Spacecraft propulsion and solar engineering

[Frank]

As long as we only look at energy sources and momentum expelled, it's not very hard to make a list of things invented and buildable from half a century ago to the far future. From chemical propellants through fission, ion, fusion to massive linear accelerators.

But there are more ideas that might be plausible, like: solar sails (quite), a Bussard Ramscoop (somewhat) and Thor (nuclear explosions, average).

After that, when you keep on solid scientific ground, you need things like being able to synthesize elements (atoms), very massive amounts of energy, and huge fleets of robotic manufacturers. Size of scale matters!

Anyway, how do you think we might plausibly evolve through all that?


Another point is Solar engineering. That starts small, with building satellites, through space stations, colonies on the Moon, asteroids, planets and other moons, building mini-worlds in the Trojans, to changing the orbit of planets (like Venus) and terraforming them.

It's even theorized that putting huge electromagnetic generators around the Sun to dampen and capture the solar wind could temper it (thereby increasing it's lifespan), while generating huge amounts of electricity and making the Sun fountain at it's poles, mass that could be used for building megastructures.

Theoretically, you might even be able to create a ringworld that way, which supplies an extremely vast living area, but it would require expelling a huge amount of momentum to counter the rotational force (which keeps it in shape and supplies the pseudo-gravity), to keep it from ripping itself apart.

The last thing would probably be a Dyson sphere, but there is no known way to do that.

What do you think is the ultimate solar engineering possible?


And last, but not least: do you think that some of the strange and phenomenal things we see far away in outer space could actually be the result of such construction efforts?

 

[_xxx_]

How would you transport enough material for a ringworld or dyson sphere?

Sounds familiar btw, are you an Asher fan?

 

[AlNom]

We'd also need a material that won't collapse from the gigantor stresses.

 

[Frank]

How would you transport enough material for a ringworld or dyson sphere?

Sounds familiar btw, are you an Asher fan?

Among others.

I was hacking at a simple 4X game, and I was wondering how to do it "right".

 

[Frank]

We'd also need a material that won't collapse from the gigantor stresses.

You could also add lots of rocket engines, that push back. Logistic nightmare, but theoretically possible.

And of course, they should work flawlessly.

 

[3dilettante]

It's even theorized that putting huge electromagnetic generators around the Sun to dampen and capture the solar wind could temper it (thereby increasing it's lifespan), while generating huge amounts of electricity and making the Sun fountain at it's poles, mass that could be used for building megastructures.

The magnets involved would be megastructures in and of themselves.

I guess we could find the necessary mass to build them by drawing material from huge matter fountains at the sun's poles that are generated by huge magnets...

edit, reworked some math

There are certain logistical concerns surrounding the magnet scheme, many of which have to do with the extreme distances that the magnetic fields would have to dominate, and the fact that they must do so in possible opposition to a 1.98x10^30 kg thermonuclear magnetic dynamo.

Even setting the magnets right in the surface of the sun, where they'd vaporize, would require an array of magnets 6x10^18 square meters. That would be 6x10^12 kilometers.
We'd have to figure the mass of magnetic material for this array. A magnetic dipole's field strength falls according to an inverse cube of the distance, so a big change in strength doesn't carry all that far.

Even the most massive terrestrial magnet, the Earth itself, has a magnetosphere that can only project an area of influence with a cross section at its most cylindrical area of ~160,000 km, and that is at a distance of 150 million km.

If we just assume that the Earth's magnetic cross section could be maintained at at the sun's surface, it would take 37,500,000 minus some number at the polar outlets to heavily influence the solar wind.

For the record, the sun is about 333,000,000 times more massive than the earth.

As the solar wind is not completely stopped by the Earth's magnetosphere, we'd need something stronger even at our orbit, much less the surface of the sun.

The area problem scales quadratically, so it's no easy matter to move further out.

We could hope on something more exotic, but we'd need something some billions of times better than we know of right now.

Theoretically, you might even be able to create a ringworld that way, which supplies an extremely vast living area, but it would require expelling a huge amount of momentum to counter the rotational force (which keeps it in shape and supplies the pseudo-gravity), to keep it from ripping itself apart.

