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How to build a Dyson sphere in five (relatively) easy steps
September 7, 2012 1:03 PM   Subscribe

How to build a Dyson sphere in five (relatively) easy steps.
posted by Egg Shen (80 comments total) 24 users marked this as a favorite

 
What could go wrong with completely covering the sun?
posted by motorcycles are jets at 1:08 PM on September 7, 2012 [2 favorites]


Aha, but! the article fails to mention that scrith hasn't been invented yet.
posted by Twang at 1:09 PM on September 7, 2012 [2 favorites]


"Ever since the beginning of time, man has yearned to destroy the sun. I shall do the next best thing: block it out.”
posted by leotrotsky at 1:13 PM on September 7, 2012 [15 favorites]


Boys, that's one of the finest veins of pure handwavium I've seen in a long time.
posted by octobersurprise at 1:13 PM on September 7, 2012 [12 favorites]


...we are going to have to disassemble not just Mercury, but Venus, some of the outer planets, and any nearby asteroids as well.

God forbid we get to this step before it becomes cheaper to send robots than people.
posted by griphus at 1:17 PM on September 7, 2012


Maybe this is the first step in the one thousand years of darkness Chuck Norris's wife was talking about.
posted by MCMikeNamara at 1:18 PM on September 7, 2012 [5 favorites]


See, here's my issue with the Dyson sphere/swarm concept. Say this is something we can do. Now we've got electricity and/or heat in a billion collectors scattered across several cubic AU of volume. Umm... now what? We'd have to concentrate that energy at discrete points to do anything useful with it, and that involves shooting across millions of miles of space. At those distances, a difference of a thousandth of a degree would cause a beam to miss by dozens or hundreds of miles. Seriously, at 5 million miles, a thousandth of a degree is like 44 miles. Oh, and angle corrections would take no less than a minute a piece.

And shooting all that energy towards Earth? Well you've certainly got a target that's big enough to plausibly hit over those colossal distances, but "global warming" suddenly becomes "ants under a magnifying glass." Seriously, we do not want even a tiny fraction of the sun's total output to be directed here. We're not talking about climate change or a rise in sea level, we're talking about boiling off the oceans.

This isn't just more energy than we can use, it's more energy than we can handle.
posted by valkyryn at 1:20 PM on September 7, 2012 [12 favorites]


I think a better thing to do than build a Dyson Sphere would be to build half a Dyson Sphere, using the Dyson Bubble technique that is briefly mentioned in the article. Then, we can steer the half-bubble and use it to move the Sun. Why move the Sun? Because it's awesome, that's why.

(Of course, the materials to do that don't currently exist, but we're already handwaving like crazy anyway, so why not?)
posted by ckape at 1:23 PM on September 7, 2012 [2 favorites]


It's the only way for us to keep Montgomery Scott alive!
posted by inturnaround at 1:24 PM on September 7, 2012 [1 favorite]


we're talking about boiling off the oceans

Look, do you want America to be energy independent or not?
posted by Egg Shen at 1:25 PM on September 7, 2012 [17 favorites]


Am I the only person who considers themselves scientifically literate who nevertheless thought this might be an Instructables link to a nimble DIY vacuum cleaner?
posted by oneironaut at 1:28 PM on September 7, 2012 [33 favorites]


Alas, Mercury...

.
posted by drinkcoffee at 1:31 PM on September 7, 2012


Why bother sending energy from the swarm to the Earth when you can just move humanity from the Earth to the swarm instead? Then I can get a solar satellite of my own and I can shake my space-cane at the space-kids and tell them to keep off of my space-lawn.
posted by ckape at 1:32 PM on September 7, 2012 [2 favorites]


Am I the only person who considers themselves scientifically literate who nevertheless thought this might be an Instructables link to a nimble DIY vacuum cleaner?

A spherical vacuum cleaner would only really work by adhesion. I'm guessing that wouldn't go well.
posted by Jpfed at 1:33 PM on September 7, 2012 [1 favorite]


The first step is, "Get energy".

