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Old 08-21-2018, 09:54 PM   #501
tanksoldier
 
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Default Re: New Sci Fi Setting Seeds

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Originally Posted by David Johnston2 View Post
Except that small craft require a nearby base to work from.
A moon, an asteroid, a captured hulk...

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Governments wouldn't hand out planet devastating weapons to random hoodlums.
You have way more faith in governments.. and humans... than I do.

...and ypu don't need planet devastating weapons to capture a starship.

In the Traveller setting most tramp freighters have 1g drives and no armor.

The crew can either surrender or be shot to pieces.
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Old 08-21-2018, 09:58 PM   #502
David Johnston2
 
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A moon, an asteroid, a captured hulk...
And how would these pirates move on to profiting?



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You have way more faith in governments.. and humans... than I do.
It doesn't require great faith to figure that people don't want to commit suicide en masse.
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Old 08-22-2018, 02:23 AM   #503
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Impossible without sources of nitrogen or phosphorus. You need Titan for the former and the Asteroid Belt for the latter. Without either being established already, the orbital habitats burn (in the case of too little nitrogen) and starve (in the case of too little phosphorus).
Missions to get volitiles from carbon rich asteriods, which can supply both nitrogen and phosphrorus, would make a solid plot point. Of course an asteroid of that type could already be in cislunar orbit and industrial processing could be the issue.
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Old 08-22-2018, 05:21 AM   #504
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The largest source of free nitrogen in the Sol System outside a gas giant is Venus, with Titan and Earth a distant second and third place respectively. When you do the delta-v calculations, Venus is the most expensive source while Titan is the least expensive (gravity assist around Saturn reduces effective delta-v requirements). Ammonia and nitrogen ices can be found on the moons of Neptune and on the objects of the Kuiper Belt. Other than that, you are scrapping stray nitrogen molecules (around 14 ppm by mass), meaning that you would need to process around 700 metric tons per person per year to replenish the lost nitrogen (around 70 billion metric tons per year for a population of 100 million).

I would just honestly push the disaster to a later date, to when human civilization has established asteroid mines to supply their colonies with water and nitrogen convoys from Titan to Earth Orbit to supply their colonies with nitrogen. With TL10 fusion, it would only cost $10 per kilogram to ship nitrogen from Titan to Earth Orbit, which would just be a part of the cost of living. With 100 million people in the Sol System off the Earth, they would have a chance of surviving, though it would be touch and go until they expanded their population (and, since every habitat has a hard maximum population, increased the number of habitats).
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Old 08-22-2018, 02:00 PM   #505
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A seepage of 0.1% per year is pretty good from my understanding (I think that the ISS wastes that much in a day), so I am not sure that anything less than 0.1% per year would be realistic.
Seepage by volume on the ISS is about 0.227 kg/day air. With a volume of 829.8 cubic meters, it leaks at about 7.83% per year. On the other hand, the components have differing leakage rates, ranging from less than 0.1% per year to over 58% per year. Given that:
- A space colony would be constructed with the latest technology, instead of a hodgepodge of aging technology.
- It would likely not be a modular construction which has lots of potential leak points.
- Replacing seals would be a high priority to keep the air in, because they can't rely on resupply missions replacing the lost air.

A very low leakage rate could be achieved.

Going by O'Neill's parameters, we have twin cylinders a radius of 4 km and a length of 32 km, they would have a total volume of 3216 km^3. Assuming this is the total atmospheric volume of the colony, at a partial pressure of 0.3 atm and at a volume of 300 K, there is 1.1 * 10^12 kg of Nitrogen. If we lose 0.1% per year (which I would argue is on the high side, space colonies would only be practical if we had it a 1000x lower), we only need 1.1 million metric tons per year. With an area of 904.78 km^2 per cylinder, we could support a population of 440000 people (with a density similar to Dallas-Fort Worth metroplex) to just over 12 million (with a density similar to Hong Kong).
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Old 08-22-2018, 02:35 PM   #506
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The largest source of free nitrogen in the Sol System outside a gas giant is Venus, with Titan and Earth a distant second and third place respectively. When you do the delta-v calculations, Venus is the most expensive source while Titan is the least expensive (gravity assist around Saturn reduces effective delta-v requirements). Ammonia and nitrogen ices can be found on the moons of Neptune and on the objects of the Kuiper Belt. Other than that, you are scrapping stray nitrogen molecules (around 14 ppm by mass), meaning that you would need to process around 700 metric tons per person per year to replenish the lost nitrogen (around 70 billion metric tons per year for a population of 100 million).

I would just honestly push the disaster to a later date, to when human civilization has established asteroid mines to supply their colonies with water and nitrogen convoys from Titan to Earth Orbit to supply their colonies with nitrogen. With TL10 fusion, it would only cost $10 per kilogram to ship nitrogen from Titan to Earth Orbit, which would just be a part of the cost of living. With 100 million people in the Sol System off the Earth, they would have a chance of surviving, though it would be touch and go until they expanded their population (and, since every habitat has a hard maximum population, increased the number of habitats).
It sounds like you're coming with an interesting setting of your own. What's the politics? Is there religious strife? You've got a great seed Alexander, water it a little.
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Old 08-22-2018, 02:47 PM   #507
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- A space colony would be constructed with the latest technology, instead of a hodgepodge of aging technology.
I love your optimism.

