Extra-planetary colonization

[CraigD]

Moderation note: The first 11 posts of this thread were moved from Terraforming Mars, because they are that thread’s topic

 

Somehow, this question from a few months ago slipped under my radar

What energy source are you guessing we'll use under that plan? The electromagnetic stuff Jupiter throws off? (As is apparently visualised in Accelerando, the free online PDF book that I started reading but never finished...)

I haven't heard of the process you mentioned, i was thinking nuclear power would have to be used. An intense industrial site would need huge amounts of energy and at that distance from the sun solar is just too weak.

The energy source for the “Empire of Jupiter” Stross wrote about in Accelerando, which I’ve mentioned in less-than-novel-length pieces like this old hypography post, is a very large Electrodynamic tether (the whole 5550 is, I think, a good old discussion of space elevators and space engineering, worth reading)

 

Essentially, this is a system that uses an orbiting conductor as an electric generator/motor rotor, and the magnetic field of the body being orbited as the stator. The concept was proven in the 1990s by several NASA-conducted experiments, though the thin cables used in these experiments lasted no longer than a few hours before failing, and engineering challenges that must be solved before they can be practically used by spacecraft (or vast Jovian imperial space industry ;)) remain significant.

 

The orbiting electro-tether Stross and I described consists of a pair of nearby minor Jovian satellites, connected by a strong conducting cable. Passing through Jupiter’s changing magnetic field, a voltage is induced, generating a current that’s used to power various stuff on one or both of the small bodies. This energy is extracted from the gravitational potential energy of the orbiting bodies, causing them to drop to lower and lower orbits, until, eventually, they become unusable (eg: they begin grazing Jupiter’s atmosphere) and must be abandoned.

 

By present day engineering standards, the energy available from such a system is tremendous. Take the following example, which assumes a couple of Jupiter’s smallest known satellites, combined mass [imath]10^{15} \,\mbox{kg}[/imath], dropped from an orbit of [imath]10^{11}[/imath] to [imath]10^8 \,\mbox{m}[/imath]. The change in GPE, minus the change in kinetic energy (lower orbital speeds are greater than higher ones), is about [imath]6 \times 10^{23} \,\mbox{J}[/imath]. The system should have ordinary electric efficiency on the order of 95%+, so nearly all of the extracted GPE should be usable.

 

By comparison, this is about 1000 times the energy from all sources used by humankind on Earth in a year, and about 3 times the total global energy reserves of uranium-238 using fast reactor technology.

 

I’ve been a little sneaky with the my Jovian satellites, as there are only a few high-orbit ones with combined masses of about [imath]10^{15} \,\mbox{kg}[/imath], but several tens of ones with about [imath]10^{14} \,\mbox{kg}[/imath], so scale my estimates down by about a factor of 10, or assume 10 such generators are built. Though Stross didn’t, I recall, give precise numbers for the fictional generator in Accelerando, my impression is that his was 10 or 100 times smaller than the example I give above, as Empress Amber’s empire doesn’t have very many people in it, nor it’s primarily mining operations large by Earth industrial standards.

 

PS: Mars doesn’t have an appreciable magnetic field, so electro-tethers aren’t usable for any purpose around it.

[Eclipse Now]

Hi CraigD,

some of that stuff boggles the imagination. But do we have a technology for this super-long super-strong superconductor thingy gizmo, or is this more in the same league as space elevators?

 

What about getting 'out there' with today's technology?

 

In terms of energy supply, check these paragraphs out concerning breeder reactor resources just here on earth. I wonder how Mars fares with uranium & thorium?

 

What is the size of the resource? Let's assume that only the portion of continental crust currently under dry land is exploited for its uranium and thorium content, to a depth of roughly four kilometres (the deepest mine currently operating is the TauTona mine in Carletonville, South Africa at 3,900m, and the Kola Superdeep Borehole in Russia is 12,262m). This represents a reserve of 20 trillion tonnes of fertile and fissile fuel, capable of powering our 100TW civilisation for 200 million years. This is the span of time separating us from the dawn of the Jurassic Period, when the supercontinent Pangaea was starting to break apart into Laurasia and Gondwana. Dinosaurs were just beginning to make their mark on the world, and the allosaurus, stegosaurus and diplodocus were yet to evolve.

