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Space Hotels!

Posted by: koxinga - Wed Jul 14, 2004 12:58 pm
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Post    Posted on: Fri Jul 16, 2004 4:58 pm
Mmmm.....yeah i suppose solar wind based induction should be possible but i doubt how effective it could be.

(btw, do you have a link to the study you are talking about?)

I mean, only a small percentage of the energised particles in the solar wind should actually usefully induce a magnetic field and such a comparatively weak field would not effect such energetic particles enough to deflect a significant percentage. The process may be ok for a whole planet but the effect might be too small on spacecraft scales. Don't forget, the magnetism at venus doesn't deflect all the harmful radiation, this partly contributes to its runaway greenhouse effect. oh, and i just thought, if the ship is not properly protected by this induced magnetic field it could cause havoc on the station.

I don't think that using water filled jackets would be much good either, it essentially loses the point of having an inflatable station. Water is one of the least compressible fluids known to man and is also relatively quite heavy. The reason for them designing air inflated stations is that air is easily compressed and so can easily be launched into space.

If people want to have a properly radiation shielded station then they will have to pay for the extra cost of dense materials.


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Post    Posted on: Fri Jul 16, 2004 6:01 pm
Wow. Okay, I'm now officially converted to inflatable stations, at least for small-to-medium projects (I have no idea how you'd manage to rig up one big enough for Clarke's orbital Hilton). Of course, an airlock and a few other structure would still have to be rigid and either plastic- or metal-based, but with walls like TransHab's, this sucker's sturdy.

As for radiation: there are two types of radiation shielding: active and passive.

Passive is water or some other substance that is used to line the hull of a launch vehicle or station to deflect the radiation. A material's effectiveness at resisting radiation is directly proportional to its atomic mass (aka density): hydrogen ice is miserable at it, while uranium is extremely good at deflecting radiation from other sources (although it emits radiation of its own). For this reason, most radiation shielding is made out of lead, which is the densest stable element. Unfortunately, there is a premium on launch weights: lead has the incredible disadvantage of being extrememly heavy (which is why it's good at blocking radiation). So lighter, slightly less effective elements are used. Water (which, at just under 18kg/gal is much less massive than lead) is also extremely effective, especially so-called "heavy water" (which contains the deuterium isotopes of hydrogen rather than the regular isotopes -- deuterium has an extra neutron, thus doubling its atomic mass). The biggest advantage to water is that it can be circulated, giving even greater protection, and does not absorb radiation well.

Active shielding is the kind that Ekkehard Augustin brought up -- the use of an electromagnetic field powerful enough to deflect the charged particles that are the most dangerous component of the solar wind, thus allowing the passive shielding (against other EM radiation) to be much less massive. The best candidate is a "warm-temperature" superconductor, which, unlike a normal magnet, does not have poles to funnel radiation into. Of course, this must still be cooled to very low temperatures for it to function at all, and still requires rather copious amounts of electricity: so if the power goes out, you get turned into one crispy critter in very short order. Obviously, the prerequisite for an active radiation shielding system is an internalized, guaranteed power source.

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Post    Posted on: Sat Jul 17, 2004 4:53 am
How abt Kapton foil shielding? They use them on the Apollo missions.


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Post    Posted on: Sat Jul 17, 2004 8:58 am
Hello, Nova,

I'm going to look for the article, the scientists and some links and post it here.

Conserning the efficiency of shielding by gases or fluidables and solar wind it might be possible to compress the gases in comparison to the venusian atmosphere and it is possible to compress them in comparison to our atmosphere.

Second I suppose combinations of several methods of shielding to be possible to reduce of the weight of metal required for shielding purposes.

Your'e argiúment may be right, but the magnetic shield of Venus has a very surface and that of our plante will have a very large surface too - for purposes of a spacecraft or a space station it doesn't need to have a large surface. That may be an advantage.

At the NIAC homepage there is a study explaining how to use the thrsut of the solar wind as a drive for a spacecraft. This thurst seems to be strong. That seems to be due to the number of paticles too. Th thrust is pushing on a magnetic field. So the number of particles and their speed may be sufficient for active shileding too

Hello, spacecowboy,

there might be several additional solar sails required to protect the ISSS by active shielding. But may it be possible to use the solar wind as a source of electricity as well as a source of shielding? I have been thinking about nanocarbontube-shild against debris earlier in this diskussion - nantubes are conducting elektricity. If it is possible tu induce electricity in nanotubes thtis short pulses may be stored to use it later as a source of stable voltage and power. It may partly depend on nanotechnology. Additionaly i remember to have read of ideas to store solar energi at satellites by a new method: the motion of big wheels.