The remaining four seem like an awful lot of trouble. Couldn't we just do the first one?
posted by Sing Or Swim at 1:37 PM on September 7, 2012 [2 favorites]


Well, it DOES allow us to work up to an unimaginably large population. Just building the Ringworld give us three million times the surface area of the Earth.
posted by Chrysostom at 1:37 PM on September 7, 2012


1. Get energy.
2. ?????
3. Profit!
posted by meronym at 1:37 PM on September 7, 2012 [1 favorite]


I'm guessing that wouldn't go well.

Wit and nerd prowess, you're doing it right.
posted by RolandOfEld at 1:37 PM on September 7, 2012


"The Ethical Implications of Dismantling the Planet Mercury"
posted by Egg Shen at 1:38 PM on September 7, 2012 [5 favorites]


Wouldn't it be smarter (from an engineering standpoint) to build a sphere around Jupiter or Saturn, work out the kinks there, and then scale up to destroying planets for one around the Sun?
posted by Blazecock Pileon at 1:38 PM on September 7, 2012 [1 favorite]


1. Get energy.
2. ?????
3. Profit!


I think you mean:
1. ?????
2. Get energy.
3. Profit!
posted by advil at 1:41 PM on September 7, 2012 [3 favorites]


Why move the Sun? Because it's awesome, that's why.
“Have you guessed the worst of it? I compute that the sun can probably be moved. The sun can be made to jet plasma, and the plasma can be made to act as a gas laser, forming a photon drive for the sun itself. The Ringworld would be pulled along by the sun's gravity. But even the maximum thrust would be minuscule, too little to help us. At anything over two times ten to the minus fourth power gravities of acceleration, the Ringworld would be left behind. In any case, radiation from the plasma jet would ruin the ecology. Louis, are you laughing?”

Louis was. “I never thought of moving the sun. I never would have. You actually went ahead and worked out the math?”

Wintry-cool and mechanical, that voice. “I did. It can't help us. What is left?”

-- Larry Niven, The Ringworld Engineers
posted by sidereal at 1:42 PM on September 7, 2012 [2 favorites]


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

My god, that's enough to power over 200 quintillion DeLoreans.
posted by mightygodking at 1:42 PM on September 7, 2012 [11 favorites]


If you wish to make a dyson sphere from scratch, you must first destroy the universe.
posted by 2bucksplus at 1:46 PM on September 7, 2012 [1 favorite]


The problem with moving the Sun is the risk of forgetting where we put it.
posted by Egg Shen at 1:46 PM on September 7, 2012 [2 favorites]


I like the way he admits that the thing will need to be made of unobtainium, and doesn't even let it slow him down. Apparently there is a point in the near future where unobtanium spontaneously decays into surplusium.
posted by ubiquity at 1:46 PM on September 7, 2012 [9 favorites]


It's the only way for us to keep Montgomery Scott alive!

...

My god, that's enough to power over 200 quintillion DeLoreans.

Great Scott!
posted by chemoboy at 1:50 PM on September 7, 2012 [2 favorites]


So now that we have acquired 600 million times more area to inhabit and have all the electricity out iPods need to keep kickin', are there a bunch of cool water fountains cloating around out there that will let all these numbnuts living on solar sailors continue to... you know... live?
posted by SharkParty at 1:52 PM on September 7, 2012 [2 favorites]


I know, this is heavy.
posted by Cash4Lead at 1:52 PM on September 7, 2012


mmmm typos! REFRESHING.
posted by SharkParty at 1:53 PM on September 7, 2012


So, is there a good reason to destroy Mercury instead of mining the asteroid belt? Getting to and from Mercury gets to be rather difficult and expensive what with it sitting so close to the Sun.
posted by ckape at 1:55 PM on September 7, 2012


So now that we have acquired 600 million times more area to inhabit and have all the electricity out iPods need to keep kickin', are there a bunch of cool water fountains cloating around out there that will let all these numbnuts living on solar sailors continue to... you know... live?

Isn't that what Mars is for?
posted by Cash4Lead at 1:58 PM on September 7, 2012


Louis was. “I never thought of moving the sun. I never would have. You actually went ahead and worked out the math?”

Wintry-cool and mechanical, that voice. “I did. It can't help us. What is left?”


Rishathra.
posted by procrastination at 2:00 PM on September 7, 2012 [6 favorites]


SharkParty: "So now that we have acquired 600 million times more area to inhabit and have all the electricity out iPods need to keep kickin', are there a bunch of cool water fountains cloating around out there that will let all these numbnuts living on solar sailors continue to... you know... live?"

