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[GreatWyrmGold]

It could help, but we'd need a coordinated effort to actually save Earth and humanity.

...so mankind is stuck on this rock forever. 
PTW.

More like "humanity is doomed, barring coordinated effort, so if your goal is to save humanity from itself you need organization more than space colonies."

-snip-

Nice theories, but they seem to be assuming you want self-sustaining colonies and not much more.
Most sources of metal are in gravity wells, so either expansion will be stopped at some point or you'll need to get to a gravity well eventually.
Besides, making a large-scale lunar colony requires less resources than an equally-large floating space colony. Potentially much less.
Free-floating colonies aren't a bad thing, but you still need world-based colonies.

Mainiac, we got abundant Iron and water on Earth, and it's way easier to get around here. Why can't we build more real estate here?

Anything that can be done on the Moon can be done more easily on Earth, or in LEO. (Except a space shipyard).

First off, he was talking about free-floating bases. Kinda like spaceships, but they don't need to move.
Second, we have a gravity issue and a "sunlight is horribly finite here" issue. Sure, it's finite in space too, but you can just move the space stations farther apart.
Third, Lunar real estate is cheaper than Terran. Less environment, less people, more undergrounding...

Gravity, I would assume. Lunar gravity is a sixth that of Earth's; assuming there are no exponential or polynomial relations I'm not aware of, that means it's as easy to build something six hundred meters high on the Moon (all things being equal) as something a hundred meters high on Earth.

No, you don't want to build on the moon at all.  You launch the materials off the moon and then build in space.  The surface of the moon has gravity and a day night cycle, neither of which you want.  The gravity is too weak for human habitation, it would cause long term health problems.

The gravity in space is even lower...

If you build entirely in space your architect passively controls every aspect of the environment, including space.  You don't need to settle for 1/6 gravity when you can set the spin rate and size of your station to give you exactly the gravity you want.  Depending on the emissivity of the materials you use on the outside of the station you can pick whatever temperature you want it to be inside year round.  By tweaking the shape of the station you chose how strong the winds inside will be.  Set the day night cycle to whatever you want by scheduling the illumination mirrors to shine sunlight into the environment (ok, that part isn't quite passive). 

Anything preventing centrifuges on Luna from working? It would probably be simpler if nothing else, because you have something to anchor to. The only downside is that if you stuck a whole city in the centrifuge, gravity would shift by 1/3 G each revolution.

You can even set the exact parameters of these matters to different levels at different parts of the station.  For the residential and commercial levels you probably want the gravity near 1 g so you put them on the rotating ring.  Agriculture might not need as much gravity so you make the greenhouse structure rotate more slowly or make it smaller in radius.  Industry you want zero g so you make that not rotate at all.  You give the residential sections a day night cycle but for agriculture, commerce and industry you can just have daylight 24/7.  All of this can be done without any active energy expenditures to maintain the light/gravity/temperature levels you want.

Why would you want commerce and industry to be light 24/7? It wastes electricity.

Anyways, most of that environment-control stuff can apply to Lunar or even Terran bases. Electric lights, shades, building underground...

Well sort of but the ships would have no locomotion and wouldn't actually be built at the moon.  You'd launch iron ore from the moon and then smelt it at a refinery in space.  (Space would be a good place for smelting because you could get very high temperatures on the cheap if you just shine a lot of light on your smelting material and then don't radiate it.)  So the moon is really just a mining site and launching point.

The problem with space smelting is, you can't get rid of the heat...
Lunar smelting makes more sense. You can use sunlight as well, dissipate the heat easier, and the ore is probably heavier than the finished metal.

[MetalSlimeHunt]

Space is a good place for heating!?

I mean, the fact it's permanently near absolute zero, the fact it's in a vacuum, and that getting equipment to heat stuff into space would be ridiculously expensive?

May as well smelt it on the moon. Also, the useless stuff (e.g. sulphur) wouldn't be blasted into space along with the useful stuff (i.e. the iron).

It is not permanently near absolute zero. The temperature of space is related to how close you are to a star. If you stepped out onto the light side of the moon without a suit, it would be very hot and you'd instantly get extreme sunburn due to the exposure.

The vacuum is a good thing. Heat is about transfer. The heat is transferred away from the heater by the matter around it. What makes an insulator is something that is resistant to this transfer, and because a vacuum is a vacuum there is nothing for the heat to transfer to. It can only radiate away, and this makes vacuum an extremely efficient insulator.

