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Post by Leo Kerr on Jan 20, 2019 22:02:07 GMT -5
Destiny is turning into something of a scary planet.. we've got some areas that do oxygen/nitrogen separation, and if the O2 levels get over about 25% the alarms go off something big. I was kind of curious about the pressure differences - about the only thing I know about pressure is from watching the film Abyss, so.. the idea of the wind 'shaping' trees, though, is a very good one. There are some incredibly twisted copses of tree-like shrubs in western Newfoundland, although I can't recall what the local term for them was. I want to say 'tuckamore,' but don't quote me on that! (Or should that be 'shrub-like trees'?) That persistent wind, though, does make me wonder.. is it a jet-stream like artifact? Overall, the planetary geography is kind of an interesting game of "what-if?" If by making one change - say air-pressure - what else has to change? Or, in a different sense, what did Wes change first, and then saw that other things had to change, or ended up asking, "if we have X condition, what else has to change to make that possible?"
I've often been impressed at the amount of research and background that goes into Wes's writing; I wonder what else we'll find here over the next few weeks?
Arm-chair exogeography. Who knew?
Leo Kerr
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Post by Not Wes on Jan 20, 2019 23:21:46 GMT -5
"Tuckamore" is a Labrador and Newfoundland term for Krummholz or Krumholtz effect to trees, basically where high and persistent winds blow branches downwind and they stay there. German term.
I worry about Wes's O2 and high pressure being too much. I don't know.
Everything changes something else. The local flora and fauna have adapted. Can man do it?
Thanks, Leo.
Not Wes
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Post by Leo Kerr on Jan 22, 2019 22:23:35 GMT -5
I'm not sure when O2 levels become actually dangerous (from a fire-hazard perspective.) Where I work, (a) we're a bit paranoid about fire, and we're doing nitrogen enrichment as fire-suppression in one area (at ~14%, fire won't burn, but at 1019mbar, the total oxygen availability is similar to something like 12,000 feet. I know I shouldn't be mixing units, but..) But (b) where we have the nitrogen enrichment, we're also then dumping "waste" oxygen. So it's a major potential fire hazard. I think -- under standard pressure (nominal 1019mb) oxygen poisoning doesn't kick in for a while - and as the space program demonstrated, people could function at low pressure 100% oxygen for quite some time. (I think the Apollo capsules were pressurized to 5psig. More mixed units!) For some reason, I'm thinking the long-duration Apollo mission was 18 days? I have no idea what the atmospheric regulation of the ISS or Mir - or heck, even Skylab was. (Although at a guess, I'd speculate that Skylab was similar to Apollo.)
Something else - I have no idea if this has an influence on the story or not, but as the atmospheric pressure increases, so too does the speed of sound, and all of its aerodynamic influences, change. Um; it might make things "easier" - higher pressure means it's "faster" .. except some preliminary research I'm seeing suggests that density of air doesn't matter too much for the actual "speed of sound," but it may make things "sound funny." Think Helium-voice except in reverse? (I recall a Mythbusters episode where Adam took a whiff of sulfur hexafluoride (SF6) and spoke in a monster-deep voice...
Sketching this out, I realize I really don't understand some of these issues. I'm a geographer by training, and a lighting scientist/artist by vocation (no, it does not compute,) and know I'm really out of my depth on some of this. (Actually, I'm kind of surprised I remembered the right word for the wind-twisted trees in Newfoundland. I was sixteen when I was last up there in Gros Mourn National Park. Beautiful territory; a really amazing place. Though I don't recall ever hearing the German term before.)
On the last bit - "local flora and fauna have adapted. Can man do it?" - I'd suspect that over the course of a couple generations people could probably adapt, and maybe in more generations be able to populate the lower altitudes. (Interesting social/psychological question: would the higher hills or the lower plains be deemed "more desirable"?) But I do still wonder - my own interpretations might be overly simplistic, but I feel like the fire situation would be... challenging at the least. Actually, there might be all sorts of interesting longer-term physiological issues: how fast for things to rot; for food to spoil..? I remember hearing about a NASA conversation between Apollo and Houston: how long could the prepackaged, dehydrated, rehydrated tuna "survive" in 100% oxygen at 5psig? I don't think they came up with an answer.
Yeah, everything changes something else.
Leo
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Post by Andy Haworth on Jan 23, 2019 12:24:57 GMT -5
Talking oxygen levels, which I also know very little being a nerdy electronics type, or if it is relevant. But would increased oxygen levels affect life expectancy, somewhere in the back of my mind I seem to have got the idea that some, maybe many, body parts oxide and that it is the primary reason for failure.
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Post by Davidh on Jan 23, 2019 23:00:02 GMT -5
How large is the area they're on. With twenty thousand adults how many generations till they overload the ecosystem. IE not enough area for food plants and animals?
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Post by IanS on Jan 24, 2019 23:29:27 GMT -5
As a retired diving instructor oxygen poisoning has been of interest to me the following is from memory of 30 years ago.
It is split into chronic and acute.
Oxygen levels are measured in partial pressure, if we approximate the atmosphere at sea level is 1Bar and the oxygen is 1/5th or 20%, giving a partial pressure for oxygen of 0.2Bar here on earth at sea level.
During WW2 the British navy used oxygen rebreather (pure oxygen) for clandestine underwater operations. With fit young men they could work down to about 30 to 35 feet where the total pressure is 2Bar deeper than that acute oxygen poisoning started to be a problem. Acute oxygen poisoning comes on relatively quickly and causes muscles to spasm uncontrollably and if the partial pressure is not reduced will result in death.