Obviously, we harvest Europa and Saturn's rings.
posted by Chrysostom at 2:02 PM on September 7, 2012


So... there's a Kickstarter for this, yes?
posted by LordSludge at 2:02 PM on September 7, 2012 [1 favorite]


is there a good reason to destroy Mercury instead of mining the asteroid belt?

Well, I assume the dingus would be built, if not Mercury-close to the Sun, much nearer to there than to the asteroid belt - where there will be a lot less energy to collect.

At that point, you have to deal with the energy costs of blasting the asteroids out of their current orbit towards where you want to get them - and then stopping them when they get there. Who needs the headache?

And sentimentality aside, what's the argument for preserving Mercury? Why leave a perfectly usable planet sitting in the barn doing nothing?
posted by Egg Shen at 2:03 PM on September 7, 2012


I don't really care about preserving Mercury, I just remember all the talk about how difficult it was to get Messenger in to Mercury orbit.
posted by ckape at 2:05 PM on September 7, 2012


The indigenous species of the planet probably won't mind, if they in fact pay attention to the process at all.

They can be a bit . . .

Mercurial.
posted by Curious Artificer at 2:06 PM on September 7, 2012 [3 favorites]


Then I can get a solar satellite of my own and I can shake my space-cane at the space-kids and tell them to keep off of my space-lawn.

Especially that little troublemaker from Satellite B-612.
posted by RonButNotStupid at 2:11 PM on September 7, 2012 [1 favorite]


much nearer to there than to the asteroid belt - where there will be a lot less energy to collect.

Same amount, just more spread out.
posted by empath at 2:14 PM on September 7, 2012


Hey don't fret so much, valkyryn, we're on track to boil off the oceans in about 450 years anyway.
posted by fantabulous timewaster at 2:15 PM on September 7, 2012


They can be a bit . . .

Mercurial.


That was terrible, and you are terrible. You should feel terrible. I feel terrible just knowing it exists.

Now I have to go drink something terrible, maybe a Bud Light or something, just to punish myself for knowing it exists. My brain hurts right now, but it doesn't hurt enough.

Next up: weaponized humor!
posted by aramaic at 2:23 PM on September 7, 2012


Weird. The first time I'd ever heard of a Dyson sphere was just this past week watching a Star Trek rerun (Deep Space Nine, I think.) Now here we are with a thread!




I still thought we were talking about vacuum cleaners at first.
posted by St. Alia of the Bunnies at 2:29 PM on September 7, 2012 [2 favorites]


And shooting all that energy towards Earth? Well you've certainly got a target that's big enough to plausibly hit over those colossal distances, but "global warming" suddenly becomes "ants under a magnifying glass." Seriously, we do not want even a tiny fraction of the sun's total output to be directed here. We're not talking about climate change or a rise in sea level, we're talking about boiling off the oceans.

Uhhh.... Who says we need to collect it on Earth or even send it back to Earth?
posted by Talez at 2:29 PM on September 7, 2012 [1 favorite]


This would be a great project for my Arduino board!
posted by PlusDistance at 2:33 PM on September 7, 2012 [1 favorite]


If we're going to build a Dyson sphere, we may as well just assume practicable faster-than-light travel, so we can charge ginormous batteries at some point close to the surface of the sphere (or on the sphere itself) and ship them back to Earth when they're full.
posted by Holy Zarquon's Singing Fish at 2:40 PM on September 7, 2012


Speculative engineering is sorta like masturbating- lots of wild fantasy, an explosive outpouring of potential, and then the whole thing peters out due to some missing bits of reality.
posted by Phyllis Harmonic at 2:40 PM on September 7, 2012 [4 favorites]


And shame. Don't forget the shame.
posted by LordSludge at 2:49 PM on September 7, 2012 [3 favorites]


One problem with mega scale engineering that I never see addressed is this: everything wears out. Everything. Eventually.

So we've taken apart Mercury and built a mini Dyson Cloud of solar collectors to power Stage Two. Wonderful. But how long will those collectors operate, so close to the Sun? They're going to blister and crack, anything synthetic in them will outgas into the vacuum, the Solar Wind will hammer into their collection surfaces ceaselessly, until eventually the cloud's power output drops to zero. So we'll need to continuously rebuild the cloud, presumably by recycling it's material in an endless Ouroboros kind of process. But nothing is 100% efficient, so we'll need more material to replace things that can't be recycled, and on and on.

