it is indeed sci-fi! but with our current level of technology, we're probably past earth's carrying capacity. it's anywhere from 1 to 10 billion, depending on who you ask.

but since it's sci fi...

i watched this episode of Extreme Engineering on the Discovery Channel. it was about "mega structures" or something like that, covering two project proposals going on in Japan to help with Tokyo's population problem. one's basically the skeleton of a giant pyramid build of subway tubes; from the intersection points hang sky scrapers. the other were these three multi-mile high towers with additional, open-air habitation levels connecting all three every few hundre feet. those super towers would also be connected with other triplets of supertowers, creating a miasma of human habitation reaching miles into the sky. of course, neither is past the blue print stage. it was still a cool episode.

but the real issue of earth's carrying capcity isn't space. the entire 6.5 billion people could fit happily into suburban-track style homes and take up no more space than the area of Texas. the entire populat could stand shoulder-to-shoulder in a space no bigger than Rhode Island. the real issue is food, and the rest of what we consume (which can be collectively called our ecological footprint). Americans currently have an ecological footprint of about 5-10 hectares. the figures for Europe and Japan are similar. IIRC the planet only has about half a hectare per person of usable land for a population of 6 billion.

the real carrying capacity will be subject to technology. we may be able to make more of the land useable, and we can definately extract more from the land we do use now (and maybe even sustainably). i'll have more to say on this later.



as i said previously, i don't imagine metal will be our one primary building material. glass is pretty strong, and silicon is pretty common. ploymers and ceramics are also extremely useful, and they're both made maily from carbon. i don't think iron is going to be a major building material because it's so heavy. aluminum and titanium make a lot more sense, at least if you ever need to move the materials (even just into place for final assembly). though, iron could be extracted from a planet and sent into orbit on a space fountain pretty cheaply...

but the bigger point i had is, does a base on mars actually use less resources than a base in orbit? i don't think so. about the only thing the space station would need to deal with that the planetary base wouldn't is generating artificial gravity. the planet, on the other hand, would need to deal with constructing a launch site and generating the resources to get things into space. launching things (big things anyway) from orbit is WAY cheaper than from the surface of a planet. it takes immense amounts of energy, relatively speaking, to escape a gravity well. that's why i've been suggesting the use of space fountains to shuttle things off a planet and into orbit.

for that same reason i don't believe planets will be our primary source of heavy elemental resources. we can get everything we need from the asteroid belt, without having to deal with gravity (or course, the danger of asteroid collisions is the big trade off).

another issue with colonizing planets first is that we might want to terraform them. that article is really interesting, to me anyway. the one thing it leads me to conclude is that: we currently have no idea of whether terraforming will be possible in theory or in practice. at bare minimun it seems like terraforming would take centuries, and it wouldn't always be a process through which surface inhabitants could survive. but given that, it seems to me we'd start building surface structures long before we thought about terraforming. from what i can say, it seems like incompletely terraforming Mars would be possible (because the planet is smaller and its core has cooled down, it has less gravity to retain an atmosphere, and no magnetosphere to deflect solar wind). Mars would need more atmosphere and probably more water (to facilitate a higher greenhouse effect). on the other hand, we'd have to find a way to reduce Venus' atmophere. it'd probably be a much drier planets, since greater amounts of water would contribute to greenhouse effect. but in any case, the ability to do either seems to be reliant first on having an infrastructure capable of supporting frequent space travel.

ultimately it'll all be a matter of cost. after enough time, it's hard for me to imagine us not exploiting all the resources we can in our solar system... except in the event that we destroy ourselves or know ourselves back to the stone age.



absolutely massive; bigger than any single thing humans have ever built before, by a wide margin.



oh, agreed. treaties don't mean a damn when you've got the power to ignore them. just look at the U.S. history of accused war crimes, our history of nuclear non-proliferation, etc.



as in meat? meat takes such a huge investment, and with the exception of omega-3 fatty acids in cold-water fish (which we can also get from flax), meat doesn't provide us with nutrition we can't get from other sources. plant protein isn't really inferior to animal protein as a dietary source; it's just less abundant. it's a little less effecient, but not detrementally so. most skinny vegans are skinny because they don't take take the effort to balance their diets. a friend of mine decided to take up body building after he'd been a vegan for 4 years; he doesn't eat meat for spritual reasons. either one of his arms is thicker than my neck. he uses that muscle building powder crap, which is mostly soy protein.

but maybe you meant something else...

