Change Log for 6.40 Discussion

[Jorgen_CAB]

[ooc][/ooc]

UG-infraststructure is awesome! Steve you didnt say anithing about it but wouldnt it make sense to limit it somehow? I mean the size of most asteroids mean s that you cant fit billions of people into one.

I assume that civilians will not build underground infrastructure so you will have to provide all the material for it yourself. If this is the case we can always put that limit on our self.

I wouldn't mind a slightly more complex population distribution/growth on planets with limitations and more social issues. But perhaps in the future Aurora will get some love in that area. 

I must also say I like this new feature, makes hidden underground fleet bases a new interesting concept.

Perhaps a suggestion to reduce the EM/IR signature of populations living in underground structures would make it even more interesting.

[Steve Walmsley]

UG-infraststructure is awesome! Steve you didnt say anithing about it but wouldnt it make sense to limit it somehow? I mean the size of most asteroids mean s that you cant fit billions of people into one.

There a some limits already. Firstly, it will take a lot of effort to get this going because you can't transport the infrastructure in - you have to build it in place. Using construction brigades will take a while.  Secondly, you can't terraform so the pop will only grow if you build more infrastructure. Thirdly, its colony cost 3.0 so with large pops the service sector and agricultural sectors combined would take up 95% of the population so its not a good idea to let it get very large anyway.

Besides, if you think about it, you could get a huge amount of people into a large interior space. Lets assume that 2x3x4 = 24 cubic meters is enough room for one person. In a sphere 10 kilometers in diameter, you could fit triple the current population of the Earth

[Bremen]

You mention the world is treated as cost 3, is that regardless of temperature? Alternately it might make sense to have it ignore low temperatures, but still have increased cost from high temp. But maybe that's getting overly detailed.

Speaking of overly detailed, the first thing I wondered when I saw the new feature is if it would provide resistance to planetary bombardment. Probably not an important feature, but that would also provide the possibility of using it as bomb shelters on otherwise ideal habitable worlds.

[Steve Walmsley]

You mention the world is treated as cost 3, is that regardless of temperature? Alternately it might make sense to have it ignore low temperatures, but still have increased cost from high temp. But maybe that's getting overly detailed.

Speaking of overly detailed, the first thing I wondered when I saw the new feature is if it would provide resistance to planetary bombardment. Probably not an important feature, but that would also provide the possibility of using it as bomb shelters on otherwise ideal habitable worlds.

My original idea was that population sheltered by UI would have an upper limit on Col Cost, maybe 4-5, and that you could mix it with normal but it was too complex. The standard 3.0 makes it nice and simple on the basis that a self-contained underground complex wouldn't be significantly affected by surface conditions.

Other benefits might be added, such as resistance to bombardment, lower signatures or increased defence ratings for ground units. For the moment though I just want to make sure the basic idea is working.

[alex_brunius]

Other benefits might be added, such as resistance to bombardment, lower signatures or increased defence ratings for ground units. For the moment though I just want to make sure the basic idea is working.

Funny, I just went here to write a question about resistance to bombardment and lowered signatures when I read this

Nice work and an interesting feature (especially if this can be added later on).

[Paul M]

I think this is a good idea but I think you are opening a bit of a can of worms here.  You want a specific thing:  a hollow asteroid base, yet you are adding in something that has a lot of other implications.  No one isn't going to build underground when they are on a hostile environment world (outside of structures that need to be above ground).  If you take Faewald and Forge from my AAR both colonies are underground.  In the case of Faewald it is because there is no atmosphere and they are close to the sun, in the case of Forge it is because there is a hellish atmosphere.  The same is true of Venus, Luna, Callisto, Ganymede or Io.  For any number of reasons basically a standard hostile environment colony will be largely underground.  I mean to be blunt the first house a new settler to Canada lived in was a "sod house" which is basically hole in the ground with a sod roof so it isn't a unusual thing in a hostile environment.

I would think this is something better handled as a project with a fixed cost.  Hollow out asteroid for x million people, cost y BPs.   Otherwise you introduce a new item that conceptually doesn't make any sense since there is no reason that a normal colony with normal infrastructure would not be underground in most cases.  As was suggested "bomb shelters" that makes a lot more sense.

I also have to say that one thing I have noticed in at least 6.1 is that asteroids are useless for TN minerals, which is odd as comets are loaded with them.  I have found very very few astroids with any amount of TN minerals, I think of 300 asteroids in one system less than 5% had TN minerals. 

[MarcAFK]

It sounds that what you're really debating is the actual definition of underground infrastructure, perhaps what steve is adding to the next version is actually "low gravity" infrastructure, and people would like a third type of "underground infrastructure" which could be added to any type of planet regardless of gravity cost which can be used for protection from planetary bombardment, lowered thermal emissions, and fixed colony cost regardless of other factors.
Something like this might be useful for putting people onto venus without orbital habitats or large scale terraforming, but would make putting population onto already colonisable worlds possibly far to easy. Whereas the proposed underground infrastructure is basically adding to the game something new, allowing previously uncolonisable worlds available. Besides extremely high gravity worlds would basically be completely uninhabitable without some kind of amazing antigravity technology, whereas very low gravity environments are already inhabitable, at least for the short term.