The only kind of giant structure that could last over truly long term time scales would be something that's alive, and capable of efficiently recycling itself through regrowth.
posted by Kevin Street at 2:58 PM on September 7, 2012 [5 favorites]


what's the argument for preserving Mercury?

It only governs all transportation and communication issues!
posted by Zed at 3:56 PM on September 7, 2012


This page has some great animations of Dyson donuts (though you'll need to enable Java), which I get the impression would be the easiest arrangement to build up.

Would we really need impossible materials to build something like that? It seems like we could make a bunch of satellites now with large solar panels, and maybe using an LCD manoeuvring technique like IKAROS to correct course errors.

What they might be useful for, I'm not sure. Maybe give them giant lasers to power our solar sail ships.
posted by lucidium at 4:03 PM on September 7, 2012


Can I ask a stupid question? Considering that there are all these comets and meteors that careen around the solar system that every time one of them gets within a 1-in-10,000 chance of hitting the Earth the media is filled with speculations along the lines of COULD THIS BE THE ONE, if we were to, say, remove a whole planet from the solar system, wouldn't that slightly alter the orbits of those careening bodies, moving them out of any state of equilibrium they've established for themselves over billions of years of not smacking into us?

Hey, stupid question #2. If we had all this energy, what is to say we wouldn't come up with uses for it all and just want more? Since energy is the capacity to do things, and due to the existence of computing machines thinking of things to do with it is itself one of the things we do, what's to say we won't just move a few orders of magnitude up the scale regarding what we consider to be our wants and needs?

Okay just one more. How the hell does this guy say that mining away the mass of Mercury won't take more than 40 years? Even if we assume his array of self-replicating robots is possible in the near-future time frames he posits for it (which is ludicrous), when you start reproducing things automatically like this you start to run into another whole class of problem which scientists have thought little about: this is what life looks like, and any process-drift created through manufacturing errors starts to look like mutations, mutations which will self-select for survival, and these kinds of automated processes can get out of our control very quickly.

(Yeah, there's a me in a parallel universe who's a science fiction author. We talk sometimes.)
posted by JHarris at 4:38 PM on September 7, 2012 [4 favorites]


"...if we were to, say, remove a whole planet from the solar system, wouldn't that slightly alter the orbits of those careening bodies, moving them out of any state of equilibrium they've established for themselves over billions of years of not smacking into us?"

Possibly, yes. The Solar System is an immense n-body problem - a real life example of Newton's Law of Gravitation where n = billions of bodies of different size, continuously interacting with each other at varying distances. So far as I know it's vastly more complicated than anything we can calculate with current technology. (There's a job for the Dyson sphere!) But in general, larger bodies are going to effect the system far more than smaller ones. So if you did something to the gas giants like Jupiter or Saturn it would have a large effect on everything else, but dismantling the comparatively shrimpy planet Mercury (mass = 0.055 Earths) would have a much smaller effect.

There is the question of all that complexity to consider, though. We may not be able to predict the effect of removing Mercury with enough precision to be completely sure we're not setting ourselves up for disaster years down the line. And in the smaller neighborhood of sun grazing asteroids and comets, Mercury's loss would probably be a big deal. But we'd probably scoop them up too, since they'd be so close to the construction site.
posted by Kevin Street at 4:59 PM on September 7, 2012 [1 favorite]


Never any love for Alderson disks.
posted by Chrysostom at 6:27 PM on September 7, 2012


At those distances, a difference of a thousandth of a degree would cause a beam to miss by dozens or hundreds of miles.

I'm a little skeptical that a civilization that can completely enclose the Sun in matter can't aim a laser better than a millidegree. We can already aim better than that with current technology.
posted by DU at 6:31 PM on September 7, 2012 [1 favorite]


remove a whole planet from the solar system

But would you have simply removed it, or smeared its gravity well out a little? All that mass is still there, its just distributed a little differently.

There must be some 'optimal' configuration that will disrupt orbital mechanics the least. There's likely a timing and sequence component too, not just the final distribution.
posted by porpoise at 6:45 PM on September 7, 2012 [1 favorite]


I'm a little skeptical that a civilization that can completely enclose the Sun in matter can't aim a laser better than a millidegree. We can already aim better than that with current technology.