BTW, i'm really enjoying this conversation everyone.

it takes 14 different plant types to get the same nutrients of meat. and then you have to take Vita. pills to make up for what you don't get.

A space station need supllies just like any place. But space stations have no way to generate those supplies themselves. A space station will require many supply ships to be launched from whatever planet it orbits in order to sustain itself. A planetary colony can draw resources for energy from whatever is availiable. Planets are the batteries that sustain all our activities. A space station on the other hand is no more than an extension of its parent world.

I think it's totally dependant on what you want to do with the base. They both have advantages and disadvantages.

Ground base:
Easier to build
More space to build on
Gravity
Ability to harvest resources locally
Space travel very difficult

Orbit base
No gravity (can be plus)
More dificult to build
Dependant on resource shipments from somewhere
Space travel is easier

I think ultimately, for any longe term base to survive, you will need both. An orbital base would handle "space traffic" and a ground base that would produce some resource or commodity. The space fountain idea would probably link the two.



This brings up another intersting point. With multivitamins, protien pills, etc we've essentially gotten to the point where we can place all the nutrients required for a person into a few capsules. Hospitals can pump nutrients ("food") into people's systems with out the need for mastication. It could be possible in the near/distant sci-fi world for a person to get a day's calories and nutrition from a few pills and a shake or two (kinda ala the Jetson's). Of course, I prefer the taste of real food, but in a future world where food is less abundant, perhaps real food will be a luxury and everyone else eat pellets (hehe, makes me think of my cat's food, lol).

A space based hyproponic farm or whatever still need resources from the planet (fertilizer, water, etc), but if you mined carbons and ran them through reactors to create nutrients (vitamins, sugars a human can process), you wouldn't rely on a planet nearly as much in terms of raw resources. At the moment we can't do this, but if we could mine carbons in space and convert them to a really simple sugar to say, feed genetically engineer bacteria that would excrete something useful that humans could use (like vitamin A or whatever!), we'd have the food thing taken care of.

i did mention edible moss growing everywhere. i know got it from enterprise.





fertilizer can be gotten from the stocks of the plants. from the livestock ranch modules. if done right water can be recycled this would be the main reason for the size of the family station(or whatever you would call them).

yes, and no amount of meat can make up for what you'd lose if you didn't eat vegetables and fruits. statistics like that are generated by the meat industry; while not technically fictitious, they're highly scewed.

1) consider the fact that raising an animal for food means you have to feed it for its entire life. IIRC you get about 7% the usable food mass as opposed to just eating the animal's food yourself. raising animals in small numbers works on a planet like earth, where many of the wild-growing plants cannot be consumed by humans. but anything we bring to space will be for us, and will have to be optimally effecient. animals as food simply are not.

2) raising animals also requires a lot of space. well, not mass-produced chickens. they're raised in boxes; their feet and beaks are cut off to keep them from hurting each other, and they're fed through tubes. buy free-range. but getting back to the point, that space will also have a high premium on it in a space station or an offworld planetary base.

3) true, animal meat does have a number of useful nutrients, and you'd need to eat a mix of 9 or so cereals, pulses, fruits and vegis to replace them. but if you ate those instead of meat, you'd also be getting lots of nutrients that are not in meat, as well as the myriad enzymes that only occur in plants and can have great benefits for the body.

4) meat has high levels of cholesterol, saturated fat and triglycerides. all of these things are very bad for people. most plants on the other hand have much higher levels of unsaturated and polyunsaturated fat, "good" cholestorol, and omega 3 and 6 fatty acids, all of which are much better sources of fat (which is an important part of the diet).

