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A problem with centrifuge based colonys!
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Marsman
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PostPosted: Fri Jun 16, 2006 10:54 pm 
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But the fact remains that building cities in space will rely upon technologies not yet developed(as will a Mars city). The difference being a planet provides much more in the way of natural resources and some protection from the vacuum of space. Ask any astronaut where they would rather work, space or Mars and most of the time they wil choose Mars. People like to have earth under their feet too. It seems to me a natural evolution to go from one planet to another seeing we are already quite experienced with that way of living and working. Working in space, especially low Earth orbit is highly dangerous and so far very tedious. Microgravity is not at all healthy for human physiology either as we all know and I think we will have enough problems adjusting to the lower Mars G then no gravity at all. Look how long it took to construct the ISS. Do you really think a city around Earth is possible before a city on Mars? There is also the problem of people having no will to do any of this. If space cities were so popular where are their big advocacy groups? All of the current focus of the space community is on return to the Moon and going to Mars. There may be a few private hotels and stations in orbit but my guess is that a city will be around 2 centuries off yet. In that same period Mars will easily have a city even based on current technologies. Many proponents of space cities talk about how close and convenient it will be to have such places but it is not exactly easy to get anything into that part of space as we all know. I don't think there is any comparison to living and working on a planet as opposed to space.

Radiation, micrometeorites, space junk(a million bits at last count) and no readily available resources will be constant problems for the space city builders. On Mars the resources are there already. Certain manufacturing functions will have to be set up to begin with but once done they will soon benefit from working on a planet. For example, if a load of metal tubing needs to be transported from the factory to the city work site it only takes loading it on a truck and off you go. For a space city, if they need extra supplies another launch has to be prepared and added to the cost. Without a space elevator(I think its still 50 years away) supplies will not come easy for such ventures. Another issue is the power problem. It might seem easier to build a totally artificial habitat in orbit, but the power requirements will demand more than just solar arrays. Will people of Earth like the idea of having nuclear power hovering over their heads? It is going to be hard enough to get such a power source to Mars let alone orbit. But you know me, I'm a Mars fan in the extreme. But you know if we get to see cities in space before Mars, that's fine by me too. As long as we do it.

Also, here is an article in support of space colonies. Kind of shoots me in the foot but hey, I have to be fair. http: www fordianvillage com article_read asp?id=45
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JWSmith
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PostPosted: Sat Jun 17, 2006 3:45 pm 
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Marsman wrote:
Will people of Earth like the idea of having nuclear power hovering over their heads?


Read Robert Heinlein's "Blowups Happen". Writen in the late 40's it still is instructive.

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It is going to be hard enough to get such a power source to Mars let alone orbit.


I do not know about that.

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But you know me, I'm a Mars fan in the extreme. But you know if we get to see cities in space before Mars, that's fine by me too. As long as we do it.


I also am a Mars fan to the extreme and I feel the same way. Not only do I belong to numerous Mars groups but am active in many "space settlement groups" as well as a few Venus settlement groups. Knowledge is where you find it.

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Also, here is an article in support of space colonies. Kind of shoots me in the foot but hey, I have to be fair. http: www fordianvillage com article_read asp?id=45


I am not sure that this shoots you in the foot. If you read it like I read it, it reinforces your position.
Like me Al Globus is a member of a number of Mars groups as well as "Space Settlement" groups. I read something he post daily. He has good ideas on Mars as well as general space.
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Marsman
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PostPosted: Sun Jun 18, 2006 11:32 pm 
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For that matter, what are these "space settlement" groups made up of? I have not really noticed them too much, certainly not like the Mars movement, I wonder where they rank in terms of popularity and support in space priorities these days?
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BEM
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PostPosted: Sat Mar 31, 2007 9:24 am 
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A problem that no one seems to have mentioned is some joker looking out a window and shouting "Hey, everybody look at this!" The population all runs over to the window, unbalancing the wheel..

..or less imaginatively, soil or water flowing to one location. this would be most obvious with a narrow spinning cylinder. material could gather at a point on the rim at top or bottom and instead of rotating along the axis, the whole thing would degenerate to 'spin the bottle'.
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MirariNefas
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PostPosted: Sat Mar 31, 2007 4:31 pm 
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The Kalpana One plan includes wobble control (pg. 5).

http: alglobus net NASAwork papers KalpanaOneASCE2006 KalpanaOneASCE2006 pdf
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Gourdhead
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PostPosted: Sat Mar 31, 2007 6:18 pm 
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A problem that no one seems to have mentioned is some joker looking out a window and shouting "Hey, everybody look at this!" The population all runs over to the window, unbalancing the wheel.
The centrifuge's diameter will be sufficiently small that windows would be disconcerting due to the rotation speed. Tv images would be used taken with cameras on the stabilized hull of the ship.
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BEM
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PostPosted: Sat Mar 31, 2007 7:37 pm 
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MirariNefas wrote:
The Kalpana One plan includes wobble control (pg. 5).
http: alglobus net NASAwork papers KalpanaOneASCE2006 KalpanaOneASCE2006 pdf


yes.. to quote:
Quote:
Wobble control is provided by a combination of exterior teleoperated robots moving
weights about and weights attached to cables on motorized winches.


Sounds like hard work. I wonder why not just have a counter weight and a long cable, or something like a dogs bone that spins end over end, instead of a cylinder or wheel. It might have limited areas at 1 g, but there would be a lot of ascending and descending stairs so even in low g areas the body would be getting exercise and impacts

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The 1st level
is 100m from the hull providing ample head room to avoid claustrophobia.


hmmmm. I'd like to think someone researched carefully before throwing a figure like that in.. but I dont. Very Happy
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MirariNefas
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PostPosted: Sun Apr 01, 2007 12:00 am 
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Sounds like hard work.