Edit: I've reading about the energy requirements for speeding up a planets rotation, well the moon actually, it seems 10^25 joules would be required merely to speed the moon upto 24 hour rotation. 10^28 jules would actually deorbit it or possibly be enough to actually blow it into chunks which would basically deorbit anyway. The energy needed to speed it's rotation enough for artificial gravity would be far more than the energy needed to merely push it into an orbit which would make the surface more habitable, at least from a temperature standpoint. Perhaps a new terraforming option could be used for very small low gravity bodies, which allows changing the rotation period enough to allow artificial gravity?
I'm not debating the utility of the proposed underground infrastructure, just the science behind them, it would be cheaper to merely put your colonists inside giant centerfuges if the body is too large to actually move.

Edit 2: Some very basic and possibly flawed math leads me to the following conclusion.
 In the case of triton with a gravity of .08 being just barely below standard habitability has a mass 29% of the moons, and would require perhaps 8.5% the energy to rotate.
For a body like ceres with .03 gravity and a 61.5th the mass of the moon something like 4 millionth the energy would be required. (unless my knowledge of physics is horribly wrong) leaving something like 2.5^19 jules.
Tsar bomba was estimated to have released 4.2^18 if it hadn't had it's yield halved by the addition of a lead tamper, so conceivably it's within reason that a body that small could actually be given enough spin for artificial gravity.

[Paul M]

It sounds that what you're really debating is the actual definition of underground infrastructure...

Pretty much.  If it was called "extreme environment infrastructure" then at least you avoid what to me is the question of "how does this really differ from what I have now called infrastructure."  I really can't see why anyone in any sort of hostile environment would not be underground. 

But still I would think this should be closer to an orbital habitat in terms of implementation.  So it has a cost per so many million people (or whatever number) rather than tracking it the way infrastructure is currently.  It is basicaly a specific installation rather than a distributed system.

Also spinning up moons would be energy inefficient not to mention dangerous due to unpredicable side effects, but spinning up an asteroid of modest dimensions isn't that much more complex then spinning up a traditional o'neil colony. 

[alex_brunius]

Edit: I've reading about the energy requirements for speeding up a planets rotation, well the moon actually, it seems 10^25 joules would be required merely to speed the moon upto 24 hour rotation. 10^28 jules would actually deorbit it or possibly be enough to actually blow it into chunks which would basically deorbit anyway. The energy needed to speed it's rotation enough for artificial gravity would be far more than the energy needed to merely push it into an orbit which would make the surface more habitable, at least from a temperature standpoint. Perhaps a new terraforming option could be used for very small low gravity bodies, which allows changing the rotation period enough to allow artificial gravity?
I'm not debating the utility of the proposed underground infrastructure, just the science behind them, it would be cheaper to merely put your colonists inside giant centerfuges if the body is too large to actually move.

Edit 2: Some very basic and possibly flawed math leads me to the following conclusion.
 In the case of triton with a gravity of .08 being just barely below standard habitability has a mass 29% of the moons, and would require perhaps 8.5% the energy to rotate.
For a body like ceres with .03 gravity and a 61.5th the mass of the moon something like 4 millionth the energy would be required. (unless my knowledge of physics is horribly wrong) leaving something like 2.5^19 jules.
Tsar bomba was estimated to have released 4.2^18 if it hadn't had it's yield halved by the addition of a lead tamper, so conceivably it's within reason that a body that small could actually be given enough spin for artificial gravity.

Remember that we don't need to duplicate full Earth gravity to make it "habitable". We only need the minimum habitable gravity which IIRC is 10% of Earths (+ whatever minimal gravity the body naturally has that needs to also be overcome)

[MarcAFK]

It seems that any body with significantly less gravity than .1 has such a low mass that spinning it to artificial gravity speeds would only require a few carefully timed fusion bombs, to say nothing of whatever could be done with transnewtonian propulsion.
However, wouldn't a normal asteroid rotating at that speed basically blow itself apart from centripedal force?

[Steve Walmsley]

It seems that any body with significantly less gravity than .1 has such a low mass that spinning it to artificial gravity speeds would only require a few carefully timed fusion bombs, to say nothing of whatever could be done with transnewtonian propulsion.
However, wouldn't a normal asteroid rotating at that speed basically blow itself apart from centripedal force?

After reading Paul's first comment, I immediately started looking at the "gravitational" effect of rotation speeds for different size bodies and the energy requirement of spinning-up a slow-rotating body so it could be called low-grav infrastructure rather than underground infrastructure and would only be useful on bodies with enough spin to produce 0.1G of artificial gravity. I can see I wasn't the only one with that thought. It would make faster spinning low mass bodies more attractive for this type of colony. Maybe a ship with very large engines - similar to a tug, could be clamped to the asteroid to slowly increase its spin. Might take months or years but could be done simultaneously with building the infrastructure.

