in flammable oils. It requires fire to open its seed pods, which resemble small dark mushrooms or umbrellas approximately 5 cm across; these float away on the updrafts to colonize new areas. With proper filtering and treatment, the oil is edible by transhumans, and has a rich, smoky flavor when used in cooking.
Fauna:
  • Skywhales; the largest flying animal on the moon, these animals resemble a large flying catfish, increased in size to roughly 900-1000 kilograms, with an 8 meter wingspan and internal air bladders. They are herbivorous, and feed on aerial plankton.
  • JellyKites: large (5+ meter) flying animals; resembling a cross between a jellyfish and a stingray, these animals feed off of the water of the Zen Pools and the animals that colonize them in a symbiotic relationship with the Pools. Lacking true flight, they fly in the constant wind of the dense atmosphere by anchoring themselves to the canopy with their tendrils and acting as a kite, and move from place to place essentially by crawling tendril over tendril. In high winds, they simply release their hold and let the wind take them away, maintaining enough control to avoid being ripped to pieces. They are expert gliders.
  • Eusocial arthropods: with over 500 species currently identified, the eusocial arthropod species are the apex predators on the moon, and are almost universally aggressive, lethal and hostile, and identify biomorphs as potential prey; a number of species belonging to the order are herbivorous, and some engage in farming behaviors but even these are still highly dangerous and territorial. Many of these species have a mean body size of over 15 cm in length, and use pheromones and acids to great effect.
  • Stiletto wasps; one of the largest families, both in number of species and size of individual members, these arthropods are bilaterally similar, with two sets of small wings, an exquisitely well adapted set of senses for smell, hearing and sight, a suite of pheromones for marking territory, prey and threats, and a stinger at the end of the highly flexible thorax that is long, thin, capable of punching through the armor of other arthropods, averages 10+ cm in length across all identified species, and delivers a toxin that is an acidic paralytic to native species, and triggers a lethal allergic reaction in transhuman biologies, in addition to the damage from the acidic nature of the sting.
  • Switchblade hornets; a successful genus of the stiletto wasp family that merits attention; similar to most of the rest of the family in major respects, this genus features an impressively nasty stinger deployment mechanism. The stinger is kept within the thorax, protecting it from day to day damage, and can be extended with significant force via muscle action, granting additional penetrative power to their attacks.
  • Dragnet spiders; these arthropods take cooperative aerial hunting in an unusual direction, aided by the dense air and low gravity. These spiders (so named for their propensity for spinning silk) will spin nets between branches, as a frame, and then detach the net from its moorings to take it "fishing"; anywhere between 6 to three dozen spiders will grab hold of the net and fly through the air, capturing smaller airgoing prey in the net, which is then brought back to the nest for consumption. It is suspected that these predators use either highly successful scouts to mark potential prey items, or that they are potentially engaging in some form of herding behavior. Powerful flyers, they have extremely high lifting capacities. There have not (yet) been confirmed attempts at biomorph capture by these species.
  • Piranha beetles; a smaller but still very successful family of species, these arthropods (which resemble Earth beetles with two extra sets of limbs in a wonderful display of convergent evolution) don't bother with toxins or venoms for taking down their prey, instead preferring to flock in numbers of a hundred or more, swarming a target, and chewing it to pieces. The beetles eat their fill, and then carve up the remainder of the corpse for transport back to the nest. Extremely aggressive, persistent, and thus far resistant to most repulsive methods of deterrence from eating transhuman biomorphs. Individuals range in size from 4 to 40 cm in length, and feature a set of jaws capable of inflicting serious harm on most morphs not armored for heavy combat.
  • Shiv bees; a successful family, and one that has numerous herbivorous families that gather nectar and produce a honey-analogue (heavy with glucose and other such products, it is an impressive example of convergent evolution with Earth's bees and honey). The shiv bees themselves have very sharp secondary limbs, as opposed to a single stinger, which they use to great effect in defense. These limbs have large venom reservoirs, and are frequently left in the body of the target--the bee can regenerate these limbs, given sufficient time and food.
  • Marine ants; one of the largest varieties, these are of sufficient size that they typically reserve flight only for scouts and for evacuation away from fires. They are vicious, nasty, and one of the few varieties that can and will destroy armored vehicles through a combination of acid attacks and strong jaws. Some varieties can reach over two meters in length for their soldier castes, although such individuals are rare, due to the time it takes to grow to such size.
Spoiler: Highlight to view
(Yes, I will admit to inspirations and the occasional outright theft from various works of television and literature. I prefer to think of them as homages. ^_^ )

"Democracy is two wolves and a lamb voting on what to have for lunch. Liberty is a well-armed lamb contesting the vote." -Benjamin Franklin

thezombiekat thezombiekat's picture
@ hhexo. I think your making
@ hhexo. I think your making a mistake in the goal of magazine size optimisation. It will not approach the number of bullets used in the typical engagement. No soldier or commander will be upset that after 90% of engagements there are still bullets in the clip. Magazine size for automatic weapons focuses on having as many bullets as practical without making the weapon too expensive, too heavy or too bulky to use effectively. If it was practical to give a sniper a 10000 round magazine they would have it @ LatwPIAT. No need to say the lack of recoil penalties is magic. First there have been a number of weapons developed in the real world with negligible recoil effect on accuracy, the bren gun if memory serves. The traits that cause this could become better understood and more widely used. Second you do a lot less damage with a 10 round burst than 10 single shots. This suggests to me that your not scoring a solid hit with all 10 bullets. Your aim is being thrown off by the automatic fire. The system is assuming that when firing full auto your no less likely to hit with the first bullet and you will be able to control the recoil enough to get several of the bullets to hit but never all of them. Ok there are no rules for what happens to the stray bullets but that’s just the system trying not to go overboard with realism at the cost of smooth flowing combat.
Arenamontanus Arenamontanus's picture
Very nice worldbuilding!
Very nice worldbuilding! It feels like the environment is pretty frantic - large energy and biomass flows. Maybe it is quieter underwater.
Extropian
bibliophile20 bibliophile20's picture
Arenamontanus wrote:Very nice
Arenamontanus wrote:
Very nice worldbuilding! It feels like the environment is pretty frantic - large energy and biomass flows. Maybe it is quieter underwater.
Thank you! Of course, I do have to admit that the initial idea was the Blue Moon show from a few years back; I just took it and ran with it, and worked out the hard numbers that they didn't share in the show. As for underwater being "quieter", I dunno. With this sort of environment, I imagine that megafaunal predators are pushing the limits on the size ceilings of their biological limitations. Sea serpents that consider a transhuman a light snack are probably only in the middle of the food chain...

"Democracy is two wolves and a lamb voting on what to have for lunch. Liberty is a well-armed lamb contesting the vote." -Benjamin Franklin

Arenamontanus Arenamontanus's picture
Also: geological activity
Also: geological activity means earthquakes means tsunamis - and in low gravity waves get higher...
Extropian
bibliophile20 bibliophile20's picture
However, with the low
However, with the low rotational speed for the globe (I did the math; the day/night terminator on this moon moves at a glacial 33 kph), there won't be as much in the way of Hadley cells or hurricanes. Epic thunderstorms, yes, but significantly less regular surface wind patterns (ex: trade winds) that would drive wave activity. And tidal lock to the parent planet means no tides of any notable volume. So, I guess that means that, when you do get tsunamis, they're epic, in size and damage... because most of the native life is not adapted to massive wave action.

"Democracy is two wolves and a lamb voting on what to have for lunch. Liberty is a well-armed lamb contesting the vote." -Benjamin Franklin