Not really. One or two guys sitting in a room, confirming some calculated best move values for weights seems pretty simple. But we can always automate it if we get too lazy.

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I wonder why not just have a counter weight and a long cable, or something like a dogs bone that spins end over end, instead of a cylinder or wheel. It might have limited areas at 1 g, but there would be a lot of ascending and descending stairs so even in low g areas the body would be getting exercise and impacts


This still wouldn't prevent wobble from building up if mass distribution became uneven. A long structure is more stable, but not perfect. In any system if you want it to be perfect for a long period of time, you need active controls. As long as you're going to have active controls, you might as well choose the design that maximizes livable volume. And we all know people would use the elevators.

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hmmmm. I'd like to think someone researched carefully before throwing a figure like that in.. but I dont.


Why? Claustrophobia varies. Hell, tolerance to rotational rate varies. This design here intentionally chooses a rotation rate that makes some (but not all) people uncomfortable. The idea is an initial settlement on a budget, which will only support a relatively small and specific population. Without having done the research maybe we aren't sure if that excludes 40% of the population, or 90%, but who cares? Enough people will be fine with it, there's plenty of data on that. After the first few settlements like this, when the economy is ready, we can waste resources on the people who need more than 100 meters.

Seriously though, that aside, who would really need more than 100 meters? That's huge. Sure, it's not huge enough to convince people that they're outside. And when I travel to Russia, nobody can convince me I'm in sunny California. Things will be different, that's only to be expected. But I can't imagine who wouldn't be able to acclimate to 100 meters if they wanted to.


Last edited by MirariNefas on Sun Apr 01, 2007 12:44 am; edited 1 time in total
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BEM
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PostPosted: Sun Apr 01, 2007 12:43 am 
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MirariNefas wrote:

Why? Claustrophobia varies. Hell, tolerance to rotational rate varies. This design here intentionally chooses a rotation rate that makes some (but not all) people uncomfortable. The idea is an initial settlement on a budget, which will only support a relatively small and specific population. Without having done the research maybe we aren't sure if that excludes 40% of the population, or 90%, but who cares? Enough people will be fine with it, there's plenty of data on that. After the first few settlements like this, when the economy is ready, we can waste resources on the people who need more than 100 meters.


this figure was for ceiling height of the main level, not radius for spin. Im sure I would be fine with a 4 meter ceiling. that could let you squeeze 25 times as many levels in that 100 meters. It could still include open mall areas etc, with nice projected skies.

Perhaps I misunderstood the intention of this 100 meter tall level and it actually includes multistory apartments, which would begin to make space sense to me again.
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MirariNefas
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PostPosted: Sun Apr 01, 2007 12:49 am 
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Oh, I get it, sorry. I thought you were saying that 100 meters wasn't enough. The stuff on spin was just to illustrate that the design ignored people who are too sensitive in one way or another.

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Perhaps I misunderstood the intention of this 100 meter tall level and it actually includes multistory apartments, which would begin to make space sense to me again.


Yeah, that was my understanding. I'm expecting them to have some pseudo dirt or gravel and traditionally constructed buildings on this level, and due to the space premium, that should mean an urbanized architecture. Sticking suburbia under 100 meters of sky would just be a waste, at least for an early colony.



I think you and I might be able to agree that a better early design would actually go with that 4 meter ceiling, and just incorporate most buildings/rooms straight into the structure. It couldn't use much passive lighting anymore, but solar panels are easier to manage in space than living area.
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PostPosted: Wed Jan 09, 2008 11:22 pm 
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The old Skylab did this and the astronauts were able to run on the inner surface of the mod'd Saturn V prior to full operational deployment. It is simple physics and does not involve gravity. It is the same way that a gyro manages to stabilize a satellite. It uses coriollis effects and centripetal forces. The maximum velocity should not exceed 2 RPM however, as this is the maximum that the average human can withstand over an extended period of time. This requires the object in rotation to be larger and have a more gradual angle over distance to establish a high enough velocity at 2 rpm to accomodate the astronauts desired pull.

It will work, and a larger station will have very stable simulated gravity from this design. It is really idiotic that NASA did not do this with the ISS. That is an organization run by politicos and not scientists. Any space business with their budget, technology and infrastructure could do 5 times more than they achieve with their old union mentality and risk aversion.
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Terraformer
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PostPosted: Fri Jan 11, 2008 5:12 pm 
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But, if I understand correctly, anyone one a building that projects into the middle would be weightless, above that they'd feel a force tugging them up.
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MirariNefas
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PostPosted: Fri Jan 11, 2008 11:28 pm 
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The O'Neil cylinder space colony design calls for a radius of two miles. The difference in gravity from the floor of a 100 foot building and the roof would be about 1%.

Different designs vary, but all have similarly large scales. So there won't be any problems because buildings just won't go up that high.
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Terraformer
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PostPosted: Sat Jan 12, 2008 12:28 pm 
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I've got a new idea. How about it being concentric, with the areas with one (or possibly more) G for exercise, moving inwards living space, until you reach the middle with the Zero-G labs and such like.
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MirariNefas
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PostPosted: Sat Jan 12, 2008 4:49 pm 
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This is certainly a good way of maximizing usable space, though to some people it may seem more claustrophobic. The Kalpana One design works like you say. It's not as big as an O'Neil - more like a Deep Space Nine or Babylon Five kinda thing, designed to be among the first space habitats. The design is very practical, catering to the industrial and research uses of space, so it doesn't worry so much if people will be comfortable with a roof over their heads. Comfort can come later, when we've got more space resources firmly under our control.
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