March 20, 2012

How to build a Dyson sphere in five (relatively) easy steps

Let's build a Dyson sphere!

And why wouldn't we want to?

By enveloping the sun with a massive array of solar panels, humanity would graduate to a Type 2 Kardashev civilization capable of utilizing nearly 100% of the sun's energy output. A Dyson sphere would provide us with more energy than we would ever know what to do with while dramatically increasing our living space. Given that our resources here on Earth are starting to dwindle, and combined with the problem of increasing demand for more energy and living space, this would seem to a good long-term plan for our species.

Implausible you say? Something for our distant descendants to consider?

Think again: We are closer to being able to build a Dyson Sphere than we think. In fact, we could conceivably get going on the project in about 25 to 50 years, with completion of the first phase requiring only a few decades. Yes, really.

Now, before I tell you how we could do such a thing, it's worth doing a quick review of what is meant by a "Dyson sphere".

Dyson Spheres, Swarms, and Bubbles

The Dyson sphere, also referred to as a Dyson shell, is the brainchild of the physicist and astronomer Freeman Dyson. In 1959 he put out a two page paper titled, "Search for Artificial Stellar Sources of Infrared Radiation" in which he described a way for an advanced civilization to utilize all of the energy radiated by their sun. This hypothetical megastructure, as envisaged by Dyson, would be the size of a planetary orbit and consist of a shell of solar collectors (or habitats) around the star. With this model, all (or at least a significant amount) of the energy would hit a receiving surface where it can be used. He speculated that such structures would be the logical consequence of the long-term survival and escalating energy needs of a technological civilization.

Needless to say, the amount of energy that could be extracted in this way is mind-boggling. According to Anders Sandberg, an expert on exploratory engineering, a Dyson sphere in our solar system with a radius of one AU would have a surface area of at least 2.72x1017 km2, which is around 600 million times the surface area of the Earth. The sun has an energy output of around 4x1026 W, of which most would be available to do useful work.

I should note at this point that a Dyson sphere may not be what you think it is. Science fiction often portrays it as a solid shell enclosing the sun, usually with an inhabitable surface on the inside. Such a structure would be a physical impossibility as the tensile strength would be far too immense and it would be susceptible to severe drift.

Dyson's original proposal simply assumed there would be enough solar collectors around the sun to absorb the starlight, not that they would form a continuous shell. Rather, the shell would consist of independently orbiting structures, around a million kilometres thick and containing more than 1x105 objects. Consequently, a "Dyson sphere" could consist of solar captors in any number of possible configurations. In a Dyson swarm model, there would be a myriad of solar panels situated in various orbits. It's generally agreed that this would be the best approach. Another plausible idea is that of the Dyson bubble in which solar sails, as well as solar panels, would be put into place and balanced by gravity and the solar wind pushing against it.

For the purposes of this discussion, I'm going to propose that we build a Dyson swarm (sometimes referred to as a type I Dyson sphere), which will consist of a large number of independent constructs orbiting in a dense formation around the sun. The advantage of this approach is that such a structure could be built incrementally. Moreover, various forms of wireless energy transfer could be used to transmit energy between its components and the Earth.

Megascale construction

So, how would we go about the largest construction project ever undertaken by humanity?

As noted, a Dyson swarm can be built gradually. And in fact, this is the approach we should take. The primary challenges of this approach, however, is that we will need advanced materials (which we still do not possess, but will likely develop in the coming decades thanks to nanotechnology), and autonomous robots to mine for materials and build the panels in space.

Now, assuming that we will be able to overcome these challenges in the next half-decade or so—which is not too implausible— how could we start the construction of a Dyson sphere?

Oxford University physicist Stuart Armstrong has devised a rather ingenious and startling simple plan for doing so—one which he claims is almost within humanity's collective skill-set. Armstrong's plan sees five primary stages of construction, which when used in a cyclical manner, would result in increasingly efficient, and even exponentially growing, construction rates such that the entire project could be completed within a few decades.

