Author Topic: Space colonies using rubble piles  (Read 4443 times)

Offline alexterrell

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Space colonies using rubble piles
« on: 02/28/2010 09:00 PM »
Over here - http://forum.nasaspaceflight.com/index.php?topic=18759., we discussed the concept of inflating a habitat inside Phobos. This would instantly provide a large shielded space.

Larry Niven's "Farmers World" was a large iron asteroid, which was rotated, filled with water bags, and then melted, and hey presto, a large rotating cylinder colony was made.

Perhaps more realistic, given that a lot of asteroids are rubble piles (no tensile strength):

1. Find a 400m diameter rubble pile (about 60 million tons)
2. Process some of the material to make a metal shell, a km in diameter and a few mm thick, with the rubble pile at the centre.
3.  In the centre of the pile, inflate, under low pressure, a balloon. Gradually inflate whilst controlling the position, until all the rubble forms a 10m thick shield just inside the metal shell
4. Next inflate a second shell to give about 10m clearance. Then line this shell with fibres (carbon nanotube, preferably, but any strong fibre will do), until it's strong enough to withstand air pressure and internal forces.
5. Rotate to provide artificial gravity

You have a Bernel Sphere, with very limited material processing. You can scale up, though the pressure vessel mass increases with the cube of diameter.

As an alternative, to above steps:
3. Attach electron guns to the metal shell. Fire electrons at the rubble pile, to give it a negative static charge. The metal shell will become positively charged. After a while, the rubble pile will be stuck to the metal shell.

Yes, I know the eventual colony is in a solar orbit and needs a lot more work, and silly amounts of nitrogen, but it's a quick start.

Offline JasonAW3

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Re: Space colonies using rubble piles
« Reply #1 on: 03/01/2010 05:52 PM »
Over here - http://forum.nasaspaceflight.com/index.php?topic=18759., we discussed the concept of inflating a habitat inside Phobos. This would instantly provide a large shielded space.

Larry Niven's "Farmers World" was a large iron asteroid, which was rotated, filled with water bags, and then melted, and hey presto, a large rotating cylinder colony was made.

Perhaps more realistic, given that a lot of asteroids are rubble piles (no tensile strength):

1. Find a 400m diameter rubble pile (about 60 million tons)
2. Process some of the material to make a metal shell, a km in diameter and a few mm thick, with the rubble pile at the centre.
3.  In the centre of the pile, inflate, under low pressure, a balloon. Gradually inflate whilst controlling the position, until all the rubble forms a 10m thick shield just inside the metal shell
4. Next inflate a second shell to give about 10m clearance. Then line this shell with fibres (carbon nanotube, preferably, but any strong fibre will do), until it's strong enough to withstand air pressure and internal forces.
5. Rotate to provide artificial gravity

You have a Bernel Sphere, with very limited material processing. You can scale up, though the pressure vessel mass increases with the cube of diameter.

As an alternative, to above steps:
3. Attach electron guns to the metal shell. Fire electrons at the rubble pile, to give it a negative static charge. The metal shell will become positively charged. After a while, the rubble pile will be stuck to the metal shell.

Yes, I know the eventual colony is in a solar orbit and needs a lot more work, and silly amounts of nitrogen, but it's a quick start.

Ok, let's get a tad crazy with this one!  (This is FUN!)

     Let's buid and inflate a REALLY big Bigalow inflatable. (Build a one way SSTO as the core of the inflatable, (Hybrid Solid / Liquid fuel beast maybe?) with a light weight, cardboard/resin outer shell, launch into about a 300+ mile orbit) next, build a solar furnace, (A big parabolic mirror) collect spent stages and satillites, melt them down, (seperating the different metals via spin settlement, put a positive charge on the exterior of the inflated habitat module, then start spraying the module with negtatively charged moltant metal.  The metal cools on contact and you build up a metal, seamles shell in fairly short order.  Structural ribs can be incorporated via simple pleating of the inflatable, and allow the metal in those pleats to build up until level withe the rest of the outer shell.
      After finishing the outer shell, depressurize the Habitat inflatable and then repeat the above actions on the inside of the module and then outfit the interior as a spin habitat.