Okay, but at five million miles away, a millidegree is 87 miles. Double the distance, and you double the arc. To hit something a mile across at five million miles distance you need control to within .0000145 degrees. Not millidegrees, but 15 microdegrees. At targets that are moving a few dozen miles per second at different vectors in three dimensional space.

If you miss, you probably wouldn't be able to tell by how much or even in what direction. And even if you could, you'd only be able to make corrections about once a minute, which means calculating an entirely new firing solution to correct for the constantly changing positions of both the origin and target.

Even if you could make that shot, simply making it for an instant isn't enough. You have to keep that beam trained constantly, which means constantly calculating and recalculating your firing solution.

And mind you, a five-million mile shot is in all likelihood only going to get you a fraction of the way to wherever it is you're going. That's a trivial distance in interplanetary scales.

So I'm thinking that whatever power such a system could collect would have to be used more-or-less locally, on interplanetary scales. Hitting something a few hundred thousand miles away is hard, but literally orders of magnitude easier.

*My earlier math was wrong.
posted by valkyryn at 6:50 PM on September 7, 2012


Not millidegrees, but 15 microdegrees. At targets that are moving a few dozen miles per second at different vectors in three dimensional space.

But we can do millidegrees pretty much routinely (in space anyhow) already. By the time we can dismantle the asteroids to build a shell around the Sun, I would think we could improve our aim by a measly two orders of magnitude.

Now that I think about it, I bet Hubble/Spitzer has repeatability below a millidegree. Indeed: The telescope is able to lock onto a target without deviating more than 7/1000th of an arcsecond...

1 arcsecond is 1/3600 degree, or about .3 millidegrees. 7/1000 that is .000001 degree, or 1 microdegree, already an order of magnitude better than you think we need.

If you are still nervous, the solution is easy. Aim for the Moon (or elsewhere). A little slop there doesn't matter and then you can aim for the Earth from that waypoint with a lot less accuracy needed.
posted by DU at 7:01 PM on September 7, 2012 [3 favorites]


"But would you have simply removed it, or smeared its gravity well out a little? All that mass is still there, its just distributed a little differently."

Good point. And there's still about 49% of Mercury floating out there. All the useless dross (according to Dr. Armstrong) like silicates and such that can't be used for the Dyson cloud, probably settling back into a sphere.
posted by Kevin Street at 7:03 PM on September 7, 2012


if we were to, say, remove a whole planet from the solar system, wouldn't that slightly alter the orbits of those careening bodies

Technically? Yes. Effectively? Not really.

The Sun contains 99.86% of the solar system's mass, and Jupiter and Saturn together contain 90% of the remainder. That means that Uranus, Neptune, Earth, Mars make up about 0.014% of the total, and of that, Uranus and Neptune make up 94% of that, so the terrestrial planets only count for 0.00084% of the total. Mercury isn't even a rounding error. Being so close to the Sun, it's likely that comets don't even notice its presence one way or the other.
posted by valkyryn at 7:03 PM on September 7, 2012 [4 favorites]


Now that I think about it, I bet Hubble/Spitzer has repeatability below a millidegree.

Yeah, but they're trying to lock on to stars, which for all intents and purposes don't move. We're talking about targets that, depending on the distances and vectors involved, could easily be moving several arcseconds every second.

And if Hubble "misses," hey, no big deal. Starlight never hurt anyone. But you probably don't want to be anywhere behind the receiver for a Dyson power beaming station that misses.
posted by valkyryn at 7:11 PM on September 7, 2012


GROWTH FOR THE GROWTH GOD!
posted by [expletive deleted] at 7:23 PM on September 7, 2012 [1 favorite]


Dyson construction will make an infinite surplus of energy available, just in time to convert the last of the homosaps into the post-human paradigm, and Mother Earth, which will have been long since exhausted its capacity to sustain orgnanic life, will be added to the mass. Post-humanity will be able to travel at the speed of light. If needed, we can harvest the entire effective output of the sun. And that's just for starters.

To the Galaxy!-- and beyond!