Broken down into five basic steps, the construction cycle looks like this:
  1. Get energy
  2. Mine Mercury
  3. Get materials into orbit
  4. Make solar collectors
  5. Extract energy
The idea is to build the entire swarm in iterative steps and not all at once. We would only need to build a small section of the Dyson sphere to provide the energy requirements for the rest of the project. Thus, construction efficiency will increase over time as the project progresses. "We could do it now," says Armstrong. It's just a question of materials and automation.

And yes, you read that right: we're going to have to mine materials from Mercury. Actually, we'll likely have to take the whole planet apart. The Dyson sphere will require a horrendous amount of material—so much so, in fact, that, should we want to completely envelope the sun, we are going to have to disassemble not just Mercury, but Venus, some of the outer planets, and any nearby asteroids as well.

Why Mercury first? According to Armstrong, we need a convenient source of material close to the sun. Moreover, it has a good base of elements for our needs. Mercury has a mass of 3.3x1023 kg. Slightly more than half of its mass is usable, namely iron and oxygen, which can be used as a reasonable construction material (i.e. hematite). So, the useful mass of Mercury is 1.7x1023 kg, which, once mined, transported into space, and converted into solar captors, would create a total surface area of 245g/m2. This Phase 1 swarm would be placed in orbit around Mercury and would provide a reasonable amount of reflective surface area for energy extraction.

There are five fundamental, but fairly conservative, assumptions that Armstrong relies upon for this plan. First, he assumes it will take ten years to process and position the extracted material. Second, that 51.9% of Mercury's mass is in fact usable. Third, that there will be 1/10 efficiency for moving material off planet (with the remainder going into breaking chemical bonds and mining). Fourth, that we'll get about 1/3 efficiency out of the solar panels. And lastly, that the first section of the Dyson sphere will consist of a modest 1 km2 surface area.

And here's where it gets interesting: Construction efficiency will at this point start to improve at an exponential rate.

Consequently, Armstrong suggests that we break the project down into what he calls "ten year surges." Basically, we should take the first ten years to build the first array, and then, using the energy from that initial swarm, fuel the rest of the project. Using such a schema, Mercury could be completely dismantled in about four ten-year cycles. In other words, we could create a Dyson swarm that consists of more than half of the mass of Mercury in forty years! And should we wish to continue, if would only take about a year to disassemble Venus.

And assuming we go all the way and envelope the entire sun, we would eventually have access to 3.8x1026 Watts of energy.

Dysonian existence

Once Phase 1 construction is complete (i.e. the Mercury phase), we could use this energy for other purposes, like megascale supercomputing, building mass drivers for interstellar exploration, or for continuing to build and maintain the Dyson sphere.

Interestingly, Armstrong would seem to suggest that this might be enough energy to serve us. But other thinkers, like Sandberg, suggest that we should keep going. But in order for us to do so we would have to deconstruct more planets. Sandberg contends that both the inner and outer solar system contains enough usable material for various forms of Dyson spheres with a complete 1 AU radius (which would be around 42 kg/m2 of the sphere). Clearly, should we wish to truly attain Kardashev II status, this would be the way to go.


And why go all the way? Well, it's very possible that our appetite for computational power will become quite insatiable. It's hard to predict what a post-Singularity or post-biological civilization would do with so much computation power. Some ideas include ancestor simulations, or even creating virtual universes within universes. In addition, an advanced civilization may simply want to create as many positive individual experiences as possible (a kind of utilitarian imperative). Regardless, digital existence appears to be in our future, so computation will eventually become our most valuable and sought after resource.

That said, whether we build a small array or one that envelopes the entire sun, it seems clear that the idea of constructing a Dyson sphere should no longer be relegated to science fiction or our dreams of the deep future. Like other speculative projects, like the space elevator or terraforming Mars, we should seriously consider putting this alongside our other near-term plans for space exploration and work.

And given the progressively worsening condition of Earth and our ever-growing demand for living space and resources, we may have no other choice.

25 comments:

nazgulnarsil said...

What resources on earth are dwindling?

we have massive energy reserves in thorium. thorium reactors can be built on an assembly line. our current energy problems are regulatory rather than technical.

