[Moontanman]

I have promoted space colonies several times in widely varying posts. Often they were dismissed as living in a can in the vacuum of space. Here is a more descriptive version.

http://www.belmont.k12.ca.us/ralston...C75-1886f.jpeg

What is an Orbital Space Colony?

[UncleAl]

1) International Space Station Freedom FUBAR Space Hole One Alpha, giggle.
2) If ya had 'em, what would ya do with 'em to justify cost and upkeep?
3) Annual Quadrantid, Orionid, Taurid, Leonid, Perseid, etc. meteor showers.
4) Orbital Debris Graphics
5) Massive solar coronal eruptions - everybody gets cooked. Incidence of radiation cataracts in Mir and ISS FUBAR asstronaughts is ~100%.
6) Where do you put the orbit? In close (to 200 mile atlitude) the orbit decays from residual air resistance. Out further you are in the van Allen radiation belts. Out further still and ground to orbit is way expensive (and lethally slow in an emergency).
7) Internal security.

Before you set out on an expensive trip it helps to have a destination.

[Thunderbird]

Moontanman are you familiar with the bio-sphere 2 project ?
fiasco
http://http://biology.kenyon.edu/slo...e/lessons.html

[Moontanman]

Originally Posted by Thunderbird

Moontanman are you familiar with the bio-sphere 2 project ?
fiasco
http://http://biology.kenyon.edu/slo...e/lessons.html

Your link didn't work but if you are referring to the big greenhouse in the desert it was far too small and relied on natural processes to maintain the atmosphere. what my link should have taken you to is far bigger, they even say habitats tens of kilometers across are doable and they wouldn't simply try to maintain a natural biosphere to feed the inhabitants and provide an atmosphere.

[Moontanman]

1) International Space Station Freedom FUBAR Space Hole One Alpha, giggle.

You are of course correct, all these "space stations" were doomed from the start, far too small and flimsy. You can't build in space by bringing materials from the earth.

2) If ya had 'em, what would ya do with 'em to justify cost and upkeep?

They are colonies, the initial purpose would be to expand the human race but they could also be a base for asteroid mining, zero gee manufacturing, places to grow food stuffs to support all types of space initiatives, (IE space power stations) and simply places to get away from the Earth. Any way you look at it they would have to pay for themselves in some way.

3) Annual Quadrantid, Orionid, Taurid, Leonid, Perseid, etc. meteor showers.

Meteors could be a problem although most sources seem to think they can be overcome by special materials for small ones and defensive measures for larger ones. I am not trying to dismiss this out of hand but meteors should not be a big a problem for a small object as they are for an object as big as the earth. Even a very large meteor shower for the earth where you might see several a second would not be a problem for a small object with a cross section many orders of magnitude smaller.

4) Orbital Debris Graphics

Since no colony would be in Earth orbit this is not a problem.

5) Massive solar coronal eruptions - everybody gets cooked. Incidence of radiation cataracts in Mir and ISS FUBAR asstronaughts is ~100%.

A large colony would would have walls more than thick enough to protect it's inhabitants from particle radiation, Magnetic fields and charged fields could provide even more. The thick walls would be more than enough protection from EMR.

6) Where do you put the orbit? In close (to 200 mile atlitude) the orbit decays from residual air resistance. Out further you are in the van Allen radiation belts. Out further still and ground to orbit is way expensive (and lethally slow in an emergency).

First of all, as I said colonies would not be in Earth orbit a really big colony wouldn't benefit from being rescued from the earth to begin with. No space craft would be big enough to carry hundreds of thousands of people back to earth. So this is a moot point. where in orbit? Lagrange points of Earth orbit and the moons orbit. Jupiter's Lagrange points, Saturn, the closer resources are to the colony the better the position. the whole idea of colonies is to get away from the Earth and close to resources. a colony could not be supported from earth or even built from the earth.

7) Internal security.

I not sure what you mean, a colony tens or even hundreds of kilometers across would be very robust and difficult to really damage. Keeping nuclear weapons and really powerful chemical explosives from people should not be a big problem. I would think that people who wanted to colonize bad enough to travel to and help build these structures would probably not be looking to kill everyone in them. At first you might get people with an agenda that might be other than colonization but after generations lived and struggled to build ever bigger and better habitats this would be an easier problem to get a handle on. I am not talking about forcing people to go to these colonies, this would have to be a labor of love not a punishment for malcontents.

Before you set out on an expensive trip it helps to have a destination.

This true, the destination would be the solar system, the galaxy and the future!

[UncleAl]

What wall will stop a gram meteor traveling at 20 miles/sec relative? Shaped charge jets top off at 1 mile/sec strike velocity. "capable of piercing armor equivalent to 900 mm thickness." That is 35 inches. Kinetic energy = (mv^2)/2.

"Babylon 5 is five miles long and weighs 2.5 million tonnes."

The Space Scuttle boosts maximum 22 tonnes into low Earth orbit (derated for "safety"). At 100% Official capacity it would be 114,000 launches. Lose the idiot Space Scuttle and only use the engines. That gains 60 tonnes of payload. Call it 80 tonnes payload/launch for only 31,000 launches. One launch/week for 600 years. giggle.

