Space stations beyond ISS

samy · 2008-02-16 10:09:28

BTW, where did you get your figures for the amt. of m^2 /person (foodwise)

The "Eat like a Martian" thread (the link is right there in the post where I discussed the matter).

I'm confused. Is it about space stations orbiting Earth, or space colonies orbiting the sun?

Either or. General space colony rather than a moon or planet colony. You can discuss heliocentric or geocentric ones, either works.

samy · 2008-02-16 10:48:23

Here's a thought experiment following Bigelow's big idea -- inflatables.

If we wanted to construct a 450m diameter torus in space, bringing the rigid construction materials from Earth would require many many loads. You couldn't stuff the entire 450m diameter thing into the Space Shuttle cargo bay and just offload it in one fell swoop.

However, with an inflatable, you *can* get a 450m size torus in space with *one* Space Shuttle cargo bay, because it's compressed, and then inflated when it is out of the cargo bay.

Here's some rough calculations.

A torus that is 225m in radius, with the tunnel 5m in radius, with 5mm (1/5 inch) thick Vectran walls, would consist of 222 cubic meters of Vectran.

The Space Shuttle cargo bay is roughly 4.5m x 18m, which is 286 cubic meters. So, dimensionwise, you could compress the torus, stuff it in the cargo bay, launch, exit it in orbit, and then inflate it to full size.

However, 222 cubic meters of Vectran would weigh 311 tons while the shuttle's maximum payload is 25 tons...that's what shoots us down. Not the dimensions but the mass.

In order to fit the shuttle's maximum payload mass, the Vectran walls would need to be 0.4mm thick, at which point the torus would compressed be 18 cubic meters, and mass 25 tons.

If such thin walls would be viable, we could launch the torus whole and inflate it to 450m diameter in space. This would be just the air bladder of the station. After inflation, it should be coated both inside and outside with other materials to shield it from damage. On the outside, shielding against micrometeorite damage, and on the inside, against the mechanical scuffing resultant from human activity. Materials for the interior and exterior coating could have been launched prior to the air bladder launch and been left floating in space waiting for the air bladder to arrive. The interior and exterior coatings would not need to be airtight, their purpose is just to mechanically shield the air bladder. This reduces the shielding construction complexity. Theoretically, we could just spray the outside of the air bladder with layers and layers of hardening foam or whatever.

The key chokepoint of this technique is the required wall thickness for the air bladder to be able to contain a 1000mb (or 500mb, if we want to try working in low pressure) pressure differential with the vacuum. The wall thickness factors directly into the launch mass of the air bladder. If the construction material requires a high wall thickness, then you can't launch because it's too heavy. A high tensile strength material that can contain a 500-1000mb pressure differential at extremely low thickness is mission critical to the concept of building a 1g space station as an inflatable torus.

I'll try to look into the burst strengths of Vectran and other materials another day unless somebody can work that sooner.

One problem I see with inflatables is installing windows, or any other expansions. I don't see cutting holes in the air bladder as a particularly good idea. As such, an air bladder construction may be suitable for quick short-term setup, but long-term, a different architecture might be best.

In other words, first inflate an air bladder as a skeleton, then once you can shirtsleeve inside the "bicycle tire", construct an improved new airtight shell from the inside, and finally ignore the air bladder once the new airtight shell has been finished.

Terraformer · 2008-02-16 12:04:11

Or just add extentions.

Could a Shipyard using Bigelow modules be assembled in one Shuttle mission by launching the modules unmanned? Get a crew up and launch supplies unmanned.

samy · 2008-02-16 12:18:37

Depends on how big a shipyard. If it takes 1 cubic meter, sure. If it takes a million cubic meters, no. How many cubic meters does a shipyard need? Answer that, and you have the answer to your question.

cIclops · 2008-02-16 14:39:24

Perhaps we need a new forum for these fantasy projects. Compared with fusion engines, spacewarps and human AI computers, space shipyards are quite feasible.

Terraformer · 2008-02-16 15:30:27

Interesting how you wrote them in the order of Feasiblity: Fusion, spacewarps, then Human AI computers.