Davery said...

Some problems with this.

1) Comets and asteroids have eliptical orbits in and out of the 1AU radius consitantly. The Dyson sphere would be bombarded fairly consistantly which would mean constant repairs or some kind of defense system.

2) Mucking around with eons old gravitational mechanics on this scale (i.e. removing entire planets from orbit and placing the material at a different level) may have very unforseen consequences to the orbit of the mother home planet. That would need serious number crunching before implementation.

3)Solar panel effeciency is expected to improve radically . Ther may be no need for such a wide scale sphere, as the amount of light energy falling on our local area should be more than sufficient to get us to a tier II civilisation. Nice project , but unneccessary, therfore not signed off, therfore not going to happen.

That Neil Guy said...

This may seem stupid, but is it ethical to dismantle Mercury? Is it "ours" to do with as we please?

Gareth Hailes said...

Hi, Please ignore my previous comment. I just linked the FHI talk. Thanks

Sean the Sorcerer said...

I'm a bit confused by the idea of using a Dyson sphere for living space. Are we assuming some kind of post-human species that doesn't require gravity? If we're going to engage in fantasy speculations, why not just assume that we shrink ourselves to the size of insects? Problem solved!

Anton Sherwood said...

Breaking up a planet should make the remaining planets' orbits less chaotic, not more.

My main worry is that enclosing the Sun will change the illumination of Earth (one way or another).

Meanwhile who's the "we" that would attempt a crash project? It's more plausible to suppose that a Dyson swarm will form "naturally" and incrementally as more stations (habitats, factories and whatnot) are built. But then a concern is competition – portrayed in one of Blish's Cities in Flight novels, iirc – for low orbits and first crack at the sunlight.

beginner said...

@Neil, that's not a stupid question at all. The fundamental rights of the land are critically important to protecting things like entire planets.

The Mars Trilogy by Stanley Kim Robinson discusses the issues extensively in the context of terraforming mars.

Accelerando by Charles Stross is a good cautionary tale about what happens when a post singularity civilization starts turning the planets into a giant supercomputing Dyson Sphere.

Starcraftre said...

@Davery
An answer, an agreement, and a disagreement:
1) Since this will be made up of individual panels, the odds of impacts go way down. They will occur, but it should be rare enough that having a hundred "spares" should be sufficient.
2) Agreed. Also, in conjunction with your first point, would a near-miss on one of the swarm's panels knock it out of orbit far enough to threaten earth itself?
3) Solar panel efficiency WILL get better, but the definition of a Type II civilization is one that harvests the entire energy output of a solar system. You can get maybe a tenth of a percent of that from sticking to our local area. A Dyson-style megastructure is the only feasible way to do that.

Richard said...

Note: Everything but Europa.

Jay Dugger said...

G.D.:

Have you seen Keith Lofstrom (of the launch loop proposal) discussing Server Sky? You might find it interesting reading, as it puts numbers to an less ambitious mega-engineering project with incremental pay-offs and higher technological readiness.
It is easier to move bits than atoms or energy.

Server Sky thinsats are ultralight films of glass that convert sunlight into computation and communications. Powered by a large solar cell, propelled and steered by light pressure, networked and located by microwaves, and cooled by radiation into deep space. Arrays of tens of thousands of thinsats act as highly redundant computation and database servers, as well as phased array antennas to reach thousands of transceivers on the ground.

First generation thinsats are 18 centimeters across (about 7 inches) and 0.05 millimeters (50 microns) thick, and weigh 3 grams. They can be mass produced with off-the-shelf semiconductor and display technologies. Gallium arsenide radio chips provide intra-array, inter-array, and ground communication, as well as precise location information. Thinsats are launched stacked by the thousands in solid cylinders, shrouded and vibration isolated inside a traditional satellite bus."

http://server-sky.com/
"

Chakat Firepaw said...

@Starcraftre:

You missed the two main reasons why the swarm wouldn't be at too much risk from asteroids:

First, since this is a swarm they can avoid any incoming asteroids.

Second, with how hungry the project is for matter anything that conveniently placed is going to be used.