The last thing would probably be a Dyson sphere, but there is no known way to do that.

What do you think is the ultimate solar engineering possible?

For each of the possibilities above, we just need to arrive at a rough density of material at the desired orbit and the orbit radius.
I believe the ring-worlds I've read about in science fiction either glossed over this or assumed a powerful alien race carted material from somewhere else.
The sun itself might not be massive enough to sustain such a building effort and still function.

It's an awfully huge expenditure on one system, which either speaks to a obsessive compulsiveness or extreme whimsy.

And last, but not least: do you think that some of the strange and phenomenal things we see far away in outer space could actually be the result of such construction efforts?

It would likely be a result of an incredibly bored all-powerful race to go through all the effort, considering the scales of time and effort involved.

It would be massively inefficient for any practical use, so it must mean the race thinks nothing of losing more mass than found in some star clusters, and more energy than some galaxies will ever expend in the course of the lifespan of the universe.
With all the effort involved, they seem awfully subtle about it. Not one "hi how are you", weird kitchy new-agey symbolism, or "my galactic e-penis is bigger than yours" plastered in the cosmic background microwave radiation.

Except for the big explosions and gamma ray bursts. War never changes, so maybe we're seeing them killing each other.
That I could be a possibility.

 

[Frank]

The magnets involved would be megastructures in and of themselves.

I guess we could find the necessary mass to build them by drawing material from huge matter fountains at the sun's poles that are generated by huge magnets...

Definitely, on an equal scale to a ring world by itself. And I agree you would need them to get enough material, energy and reaction mass for themselves and that ringworld to be able to exist. Use all the planets and other matter to build them, build a ringworld by transmutating the matter captured...

There are certain logistical concerns surrounding the magnet scheme, many of which have to do with the extreme distances that the magnetic fields would have to dominate, and the fact that they must do so in possible opposition to a 1.98x10^30 kg thermonuclear magnetic dynamo.

Even setting the magnets right in the surface of the sun, where they'd vaporize, would require an array of magnets 6x10^18 square meters. That would be 6x10^12 kilometers.
We'd have to figure the mass of magnetic material for this array. A magnetic dipole's field strength falls according to an inverse cube of the distance, so a big change in strength doesn't carry all that far.

Even the most massive terrestrial magnet, the Earth itself, has a magnetosphere that can only project an area of influence with a cross section at its most cylindrical area of ~160,000 km, and that is at a distance of 150 million km.

If we just assume that the Earth's magnetic cross section could be maintained at at the sun's surface, it would take 37,500,000 minus some number at the polar outlets to heavily influence the solar wind.

For the record, the sun is about 333,000,000 times more massive than the earth.

As the solar wind is not completely stopped by the Earth's magnetosphere, we'd need something stronger even at our orbit, much less the surface of the sun.

The area problem scales quadratically, so it's no easy matter to move further out.

We could hope on something more exotic, but we'd need something some billions of times better than we know of right now.

Electromagnetic forces and superconductors. Look at how a He3 fusion reactor should work.

For each of the possibilities above, we just need to arrive at a rough density of material at the desired orbit and the orbit radius.
I believe the ring-worlds I've read about in science fiction either glossed over this or assumed a powerful alien race carted material from somewhere else.
The sun itself might not be massive enough to sustain such a building effort and still function.

It's an awfully huge expenditure on one system, which either speaks to a obsessive compulsiveness or extreme whimsy.

Definitely. But the practicallity of the matter is most of the time not the reason why things are done. "Because it's there!" "Because it could be done!" Especially when it's not the only solar system you depend upon.

It would likely be a result of an incredibly bored all-powerful race to go through all the effort, considering the scales of time and effort involved.

It would be massively inefficient for any practical use, so it must mean the race thinks nothing of losing more mass than found in some star clusters, and more energy than some galaxies will ever expend in the course of the lifespan of the universe.
With all the effort involved, they seem awfully subtle about it. Not one "hi how are you", weird kitchy new-agey symbolism, or "my galactic e-penis is bigger than yours" plastered in the cosmic background microwave radiation.