Terraformer · 2008-02-16 15:51:40

How about anti-sicknes drugs to tolerate higher RPM?

Say about 0.75g and 3 RPM, how big would it have to be? And it doesn't neccersarily have to be a torus. A central Cylindar with spokes coming of it that are connected to habs would work, wouldn't it? An elevator system could be used that uses the collects the wasted energy when it flies out towards the edge and recycles it back into the system. That would both slow the elevator down and recycle energy. The central Cylinder would be a hanger/ship-station building area.

samy · 2008-02-16 16:05:08

How about anti-sicknes drugs to tolerate higher RPM?

I'm definitely interested in any and all research into such medicines, so if you have any new info to share, I'm all ears.

And it doesn't neccersarily have to be a torus. A central Cylindar with spokes coming of it that are connected to habs would work, wouldn't it?

Correct.

Say about 0.75g and 3 RPM, how big would it have to be?

75m radius, 150m diameter.

Terraformer · 2008-02-16 16:39:58

I was just thinking about the sort of Car-sickness and Sea-sickness drugs for Nausea that already exist.

samy · 2008-02-16 16:54:12

I'm pretty sure there are *some* g-loc medicines, but I have no idea about how effective they are.

Incidentally, a "Titan Jr." station training astronauts for Titan gravity would only need a 31m radius of rotation. I suppose it'd be a good test bed/scale model to try out before building a full-on 1g habitat.

neviden · 2008-02-17 08:56:25

The "next space station" should definitely be built not assembled. The problem is of course where do we get all that material. We could get it from Earth in the form of melted upper stages, or we could get it in the form of material from NEOs that would get to HEEO via moon flybys. Either way the whole thing would need two technologies:

1) Knowing how to make metal plates. Upper stages are already mostly made from aluminium, therefore we would have to melt it and pour it into plates. Rotation would make things as simple as doing that on earth and vacuum would be even better, since there is no oxygen to get in the way. Some NEOs are already basically steel chunks or have high amounts of metal oxides that could be separated into O2 and metals.

2) Knowing how to weld those metal plates together. A satellite with two or more robotic arms and an electron beam welder would make everything work quite nicely.

After that you build a large barrel. In the center you could have 0g docks, hangar(-s) and low g working area. The rest of the volume could be made with plates into levels for different things and uses. The lowest levels could have 1g gravity and you could eventually even pour concrete or simply put gravel on the floor to reduce danger from radiation or punctures. For extra protection against radiation you could have a form of aquaculture where the lowest flour would have fish in the “radiation shield” that would be connected with hydroponics system for growing vegetables. That system would be mutually supportive, robust and would produce good food (we know how to do this on earth since we already do this in many locations).

If it would be in some stable orbit it wouldn’t go anywhere therefore it wouldn’t matter how heavy it would get. Actually the bigger it would be more shielding we would get. That way you get safe, large volume of “Earth like” space where you can essentially do anything you would do on Earth. If you grow food, recycle air and have enough people to run a decent machine shop, that means you only need to deliver small amounts of things that you can’t easily build in space. That also means that your crew can stay there for more then 6 months and can actually comfortably live there and have large “T-shirt” protected hangar where they could make, fix, test and assemble things.

Simply imagine that thing as a mix of cruise liner, oil rig and arctic station. I do have doubts that we could get that much construction material to LEO safely and cheaply, but that thing could work out just as easily in some HEO (material from the Moon or NEOs). There wouldn’t be anything that we couldn’t easily fix and that thing would actually be usable for decades or even centuries..

Terraformer · 2008-02-17 09:06:01

I see only one flaw in your plan: we need a station up there to make the metal plates. A shipyard is the way to go. Having the craft being able to dock in the middle would require the craft to rotate in synchronocity with the hanger, or have the docking rotate so as to keep it syncronised with the incoming ship.

neviden · 2008-02-17 11:13:11

Yes, we would probably need rotating thing from the start. But why is that such an impossible thing to build?

http://ntrs.nasa.gov/archive/nasa/casi. … 019854.pdf

Terraformer · 2008-02-17 11:28:13

I said it can't be the next station, as we need one up there to make the plates.

neviden · 2008-02-17 12:17:12

Sure. You need initial three parts. one in the middle (where you dock) and two for each end of a tether. Spin – gravity – melt – pour – metal plates – weld – station. The middle part becomes a convenient docking port and you can weld it into station (probably at the end when it is the only missing piece of a barrel.