     A really big one could be made via zip together segments, enbeded rubble electroplated over as above.

     reviewing the various options, I don't honestly feel that conventional manufactoring and assembly techniques would work toowell on these huge structures would be safe or effective, whereas fast, reliable painting-like technique could do the job more safely, reliably and even quicker than other techniques.

Jason
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Offline Jim

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Re: Space colonies using rubble piles
« Reply #2 on: 03/01/2010 06:02 PM »
  Structural ribs can be incorporated via simple pleating of the inflatable, and allow the metal in those pleats to build up until level withe the rest of the outer shell.
     

And what is going to make the metal flow into the pleats?

Offline Jim

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Re: Space colonies using rubble piles
« Reply #3 on: 03/01/2010 06:03 PM »
I don't honestly feel that conventional manufactoring and assembly techniques would work toowell on these huge structures would be safe or effective, whereas fast, reliable painting-like technique could do the job more safely, reliably and even quicker than other techniques.


You can't make such a claim. You don't have the data to go either way.

Also, spraying molten metal in zero g is a great way to increase the orbital debris.  Even with 99.999% capture of the metal to the target, it still cause issues.
« Last Edit: 03/01/2010 06:06 PM by Jim »

Offline mmeijeri

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Re: Space colonies using rubble piles
« Reply #4 on: 03/01/2010 06:05 PM »
I vaguely recall reading about a related concept, it may have been on the PERMANENT website. There the idea was to use a large inflatable balloon around a suitable metal-containing asteroid and to heat the asteroid. Metals would then deposit on the inside of the balloon, giving you a metal structure. I have now idea how practical this would be.
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Offline Rhyshaelkan

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Re: Space colonies using rubble piles
« Reply #5 on: 03/01/2010 11:59 PM »
Thinking of the possibilities out there. Why not find a good NEA or MBA of 20x20km. While mining for resources, hollow out a nice 10kmx10km dia. void. Then with thrusters of some sort, stabilize the asteroid's tumble, and then impart a spin to generate gravity on the inside. Fuse or plate the exterior of it if it seems like it wants to spin itself apart. The entire exterior can be inlayed with solar cells to generate power. Now you have 100 square km(24,710 acers) of land for use. A nice place for space food production. Or a weigh station for those that wish to recondition their bodies to 1g gravity.
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Offline JasonAW3

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Re: Space colonies using rubble piles
« Reply #6 on: 03/02/2010 01:16 AM »
  Structural ribs can be incorporated via simple pleating of the inflatable, and allow the metal in those pleats to build up until level withe the rest of the outer shell.
     

And what is going to make the metal flow into the pleats?

Have you ever done any electroplating?  The positive charge of the inflated structure will draw the negatively charged moltent metal to it, thus filling in the pleats.  contin uing to add layers of metal into the trench that is made by the pleatwould build up uthe ribbing from the inside out.

Jason
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Offline JasonAW3

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Re: Space colonies using rubble piles
« Reply #7 on: 03/02/2010 01:32 AM »
I don't honestly feel that conventional manufactoring and assembly techniques would work toowell on these huge structures would be safe or effective, whereas fast, reliable painting-like technique could do the job more safely, reliably and even quicker than other techniques.


You can't make such a claim. You don't have the data to go either way.


Actually, yes I can.  NASA itself has had to make specially adapted tools and techniques for repairs and assembly in space.  A panel by panel assembly approach, like what was typically done in the early days of ship construction on Earth, would not only be inefficent, but actually dangerous, unless you intend on using multiple Canadarms to piece the assembly together while you weld it.  In this case, the same argument about moltent metal would apply as well.

[/quote]

Also, spraying molten metal in zero g is a great way to increase the orbital debris.  Even with 99.999% capture of the metal to the target, it still cause issues.
[/quote]

     If you've ever done any electroplating, such as I described previously, (putting a positive charge on the inflatable and giving the sprayed on moltent metal a negative electrical charge, the metal will be attracted to the nearest positively charged object it comes across.  Of course, it would most likely be a good idea to do this in a high orbit, such as L-4 or L-5, and then at a distance of only a few feet from the surface of the inflatable, being certain NOT to touch the inflatable until you have finished coating it, otherwise you will neutralize the electrical charge and the moltant metal spray would then become a SERIOUS issue.
     But you made a good point.  Spraying moltant metal like an airbrush onto a neutrally charged surface is quite liable to cause a splash back effect that could be QUITE dangerous in orbit.