 

It will be a very long time before whoever comes after us in the far distant future will need to worry about mining ordinary crust. The science is clear: There is more than enough high grade uranium ore in the short term to allow us to transition to a completely nuclear-powered economy during this century, and a supply of fuel for the breeder reactors of the future so vast as to leave no doubt that nuclear power is completely sustainable in any meaningful sense of the word for far beyond the probable lifetime of our civilisation, and indeed, of our species.

 

Channelling the Strong Force: Is Nuclear Power Sustainable?

 

Yes, I'm an old fashioned sort of guy that still wants to see humanity thriving on a planet, stuck in the gravity well. I don't mind the idea of dozens of settlements floating around the asteroid belt, or experimenting with stuff in orbit around Jupiter, but to me... planets say "home". They are just so planety, you know? :hyper:

[prometheuspan]

but to me... planets say "home". They are just so planety, you know?

 

thats why this keeps running on. Its counter intuitive for most people. Our inner animal just can't accept it.

We want more real estate, not a spinning torus in space.

 

But what it comes down to is that mars is too small. It can't hold a strong magnetic field and so it

can't keep an appreciable atmosphere. You can't get around the muscle atrophy problem.

 

By contrast, you can have 1 G pseudogravity always at a given level of the torus, you can enclose

an atmosphere, and you can even make it large enough that it feels like real estate.

 

I know its been said before, but i will just join in the chorus. Long term human settlement on mars

is science fiction and until we have gravity plating ala star trek, thats all it can ever be.

 

Yet, there are trillions of colonizable objects in the solar system, such as cruithne or Phobos and Deimos.

 

:hyper:

[Eclipse Now]

Yet, there are trillions of colonizable objects in the solar system, such as cruithne or Phobos and Deimos.

:cheer:

 

So just hollow them out and spin them AKA Greg Bear's EON?

Would you use mirrors and windows, or survive on artificial lighting?

 

 

Ooops... this one must have gravity plating on the bottom. :hyper:

[prometheuspan]

yes. Colonization would require a payload of robots to be delivered the asteroid. They then

mine it, extrude what can be extruded for useful metals and minerals, and then use the mass

to build a very large and very hollow torus or cylinder.

 

It won't look much like that image except for maybe as concept art. I will go ahead and upload

 

X-3 (asteroid colonies) from my hard drive to RBEF and then repost for a link.

(the reason for this is that this site doesn't give a download option, and I need these

images to live on the net somewhere, plus, 10 pages of images would kind of spam this thread. Also the limits and types of files allowed by the forums gallery ...problemz...)

:hyper:

[Eclogite]

It does seem that most asteroids are rather poorly consolidated. They are rubble piles rather than cohesive objects. Spinning them would likely be enough to break most of them up.

[DougF]

You could alway upload this Pictures to a Photo album then cross reference them to this thread? Gust a thought?

 

 

yes. Colonization would require a payload of robots to be delivered the asteroid. They then

mine it' date=' extrude what can be extruded for useful metals and minerals, and then use the mass

to build a very large and very hollow torus or cylinder.

 

It won't look much like that image except for maybe as concept art. I will go ahead and upload [/quote']

 

 

As to mining asteroids I think something along this line will happen, we will start small mining a spot just until we fill our cargo bay then go back to base, after some trips like this we will have a compound that will be worked while the ship transports the "ore" while the mining is still carried out 6 months on 6 months off type of thing.

[Eclipse Now]

I'm wondering if there is uranium spread equally throughout the solar system? IFR reactors could not only power the mining operation, but then even at small concentrations uranium ore could provide the power to build further settlements out there... allowing exponential growth throughout the asteroid belt.

 

Then with more eyes out there (with a few nukes handy) humanity might be able to more adequately protect the inner solar system planets from some of the rouge dinosaur killers. Or maybe, with enough warning, attach a few rockets to shift the thing into a safer orbit and mine it as well?

