Thread: Dyson sphere or rotating habitat?

I have never been terribly impressed by the Dyson Sphere idea. It would be inordinately difficult to make, and would tie a population to one sun, with the vulnerability that implies.

My thoughts are that a trillion rotating habitats would be far better. By the time a civilisation has reached the development level needed to build a Dyson Sphere, they would be mobile in their stellar system, and have effectively unlimited nuclear fusion energy based on deuterium.

Such a society would have little difficulty building a cylindrical habitat in stellar orbit, rotating for gravity, capable of holding a population of a million or more. When that is built, then build another, and another. The total population size is almost limitless. Each such habitat can glean water and minerals from everywhere inside the stellar system. If our own solar system is typical, then there is enormous amounts of each in comets, rings, moon, asteroid belts, Kuiper belts etc. A rotating habitat is, unlike a Dyson Sphere, totally mobile. If the star it orbits gets fractious, then it would be simplicity itself to head off to another star for safety. (Take a few decades, of course. But a self sufficient habitat, well stocked, would have no problem with that.) Or even hide out in the Kuiper Belt.

Building a Dyson Sphere is kind of all or nothing. There is no benefit in half a sphere. Yet each and every habitat built becomes a home. Much more sensible.

On the energy side, Earth has enough deuterium in its oceans to provide enough energy at current rate of use for a billion years. But Saturn's rings have 30 times as much water as Earth's oceans, and there is evidence to suggest that this amount is dwarfed by what is in the Kuiper Belt. And Jupiter, of course, has so much hydrogen as to dwarf all the hydrogen in the rest of the entire solar system (excluding the sun). Energy in extraordinary abundance!

So am I correct? Is the Dyson Sphere idea silly compared to a vast number of mobile and rotating habitats?

No reason it has to be a single solid shell- and no reason for a lot of good starlight to go to waste. But you DO make some excellent points RE fusion etc.

Oort Cloud space colonies

Most schemes are some kind of aerospace model: a sort of ship, built of metal. They begin with human habitation, then add small nods to agriculture and possibly natural environment. Kinda like aircraft carriers with houses and topsoil on the deck. Everything depends on motors and gaskets, complex hydroponic systems. They'd work great for us if we could buy them off the shelf from Toys 'R Us. But then the colonists must spend all their time as spacewalking greasemonkeys and nuclear technicians, if they are to survive. Maybe better design a truly long-term habitat that would be self-sustaining (for human life) in spite of human failings?

That would be a biosphere, which recycles our wastes and produces our necessities, as on Earth. You can't build an Earth, but I believe a self-stable biosphere is conceivable. Then, contrary to traditional habitat schemes, humans find their place in it. As we have on Earth.

Since a biosphere needs water - and traditionally is mostly water - the obvious start is gathering a large ball of water in space. The outside will be frozen but a modest energy input will keep the interior liquid. A biosphere needs life too, so we would seed this ball of water with... well, random pond scum would probably do nicely, provided some crushed rock, heat (above zero), and a little light (pondbottom levels). Gradually work up to insects and fishes. At that stage we have a perfect waste disposal & recycling system.

A complete biosphere includes air, plus plants and animals that like air. So we create an air bubble inside our water ball. I'm afraid the scheme here demands man-made structure, in the form of some flimsy web-work or such to keep the air bubble from drifting off to one side. Where air and water meet, dirt (i.e. dead weeds, fish poop) will tend to settle. This is "land" that terrestrial plants may root in. A light source near the bubble center acts as sun, and "up". But there is no gravity in this scheme. Few plants or animals (especially aquatics) really need gravity.

As on Earth, a biosphere able to sustain the load of humanity must have far more mass than us. In other words a very small portion of a sustainable space habitat would be dedicated to actual human habitation.

Though nothing that we need requires artificial gravity, we do personally. This would be a "human module", probably man-made, probably floating (rotating) within the central air bubble. I prefer a double helix over a torus. Besides it mirroring humanity's preferred role in nature, it's a very easy form to reproduce by gradually unscrewing one helix as it is assembled by the other complete helix, assembly-line fashion, and gradually populating it much as vacant lots in a partially developed town are populated. A lone, complete helix then begins to assemble its own copy "on site", and so on.

Eventually we would want more balls of life-inoculated water to infect with our human modules. But you needn't suddenly complete an entire living habitat, built from scratch in the vacuum of space. The most comfortable way (for humans) is to accumulate more and more mass to an existing habitat, then, when it is nearly double optimal mass, divide it (always working from the inside). Hopefully the human modules that go with each habitat "cell" will continue traditional best practices, but if they try their own variations that's good too.

There's a different take on the notion, although the Oort cloud habitat in the link #2 relies on ice as a structural material too. How exactly does your idea prevent the consequences of "human failings"?

As you may have noticed, Pong, we live in a biosphere already- it is not altogether hazard free, and if you believe the IPCC, "human failings" are overwhelming it.

Originally Posted by Arthur Angler

How exactly does your idea prevent the consequences of "human failings"?

