[Space] What’s the minimum resources required for Asteroid or Comet habitats?

[Johnny1A.2]

Originally Posted by Brett

Ah!

I figure that chalcophile elements are going to be scarce in space. Siderophiles ought to be found in the nickel-iron material, lithophiles in the stony asteroids, and atmophiles in the ices. But I don't know of any material in space that is enriched with chalcophiles to anything like the richness of a commercial ore. The material imply isn't differentiated enough.

Sulphur itself probably isn't terribly scarce, but silver, arsenic, bismuth, cadmium, copper, gallium, germanium, mercury, indium, lead, polonium, antimony, selenium, tin, tellurium, tantalum, and zinc probably only exist in ores about as rich as concrete.

Also, don't be too blasé about, for instance, the platinums. Iron-type asteroids are platinum-rich compared with the Earth's crust average, but not as rich as a good commercial ore.

This is one of those subjects about which enormous amounts of speculation get done, on a very thin basis of hard data, in both directions. Are the processes that enrich ore on Earth operating on the Moon, the asteroids, etc? Of course not. Can we say with confidence that this means that no good ore exists? That doesn't necessarily follow.

But either way, much depends on the technology of recovery, and the cost of energy.

[Mgellis]

One thing to keep in mind is that, for a game, you can make a few assumptions.

A small space habitat, suitable for a few thousand people, will mass a few million tons. Most of that will be structure and atmosphere. Structure can be iron if the diameter is less than a few miles (which it will be in this case) or carbon. The atmosphere will be a typical nitrogen-oxygen mix. (And, if you are short on nitrogen, you can use a mostly oxygen atmosphere at reduced pressure.)

A potato-shaped 10-km. asteroid or cometary nucleus might mass sixty or seventy billion tons (if it was solid, it would probably mass more, but it's probably a loose rubble pile).

Using...

http://www.cds.caltech.edu/~shane/pa...ining-2001.pdf

...as a source, it looks like, by mass, most small bodies are mostly oxygen (although it's locked up in various minerals) but you can usually count on a few percent being iron and carbon, a few percent volatiles, and a lot more being silicon. More than enough to build dozens of small habitats.

There are tens of thousands of asteroids of this size. And probably tens of millions of cometary bodies in the outer regions of the solar system.

As for any additional "required" material, that can be role-played. There's no reason why a particular asteroid has to be .1% nitrogen or phosphorous or whatever chemical is needed...it might be only .001%. And that becomes a problem for the characters.

Anyway, I hope all this helps.

Mark

[Agemegos]

Originally Posted by Trachmyr

1) I've already stated that water and methane ices are common (methane is used for extraction and production of organics), but how common would Ammonia Ice be? If helpful the star is K1V, Luminosity 0.50, and the belt extends to 3.83 AU, 0.4AU past the snowline.

That's the current snow line, not the formational snow line. ie. not the snow line you ought to use in generating the planets.

Looks like your K1 V is rather luminous, and probably pretty old.

Ammonia shows up spectroscopically in the comas of comets, which means that ammonia ice must be present in the nuclei. I guess that it is shielded from the light that would otherwise break it down by an overlying layer of dust, other ices, and the hydrocarbon residue that we seem to find coating comets' nuclei.

Ammonia tends to break down in the presence of UV light. But when it does it leaves nitrogen behind, and N2 actually has a higher molecular weight than NH3, so it is less prone to be stripped away by Jeans Escape. So even where the sunlight is too energetic for ammonia to exist you may find moons or small planets like Titan with nitrogen-rich atmospheres.

For sources of nitrogen, look for places where (a) ammonia is a solid that may be mixed with a shielded from UV by other material, (b) nitrogen is a solid, or (c) escape velocity is high enough and temperature low enough that nitrogen forms an atmosphere.

(a) Ammonia freezes at about 193K. But water freezes at 273K, and the snow line corresponds to 126 K. I'm not sure of the physical chemistry here, but I think the outer reaches of your belt might be a bit warm for ammonia ice. You might have to go out as far as 6.9 AU for ammonia ice, or wait for comets to bring material in from thereabouts for you.

(b) Nitrogen ice is going to be even more inaccessible than ammonia ice.

(c) Got any Small planets or moons out there? They'll have nitrogen atmospheres.

If present, would it be possible to extract the Nitrogen from Ammonia Ice?

Yes. Even better, ammonia can be converted directly to fertilisers and other chemical-industry feedstocks. Very often the first step for using nitrogen for anything really important is to convert it to ammonia.

2) How plausible is it to streamline industry to use only more abundant elements, at least for most mass production.

Economics is all about adapting to the constraints you are under, using plentiful stuff lavishly and scarce stuff sparing, making tradeoffs and substitutions. Also, where possible, engaging in trade with someone whose constraints are different.

There isn't unlimited room for substitution. But there is nearly always some room for substitution of something.

3) How will focusing on industry and lifesupport to the absence of commerical and recreational facilities/products affect the need for certain resources.

I don't think we know enough to say.