 

Then one day we'd build an arkship out of one of these suckers, mine enough uranium and thorium from surrounding asteroids and moons to last a hundred thousand years, load up future DNA databases and frozen ecosystems while growing out some on the interior of the artificial world, and set off for the stars...

[Moontanman]

The idea of hollowing out an asteroid and rotating it to make significant gravity is unlikely in my opinion. Such a structure would be inherently unstable and prone to flying apart or cracking as various parts settle under the influence of centrifugal force.

 

I think hydrocarbons will be even more important once we start colonizing space than they are now. Oil and other hydrocarbons should be industrial feed stocks now instead of burning them away as fuel.

 

By the time we start colonizing space and building rotating bodies to make artificial gravity hydrocarbons will be important as feed stocks for building materials. Carbons tubes and or other carbon containing fibers will be important to building the rotating torus type structures we will need to live in.

 

A rotating torus big enough to be a real colony will be built like a endless suspension bridge not a rotating metal cylinder, the carbon containing fibers will hold the torus together and are far stronger than metals.

 

Lighting the inside of a torus to create an environment the imitates a planets surface when you are as far away from the sun as in the Kuiper belt or other places where carbon compounds will be easily mined will be our biggest problem and it might prevent the large structure that will be needed to have things like forests and rivers in our colonies.

 

Once we do manage to make these large structures, powering them will be a problem if for no other reason heavy metals like uranium and thorium are unlikely to be concentrated in amounts large enough to mine them, fusion will almost certainly be needed unless some other source of energy is found.

 

Ultimate the idea of terraforming any planet will seem quaint and planets will just be parks and places to obtain wild type genetic stocks to use to create ecosystems in our artificial worlds.

 

It might be interesting to build an enclosing clear envelope around a minor planet like Ceres to hold in an atmosphere and warm it up. this would be like building a greenhouse around the entire planet, low gravity might prevent humans from living there permanently but it would make a very interesting vacation spot and allow the evolution of some unique ecosystems and animals.

 

While it would requite an enormous amount of hydrocarbons to do this the solar system most certainly does contain such large amounts of hydrocarbons if we can figure out a way to create new ones in large amounts.

[Moontanman]

I'm wondering if there is uranium spread equally throughout the solar system? IFR reactors could not only power the mining operation, but then even at small concentrations uranium ore could provide the power to build further settlements out there... allowing exponential growth throughout the asteroid belt.

 

Then with more eyes out there (with a few nukes handy) humanity might be able to more adequately protect the inner solar system planets from some of the rouge dinosaur killers. Or maybe, with enough warning, attach a few rockets to shift the thing into a safer orbit and mine it as well?

 

Then one day we'd build an arkship out of one of these suckers, mine enough uranium and thorium from surrounding asteroids and moons to last a hundred thousand years, load up future DNA databases and frozen ecosystems while growing out some on the interior of the artificial world, and set off for the stars...

 

If I understand how uranium deposits come to be on the Earth it takes processes that only occur on a large planet like the Earth. On the other hand if we are processing entire asteroids for all their contents traces of thorium and uranium should be extractable. The question is would the extraction take more or less energy than you would get out of them in the long run?

[Eclipse Now]

Because IFR's and other breeders reprocess the uranium, and get it closer to E = MC2, well, each speck of dust contains a LOT of energy in it. :D

 

The following is based on very low parts per million in the earth's crust once all the 'conventional' concentrated sources of uranium are mined. Would it be that different on asteroids?