But first, we need to figure how what to do with all these little doodads that got thunk up during the cold war. Internet? Oh, great. Infinity knocks on the door and all we get is a goodam iphone.

sheesh
posted by mule98J at 8:20 PM on September 7, 2012 [1 favorite]


On asteroid orbits and Mercury: the point doesn't have to do with the relative masses of the Sun compared to planets, but with how orbits interrelate to each other. Like how irregularities in the orbit of Neptune hinted at the existance of Pluto. Any significant mass you move around changes the equations, and we don't know anywhere near how many of those rocks there are zooming around.

My objective here isn't to cast a pall of DOOOM over big ideas. It's to remind that, if we pursue really really big ideas, we should be sure to consider if there are consequences of those ideas. If we're adult enough, as a species, to dare to engage in large-scale planetary engineering, we should make sure we're adult enough to deal with the consequences.
posted by JHarris at 8:41 PM on September 7, 2012


Dyson construction will make an infinite surplus of energy available,

I doubt that- you wouldn't build a structure like that unless you REALLY need the energy. We're on the position of a medieval person being told about fossil fuels, and saying "what could they ever use all that energy for?

Incidentally, if Dyson spheres/swarms are that easy to make, then that's an argument against extraterrestrial civilizations, because we haven't detected anything with the IR signature a Dyson sphere would have.
posted by happyroach at 9:51 PM on September 7, 2012 [1 favorite]


Wikipedia's article on Space-based solar power is more comprehensive than I expected. Really, if we're going to do this, this is the first step.
posted by wobh at 10:33 PM on September 7, 2012


Wikipedia's article on Space-based solar power is more comprehensive than I expected. Really, if we're going to do this, this is the first step.

Didn't some kid fill his teacher's house full of popcorn with one of these things? No wait, that was the 80's. I know...Steven Segal ran his train into....no, that was the nineties....

I know this is a good idea and all, but just in case, they should put the receiver right next to the nuclear power plant, to make sure nothing goes wrong.
posted by mule98J at 10:46 PM on September 7, 2012


We'd have to concentrate that energy at discrete points to do anything useful with it, and that involves shooting across millions of miles of space.

By the time we have the ability to create anything remotely like this, "do something useful" will rarely mean anything more than "perform some computation." We will have long since mastered the problem of distributed computing, so we won't bother to beam the power back to earth; we'll just use it in place to crunch a lot of numbers, and the connection with Earth will be a whole lot of substantially lower-powered communication lasers.
posted by Mars Saxman at 11:05 PM on September 7, 2012


I don't "get" a Dyson sphere- in particular what actual problem it is trying to solve. And is there even enough mass in the solar system to create a giant solar panel sphere (or swarm) around the sun?

Is the point that it offers a lot of living space? Because unless we fucked like bunny rabbits (and everything we've seen suggests that if our prosperity increases, our population rate slows or even goes negative), our population wouldn't increase enough to fill up Jupiter- a.k.a. Earth III- for millenia, after we populate Mars. Also, maybe the gravity works to keep an atmosphere clinging to the inside of the sphere similar to that of earth... but as SharkParty asks, where did we get the matter to comprise the water and air and soil on the interior of this incomprehensibly vast sphere?

Okay, so it's not for living space... so is it just to generate an obscene amount of energy? Admittedly, we could fuel our current energy and near-future energy just on the solar power generated on a square of land that would barely be visible from space. A Dyson sphere would offer billions or trillions of times that much energy if we could create it.

But... if you needed/wanted that much energy, why would you use the Dyson sphere for energy collection at all? If we were that sophisticated technologically, wouldn't we just have developed 99%+ effective mass->energy conversion in our Mr. Fusion devices, which is far more energy than we'd get from turning the whole solar system into a solar array? After all, that's all the sun is doing- turning mass into energy- so why not emulate it with microscopic suns to power all our needs? Some quick napkin math shows that turning Mercury into matter, instead of solar shields, would give us all the energy the inside of a Dyson sphere would offer for thousands of years. And that's the smallest planet in our solar system.

So the Dyson sphere must mean we want a ridiculously, incomprehensibly huge amount of energy for a really, really long time- but at that point, we as a species would be facing the realistic extinction of the sun, and would long since have left the solar system and possibly the galaxy- and have found more matter to turn into energy, much closer to whatever activity we were doing than the ancient old human sun was, way back in our genetic past.