Jaso9n
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Offline Jim

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Re: Space colonies using rubble piles
« Reply #8 on: 03/02/2010 03:26 AM »

Have you ever done any electroplating?  The positive charge of the inflated structure will draw the negatively charged moltent metal to it, thus filling in the pleats.  contin uing to add layers of metal into the trench that is made by the pleatwould build up uthe ribbing from the inside out.


Do you understand surface tension and zero g?  The metal is going to spread itself equally over the whole surface and not fill gaps, unless many layers are used.
« Last Edit: 03/02/2010 03:36 AM by Jim »

Offline Jim

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Re: Space colonies using rubble piles
« Reply #9 on: 03/02/2010 03:30 AM »

Actually, yes I can.  NASA itself has had to make specially adapted tools and techniques for repairs and assembly in space.  A panel by panel assembly approach, like what was typically done in the early days of ship construction on Earth, would not only be inefficent, but actually dangerous, unless you intend on using multiple Canadarms to piece the assembly together while you weld it.  In this case, the same argument about moltent metal would apply as well.


"conventional manufactoring and assembly techniques " is not the panel by panel method.  Join modular  components (block construction used in ships) that are built up elsewhere is SOP. 
« Last Edit: 03/02/2010 03:35 AM by Jim »

Offline Hop_David

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Re: Space colonies using rubble piles
« Reply #10 on: 03/02/2010 02:03 PM »
Thinking of the possibilities out there. Why not find a good NEA or MBA of 20x20km.

What is an MBA?

Online AnalogMan

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Re: Space colonies using rubble piles
« Reply #11 on: 03/02/2010 02:24 PM »
Thinking of the possibilities out there. Why not find a good NEA or MBA of 20x20km.

What is an MBA?

Main Belt Asteroid?

Offline Rhyshaelkan

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Re: Space colonies using rubble piles
« Reply #12 on: 03/02/2010 03:49 PM »
Thinking of the possibilities out there. Why not find a good NEA or MBA of 20x20km.

What is an MBA?

Main Belt Asteroid?


Nope, Master of Business Associate, everyone knows we have enough of those worthless things on this planet to make a whole universe :P

Yes, Main Belt Asteroid.
I am not a professional. Just a rational amateur dreaming of mankind exploiting the universe.

Offline alexterrell

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Re: Space colonies using rubble piles
« Reply #13 on: 03/02/2010 05:38 PM »
I vaguely recall reading about a related concept, it may have been on the PERMANENT website. There the idea was to use a large inflatable balloon around a suitable metal-containing asteroid and to heat the asteroid. Metals would then deposit on the inside of the balloon, giving you a metal structure. I have now idea how practical this would be.

Nice idea.

I can't see a reason why this wouldn't work. A couple of engineering issues:
1. Need lots of power
2. The balloon might melt
3. Impurities in the metal might weaken the structure

<Edit 4. How would you turn the metal into a true vapour? It would melt first, then droplets would detach and head for the shell, but would solidify before reaching it. Perhaps a multi GW pulse laser would do the trick?>

Basically, there are two structural needs: A shield and a pressure vessel. The shield needs to be about 10 tons / m2, but can be made of any material. The pressure vessel needs to withstand huge force, but can be light weight.


« Last Edit: 03/03/2010 07:38 AM by alexterrell »

Offline Downix

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Re: Space colonies using rubble piles
« Reply #14 on: 03/02/2010 07:52 PM »
Thinking of the possibilities out there. Why not find a good NEA or MBA of 20x20km.

What is an MBA?

Main Belt Asteroid?


Nope, Master of Business Associate, everyone knows we have enough of those worthless things on this planet to make a whole universe :P

Yes, Main Belt Asteroid.
Hey now, my wife is working on her MBA...

and she is in full agreement, too many of them.  8)
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Offline Patchouli

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Re: Space colonies using rubble piles
« Reply #15 on: 03/02/2010 08:52 PM »
Over here - http://forum.nasaspaceflight.com/index.php?topic=18759., we discussed the concept of inflating a habitat inside Phobos. This would instantly provide a large shielded space.