[mainiac]

Space is a good place for heating!?

I mean, the fact it's permanently near absolute zero, the fact it's in a vacuum, and that getting equipment to heat stuff into space would be ridiculously expensive?

May as well smelt it on the moon. Also, the useless stuff (e.g. sulphur) wouldn't be blasted into space along with the useful stuff (i.e. the iron).

(Space would be a good place for smelting because you could get very high temperatures on the cheap if you just shine a lot of light on your smelting material and then don't radiate it.)

This is thermo 101, if heat goes in and it doesn't go out then temperatures rise.

Nice theories, but they seem to be assuming you want self-sustaining colonies and not much more.
Most sources of metal are in gravity wells, so either expansion will be stopped at some point or you'll need to get to a gravity well eventually.
Besides, making a large-scale lunar colony requires less resources than an equally-large floating space colony. Potentially much less.
Free-floating colonies aren't a bad thing, but you still need world-based colonies.

Not all gravity wells are created easily.  Jupiter has a larger well then earth has a larger well then the moon.  That's why the moon is a good source, earth is an okay source and Jupiter is basically impossible.

You don't need world based colonies because people could easily live in space and commute to the moon to work in the mines.  We aren't talking three day journeys like the Apollo program, the closest colony could be right in lunar orbit.  Saying that you need a planetside colony is like saying you need the miners to live inside the iron mine.  Maybe you want them to live near the mine surface but inside is just silly.

The gravity in space is even lower...

The gravity in space is whatever you want it to be.  Artificial gravity is easy as pie for a large structure.

Why would you want commerce and industry to be light 24/7? It wastes electricity.

Read what I wrote more carefully.  The whole point is that you don't need a watt of electricity to provide all the light you want.

The problem with space smelting is, you can't get rid of the heat...

Yes you can; just build a radiator.  In space you can insulate with vacuum until the smelting is finished then connect it to your radiator bank which can exist in three dimensions.  Keep in mind that a little patience goes a long way.  Make your radiators able to survive high temperatures and then allow a couple weeks for the heat to smelt away.  You can afford to be patient because you can just move the smelting equipment on to the next batch while you wait for the stuff to cool.

All these problems are just pretty basic engineering constraints that can be cheaply solved with an ounce of planning.  Think outside the box a little here, we are talking speculation here so try to understand how things could be different before insisting they wouldn't work.

[GreatWyrmGold]

Space is a good place for heating!?

I mean, the fact it's permanently near absolute zero, the fact it's in a vacuum, and that getting equipment to heat stuff into space would be ridiculously expensive?

May as well smelt it on the moon. Also, the useless stuff (e.g. sulphur) wouldn't be blasted into space along with the useful stuff (i.e. the iron).

(Space would be a good place for smelting because you could get very high temperatures on the cheap if you just shine a lot of light on your smelting material and then don't radiate it.)

This is thermo 101, if heat goes in and it doesn't go out then temperatures rise.

And then problems arise once you're done smelting. Besides, don't liquids not exist at zero pressure?

.

Nice theories, but they seem to be assuming you want self-sustaining colonies and not much more.
Most sources of metal are in gravity wells, so either expansion will be stopped at some point or you'll need to get to a gravity well eventually.
Besides, making a large-scale lunar colony requires less resources than an equally-large floating space colony. Potentially much less.
Free-floating colonies aren't a bad thing, but you still need world-based colonies.

Not all gravity wells are created easily.  Jupiter has a larger well then earth has a larger well then the moon.  That's why the moon is a good source, earth is an okay source and Jupiter is basically impossible.

How is that relevant to my argument specifically against relying on orbital/free-floating stations?

You don't need world based colonies because people could easily live in space and commute to the moon to work in the mines.  We aren't talking three day journeys like the Apollo program, the closest colony could be right in lunar orbit.  Saying that you need a planetside colony is like saying you need the miners to live inside the iron mine.  Maybe you want them to live near the mine surface but inside is just silly.

In that case, why bother with the orbiting station?

The gravity in space is even lower...

The gravity in space is whatever you want it to be.  Artificial gravity is easy as pie for a large structure.