5) good luck getting a cow in a rocket.

(that one was a joke, i know you could use sedatives).

don't get me wrong, i think meat is part of a more optimal diet in a vacuum. animal protein is more easily used to build muscle, and it also triggers a 5th taste bud wired to detect animal fat (thus releasing more dopamine and increasing the pleasure we take in eating, which is an important part of mental health).

but how many people eat optimal diets? most of the people of the world don't have the money to. those of us that do, tend to prefer things that are even worse for us, like diets extremely high in meat, fats and refined carbs (which are probably the worse thing for you).

a serving of cooked steak is the size of a deck of standard playing cards. you need 1 or 2 of those a day. or you could replace a serving with one egg, half a medium chicken breast, or a fish fillet. or a cup of beans, which are very easy to grow. but more meat than that, and it's doing you as much harm as good.



honestly, i think when we get to the point that we can do either, we'll probably be doing both right around the same time. start with a small space station to help with traffic. then, a small ground base to start building infrastructure. i think both would be gradually expanded.

but there's the issue of terraforming still. that's a much taller order than building small bases. it's probably also a taller order than building bases that could support sizeable populations. if it's even possible, i can imagine two methods. small, incremental steps, taking thousands of years. or major marvels of engineering taking only centures. the former would amount to ground based machines to generate or reduce, and mostly convert atmosphere. the later would amount to redirecting a solar flare using magnets to burn off some of Venus' "extra" atmosphere, for example. but in the latter case, we'd have more immediate rewards, but might cause major problems for structures already on the planet.

the case of Mars is different though. There, we want to heat things up. Not just the air, but the core itself, since it's cool and generates no magnetic field and no plate tectonics (which means no circulation of gases and minerals trapped below the surface, much like most of Australia). Bombs won't do much to the core of a planet, but they might be able to stir up the surface elements (in effect, re-fertilizing the soil... if we don't irradiate it in so doing).

but without a magnetosphere, even if we and generate an atmosphere on Mars, it'll blow away in time without maintanence. So maybe the gradual approach makes more sense for Mars, where we'd more likely have bases already anyway.

i was thinking some kind of sling so the g's wouldn't be that hard on it.



we call them caves. and mars does have an ozone layer. i learned that about two weeks ago.

I still think that private visionaries or small groups of fleeing people with a common purpose (ie, shared religious beliefs, refugees from world war 3, etc) are the most plausible reason to head out of the solar system. No earth based government, business, or power stands to really gain anything from the transaction barring development of the aforementioned faster than light technologies, which is a bit far fetched to use in hard sci fi.

Imagine, for example, some kind of half-mad, fabulously wealthy visionary who realizes that his dreams of a perfect society can't be realized on Earth. He gathers his small, cult-like group of followers, prepares for the trip in secret, and they all head starwards in pursuit of his grand design. That ignores the engineering challenges, sure, but that would provide the motivation!

To such a group, the passage of time and distance would be completely irrelevant. Keep in mind, also, that humanity might have solved the problem of aging by then, making them effectively immortal (providing they don't go insane or get hit in the head with a particularily large rock). Hell, some people say that'll be achievable in 25 years or less... though I wonder just what evidence they're basing that on.

how do you build a generation ship in secret. first it has to be built in orbit. even if you only plan on 10 people starting the trip. you have to assume that there are going to be close to 100,000 by the time you get there. to prove my point my church says that there are only 40 generations between us and Noah.

you can't grow much in caves. fungi. that's about it.

also, Mar's ozone layer is very thin (thinner than our's despite all the depletion, and not enough to make up the extra difference between Mars and the sun). moreover, the ozone layer isn't the only thing protecting us from solar radiation. the magnetosphere deflects a great deal of high-energy EM radiation, and gathers another great deal of it into its weakest points, the magnetic poles. that's why we have aurora phenomena in those two places alone. without our magnetosphere, gaseous molecules would become much more energetic; many would reach escape velocity and fly off into space. it's take centuries, and someday when our core cools, it will happen to the Earth (if we don't take measures to prevent it).