Or if you prefer you can design some fancy centrifuge that will create gravity. But tethers seem so much simpler and lighter. You don’t even care how much g’s or how fast you spin. As long as the plates are more or less the same, then they are ok. Few cm thick should be more then enough for a basic shell. You can always continue the work inside later, in T-shirt, 1 g environment of course.

Terraformer · 2008-02-17 13:48:09

Er.. this thread *is* about the next space station, not the one after the next. How do we build the place to make the plates?

Commodore · 2008-02-17 19:53:36

Or, you could just do your forging on a smaller gravity well with much less of an atmosphere. Thats why we have a Moon. NEOs could work as well, but are more complicated. Build some smelters and mass driver on the Moon and you'll soon have more metal plates then you know what to do with.

As for something to apply them too, I've always liked the basic architecture from the Space Island Group, even though they grossly underestimate the modifications required to the ET to get there.

Martian Republic · 2008-02-17 20:19:49

Sure. You need initial three parts. one in the middle (where you dock) and two for each end of a tether. Spin – gravity – melt – pour – metal plates – weld – station. The middle part becomes a convenient docking port and you can weld it into station (probably at the end when it is the only missing piece of a barrel.
Or if you prefer you can design some fancy centrifuge that will create gravity. But tethers seem so much simpler and lighter. You don’t even care how much g’s or how fast you spin. As long as the plates are more or less the same, then they are ok. Few cm thick should be more then enough for a basic shell. You can always continue the work inside later, in T-shirt, 1 g environment of course.

I have no problem with the basic idea of a spinning space station, but what your are describing would take a lot of resources and need something to manufacture those plates to make the basic space station. There would be absolutely no way to build the next space that we build, doing what your suggesting that we do. It would probably take twenty to thirty years to even be in a position to even start building such a project even. If we set up a lunar mining and manufacturing facility and/or could mine the asteroids or possibly have an intermediate space station up there first, then what your suggestion might be possible, otherwise it won't be possible. It won't be possible, because it requires too much resource to put it together and manufacturing capabilities in space that we don't currently have to do such a project like that.

Larry,

neviden · 2008-02-18 02:58:41

..or possibly have an intermediate space station up there first

That is exactly what I am talking about. Ok, let me go more into details on how and why this would work.

First you send central “docking section”, then you send “manufacturing section” and then you send “living section”. With those three sections you build a long (200 m) station that rotates (kind of like the NEP ship in the proposal).

I personally don’t think that we need nuclear power and that solar power could provide more then enough power. In that case we unfurl 2 large wings (200 x 100 m) and “hang” them onto the main support structure. That way we get about 10 MW of electric power that we can use it to either move our “construction station” to higher orbit by using electric propulsion, moon orbit, NEOs or Mars orbit (Phobos and Deimos) or power our smelter. If nuclear power would be preferable then it would look a lot like NEP on a link. That thing should weigh anywhere from 50 mT to 200 mT (or more) depending on how big we build but what are we talking about is in the range of Mir station.

After everything is working, we must find material to melt into plates. In LEO that could be used upper stages, old satellites, junk, used parts of ISS,.. anything that could be economically brought to the “construction station” would be transferred there with our “welding robot/tug”, cut up, melted and converted into plates. There is probably not enough material in LEO to make this worth it, but it could be done.

But my focus isn’t on the LEO (since it lacks materials in any great quantity) but on NEOs or the Mars moons. You move your “construction station” to some easily accessible NEO. You pick up pieces of one, melt them, store O2 and store plates (maybe even start building station). When we have enough of them use O2 as propellant (SEP/NEP) for our station to move it back to high earth orbit (probably via moon flyby). You can further lower it (via SEP or aero braking) to LEO, but HEO is also good orbit to put a station in.