Except for the big explosions and gamma ray bursts. War never changes, so maybe we're seeing them killing each other.
That I could be a possibility.

When did we ever need more reason than the: "My galactic e-penis is bigger than yours!" one?

If it can be done, I think it will be done.


Think scales. If their Bill Gates or US government controlled a hugely massive army of robot workers, spanning multiple solar systems, what use would they put them to?

 

[3dilettante]

Electromagnetic forces and superconductors. Look at how a He3 fusion reactor should work.

I'm not seeing piping quadrillions of tons of liquid nitrogen to the photosphere of the sun to cool superconductors as being productive.

Even the largest fusion chambers theorized have sizes on the scale of meters.
They are 18 or so orders of magnitude too small, and they would be directly fighting a garguantuan spinning ball of plasma.
The sun's own chaotic magnetic field is a problem at close range. If we fight this field directly, it is also possible we'll wind up severely disrupting the sun, while expending about as much energy as it puts out.
The Earth would likely freeze if we blocked a significant portion of the sun's light with a network of magnets.

Definitely. But the practicallity of the matter is most of the time not the reason why things are done. "Because it's there!" "Because it could be done!" Especially when it's not the only solar system you depend upon.

There's the "that's retarded, I'm not helping you to be even more retarded, nothing I have, will have, have had, or is in any way associated with me will help you be this retarded, if you try to something this retarded, I will kill you for being so goddamned retarded" reason that society at large will suppress it.

When did we ever need more reason than the: "My galactic e-penis is bigger than yours!" one?

Unless it's totally free and all material constraints cease to matter, which assumes an essentially god-like race, the popular pressure to lobotomize those trying this would be incredible.

If it can be done, I think it will be done.

We can only assume all other sensical options and all sane opposition to such a scheme have been exhausted.

This may be possible. If we assume an immortal, god-like race and an unending or inflationary universe where this race has been able to find a way to circumvent the heat-death of reality, it is possible that pretty much all outcomes have come and gone and all sane options have been done to death.

At that point, why not?

Think scales. If their Bill Gates or US government controlled a hugely massive army of robot workers, spanning multiple solar systems, what use would they put them to?

Probably finding more solar systems to control.
A project such as this is something a race that controlled an entire galaxy would be hard-pressed to do from a mass standpoint, let alone the physical impossibility.

I'm not finding a way for any individual getting away with a personal whimsy until the race is capable of effortlessly tossing about a galactic cluster.

By that point, however, it would be an act of boredom, if anything.

 

[Frank]

I'm not seeing piping quadrillions of tons of liquid nitrogen to the photosphere of the sun to cool superconductors as being productive.

Good point. But then again, cooling mostly requires energy: you could fire the heat back into the sun with lasers, or by firing extremely hot plasma at it.

Even the largest fusion chambers theorized have sizes on the scale of meters.
They are 18 or so orders of magnitude too small, and they would be directly fighting a garguantuan spinning ball of plasma.

Yes, but the thing is, that the particles slowed/trapped by the field generate electricity through feedback, which you can in turn use to strengthen the field. The main problem is keeping it all superconducting. And there is no theoretical reason why high-temperature superconductors couldn't exist.

If you can keep it superconducting, a network of such cables in a double DNA helix coil structure would work, with power controllers at the intersections.

The sun's own chaotic magnetic field is a problem at close range. If we fight this field directly, it is also possible we'll wind up severely disrupting the sun, while expending about as much energy as it puts out.

Yes. But then again, that might also be used to strengthen the EM fields and indirectly power them.

The Earth would likely freeze if we blocked a significant portion of the sun's light with a network of magnets.

Yes, but you can allow the protons to pass, and/or you could limit it to the surface that isn't in the equatorial region.

There's the "that's retarded, I'm not helping you to be even more retarded, nothing I have, will have, have had, or is in any way associated with me will help you be this retarded, if you try to something this retarded, I will kill you for being so goddamned retarded" reason that society at large will suppress it.

Definitely. But, think about the Space Race in the sixties.

Unless it's totally free and all material constraints cease to matter, which assumes an essentially god-like race, the popular pressure to lobotomize those trying this would be incredible.