both excellent points. and thanks, Starstriker; i actually wanted to spend more time thinking about the idea that a radical group might do it. i was dismissive of the idea at first, but it's beginning to make more sense.

though i have to point out, why would a mad bajillionaire need to build such a ship in secret at all? if anyone had a problem with it, he could easily pay them off. plus, i think most countries would be happy to let people walk into suicide (in their eyes). they could play the group off as heros. if they throw in a bit of token funding, they can even claim credit. and at the same time this would help solve unemployment and overpopulation problems. the only objection i can see for now at least might be the resources this would use. but throwing money at problems tends to make them go away, so unless people stop valuing money and start paying attention to what it's supposed to represent (productive work, at least in Marxian economics), i think this is a rather plausible scenario.

and if, centuries later, the Sol population were to learn that the colony ship actually survived and maybe even prospered, i could see it becomming something lots of people wanted to do; i could see that being a problem for governments and businesses, who need lots of people as the base of their powers. i think we've just brainstormed book 3   

if it was me and i wanted to build a generation ship.

i would convince a government that i was building a science research ship.

take a team of how ever many to the outer planets. probable just jupiter and or saturn. to get human eyes out there.

of course the ship would have to be huge to carry the supplies needed for the round trip.

and using sling shots position myself on a trajectory out of the solar system.
of course doing the jupiter and saturn science stuff on the way out.



to fight the radiation on mars you only have to build underground. and the ozone layer however thin will help too.

i think that's a good solution for the short term bases, but you can't house millions of people in caves. in face, we don't even know if Mars has caves. it's very possible it doesn't, since there's no running water on the surface. on the other hand, if they're liquid water below the surface, caves may abound and even already have the water we need. but that's a big if to plan a mission on. i suppose we wouldn't really know until we'd explored at least part of Mars fairly well.

mars has volcanoes it has caves. and you can always dig.

We can't grow much in caves. A futuristic race armed with light bulbs that mimic the sun's light spectrum, soil and fertilizer, carbon dioxide, and water could though. We already have soil, fertilizer, CO2, and water, so whats stopping us? Or do you think that advanced light bulbs are too much for us to achieve?

While finding natural caves isn't likely to yield many results, what about artificial tunnels? A hundred feet or so of rock can give all the protection we need from cosmic radiation and such, plus it would take a lot less time to introduce air in a tunnel network than an entire atmosphere. Plus, all we really need for this sort of colony to work is a ball of rock, which is relatively common compared to the requirements for surface colonies.

growing plants on mars. mars has an abundance of iron on the surface fertilizer. has an abundance of CO2 for food. all you need are greenhouses that will maintain a certain pressure lvl but also lets some of the oxygen out into the atmosphere.

funny... they'd need be to big caves... and very efficient bulbs... compact flourescents won't do it. as someone with a bit of first-hand experience with hydroponic systems using artificial lighting suited for plants (a friend of mine is a graduate student in botany, and i have some, uh, hobbies of my own), i can say it ain't cheap. and if we need tunnels we're going to rig with bulbs, why not rig a giant space station with a window instead and grow in space? yeah, too much radiation... but that can be helped with magnets and tinted windows.

see... without an itemized cost estimate sitting in front of me, it's six of one and half a dozen of the other.



have you ever worked with dead soil? it's not just nutrients plants need, they need them in the right proportions and concentrations. they don't even need that much iron. their main nutrients are what you find in miracle gro: nitrogen, potassium and phosphorous. but a plant can only use them in particular molecular configurations: gaseous molecular nitrogen is useless to most plants. yes, like animals, plants need trace amounts of metals to be healthy. trace amounts. how would you fare if a third of your diet was rust?