To make everything work you need: SEP/NEP propulsion, small smelter, living section, docking section, power source (reactor or solar wings), tug/welder (ATV/progress with robotic arms basically) and a way to get people to LEO (preferably to HEO). Nothing that couldn’t be done or hasn’t been done already.

The price of all this construction would be the development and cost of hardware, lifting 200 mT to LEO and support for multi-month (year) mission. You would still have to put things inside of your station to make it useful, but that could be done over time. You don’t even need to develop special “space hardware” since you can go to your local shop, buy things and they will work without modifications. You could pack it to survive high stress (high g) trip to LEO, put it into container, pick that up in orbit and later assemble it inside a station. That would make further construction/upgrades as complicated and expensive as renovating a house or a ship. To put things into prospective: a nuclear aircraft carrier costs about $4,5B to build and that station would be about as big as a nuclear aircraft carrier.

SEP/NEP “construction station” would also serve as a great ship for a mission to Mars, even if that mission would require further development of lander and surface capabilities. Putting smelter on the Moon has an advantage of a readily accessible material, but the problem arises as to how you put that material back to orbit and the need for a lander.

dicktice · 2008-02-18 16:29:36

I don't think manufacturing metal stock, in the form of plates and beams, in space would be the way to start. How about extruding wires, which could be coiled prior to use, and then bent, twisted, braided, woven, and finally fused in place to form the various structural elements of the space station as needed, during construction?

neviden · 2008-02-19 02:53:04

We could also just build things with jets of molten metal that would solidify on contact, but why complicate things needlessly. Beams and plates are simple enough to make and weld together. The whole process is constantly used to build things on Earth and there isn’t any particular reason why it wouldn’t also work in space.

Let me put it another way. We build ships out of metal plates. It is the most cost effective way of building large things. If I would suggest that we build the next aircraft carrier out of 100.000 tons of fused metal wire, everyone would look at me like I am completely insane.

Terraformer · 2008-02-19 04:24:14

But if you suggested building the next spacecraft carrier out of fused metal wire without any Gs to make metal plates in they'd compliment you for an excellent idea.

I assume the wires would be heated by a current to cause them to melt?

neviden · 2008-02-19 04:41:16

But if you suggested building the next spacecraft carrier out of fused metal wire without any Gs to make metal plates in they'd compliment you for an excellent idea.

If I stay with aircraft carrier comparison.. sure, they would congratulate me for a good idea on how build a ship in the middle of the sea, maybe even under the sea, but why would anyone want to do that, if you can build ship in a dry dock?

What is wrong with rotation to make Gs? I don't see any flaws in it, you do? Why shouldn't we create 1 G environment, pour plates, then simply weld them together?

Terraformer · 2008-02-19 05:40:00

Exactly. We need a station already up there before we can build a spacestation. If we didn't have a drydock, we'd have to options: Build one, or construct the ship in the middle of the sea.

neviden · 2008-02-19 05:59:35

Exactly. We need a station already up there before we can build a spacestation. If we didn't have a drydock, we'd have to options: Build one, or construct the ship in the middle of the sea.

Rotating smelter would in affect be a dry-dock, since this is not a situation where you need to keep water away from the area where you work. You only need gravity to make plates. You don't need it to weld them together (it would actually be easier to weld them in 0g).

Vacuum is quite a good environment to make an outer shell in. Once this is done and you can fill that shell with air, you don’t need any extra equipment to work in there. That means that you don’t need EVA to change a light bulb or install power lines. It’s a safe, T-shirt environment.

Let me repeat how it would be done:

1. Build small “construction station” out of 3 parts and rotate them
2. Send it (or send material to it) to where it will be able to make plates
3. Use robotic tug/welder to bring material and position/weld plates
4. Weld together a “big station”, fill it with air so that you can work inside
5. Complete the station, move “construction station” somewhere else or simply integrate it into the finished station.

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Re: Space stations beyond ISS

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