Larry Niven's "Farmers World" was a large iron asteroid, which was rotated, filled with water bags, and then melted, and hey presto, a large rotating cylinder colony was made.

Perhaps more realistic, given that a lot of asteroids are rubble piles (no tensile strength):

1. Find a 400m diameter rubble pile (about 60 million tons)
2. Process some of the material to make a metal shell, a km in diameter and a few mm thick, with the rubble pile at the centre.
3.  In the centre of the pile, inflate, under low pressure, a balloon. Gradually inflate whilst controlling the position, until all the rubble forms a 10m thick shield just inside the metal shell
4. Next inflate a second shell to give about 10m clearance. Then line this shell with fibres (carbon nanotube, preferably, but any strong fibre will do), until it's strong enough to withstand air pressure and internal forces.
5. Rotate to provide artificial gravity

You have a Bernel Sphere, with very limited material processing. You can scale up, though the pressure vessel mass increases with the cube of diameter.

As an alternative, to above steps:
3. Attach electron guns to the metal shell. Fire electrons at the rubble pile, to give it a negative static charge. The metal shell will become positively charged. After a while, the rubble pile will be stuck to the metal shell.

Yes, I know the eventual colony is in a solar orbit and needs a lot more work, and silly amounts of nitrogen, but it's a quick start.

One nice thing about a rubble pile asteroid is you might be able to separate the good stuff from the the rest with nothing more then an electromagnet and a centrifuge.

As for controlling dust etc just build a massive bag to keep your asteroid in.
A VASIMR engine could be use for clearing away dust that does escape.

Now for a low delta V source of volatiles including nitrogen I'd look at short period comets.
« Last Edit: 03/02/2010 08:54 PM by Patchouli »

Offline Hop_David

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Re: Space colonies using rubble piles
« Reply #16 on: 03/03/2010 11:19 PM »
Thinking of the possibilities out there. Why not find a good NEA or MBA of 20x20km.

What is an MBA?

Main Belt Asteroid?


Nope, Master of Business Associate, everyone knows we have enough of those worthless things on this planet to make a whole universe :P

Yes, Main Belt Asteroid.

doH! I should have figured that one out. Thanks

Offline alexterrell

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Re: Space colonies using rubble piles
« Reply #17 on: 03/05/2010 01:59 PM »
Thinking of the possibilities out there. Why not find a good NEA or MBA of 20x20km.

What is an MBA?

Main Belt Asteroid?


Nope, Master of Business Associate, everyone knows we have enough of those worthless things on this planet to make a whole universe :P

If you took all the MBAs from Planet Earth, and laid them into a shield of 10tons/m2, you'd still only have enough for a 200m diameter space station.

To go larger you'd need to add in a whole load of B.S.(Wow, the site won't let me put this in without the ".")

Regards

Alex (MBA)
« Last Edit: 03/05/2010 02:01 PM by alexterrell »

Offline Rhyshaelkan

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Re: Space colonies using rubble piles
« Reply #18 on: 03/05/2010 07:10 PM »
Hehe B-S how funny but how fitting.

Though I know many are worth their degrees, but plenty are not.

As the cutoff for good solar power is around the Asteroid Belt. Plus a viable source for water is at Ceres. It would preclude the possibility of having millions of colonists leave Earth and live in an hollowed-out asteroid.

At 34 I might one day emigrate to Luna and live out my days working there. However I think asteroid colonies will be after my time. I want to see massive industrial use and colonization of Luna. It is my major interest in space. At least until someone develops worm-hole drives to get us outside our solar system.
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Offline JohnFornaro

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Re: Space colonies using rubble piles
« Reply #19 on: 03/06/2010 02:14 PM »
I just had to add this one:

PHD, of course, means "Piled Higher and Deeper".  It's the degree after the first two you guys were talking about.  Which maybe you need for these rubble piles???
Sometimes I just flat out don't get it.

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