Nah, I don't believe that. Consider this: people are directly interested in the "small", personal things. After that, they want to accomplish the impossible.

Give them all the small things they might want, and the few who require the big stuff can have a go at it with everything that remains.

Enemies and new challenges to conquer are always a great drive.

We can only assume all other sensical options and all sane opposition to such a scheme have been exhausted.

This may be possible. If we assume an immortal, god-like race and an unending or inflationary universe where this race has been able to find a way to circumvent the heat-death of reality, it is possible that pretty much all outcomes have come and gone and all sane options have been done to death.

At that point, why not?

Ah, I don't agree here: there is always a next frontier.

Probably finding more solar systems to control.
A project such as this is something a race that controlled an entire galaxy would be hard-pressed to do from a mass standpoint, let alone the physical impossibility.

I'm not finding a way for any individual getting away with a personal whimsy until the race is capable of effortlessly tossing about a galactic cluster.

By that point, however, it would be an act of boredom, if anything.

I don't agree. After a certain point, you simply want to put all that power you aquired to good use and do something enjoyable: fun and without any practical use, simply because you like to do it and to make it totally obvious to everyone that "I DID THIS".

 

[Frank]

For another thing: what would be the best spaceship imaginable that would work without having to invent something unlikely as a jump/warp/hyperspace drive?

 

[Sxotty]

For another thing: what would be the best spaceship imaginable that would work without having to invent something unlikely as a jump/warp/hyperspace drive?

Does it really matter? You can have any shape you want if you dont have to pass the atmosphere any time.

 

[Frank]

Does it really matter? You can have any shape you want if you dont have to pass the atmosphere any time.

I mean, how are you going to propel it?

The best solution seems to be to take a large moon, drill a hole through, install a lineair accelerator inside and use that to shoot all the mass through. It mostly requires engineering on a huge scale (and a great power supply), but except from that it's the default brute-force solution.

In subjective time, the passengers can go anywhere within a few years. One-way trip, though.

Is there a more "clever" solution?

 

[3dilettante]

Good point. But then again, cooling mostly requires energy: you could fire the heat back into the sun with lasers, or by firing extremely hot plasma at it.

The point of using the magnets to surround the sun to generate energy seems kind of moot if we're doing this.

The prospect of using the sun as a star at all at this point is pretty pointless. It seems more efficient to use fantastical space powers to poison the core and use those superconductors to pipe heat away to prevent the outer layers from rebounding off from the collapse and cause the star to compress into a white dwarf or neutron star.

Then, the aliens could just strip mine the thing.

Or they could just skip it and find a ready made white dwarf or neutron star for materials.

Yes, but the thing is, that the particles slowed/trapped by the field generate electricity through feedback, which you can in turn use to strengthen the field. The main problem is keeping it all superconducting. And there is no theoretical reason why high-temperature superconductors couldn't exist.

Using a fusion containment setup to contain an actively fusing star seems pretty redundant.

At the energies involved, it becomes dubious if the electrons will even stay within the superconductors. They might just boil off like the electrons in a cathode ray tube.

Yes, but you can allow the protons to pass, and/or you could limit it to the surface that isn't in the equatorial region.

Protons don't contribute any notable amount of thermal energy to the Earth.

A gap would negate the polar fountain idea. A significant fraction of the solar wind would exit in the uncovered regions that match the Earth's orbital plane.

Definitely. But, think about the Space Race in the sixties.

This is more akin to the NASA strapping a huge rocket engine under the continental United States and launching it into the moon to spite the Soviets.

Nah, I don't believe that. Consider this: people are directly interested in the "small", personal things. After that, they want to accomplish the impossible.

Give them all the small things they might want, and the few who require the big stuff can have a go at it with everything that remains.

You are understimating the logistics of supplying a galaxy of beings with the small stuff.

Enemies and new challenges to conquer are always a great drive.

I don't see how any of this deters enemies.
A ring world is not particularly defensible and can be incredibly vulnerable.
The fact that you've expended so much of your resources that could have gone to defense and put them in a nice and easily attacked package seems to have the opposite effect.