I meant that it should function without human upkeep or oversight. That might not be fully attainable, but I do believe the scheme requires far less servicing than others. I don't think it wise to expect colonists after hundreds or thousands of years to dutifully go out on spacewalks inspecting miles of weld-joints.

And I'll bite "prevent the consequences of human failings": The scheme agrees with Skeptic's points about multitudes vs. monoliths. Half the colonies may get taken over by evangelists, or get popped by asteroids because we forgot how to fix our telescopes, but so half will survive. Because the habitats reproduce without any master template, and are free to test (or goof) variations, they are subject to selection. They aren't modeled on life accidentally. So, no, they won't prevent the consequences of human failings. Rather, they allow for humans to be far less than perfect, and they allow for evolution in how they're operated.

How is inspecting weld joints different from monitoring the oxygen level?

Biosphere 2 and the Golden Gate Bridge both require maintenance. One of them is still doing what it was designed to do, the other never really did.

Originally Posted by Arthur Angler

How is inspecting weld joints different from monitoring the oxygen level?

Ideally the system would self-regulate, much like a sealed glass terrarium that contains both plants and animals. Millipedes don't monitor the oxygen level. A human population might, out of curiosity, but we'd be adapting to conditions rather than operating a machine. Excess population would result in mass die-off, from starvation, suffocation, overheating, social tension, etc. However a colony may grow by rudely adding chunks of ice and rock to its mass, and may split as in cellular division.

Anyway, such scheme allows different colonies to try new ways of living with the habitat biosphere. If one decides a more hands-on control approach better, fine, they may mechanize their biosphere.



Biosphere 2 failed by depletion of atmospheric oxygen. I think this mainly due to the crazy disproportion of land area to water mass (oxygen was supposed to come from trees!). Another mistake was planting up the biosphere with mature specimens rather than allowing species to naturally propagate or fail to grow.

A biosphere should always be actively maintained (allowing it to self-regulate will be bad for the human occupant). Even in real life: grassland turn to woodland, and woodland turn to forrest (in each step the original species will die off and replaced with new one). An occupant of a biosphere must always try to maintain its environment or else they will die and other species will replace them...

Source: Life on Earth (free introduction to ecosystem iBook in iTunes).

It is worth remembering that, by the time humanity is ready for such technological advances, we will have very, very sophisticated robots. There will be no need for such heroics as space walks, and maintenance will be simple, with teams of these robots to do that for us. I could even envisage ecological robots maintaining the biosphere in whatever stage of ecological succession is determined to be optimal. Agricultural robots will keep food and oxygen production up to par.

Robots need not be humanoid. There may, for example, be robots that spend their entire time patrolling the outside of a habitat, testing for flaws, and repairing what needs repairing. Such robots might be flattened to hug the surface, and appear more like a slowly moving rug than anything else.

To Pong.

The biosphere failed more due to lack of CO2 (which is needed to make food and oxygen). I believe they miscalculated by using too much concrete. They forgot that concrete absorbs CO2.

Couple of questions for Dyson Sphere advocates.
First, since people will be living on the inside surface, where does the gravity come from?
Second : how do you keep its position stable with respect to the sun over long periods?

I actually see Larry Niven's ringworld concept as more viable, though it is required to have active position maintaining technology.

Buiding relatively small space habitats is technologicly doable, but just barely. A Dyson sphere requires technology that we don't begin to have, indeed it requires a mass of building material that we don't have. If technologic society does not collapes first we will almost certainly build space habitats of some sort. We already have a space station.

What we don't have is an ecconomic reason to live in space. So far our space exploration has been primarily driven by a military need to "sieze the high ground". What we need is the space equivalent of a gold rush. People will live in space when they can make a living in space. What can you do better inspace than you can on the surface of a planet? Will it make enough money that it is worth putting up with the difficulties of living in space? Nothing immediately jumps into my mind.

The day when having an address in a space habitat is not any more unusual than having an address in Europe is still a long way off. We have not demonstrated even the ablity to colonize the antartic or the continental shelf. Those are far less inhospitable environments. It takes a much greater command of an environment to make your home there than it does to just journey across it. Heck we have yet to even build a seafaring ship that is self sufficient. That would be a good precursor to a sustainable space habitat. Build a ship or floating town that sustains it self on the water, feeds its people, gathers its own bulding materials, or sells something of value enough so it can buy materials , makes its own repairs and can reproduce itself.

Sealeaf

There are a lot of people talking of building a self sustaining colony on Mars. Obviously we do not need to do that. But given time, it is still likely to happen.

To me, that is doing it the hard way. To live on the surface of Mars will require pretty much everything a space habitat will need, and you have an extra gravity well to fight at the same time. A space habitat built in Earth orbit would require only one gravity well to be fought for supply purposes. Once complete, a space habitat would be mobile and able to access anything of sufficiently low inherent gravity.

For example, the moons of Mars can be "docked with" rather than landed upon. A much less energy demanding activity. Ditto comets, ice chunks in Saturn's rings, or small Kuiper Belt objects. Each and every such object is a potential source for vital raw materials.

None of this will happen in our lifetimes, so to be honest, I don't care

And predictions about how future humanity will cooperate and decide to spend their money are worthless IMHO.