But what am I talking about, "genetic past"? I mean, looking forward even ten or twenty thousand years, we may very well have dropped our "bodies" altogether, and turned into energy, and then information, that moves at the speed of light (or faster) around the universe. And at which point, again- why would we need a Dyson sphere for anything?
posted by hincandenza at 11:19 PM on September 7, 2012


I don't think Dyson's idea was that people would set out to make a Dyson sphere (especially not as a discrete object), but that it would emerge as civilizations moved into the space beyond their native planet, like a cloud coalescing out of the moisture in the air. But I think you're onto something that I think Dyson was also thinking of. People would mainly be gathering that much energy so they could leave the solar system for another.
posted by wobh at 11:40 PM on September 7, 2012


I think it's just about taking full control of the resources available to us. On the three step Kardashev Scale, Type I civilizations can use all the energy coming down on their planet, Type II can use everything put out by their star, and Type III can harness the power of an entire galaxy. Building a Dyson Sphere or Shell would be a way of saying "We're type II, baby!" Kind of like how cities vie to host the Olympics, but on a much bigger scale.

And with proper Stellar Engineering, the interior of the Sun could be mixed around a bit, greatly prolonging its lifetime. Maybe even until the warranty on the Dyson Sphere expires.
posted by Kevin Street at 12:03 AM on September 8, 2012


Yeah, but they're trying to lock on to stars, which for all intents and purposes don't move. We're talking about targets that, depending on the distances and vectors involved, could easily be moving several arcseconds every second.

No, for all intents and purposes the stars are moving just as much as the planet is. Because the telescope is orbiting the planet, which is also moving.

I haven't worked out the math, but for an exposure of up to a few minutes, you can probably point interially and it'll Just Work down to some pretty good accuracy. But some of these images are integrated over many hours (or days?). At that point, you'll have to take all kinds of effects into account (gravitational anomalies, solar wind, orbital torques, etc).

In fact, Hubble is in LEO. That's why they were able to fix it after it launched. LEO orbits have to correct for atmospheric effects of varying strength depending on exact height. Those are notorious unpredictable and yet it still manages to work. They must be continuously controlling Hubble's pointing to that microdegree.
posted by DU at 3:07 AM on September 8, 2012 [1 favorite]


I was skeptical myself that Hubble could hold that accuracy during a LEO orbit, so I looked into it a bit. It looks like they don't actually hold it for longer than a few seconds. To get those long integrations, they must take individual images and integrate them later in a kind of lucky-shot type system:
Two guiding modes are available: Gyro Hold, and Fine Lock. Fine Lock (PCS MODE FINE) is used by default, since use of Coarse Track may be harmful to the Fine Guidance Sensors. Use of Gyro Hold (PCS MODE GYRO) is not generally recommended, even for snapshot (SNAP) observations, since the pointing accuracy is only 14". Also the drift rate is 0.0014" s-1 so exposures >100s can result in smeared images. However, if the reduced pointing accuracy can be tolerated, and the exposures are only a few seconds or less, Gyro Hold can give a significant savings in the target acquisition overhead time.
Nonetheless the point remains that the accuracy needed isn't that far from where we are now (orbit predictions in air-free space can be incredibly accurate) and considering how much advancement from current technology is implied by a Dyson sphere, it wouldn't be out of the realm if they could improve tracking systems very slightly.

And, to reiterate, they can always beam to some safe location (Moon, Lagrange point, etc) which can then relay to Earth.

It's a non-problem.
posted by DU at 4:34 AM on September 8, 2012 [3 favorites]


Little as I know about gravitation, there is some back-of-a-napkin calculations out there that show that if you remove enough mass from Mercury (or any other planet, for that matter) at some point it's going to set itself on an orbit colliding with its star.

Good? Bad? Annoying? Awesome?
posted by _dario at 5:36 AM on September 8, 2012


valkyryn : This isn't just more energy than we can use, it's more energy than we can handle.