Might something out of this sample of raw thoughts provide the amount of electricity needed?



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Post    Posted on: Sat Jul 17, 2004 12:45 pm
Hello, Nova,

I'm sorry I didn't find any link yet. The results of the computer simulation being used to calculate the model were reported on May 29th this year - may be that's the reason why there is no link and it will come later.

The calculations and the computer simulation were done by Prodessor Harald Lesch of the Institute for Astronomy and Astrophysics, University of Munich, together with his colleges Guido Birk and Christian Konz. This and the results were reported by Die Welt in an article titled "Wird die Sonne das kränkelnde Magnetfeld der Erde retten?"

Yoe will find the e-mail Adress of Professor Lesch at the homepage of the institute.

spacecowboy,

concerning the colling I remember that astronauts having done an extravehicle activity have reported several times to suffer from being th space very cold. But their suits have been heated bacuase of this. May that remove the necessity of colling at least partly? What about of cooling down at the dark side of th earth?



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Post    Posted on: Sun Jul 18, 2004 1:29 am
Ekkehard: first off, try to watch double-posting. It's just bad etiquette, but some people will flame you for it. Use the little edit button and everybody'll be happy.

Second, Nova made a good point, so let me try to explain it.

The radiation in the Solar Wind induces a very weak magnetic field in the upper atmosphere of Venus. Unfortunately, the Solar Wind is not terribly good at it: the Wind is actually fairly weak. So: the Solar Wind can only generate a noticeable electromagnetic field in an object the size of a planet. This means that a spaceship is far too small (regardless of the induction medium, be it water or solid gold sheeting) for the effect to have any impact whatsoever on the radiation.

I'm not sure about using those particular methods of electricity generation... I was personally thinking more along the lines of a fission or fusion reactor that would be contained inside the electromagnetic field (thus protecting the power source from the EM interference).

And you're right: when you're on the dark side of the Earth (or the Moon, or anything else, for that matter), the temperature of the vacuum drops to near-absolute-zero (about -273°C), because a vacuum does not absorb and retain any heat. All heat in space is radiated, so the only heat you'll receive on the dark side of the earth is what little is being emitted from the Earth's atmosphere and what less is bouncing back to you off of the Moon.

Unfortunately, when one is in sunlight, the temperature can reach several hundred degrees C nearly instantly (I think it's in the 400-500 range, but don't quote me on that). This provides the interesting dilemma whereby the side of a spacecraft (or astronaut) that is facing the sun is extremely hot, while the other side (which is not facing the sun and therefore dark) is extremely cold. This polarity of temperatures -- which, if you do no more than turn around, can totally reverse in a matter of seconds -- is one bane of any design engineer, because the vehicle has to be able to withstand the temperature change without popping neatly in half right along the shadow line.

So, in short, the answer to your question is a qualified yes: if the superconductor is kept in shadow, the need for a cooling system can be reduced, if not done away with entirely.

Oh, and koxinga: I ran a couple quick Google searches (the wrong ones, with my luck), but I couldn't find any comparisons between Kapton foil and lead sheeting. However, NASA's been researching some polymer compounds for use as lightweight radiation shielding with regards to a Mars voyage. Of course, the biggest advantages to using lead (especially on a station) are that 1) extra mass is always a good thing (it'll keep you from moving accidentally), and 2) it's fairly cheap to import from the Moon and the asteroids.

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Post    Posted on: Wed Jul 21, 2004 3:20 am
http://www.thespacereview.com/article/187/1

Another article on Bigelow and inflatables. I quote the following paragraph

"The shell of the module was to have been a foot thick, made of more than twenty different layers of foam, Nextel, Kevlar, Nomex, and other materials. It would have provided some protection against micrometorites and small bits of orbital debris. More important, it would have done a better job at shielding the people inside it from various forms of radiation. It is this characteristic that has attracted the attention of the NASA space architect and the people designing the missions that will take us back to the Moon and beyond."

How does the better form of shielding happen? From this paragraph, I gather that it is because of the different material used.


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Post great article   Posted on: Thu Jul 22, 2004 7:39 pm
thanks for posting that article.

it's got me all excited. I'm all POOFED up, as it were. *chuckles*

seriously, it's starting to sound like the corporate/government collaboration is starting to create synergy


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Post    Posted on: Fri Jul 23, 2004 9:39 pm
This whole conversation is extremely exciting to me. The very thought of "inflatable" modules joined together into a space hotel. I'd check in!

Sorry, I can't remember who spoke the desirability of lead because of being able to mine it from the moon, etc... What a great concept. It seems to me the entire point of the inflatables is to save volume and weight on the launch vehicle. Once the module is inflated, perhaps it could be coated with the heavier materials mined in space.