The Saturn 5 boosted 127 tonnes into low Earth orbit at 1/3 the Space Scuttle's cost/gram (constant dollars). 20,000 launches. One launch /week for 380 years. giggle.

[Moontanman]

Originally Posted by UncleAl

What wall will stop a gram meteor traveling at 20 miles/sec relative? Shaped charge jets top off at 1 mile/sec strike velocity. "capable of piercing armor equivalent to 900 mm thickness." That is 35 inches. Kinetic energy = (mv^2)/2.

"Babylon 5 is five miles long and weighs 2.5 million tonnes."

The Space Scuttle boosts maximum 22 tonnes into low Earth orbit (derated for "safety"). At 100% Official capacity it would be 114,000 launches. Lose the idiot Space Scuttle and only use the engines. That gains 60 tonnes of payload. Call it 80 tonnes payload/launch for only 31,000 launches. One launch/week for 600 years. giggle.

The Saturn 5 boosted 127 tonnes into low Earth orbit at 1/3 the Space Scuttle's cost/gram (constant dollars). 20,000 launches. One launch /week for 380 years. giggle.

First, meteor strikes will be a problem that will have to be worked on but you are assuming we will build with materials like solid metal and there is no comparing a shaped charge designed to penetrate with a small rock that will vaporise on impact with no directional component. Metal or even silicate foam reinforced with carbon Nano tubes several meters thick will make up the walls. Cables made of carbon nano tubes will hold the colony together like an endless suspension bridge. The outer rotating walls will be even more protected by the fact they will be rotating. A rotating object is much harder to penetrate than a stationary one. Ever try to shoot out a rotating tire by shooting the moving out side of the tread?Large meteors can be stopped by high frequency solid state lasers. Really large ones can be avoided by moving the colony out of the way. These problems are solvable, I will say again, no one can build a realistic colony by lifting materials from the surface of the Earth, even nuclear light bulb rockets that can lift the entire international space station and more in one launch would be totally inadequate. large colonies will have to be build from materials already in space, from asteroids, burnt out comets, ice moons of Saturn, the Lagrange points of Jupiter would be the great manufacturing sites, lots of all the materials you need and low energy orbits needed to transport anything. Get away from geocentric thinking, to colonize the solar system we will need to use the resources found already in space.

[UncleAl]

Metal or even silicate foam reinforced with carbon Nano tubes several meters thick will make up the walls.

Shaped charge penetration depth for concrete is double that of armor plate. Carbon unravels to atoms by about 4500 C - diamond, graphite, vitreous, fiber, nanotubes, whatever. In hydrodynamic deformation mode the major shielding consideration is mass/cm^2 (not per volume). Ductile vs. brittle failure can be balanced, hence Chobham armor. Explosively shaped projectiles - fast-traveling solid lumps - hole Chobham armor, hence the DoD's panic in Iraq when its glacis plates went all Swiss cheesy from munitions not much larger than your fist detonated 10 meters distant. The solution? Pull out the expensive tanks and substitute cheap Hummers as targets. The enemy then used buried artillery shells and land mines to do the Hummers.

Chobham armour - Wikipedia, the free encyclopedia
Not nearly good enough - weight vs. effectiveness - for gram meteors, including nanotube plus depleted uranium upgrades (density = 19 grams/cm^3) as described.

Get away from geocentric thinking, to colonize the solar system we will need to use the resources found already in space.

What transports labor? What does it breathe and eat? The Earth is differentiated by weathering and tectonics. Oxidizer is free and unlimited. The asteroid belt is random non-volatile star stuff. You can have all the nickel-iron you desire but not enough sunlight to melt it (intensity as 1/r^2). If you want copper for wires you are screwed, ditto limestone for cement, silicon for semiconductors, aluminum for beer cans... The moon doesn't have reduced metals at all nor does it have ore deposits.

Work out the distance then the Earth to target lightspeed delay. No real time conversation with the asteroid belt. Not nearly.

There is that little problem of cosmic radiation occasionally juiced by solar flares. The Earth's atmosphere at sea level is equal to 35.8 inches thickness of lead shielding. Work it out - 14.7 psi. Light element shielding won't stop hugely GeV protons. Heavy element shielding (g/cm^2 again) does pair formation thence 511 KeV photons, and neutrons from spallation. You need heavy elements to stop the photons but light elements to stop the neutrons. Everybody in Mir and ISS FUBAR gets radiation cataracts - and both are still shielded by the Earth's magnetosphere deflecting cosmic ray protons to the poles.

The only practical lunar colonization is tunnels about 30-50 feet under regolith against radiation and temperature. Nobody has volunteered lunar backhoes, robotic or manned. Explosives to excavate? You ride the bus, launch (major vibration) to soft touchdown. You need more work on the reduction to practice.