It's even easier on a planetary surface! Besides, most "health problems" from low gravity aren't much of a problem unless you return to a higher-gravity well.

Why would you want commerce and industry to be light 24/7? It wastes electricity.

Read what I wrote more carefully.  The whole point is that you don't need a watt of electricity to provide all the light you want.

Starlight on half the outside, nothing on the inside.

The problem with space smelting is, you can't get rid of the heat...

Yes you can; just build a radiator.  In space you can insulate with vacuum until the smelting is finished then connect it to your radiator bank which can exist in three dimensions.  Keep in mind that a little patience goes a long way.  Make your radiators able to survive high temperatures and then allow a couple weeks for the heat to smelt away.  You can afford to be patient because you can just move the smelting equipment on to the next batch while you wait for the stuff to cool.

I'll take your word for it. It would still be as simple to smelt it on the Lunar surface, and cheaper to ship metal up than ore.

All these problems are just pretty basic engineering constraints that can be cheaply solved with an ounce of planning.  Think outside the box a little here, we are talking speculation here so try to understand how things could be different before insisting they wouldn't work.

These ideas could work, but they're not the best.

[andrea]

Space is a good place for heating!?

I mean, the fact it's permanently near absolute zero, the fact it's in a vacuum, and that getting equipment to heat stuff into space would be ridiculously expensive?

May as well smelt it on the moon. Also, the useless stuff (e.g. sulphur) wouldn't be blasted into space along with the useful stuff (i.e. the iron).

(Space would be a good place for smelting because you could get very high temperatures on the cheap if you just shine a lot of light on your smelting material and then don't radiate it.)

This is thermo 101, if heat goes in and it doesn't go out then temperatures rise.

And then problems arise once you're done smelting. Besides, don't liquids not exist at zero pressure?

yes, metals would evaporate at high temperature in vacuum. that could be solved by a container. metal vapors would fill it until pressure was enough to keep it liquid. ( wouldn't require much pressure)
not a perfect solution, but probably workable.
another possibility, still in an enclosed container to avoid losing materials, would be producing everything out of vapor deposition. that might be tricky however.

[mainiac]

In that case, why bother with the orbiting station?

Because of all the reason I've already laid out?

Look this argument is getting contentious which means that I really dont want to continue it.  If you have any questions because you are actually interested in the idea of space habitats I'd be happy to answer them.  But these questions are kind of silly and you keep ignoring stuff that I've already explained.

Thing is, sunlight doesn't produce that much heat, other sources of heat would cost a lot to get into space, too, and no radiation is damned hard. impossible.

Still got the problem of the ore weighing more than the finished product, too.

Even if you account for the radiation lost prematurely the point is that you can radiate in more heat then radiate heat out for a while.  This is just a fairly trivial engineering problem.

[MetalSlimeHunt]

Thing is, sunlight doesn't produce that much heat, other sources of heat would cost a lot to get into space, too, and no radiation is damned hard. impossible.

Still got the problem of the ore weighing more than the finished product, too.

Direct sunlight on Earth's surface will get you to about 100 degrees in six hours. Over half of that light has been filtered out by the atmosphere. If there is no atmosphere...

[GreatWyrmGold]

In that case, why bother with the orbiting station?

Because of all the reason I've already laid out?

You can dig much more easily than you can smelt metal, assemble airtight chambers, and add air, and you don't need other worlds to ship you stuff to dig.
You never addressed terrestrial/lunar centrifuges, nor the myriad ways you can control your environment even on Earth.
What were your other ideas?

Look this argument is getting contentious which means that I really dont want to continue it.  If you have any questions because you are actually interested in the idea of space habitats I'd be happy to answer them.  But these questions are kind of silly and you keep ignoring stuff that I've already explained.

No, you're ignoring my counterarguments. Plenty of them. If I was at a computer, I'd list all the ignored counterarguments with quotes and stuff.
It's an interesting idea, and I'm not against it, but it won't replace surface living.

Thing is, sunlight doesn't produce that much heat, other sources of heat would cost a lot to get into space, too, and no radiation is damned hard. impossible.
Still got the problem of the ore weighing more than the finished product, too.

Even if you account for the radiation lost prematurely the point is that you can radiate in more heat then radiate heat out for a while.  This is just a fairly trivial engineering problem.

Again, ORE IS HEAVIER THAN THE METAL.