I'm also thinking of the old Lunar Module. Here I'll show my ignorance, I'm sure. But wasn't part of that craft (and other NASA manned craft) some very, very thin reflective material? I've always been under the impression that shielding from the radiation can be done with some sort of foil, and that the bulk of a craft's fuselage is so that it can withstand the various forces to which it is subject. Am I wrong here? If not, then, again, the whole concept of "coating" the module could easily come into play.

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Post    Posted on: Sat Jul 24, 2004 1:15 am
JustMeKevin wrote:
I'm also thinking of the old Lunar Module. Here I'll show my ignorance, I'm sure. But wasn't part of that craft (and other NASA manned craft) some very, very thin reflective material? I've always been under the impression that shielding from the radiation can be done with some sort of foil, and that the bulk of a craft's fuselage is so that it can withstand the various forces to which it is subject. Am I wrong here? If not, then, again, the whole concept of "coating" the module could easily come into play.


As far as I'm aware the material you are talking about are the insulation "blankets" that surrounded the modules (the black and gold bits). Unfortunately they were designed simply to provide protection against the thermal change that occurs to the different parts of a craft that is part in sunlight and part in shade (and it provided protection from mini-meteorites and insulated the craft). Similar coverings have been used on more recent unmanned space missions.

This does raise an important question, What exactly was the radiation protection on the lunar module and if there wasn't much how come the astronauts did not seem to suffer any ill effects? I feel a conspiracy theory coming on :D , but it is an interesting point.

I don't think, barring some amazing new super-material, that any thin material could be used to effectivly protect a manned vessel. The apollo missions had one crucial thing on their side, time. With the relative shortness of the mission it was unlikely there would be any major solar event that would really test shielding. unfortunately a permanent space station would have to weather potentially far more dangerous storms.


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Post    Posted on: Sat Jul 24, 2004 2:01 am
We will see stronger and lighter materials from Nanotechnology


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Post    Posted on: Sat Jul 24, 2004 9:28 am
Any shielding material would have to be more dense, being strong and lightweight are only secondary to this. If it where that simple they would just clad spacecraft in something like titanium (or similar) sheeting as protection.

Nanotech might be promising in this area though, as materials with modified structures on the nano-scale could theoretically provide a better ability to withstand a range of radiation. We are probably still a way away from large-scale commercial use of nanotech though.


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Post    Posted on: Fri Jul 30, 2004 9:02 am
I'm kown to an engineer being an entrepreneur too. He is partner in a nano-technology firm too. Once he told me that the main problem concerning the commercial use of nano-tech is that today there is nobody who needs nano-tech. Nobody needs a billion turbins, propellers, motors etc.

May be these amounts are useful in space or as parts of spacecrafts. Perhaps this is the market the nano-tech-firms are looking for.

If nano-structures are a good shielding material this would be an additional quality of them. But they should be tried to make use of in spacecrafts especially because of their other properties.

What way do they protect against radiation? Density only? Then they may be wasted in that use.



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Post    Posted on: Mon Aug 09, 2004 7:42 pm
Avoiding radiation shielding, another alternative to an inflatable module is a "Wet" hab, or module. This was thought about during development of Skylab, and has been suggested again. The basic idea is that when the Space Shuttle or a Heavy lift booster goes to orbit it usually discards the upper stage left to fall back to the ocean (or Australia in the case of Skylab, which accidently killed a poor jack rabbit :cry: and the United States got fined for littering.... I dont think we payed) In this case the upper stage or external tank is boosted into orbit and left as a spacestation to be renovated. The External Tank of the shuttle is 154 feet long and 27.6 feet in diameter. It could be hardened against radiation, and space effects, and launched either by the 2 SRBs and an empty orbiter or 2 SRBs and a Shuttle C depending on its weight. The Shuttle C (orbiter replaced essentially with a orbiter sized cargo container and 2-3 SSMEs) could be carrying some of the equipment or cargo for the renovation as well.


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Post    Posted on: Fri Aug 27, 2004 12:12 pm
Having in mind another discussion (or two) I looked to the Bigelow-Site for some informations but didn't find anything.

I wanted to find out what further ideas Bigelow might have concerning his inflatables. Perhaps he is already thinking about causing artficial gravity by setting them to rotation around a center. The center and the cable to connect it to the inflatable might be launched years after launching the first in orbit established hab.

Do someone know more? And might it be possible to create a torus using the inflatables at least as a basis? Are they dockable together? What about constructing a segment of a torus around the sides of an inflatable, moving it out of the new construction and docking the hab to it?



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