Why would a government construct a large space station any differently than a small one?

...and what is cutting edge and new now will be old and worn in 10 years.

Last edited by tanksoldier; 08-22-2018 at 02:59 PM.
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Old 08-22-2018, 03:36 PM   #508
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It sounds like you're coming with an interesting setting of your own. What's the politics? Is there religious strife? You've got a great seed Alexander, water it a little.
Well, the setting is 200 years in the future. Global climate change occurred around as fast as the most grim scientific articles predicted, but fusion technology evolved rapidly from 2025 on. Using D-D fusion reactors for electricity generation, He-3 became plentiful, as every 50 MW-H of fusion energy resulted in 4 grams of He-3 being produced (an equivalent am out of tritium was also produced, but it was consumed in secondary reactions) and He-3 fusion engines allowed humanity to flee a crippled Earth starting in 2050.

By 2220, the vast majority of the human population lives in orbital habitats in GEO/L4/L5, while the remainder is divided between Earth, Luna, the Main Belt, Mars, the Jupiter Trojans, and Saturn's moons. While the Earth still possesses nations, they are shadows of their glory, as the population of the Earth is only 500 million. The British Royal Family invested early in L4 development and the Japanese Imperial Famy invested early in L5 development, so they are both very powerful institutions.

Even so, the Grey Imperial Family is the most powerful family in the Sol System. It was Jessica Grey who invented the commercial D-D fusion reactor and the commercial He-3 fusion engine in 2025 and 2050. It was Mary Grey who created the Saturnian Empire in 2060 when she used her inheritance to start the Titan nitrogen trade. While the Grey Imperial Family controls 90% of the nitrogen trade and effectively owns Saturn, it keeps rates reasonable, so no one has really attempted to argue with them since doing so would threaten the survival of every orbital habitat.

Outside of L4, L5, and Saturn, the colonies of the Sol System belong to the Sol Alliance. The nations and the religions of Earth dream of returning to prominance, but the rest of the Sol System is uninterested. New religions that deal with the realities of space existence, from the Church of Forbidden Silence, which teaches its followers to avoid any moment of silence, to the Temple of Eternal Darkness, which teaches its followers to give offerings of light to spirits of darkness to keep the void at bay, dominate human religious life. The Earthly religions are considered naive at best and dangerous at worst, as the religions of the Void know that their colonies were created by people, not gods.
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Old 08-22-2018, 07:58 PM   #509
TGLS
 
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Originally Posted by tanksoldier View Post
Why would a government construct a large space station any differently than a small one?

...and what is cutting edge and new now will be old and worn in 10 years.
Alright here's four reasons:

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Originally Posted by Astromancer View Post
The space habitats are working on a program of independence from planetary imports. Mainly to make them less expensive and to make the phases in extraplanetary settlement more practical. The Moon has multiple bases and functions as the mine for the Space Habitats.
If the goal is to make your space habitat independent from planetary imports, better seals is step one. Otherwise you'll be tied to someone else's exports forever and ever.

Second, O'Neill cylinders are essentially two very long tubes that are joined at one end. You simply have fewer seals to work with, and that means less leaks.

Third, anyone who is going to be trying this is going to be at least as advanced as we are today, probably even further if you believe The Third Industrial Revolution (1975) hype. Compared to the ISS, which has a hodgepodge of technology from the past 20 years, I think it's a fairly safe bet that, at least at the beginning, the leaks will be smaller.

Four, beyond all of the previous, even if the cost of Nitrogen gas is $1 per kilogram including transportation, the cost is prohibitive for a station of this size. At that price, by my count, it would cost over a billion dollars per year (and that's ignoring oxygen too) per cylinder.

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Originally Posted by AlexanderHowl View Post
you would need to process around 700 metric tons per person per year to replenish the lost nitrogen (around 70 billion metric tons per year for a population of 100 million).

With TL10 fusion, it would only cost $10 per kilogram to ship nitrogen from Titan to Earth Orbit
That's enormously pricey, at a cost of seven million dollars per person, before you count extraction cost.
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Old 08-22-2018, 09:16 PM   #510
AlexanderHowl
 
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I think you are conflating two numbers. If you are shipping from Titan with fusion, you are paying $10 per kilogram of nitrogen. If you are getting nitrogen from Luna or an asteroid, you have to process 700 metric tons of rock per year per person to replenish your nitrogren.

In the former case, it is around $100 per person per year. In the latter case, it ends up being around $10,000 per person per year (if you are creating nitrogen as a byproduct of another mining process) to $200,000 per person per year (if you are mining primarily to produce nitrogen). Since a society of 100 million people probably does not need 70 billion metric tons of slag a year, you are probably primarily mining for nitrogen. Titan just ends up being cheaper than anywhere else for harvesting nitrogen when you have TL10 fusion.
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