TFA does mention beaming all that energy back to Earth, but realistically, we would have no reason to do so. We would instead want to send it to the point of use, which for very few purposes requires our home planet. Large-scale manufacturing, for example (as the largest single consumer of energy today), can work just as well (and in some cases much, much better) off-planet. Transportation (the second biggest consumer of energy today) may still require roughly the same amount of energy output, but getting it from beamed-microwave electric rather than from fossil fuels would eliminate a whole long chain of energy-hungry processes involved in getting dead dinos out of the ground and into our gas tanks (not to mention, it would go a looong way to cleaning up our environment). Agriculture also uses a nice chunk of energy, and again, we already know how to do that fairly well off-planet, just a specialized "manufacturing" process.

And for actual "human" use, such as HVAC and lighting and powering our recreational devices - Who says humans should stay on-planet, or at least, on this planet? Near-limitless energy makes terraforming Mars a reality. It makes giant colony-ships a reality. It makes territorial and resource disputes something of a moot point (at least on the "short term" of a few thousand years) when you can just build more territory and collect more energy.

In all seriousness, if we ever find a way to have enough energy that getting off-planet and moving around among the inner planets becomes trivial, I see us as a species eventually designating the Earth as a sort of planet-scale wildlife refuge. Well... If we don't leave it a toxic wasteland before we get to that point.


_dario : Little as I know about gravitation, there is some back-of-a-napkin calculations out there that show that if you remove enough mass from Mercury (or any other planet, for that matter) at some point it's going to set itself on an orbit colliding with its star.

...If you don't adjust its orbit appropriately.

I don't know if I'd agree that 40 years counts as a realistic timeline to mine Mercury into oblivion, but if we take it as reasonably-true, I see no reason we couldn't use some portion of the resultant abundance of energy to increase the orbital radius or velocity (or both) of what we haven't yet used. We wouldn't even need to figure out some insanely complex way of pushing an entire planet out of its orbit - On a purely practical level, we would want to launch material off Mercury on the Sunward side (for the gravitational advantage); Every such launch would give just the slightest push to the planet in the opposite direction. For our current space programs on Earth, those tiny pushes add up to nothing; For a coordinated program to remove a substantial portion of the mass of a planet, pushing back against an ever-lighter husk of a planet, it would have an effect over time.
posted by pla at 6:14 AM on September 8, 2012 [3 favorites]


Why can't the issue of accuracy in energy transference from the swarm back to Earth be handled by a network of autonomous (microwave?) repeater stations along the route? They could use electrical power to maintain position, so the trip becomes a series of feasible hops instead of hitting the bulls-eye at 1 AU.

I wonder about the "last mile" transference to the planet's surface, and the implications of waste heat radiation balance to keep from frying ourselves. We had better be able to air-condition the planet before we do this,
posted by Enron Hubbard at 8:32 AM on September 8, 2012


Space-based solar power ... is the first step.

The Sun is already in space, spraying us with 40+ Tw of energy every second. Why orbit a satellite to beam down power to collectors? Just build the collectors and eliminate the middleman.
posted by Twang at 10:06 AM on September 8, 2012 [1 favorite]


But would you have simply removed it, or smeared its gravity well out a little? All that mass is still there, its just distributed a little differently.

Redistributing mass changes its center of gravity, and as far as perturbing orbits of n-bodies goes, that's all you need. It would be ironic if we needed a Dyson-spheroidal computer to calculate how to build a Dyson sphere, without breaking up the solar system in the process.
posted by Blazecock Pileon at 12:13 PM on September 8, 2012


I think we will have the technological capability to build a Dyson sphere eventually. I'm just not sure we'll be able to figure out the patent licensing around it.
posted by RobotVoodooPower at 2:59 PM on September 8, 2012 [2 favorites]


The big issue that I like seeing in this link is heat dissipation -- in space, you only have radiation unless you're willing to sacrifice mass to evaporation. As your Dyson sphere gets more complete, the more effort it will take to get rid of the inevitable heat losses. While if we're talking aboutdeconstructing Mercury, and possibly Venus and other planets to pull this off I would imagine it would be a solved problem, finding some direction to radiate out the IR without baking another satellite might get tricky on occasion. The energy that can potentially be extracted dependent upon the differential that can be achieved between incoming and outgoing -- and it's all got to go somewhere. Considering the problems we hove nowadays with simply dissipating the heat from our CPUs, datacenters, and cities, that may well end up being the hardest part of designing a Dyson sphere.
posted by Blackanvil at 8:21 PM on September 8, 2012 [1 favorite]


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