[Moontanman]

Shaped charge penetration depth for concrete is double that of armor plate. Carbon unravels to atoms by about 4500 C - diamond, graphite, vitreous, fiber, nano tubes, whatever. In hydrodynamic deformation mode the major shielding consideration is mass/cm^2 (not per volume). Ductile vs. brittle failure can be balanced, hence Chobham armor. Explosively shaped projectiles - fast-traveling solid lumps - hole Chobham armor, hence the DoD's panic in Iraq when its glacis plates went all Swiss cheesy from munitions not much larger than your fist detonated 10 meters distant. The solution? Pull out the expensive tanks and substitute cheap Hummers as targets. The enemy then used buried artillery shells and land mines to do the Hummers.

First a meteorite is not a shaped charge made to penetrate as far as possible. Say a dime sized meteor hits something, it's energy is does not cause a shaped charge type of explosion. The energy of impact simply vaporises a small crater in what ever it hits. The vapor doesn't have the penetrating power it's speed would suggest. It's very speed would hinder anything happening but a small crater. A rock foam layer a few meters thick would be able to take quite large meteor without the damage of a shaped charge. A shaped charge uses it's own casing to cause a high speed jet of metal vapor, a meteor doesn't have anything to direct it's vapor and the speed of impact is converted into heat not a directional spray of hot dense vapor. the idea is not stop the meteor but to have it expend it's energy as heat and only destroy a small area. something like ablative armor.

Chobham armour - Wikipedia, the free encyclopedia
Not nearly good enough - weight vs. effectiveness - for gram meteors, including nanotube plus depleted uranium upgrades (density = 19 grams/cm^3) as described.

This doesn't apply for the above mentioned reasons. Brute force isn't what will stop meteors. You use their own energy against them.

What transports labor? What does it breathe and eat? The Earth is differentiated by weathering and tectonics. Oxidizer is free and unlimited. The asteroid belt is random non-volatile star stuff. You can have all the nickel-iron you desire but not enough sunlight to melt it (intensity as 1/r^2). If you want copper for wires you are screwed, ditto limestone for cement, silicon for semiconductors, aluminum for beer cans... The moon doesn't have reduced metals at all nor does it have ore deposits.

Ore deposits are not likely in the asteroid belt or anywhere but on a planet. But the elements do occur there and with nuclear power huge amounts of metallic/rocky asteroids can be processed for everything in them. It has been estimated that even a one mile in diameter nickle/iron asteroid would contain enough metals such as platinum, gold, copper, and other heavy metal to make everyone on the earth rich. (not counting the cost of getting the object into earth orbit and processing.) since we don't want to move the metal anywhere to use it that will not be problem. More than enough trace metals can be processed from asteroids as well as hydrocarbons from such things as carbonaceous chonderites and water from old comet cores and small ice moons. Moving this stuff around will be easy since it doesn't have to move fast and can be moved around using minimum energy orbits. Much of the construction will be robotic in nature but people will have to be on site to direct the machines. Nuclear rockets are more than powerful enough to bring the first waves of workers but as the colonization technology matures much if not most of the workers will come from other colonies as their population expands. You have to think of it from the stand point of a slow process. How difficult would it be to transport the entire population of the new world from Europe in one shot. It would be easy to say it's impossible but as the colonies get more wide spread the population will increase on it's own. I am not talking about a one shot deal, this will be away of life and people will reproduce.

Work out the distance then the Earth to target lightspeed delay. No real time conversation with the asteroid belt. Not nearly.

I'm not sure what you mean by this, elaborate please.

There is that little problem of cosmic radiation occasionally juiced by solar flares. The Earth's atmosphere at sea level is equal to 35.8 inches thickness of lead shielding. Work it out - 14.7 psi. Light element shielding won't stop hugely GeV protons. Heavy element shielding (g/cm^2 again) does pair formation thence 511 KeV photons, and neutrons from spallation. You need heavy elements to stop the photons but light elements to stop the neutrons. Everybody in Mir and ISS FUBAR gets radiation cataracts - and both are still shielded by the Earth's magnetosphere deflecting cosmic ray protons to the poles

.

Radiation will be a problem, workers will have to be limited in how long they can work and where but farther from the sun will make these events (flares, magnetic storms) less powerful and charge fields and magnetic fields will help as the colonies are built but once they are built they will be big and thick enough to shield everyone from radiation. Mir and ISS are too small and thin to protect anyone from anything, their metal hulls actually make things worse from the by products of cosmic rays hitting metal.

The only practical lunar colonization is tunnels about 30-50 feet under regolith against radiation and temperature. Nobody has volunteered lunar backhoes, robotic or manned. Explosives to excavate? You ride the bus, launch (major vibration) to soft touchdown. You need more work on the reduction to practice.

Asteroids are big enough for tunnels to be dug to protect the workers from radiation. and nuclear power will be used to create intense magnetic fields and charge fields to protect workers.

[TheBigDog]

Modular and repairable. If you hit a pebble in space you need to minimize the affect on the ship and move on with life. Individually sustainable modular units lets a percentage of the ship be taken out without losing the ability to continue its mission.

Bill