Chronic oxygen poisoning takes longer to start and can be days to weeks and causes irritation of the lungs with the lungs filling with fluid. This starts at oxygen partial pressures between 0.8 and 1 Bar.
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Post by Leo Kerr on Jan 25, 2019 14:12:04 GMT -5
Ooh! Some numbers! The pressure on the plateau was.. 1.8bar? X 32% means toward 0.57bar partial pressure. Your mileage may vary. So.. from that perspective, they're probably okay.
I'm not sure what levels, but premature infants are often given pure O2 that gives them permanent vision troubles. Not sure where that kicks in, but.. that's definitely a risk to be concerned about. Who knows what other issues lurk in that area.
But back to fire, I recently tracked down that.. I think it was Airgas Co. considers (I think) greater than 24% as "enriched atmosphere" with a seriously enhanced risk of fire. And as they're fond of pointing out, things we don't think of as fuel, under higher partial-pressures... become fuel. Like steel pipe.
I think I also saw something in the last day or two, about how in the fossil record, there's an implication that there were no real fires on earth (wildfire/firestorm/forest-fire/etc) until the ambient atmosphere got about something like 17%. (Which is backed up by the fire-prevention we're doing at work by keeping a sensitive artifact's chamber at ~14%.)
Odd question, and I have no idea if its in any of the writings as-yet: how much CO2 is there in the air?
Leo
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Post by IanS on Jan 26, 2019 0:33:25 GMT -5
To continue what other gasses are in the atmosphere?
If mainly Nitrogen the partial pressure is approx. 1.2Bar so well under where nitrogen narcosis becomes a problem at 3 to 4Bar
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Post by Not Wes on Jan 28, 2019 11:09:00 GMT -5
In chapter 14 there's a guess advanced that there's probably 100,000 square kilometers of tepui tops available for colonization (that's about 38,600 square miles for those of you like Wes). One of the tepuis is almost 1700 square km in area (656 sq mi), but we don't know which one. For those of you who haven't looked into it, a tepui has North American equivalents in the desert southwest, and they're called "mesas" here. There's one near Grand Junction Colorado named Grand Mesa, and it's about 1300 sq km (about 500 sq mi), the largest mesa/tepui on Earth.
Of course, not all of Destiny's tepuis are at an elevation that man can use. How long does it take for man to adapt biologically so he can use those at lower elevations with higher oxygen partial pressures? Likely a thousand years and more? Likely much more. Also, not everyone can adapt. Mountain climbers have problems with "altitude sickness," which is pulmonary edema, when atmospheric pressure isn't enough to keep blood and fluid from escaping through the cell walls of the lung tissue, and the lungs slowly fill with fluid. Hyperbaric (pressure) chambers or getting the sufferer down in elevation to higher pressure air is the best remedy. Even some "adapted" humans on Destiny will have trouble with that, just likely at different elevations/pressures than here. This problem is one reason large planes are pressurized in high-altitude flight. It is something that Wes didn't cover in the story and will be a problem for specific individuals in the colony forever. I doubt it was something that was thought of for genetic testing back on earth for crew and colonist selection.
To respond to Davidh's question of how long before they outgrow the tepui top that they're on, I'm not sure. I haven't tried to figure it out, but I'm sure it's sooner than Wes planned on. It will come out in a later chapter that Island in the Clouds is about 1000 sq km (about 385 sq mi) in area. They brought a lot of resource material with them on the ship, but can't have everything they need, even with the recycling capabilities they have. I also worry about outrunning their resources as population expands and raw material limits start to crop up. Sandstone is notoriously limited in providing raw materials for mankind's "necessities."
They can colonize more area, other tepui tops of course, but I personally think that they will have to start limiting population growth eventually, and it's sooner than we think. It took the USA less than 500 years to go from basically native population to where it is now, though there was lots of immigration in that time. With the low birthrate in the US, immigration is what keeps us above sustainability now. Figures I just looked up on the Web indicate that US population in 1800 was under 5 per square mile, and in 2010 it was 87.4 per square mile. It was figured at over 92 per square mile in 2017. 20,000 people on Island in the Clouds tepui is about 50 people per square mile. Of course the cities here are much more densely packed than that, and there is lots of basically "empty" land. The land people like to live on is the best land for growing crops. How does that affect population growth? I would think they'd eventually have to figure out how to start mining lower elevation ground (base level) for raw materials in order to keep going, as well as come up with new food sources or technology for producing such.
Not Wes
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Post by John Robert Mead on Feb 14, 2019 0:59:04 GMT -5
_If_, and that's something of an if, they can maintain extra-planetary flight capabilities, setting up mineral mining and processing off planet would be a possibility in the long run, as would space habitats, etc.
But... establishing an off-planet tech base isn't something they are looking at in this story, their focus is getting on-planet colonization to a viable level prior to their starship failing.
As has been pointed out, the tepui are _not_ good sources for minerals.
And they can't afford to utilize that space for major industrial infrastructure, not in the long run; the amount of "space habitable by humans at their current stage of development" is small enough that they have a major incentive to find some means of shifting non-agricultural activities elsewhere as soon as they can.
Especially since one of the incentives dangled before the prospective colonists was relaxed population control measures, compared to what Earth had developed.
They are going to be very reluctant to re-establish the very thing they wanted to get away from.
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