 

Average continental crust contains 2.7 ppm (parts per million) of uranium and 9.6 ppm of thorium, totalling 12.3 ppm of fissile and fertile fuel. We want to extract 100,000 tonnes of fuel each year for our 100TW civilisation. How much average rock and dirt do we need to dig up on an annual basis for this? The answer is we need to excavate about 8.2 billion tonnes of earth. For comparison, about 6.8 billion tonnes of coal was mined worldwide in 2009. Out of this, about 5 billion tonnes went to electricity production, which produced 40% of the world's electrical power, about 0.9TW (these figures were derived from information on the World Coal Institute website). It should be noted that the density of coal varies from around 1.1 to 1.5 tonnes/m^3, but the average density of Earth's crust is 2.7 tonnes/m^3. While the mass of material mined from average crust to obtain our 100,000 tonnes of nuclear fuel is greater than the mass of coal mined in 2009, the volume of material disrupted would be smaller.

 

Once we have mined our 8.2 billion tons of perfectly ordinary and unremarkable rock and dirt, we need to extract the nuclear fuel. This could be done by grinding, chemical treatment, pyroprocessing or whatever is most suitable for the particular minerals in question. We may get a reasonable estimate to the upper bounds of the energy required for this process by assuming the ore is completely melted. The power required to melt the same mass of silicon (the second most common element in Earth's crust after oxygen) is about 723 GW.y. It is likely that the whole separation process could be accomplished with less than 1TW.y of energy. This operation corresponds to an extraction and milling rate of 260 tonnes of crust each second.

 

What is the size of the resource? Let's assume that only the portion of continental crust currently under dry land is exploited for its uranium and thorium content, to a depth of roughly four kilometres (the deepest mine currently operating is the TauTona mine in Carletonville, South Africa at 3,900m, and the Kola Superdeep Borehole in Russia is 12,262m). This represents a reserve of 20 trillion tonnes of fertile and fissile fuel, capable of powering our 100TW civilisation for 200 million years. This is the span of time separating us from the dawn of the Jurassic Period, when the supercontinent Pangaea was starting to break apart into Laurasia and Gondwana. Dinosaurs were just beginning to make their mark on the world, and the allosaurus, stegosaurus and diplodocus were yet to evolve.

 

It will be a very long time before whoever comes after us in the far distant future will need to worry about mining ordinary crust. The science is clear: There is more than enough high grade uranium ore in the short term to allow us to transition to a completely nuclear-powered economy during this century, and a supply of fuel for the breeder reactors of the future so vast as to leave no doubt that nuclear power is completely sustainable in any meaningful sense of the word for far beyond the probable lifetime of our civilisation, and indeed, of our species.

 

Channelling the Strong Force: Is Nuclear Power Sustainable?

[Moontanman]

Some images of torus shaped colonies.

 

 

 

 

 

These are not what I am talking aobut when I say an endless suspension bridge. But it does get the idea of a rotating torus across.

 

Stanford tori in fiction

 

 

This is my favorite one.

Gaea trilogy - Wikipedia, the free encyclopedia

 

Map of a small section of Gaea

[img=http://www.ammon-ra.com/gaea/art/maps/gaeamap1.jpg]

Inside surface showing it's 30 kilometer thickness.

[img=http://www.ammon-ra.com/gaea/art/anatomy/floor/floor2.jpg]

image showing suspension cables above the same section as the map shown above

[img=http://www.ammon-ra.com/gaea/art/anatomy/tech3.jpg]

image of the enclosed spokes

[img=http://www.ammon-ra.com/gaea/art/anatomy/walls/skin1.jpg]

 

 

Fairest of the Fair

[Eclipse Now]

Woah, I had to pan right the way across the screen to find this typing field! (Moderators: is there any way to edit this page so it works normally again? Cheers. Not that I'm complaining... well worth it after all those pictures).

 

Moontanman, I'm still attracted to planets with an atmosphere that can take all the micrometeorites, and even some of the bigger ones. I know there's lasers, tough building materials, etc... but the torus still seems so fragile.

 

Sure I'm a fan for humanity to have hundreds of these torus stations moving around the solar system fulfilling various tasks, mining the asteroids, etc, as long as we remember that some of us apes like planets! Surely the solar system is big enough for multiple approaches.

 

(EG: Future medicine should be able to deal with the lower gravity on Mars. I understand that there's problems with the heart swelling if we live in low gravity, and Mars is 1/3rd earth's gravity, but we'll fix that won't we? Planets are packed with useful building materials!)