[lwcamp]

Originally Posted by Trachmyr

As for the air mix, I'm using what space-suits use: Total pressure of 32.4 kPa, equal to the 20.7 kPa partial pressure of oxygen in the Earth's atmosphere at sea level, plus 5.3 kPa CO2 (exhaled) and 6.3 kPa water vapor..
Thus no Nitrogen.

This will be very dangerous. It will make slight sparks tend to ignite anything flammable. Normally, each oxygen molecule that reacts has to share its heat with 4 nitrogen molecules. Without the nitrogen to spread out the energy of the reaction, the nearby oxygen gets heated instead, and becomes more reactive. Fires in atmospheres enriched in oxygen burn very quickly.

This can be ameliorated somewhat in free fall, since the waste products will hang around the source of the flame. Still, high oxygen atmospheres might be dangerous, and in any sort of spin gravity environment, or if there is external air circulation, you are looking at a fire-trap.

If nitrogen is a problem, you can use argon (also rare), neon (also rare), helium, sulfur hexafluoride, or other inert gases.

Luke

[Agemegos]

Originally Posted by Johnny1A.2

This is one of those subjects about which enormous amounts of speculation get done, on a very thin basis of hard data, in both directions.

Very true. But when you set a game somewhere you have to commit to specifics. And even though we know that there are going to be undiscovered processes going on and unexpected technologies developed, any particular unexpected resource or unanticipated technology makes our premise seem more extravagant. A cautious projection for an SF setting seems most plausible even though we pretty nearly know that it is not what we are going to find, not what is going to develop.

[Allu]

Originally Posted by Brett

I think Trachmyr is thinking of using the O2 excess to replace loss through leaks.

Yes, that makes a lot more sense.

Originally Posted by Brett

Not if you fix the carbon using plant growth and just vent the oxygen. But I'm a little puzzled as to why you figure that CO2 content in the air is going to rise.

I got the impression that the mined ice took the place of proper life support equipment. Also, with the mention that plant based life support would be fusion powered I presumed that there was no good way to get rid of CO2 aside from venting.

It seems I misinterpreted the original post rather badly.

[Agemegos]

Originally Posted by Allu

It seems I misinterpreted the original post rather badly.

Not to worry. We got it sorted out without bloodshed.

[Agemegos]

Originally Posted by Brett

(a) Ammonia freezes at about 193K. But water freezes at 273K, and the snow line corresponds to 126 K. I'm not sure of the physical chemistry here, but I think the outer reaches of your belt might be a bit warm for ammonia ice. You might have to go out as far as 6.9 AU for ammonia ice, or wait for comets to bring material in from thereabouts for you.

(b) Nitrogen ice is going to be even more inaccessible than ammonia ice.

Okay, a bit of web research has turned up relevant data. Nitrogen sublimes in vacuum at about 34 K, and ammonia sublimes in vacuum at 120 K. That means that your K1V star with a luminosity of 0.5 L☉ will permit ammonia ice at 3.80 AU (provided that it is protected from UV) and nitrogen ice at 47.3 AU.

That means that there will be ammonia ice (a source of nitrogen and precursor for nitrates etc.) in the outermost reaches of the asteroid belt in your system. It will be found in the interiors of larger bodies (which remain near average temperature even at perihelion) and in small bodies that have low orbital eccentricities so that they never come within 3.80 AU. That means that it will be uncommon, and inasmuch as there may be few close substitutes, a valuable resource.

[Mysterious Dark Lord v3.2]

Power supply - Solar and fission are good. Solar is better in terms of availability (mirrors to focus sunlight will help in the outer system), while fission is good if you need to operate energy-heavy systems. But if you need power anywhere without excessive worries, then I'd go for thermoelectricity. Once you get the thermocouples set up, any temperature gradient will generate some power. And of course if you're near a body with a magnetic field, just throw out a cable.

Construction materials - A lot of people think that the materials have to be refined. Not so. With a power source, you can melt most materials. Then mold them into shape, let them set, and voila. Of course, if you're in the outer system and using volatile materials like ice, some insulation might be recommended.

Life-sustaining chemicals - Hydrogen, oxygen, carbon. All very common in asteroidal ices, comets, and on moons of outer system worlds. Combine them in a variety of manners, and you get water, fertilizer, plastic, fuel, etc.

Industrial materials - Silicon is very common. Iron and aluminum are fairly common. Other metals are not unknown. The rare earths needed for the really advanced electronics are not quite as rare, but unlikely to be in convenient ores. Some "dumbing down" (replacing some electronics with vacuum tubes, substituting electromechanical dedicated controls for versatile digital computers, etc.) may be helpful. Substitutes for structural materials will be required.

That's my thoughts.

[Johnny1A.2]

Originally Posted by Mysterious Dark Lord v3.2

Life-sustaining chemicals - Hydrogen, oxygen, carbon. All very common in asteroidal ices, comets, and on moons of outer system worlds. Combine them in a variety of manners, and you get water, fertilizer, plastic, fuel, etc.

True, but the combining process is non-trivial, and the necessary trace elements are very necessary.