Yordan Georgiev said...

In less than 5 years there will be working fusion power plants, in 10 years transmutation will enable us to escape from the row materials shortages. The cost of the Dyson sphere will be prohibitive to compete with fusion ...

Yordan Georgiev said...
This comment has been removed by a blog administrator.
Brent said...

I am curious how we would be able to mine Venus since anything we have sent to the surface stops functioning in less than a few hours. I understand that the technology would be improving, but a mining robot is far more complicated and much more difficult to shield than the small armored probe capsules we have sent.

Surly Curmudgen said...

Hey I put in my claim to the mineral rights on Mercury many years ago. Hands of.

Move Venus out to earth orbit trailing by 72 degrees and use Mercury as it's moon.

We need three more so grab three of the gas giants moons, useful ones, and put them 72 degrees apart in earth orbit, each with a moon of appropriate size.

Andrew said...

Howdo you get the energy from the panels in the Dyson sphere back to Earth?

Stuart Dobson said...

Hi George, This article was inspiring so I wanted to think more about the ethical implications of dismantling Mercury. That, and I thought it made a fantastic blog title. http://superconcepts.blogspot.com.au/2012/05/ethical-implications-of-dismantling.html

William R. Cousert said...

> digital existence appears to be in our future

Maybe it's our past. Right now we could be playing in an MMORPG - a simulation of early 21st century Earth.

therix said...

@Anton
Wrong. Each planet is currently in a stable orbit thanks to the combined efforts of the planetary bodies from every other angle. It's been confirmed that our solar system achieved perfect synchronisation out of luck. To remove certain planetary bodies, reposition or deplete them would disrupt the gravitational balance on each remaining body. Thus planets would begin to drift, and start to realign. Earth would most certainly be dragged away from the sun by the sudden lack of the planet Mercury or others closer to Sol itself. We have a balance - to disrupt it now would mean remaining planets are dragged together.

@Nazgul
It's not just energy on earth that's dwindling - living space, oxygen, they're both resources.

Cavaron said...

Nice concept! I would prefere to terraform Venus instead of dismanteling. Its Mass is much more earth-like than Mars, but it needs water (Europa maybe) and shadow to freze its thick and hot carbon-atmosphere down. Maybe the first Dyson-panel could be the source of this shadow ;)
Mercury, asteroids and all the other moons from the gas-giants are ready to go for Dyson-Sphere imo.

qraal said...

Hi George, I really liked your post, but had to take exception to the mass inefficiency of the process proposed. Thus I wrote my own post on a statite Dyson Shell and its likely mass...
http://crowlspace.com/?p=1372

Laston Kirkland said...

well, if you're already making units as fast as we would be... the occasional destruction by comet would be a terrible thing, but not unexpected. we just rebuild,

and maybe catch and use the comet, put one of the von Neumann machines on it so by the time it comes back around, the entire thing will be neatly sorted, prepped and bundled for assembly. including the salvageable bits of the colonies it hit.

constant repairs would be the norm. but we'd have a lot of machines doing these repairs.

as far as unnecessary, if we make these ships into Mckendree cylinders, we will have far more real estate in these ships, each and every one of them a paradise the size of Texas.

Some Person said...

Yes, that seems silly. Yes, it's ours to do with as we please. Who else could possibly claim it? Aliens? Future generations? The aliens can fuck off, and future generations wouldn't care about it as much as we would - having grown up in the context of it already being gone. And they especially wouldn't complain, given the abundance of energy they'd have as a result.

If we want to tear Mercury apart, we should just go ahead and do it.

Keith Fox said...

I am all for building a Dyson sphere. A concern: How would this project effect gravity in our solar system? Could there be some kind of orbit shift, Earth or otherwise, due to the relocation of large fractions of planetary mass?- and that mass' relocation to our general orbit, 1 AU?

Loveday said...

Since March '12, much Keshe Foundation tech from Physics Engineer Mehran T. Keshe 38 years of intense work has been distributed planet-wide on an 'open-source' basis. It assures that this idea will never, nor will ever need to be attempted.