 

You mentioned the energy challenge of lighting the torus for the plants and trees to grow. What materials could act as windows, and let through the sunlight but not the radiation? (And protect us from micrometeorite damage and potentially fatal cracks?)

 

However, if we're building the torus BIG enough with high enough walls, the centrifugal force should keep the atmosphere in and we might not even need a roof.

 

I'm thinking of the impossibly large Ringworld by Larry Niven. The normal torus station is spun up so that the centrifugal force equals 1 g, and it is just the right diameter so that if we face it 'just so' against the sun, half of it has sunlight every 24 hours almost equalling a normal day and night cycle.

 

But in Ringworld the thing is so HUGE that it entirely circles the sun. So the surface would have 24 hour daylight, but for the inner circle that has huge panels that spin and provide shade.

 

 

I'm one to 'never say never' when it comes to techno-utopianism, but even I'm challenged by the sheer humungousness of this beast! I mean, if we're going to even consider a Ringworld, why not go the whole way and just build a Dyson sphere!

[Moontanman]

Larry Niven's ring world concept is as outrageous as it is intriguing. No known possible material could be strong enough to allow it but such a ring world would be equal to 1 million earths!

A dyson sphere wouldn't have gravity high enough to allow humans to live on it.

It is difficult to understand how planets would be passed over by humans and I am sure that a few humans would always want a planet. But the idea of another planet we could live on could very well be impossible, at the very best Terra forming a planet like Mars would take many thousands of years.

 

Building artificial structures with livable atmosphere would be far easier to build in a timely manner.

[Eclipse Now]

at the very best Terra forming a planet like Mars would take many thousands of years.

What if we assume asteroid mining torus ships that become self-replicating? Say it takes 20 years to build one of these beasts, and each torus (amongst other economic and mining activities) is mandated to produce another torus within 20 years? 2, 4, 8, 16, 32... that's 32 ships 100 years after the first torus is built. Then the numbers can really grow. 64, 128, 256, 512, 1024... that's over a thousand asteroid torus ships mining the asteroid belt in 200 years.

 

Now the game plan switches and they get busy fitting any watery rock they find out there with big rockets and firing them on the long journey into Mars. Depending on their composition, some rocks might be good to smash straight into the planet for extra heat energy, and some fitted out with explosives to 'airburst' on re-entry to spread their water vapour through the atmosphere.

 

And the asteroid miners could also get into building the giant focussing lens that was visualised in Kim Stanley Robinson's "Red Mars" trilogy, with the bottom line that the sun suddenly appeared 'closer' to Mars because more sunlight was concentrated on the planet, and warmed it up.

 

The more I think about it, the more these torus ships become the backbone of many exciting space based ventures we can imagine. Space based solar? You got it! Instead of launching from earth's gravity well, space solar PV is fired into orbit from the asteroid fields.

 

And of course establishing good off-world zoos and ecosystems on these torus ships would be the ultimate act of conservation!

[Eclipse Now]

All of this leads me to ask the first question again: who thinks we have the technology to build a decent sized torus today?

 

(Note: I did not ask about the money. Assume for now whatever you want about how this might be funded.

 

EG: I'm assuming a World Federation is quickly established.

We move to nuclear power, electric cars, fast rail, New Urbanism, etc

...to solve peak oil and global warming,

and while everyone maintains some level of national identity,

and their own culture's and language,

everyone can also speak English fluently as part of a new global government and community.

And then we decide to build a torus with say 1% of the global GDP!)

[Moontanman]

All of this leads me to ask the first question again: who thinks we have the technology to build a decent sized torus today?

 

(Note: I did not ask about the money. Assume for now whatever you want about how this might be funded.

 

Ok, if we used the continuous suspension bridge design like the images of Gaea above (my idea is to have the suspension wires on the outside not the inside like the John Varley one) and we could get by with 1/4 G we should be able to make one at least half the size of the one from Titan, using carbon Nano tube cables and other possible now but still not developed technologies... maybe 600 kilometers across?