Ah, I don't agree here: there is always a next frontier.

Hey, they're immortal and all-powerful. They likely already found it.

I don't agree. After a certain point, you simply want to put all that power you aquired to good use and do something enjoyable: fun and without any practical use, simply because you like to do it and to make it totally obvious to everyone that "I DID THIS".

What any race with any reasonable material constraints would consider good use and what you are positing are mutally exclusive.
The certain point where it ceases to be a bad idea is the point those material constraints cease to matter.

We're talking a race that has a monopoly of a single galaxy and has basically done everything else there is to do there and has no overriding need for the resources it will be using, or a race that can dispense galaxies like candy.

 

[Frank]

By your reasoning, the US would have no reason to exist as it does. Because it's all about the things i'm talking about. Why allow some individuals to spend as much as thousands of others however they fancy, no matter how redundant and no matter if anyone else approves? There being a slight possibility to become someone who is able to do that is what it's all about.

I was thinking in the line of the Iain M. Banks Culture novels.

 

[3dilettante]

By your reasoning, the US would have no reason to exist as it does. Because it's all about the things i'm talking about. Why allow some individuals to spend as much as thousands of others however they fancy, no matter how redundant and no matter if anyone else approves? There being a slight possibility to become someone who is able to do that is what it's all about.

That only appears true absent a sense of scale.

A matter of 18-20+ orders of magnitude differential between the resources offered by a planet compared to what is needed to support just one single star's encapsulation is not the same as a billionare whose net worth is within 4 orders of magnitude of the average net worth of a US homeowner.

Those resources would only be going towards this one single project with little return.

It's not like someone would be allowed to buy all the food in the US and throw it in the ocean. Believe it or not, the US isn't that much of an anarchic whirlwind.

I was thinking in the line of the Iain M. Banks Culture novels.

I'm not too familiar with the author, but let's ask Wikipedia.

http://en.wikipedia.org/wiki/The_Culture#Capability

The Culture is characterised by being a post scarcity society (meaning that its advanced technologies provide practically limitless material wealth and comforts for everyone for free, having all but abolished the concept of possessions), by having overcome almost all physical constraints on life (including disease and death) and by being an almost totally egalitarian, stable society without the use of any form of force or compulsion, except where necessary to protect others.

I think Mr. Banks seems to agree on my point that this really doesn't make sense until material constraint is rendered meaningless.

 

[Frank]

Accepted.

So, how would you measure the percentage of production capacity and wealth available for expansion and innovation that has no direct benefit?

 

[3dilettante]

I don't believe there is a direct measure. A lot of the evaluation is dependent on how much the society in question wants to sacrifice.

A massive engineering project such as this is a particularly large and greedy resource sink.

A lot of projects without immediate payoff can have benefits due to the economic activity in the engineering effort and technology growth.

However, that is conditional on the idea that the project's material and logistical costs don't cause it to have a lock on critical chokepoints in the economy.
Because the final payoff is so far in the future and in many ways it will always be a massive expense, the project is a gigantic black hole where resources go in and very little comes back out, sort of like a million-year fireworks display.

A stellar engineering project of that scale is very capable of monopolizing the resource output of a vast majority of the galaxy's mining and industry.
It would be capable of monopolizing the transport capacity of the galaxy, or the effort to build enough transports to compensate is likely to also impact the resource and industrial capacity of the galaxy.
The massive size and maintenance of the scheme would be a large weight all on its own.

The project's consumption must not exceed certain thresholds. The project obviously can't draw so much that the remaining resources fall below the limit the economy needs to maintain itself. In that case, the project is self-limiting, as the economy it is leeching from will disintegrate long before the work is complete.

The project shouldn't consume so much that it only allows the economy to remain stagnant.

That leaves a very limited range of possibilities.
Either the logistics and materials become inexpensive enough that the ring world no longer cripples the empire that builds it, or the empire's economy is so massive and has so much surplus that it runs out of alternatives for investing it.

This leaves out the time question. Any such project is a long-term project. Something must be done to make a project that might take many thousands to millions of years to fully complete workable.
The constant care this project needs and the massive scale will not tolerate neglect for even a short time.