Oh, and engineering can't solve everything.

Thing is, sunlight doesn't produce that much heat, other sources of heat would cost a lot to get into space, too, and no radiation is damned hard. impossible.

Still got the problem of the ore weighing more than the finished product, too.

Direct sunlight on Earth's surface will get you to about 100 degrees in six hours. Over half of that light has been filtered out by the atmosphere. If there is no atmosphere...

And then you can use the lunar surface to soak up the excess heat.

[mainiac]

Lets just agree to disagree because I'm not explaining things to you anymore.

[mainiac]

You may as well smelt on the lunar surface. The only advantage of it being in space is... well...

No heat conduction and a zero gravity environment.

[MetalSlimeHunt]

Also, getting the fecking huge heating technology into space would be a large engineering/costly challenge. You could take it up in stages, but then one thing goes wrong, the whole thing can screw up. Also, the cost would still be a factor.

It's not that huge.

But we should be building a space elevator to reduce costs anyway.

[Sir Finkus]

Here are my thoughts on a realistic mars mission.  Critiques welcome.

We begin by building a vessel using the ISS.  That way you can take it up in pieces, and you can have "dry runs" where people can live in the exact same environment that they'll be making the trip in.  It seems a lot smarter than just building a huge rocket and launching it all at once like we did with the moon

Once everything is ready, we toss the Mars ship out of orbit towards Mars  Once we reach Mars, we don't attempt to land.  The ship/station orbits Mars while the astronauts drive rovers around and do other sciency stuff.  We don't have to worry about delay or bandwidth nearly as much, and images/other data can be analyzed instantly on the space station.  It might even be a good idea to toss a space telescope or two into orbit. 

Unmanned resupply ships could be sent every two years.  Eventually we'd have enough infrastructure to build a landing vehicle and support a crew on Mars.

We'd probably need a few things:
-A way to grow food reliably on a space station.  This probably isn't such a huge issue, we just haven't scaled it up as far as I'm aware
-Better unmanned spacecraft that we trust to dock with stations correctly.  Also probably not a huge issue, we just need to get a robust system in place. 
-More research on living in space long term (some people would be probably stuck on the station for years).

[GreatWyrmGold]

You may as well smelt on the lunar surface. The only advantage of it being in space is... well...

No heat conduction and a zero gravity environment.

No heat conduction is as much a problem as a benefit, and can be achieved on the Lunar surface fairly easily with some sort of engineering solution. As to the zero-G environment...how does that help?

And would you mind at least trying to counter my arguments you dropped?

[thobal]

Anything preventing centrifuges on Luna from working? It would probably be simpler if nothing else, because you have something to anchor to. The only downside is that if you stuck a whole city in the centrifuge, gravity would shift by 1/3 G each revolution.

No real downside, you just rotate the thing 90 degrees from your mental image(axis of rotation should be perpendicular to the surface). Basically you just build the thing on rails on the inside slope of a crater. Not some silly Ferris wheel looking thing.

As for the refining moonside or space side argument, both methods probably have their place. The problem I see with spinning cities in space though is one of maintenance/materials. That thing is going to be trying to constantly tear itself apart and it'll need to be huge. I mean BIG. This is because if you make it too small then the experienced gravity will be noticeably different along the length of a standing human. Translation: Tidal forcing acting on your internal fluids.
Another issue is mass balancing. The center of gravity needs to be perfectly aligned with physical center of the station. Otherwise you get wobbling. The systems I've seen described involve a complex system of water(or mercury) filled tanks and pipes all throughout the ring automatically compensating for anyone deciding to, say, go for a walk, or move a piece of equipment around, or take a shower. Any failure of the system would cause wobbling and again, tidal forces/apparent gravity distortion.

So it's a complex issue. But I think that different applications will be useful for different things. The metal crystal thing just highlights the need for continued experimentation. Did you know the ISS was supposed to get a lunar gravity wheel? They were going to have a guy hang out inside in order to see if lunar gravity would prevent the bone degradation of free fall.

[mainiac]

Why in space would a rotating object tear itself apart?  The entire point of the exercise is that you mimic gravity, i.e. the acceleration is 9.8 m/s.  If you apply a little logic to the situation for a moment you can see that we have plenty of macrostructures that withstand such acceleration, or else all our bridges would collapse and our skyscrapers would tumble...