besides that, most plants are also finely tuned to their environments in other ways. i'm sure we could find plants that'd survive the cold on Mars. but they're also closely tuned to circadian light cycles. IF the plant survived, it'd be very confused by the different day and year lengths on Mars (or Venus, or almost anywhere else, for that matter). the likelihood that a food-producing plant would produce food under such circumstances is slim. that this would mean a very narrow and unhealthy diet, since few plants would work on another planet without intense environmental regulation.

beyond that, you can't just drop a plant somewhere and expect it to live. ecosystems are intensely interrelated. plants rely on a huge variety of microorganisms in the soil to survive, plus all the macro ones like worms to airate soil and bees to pollenate them. read up on the fate of Biosphere 2 for a more colorful picture.

i think the introduction of life that can live in an uncontrolled environment will have to start with bacteria and algea, likely ones we modify ourselves beforehand.

a martian day is only off by about 30 minutes.



take that with you. and yes i knew you would have to do something like that.

Nope. The whole reason the New World was colonized was economic, and as transport tech got better (bigger ships, sail to steam, etc.) it became cheaper to move goods. This is what I see as the spark.

There will be several small scientific stations thru our solar system. We will get better at building ships to support these stations. At some point there will be an economic impulse to develop a resource - imagine if we discovered oil on Mars that we could pump and ship to Earth for $30 / barrel. Then it begins. The resource requires people to develop it, people require services, which require more people and on and on.

Hey - instead of a Bussard ramjet, what about a solar sail? It makes for really long transit time between stars, but the tech exists now.

as things stand there is no rescue.

Ok, whether we used space station or landside colonies, there will be different environmental problems either way. But the bottom line is beyond these issues; space stations cost their altitude in fuel. If the costs of terraforming a planet are too great, a planetary colony could still be built enclosed, essentially just a space station on the ground, and it wouldn't cost whatever it took to bring fuel and supplies to an orbital station.

The only way around this is if we were able to greatly, greatly utilize solar energy more than we could today, but were talking huge solar panels in space, with incredible 50+ efficiency to feasibly support a large station with all their energy needs. Not that I would disapprove of that. A pretty neat image actually; great, shining fields of solar panels all tethered to a central station hub would look pretty sweet when approaching it from a spaceship.

But if you don't like that, then in my opinion, the only practical use for space stations are manufacturing centers and star docks for ships. But they would still require a ground colony to sustain their supply needs. Ground colonies are the first logical step.



Hobbies, you say? You looking for, er, contributions? To further cultural art forms, of course, and share in the, ah, benefits.

30 minutes can make a huge different for a plant. a difference of 30 minutes of light is the difference between winter and spring in most temparate zones. moreover, a Martian year is over 1.8 Earth years. that would also mess plants up.



unfortunately it's not quite that simple. for starters, miracle-gro itself is only useful in the short term. the nitrgen is bound up in ammonia and urea, which makes the soil acidic over time. moreover, chemical fertilizer isn't enough. there's no substitue for good quality manure and compost, which are heavy and bulky and don't give much to vacuum compression.



to an extent it does; further engineering would refine materials technology to make potentially much better sails, but as it stands we could build one. problem with using it for interstellar travel is that solar wind turns into something more like a riptide once you get past the heliopause. while there is a prevailing current (away from the center of the galaxy, IIRC, at least until you enter intergalactic media anyway), it'd be much less powerful than inside a solar system, even given the relatively higher density.

i think solar sails would make the most sense for un-manned probes as well as ships designed only for travling inside a solar system. they're just too cheap to refuse.

but i thought we just said no livestock.

everything we need we can take with to get it started.

Who say's you'd need animal manure?

Funny, and a good point, you could just use the crews poo-poo, to grow plants.

The best way to survive in space is to use everything and waste NOTHING.

In the book Andromeda Strain, there was a space disease that absorbed everything and never wasted anything. The book wasn't good but it made some good points.

this is very true



hate to tell you this but the crews are animals.


i think we will find that the answer to oxygen on stations and the answer to living on mars in the open someday will be moss.