If the above is feasible, another option that springs to mind is effectively constructing your own asteroid in deep space so you create a population anywhere. Would take a LOT of raw material though. Or if the "Ship with Really Big Engine" turns out to be feasible, you may even be able to adjust the orbit of small asteroids to put them where you need them.

Steve

[Theodidactus]

It seems that any body with significantly less gravity than .1 has such a low mass that spinning it to artificial gravity speeds would only require a few carefully timed fusion bombs, to say nothing of whatever could be done with transnewtonian propulsion.
However, wouldn't a normal asteroid rotating at that speed basically blow itself apart from centripedal force?

I believe most asteroids would roll apart pretty quickly.

I don't know about you,but I always just imagined that space ships had "artificial gravity" through some kind of transnewtonian magic floor paneling. If ships can have it, why can't colonies?

[bean]

Underground Infrastructure is an interesting idea, and I'm glad to see it added.  I would include bombardment resistance as part of the package (possibly with the ability to shelter more people from bombardment than it normally holds.

It seems that any body with significantly less gravity than .1 has such a low mass that spinning it to artificial gravity speeds would only require a few carefully timed fusion bombs, to say nothing of whatever could be done with transnewtonian propulsion.

Energy isn't the only consideration here.  Angular momentum must also be conserved, which is a bit of a pain in cases like this.  Particularly because the energy fraction is inversely proportional to the relative mass.  Also, the bombs are going to break things, which is bad because structural integrity is important.

However, wouldn't a normal asteroid rotating at that speed basically blow itself apart from centripedal force?

Absolutely.  Rocks are weak in tension, and I don't think most asteroids are really that strong as rocks go.  I don't have the math on this at the moment, but I'd be surprised if you could get much negative G at all.  
However, there is a simple way around this.  I assume that TN tech has some way of creating artificial gravity.  Assume that's what is used here.  No need to spin asteroids, and you can put it on high-G worlds as well.  Just call it 'extreme environment infrastructure' as suggested above, and give it a flat cap of 3 on the colony cost.

[Paul M]

Most large asteroids are solid blocks of nickel-iron (but not quite of the number you see in films...).  They naturally rotate and bringing one the size of a typical o'neil colony up to a point where it is is generating 1 G of gravity would not be particularily difficult.  This is not something that would not take more than days, once you got the shape "balanced" so that it didn't wobble too much, assuming you just used mass drivers to throw chunks of the surface off at a tangent.

This is not a big object we are talking about (0.25 km radius, 1-2 km length).

The speed of rotation would not be so great (if my memory serves it is v^2/R so for 10 m/s2, v= 50 m/s which is a fairly low angular velocity for this size) for 1 G.   The trouble is that you need something rather uniform (both in shape and density) or else it will wobble and that is a "bad thing" in general.  I'm not sure it would make a lot of sense to go to the effort of this...as opposed to hollowing one out as a temporary work space/living quarters.  Grav plates simplify the issue.

The whole concept of people living in asteroids is fairly old in Sci-fi literature, but its practicality in Aurora seems rather dubious.  Still probably there are people with resources to throw at things which aren't that practical.

[bean]

For a body like ceres with .03 gravity and a 61.5th the mass of the moon something like 4 millionth the energy would be required. (unless my knowledge of physics is horribly wrong) leaving something like 2.5^19 jules.

Sadly, your knowledge of physics is horribly wrong.  For Ceres, rotating fast enough to have 1G at the equator, and neglecting Ceres's own gravity (because I forgot when I did the math) it would have rotational energy of 9E26 J.  To put this into perspective, the gravitational binding energy of Ceres is only 7.4E25 J.  That alone settles if spinning up a body of that type is possible. 

Most large asteroids are solid blocks of nickel-iron (but not quite of the number you see in films...).

No, they aren't.  Iron meteorites only compose about 6% of all meteorites, and IIRC the proportion of nickle-iron asteroids is similar.  Also, they aren't solid blocks.

They naturally rotate and bringing one the size of a typical o'neil colony up to a point where it is is generating 1 G of gravity would not be particularily difficult.  This is not something that would not take more than days, once you got the shape "balanced" so that it didn't wobble too much, assuming you just used mass drivers to throw chunks of the surface off at a tangent.

Wrong again.  The amount of energy and momentum involved is substantial. 

This is not a big object we are talking about (0.25 km radius, 1-2 km length).

It masses on the order of 2E9 kg and has a moment of inertia of 6.4E13 kg*m^2.  That's pretty big in my book.

The speed of rotation would not be so great (if my memory serves it is v^2/R so for 10 m/s2, v= 50 m/s which is a fairly low angular velocity for this size) for 1 G.

Your memory is correct, but it's not really low.  Rotational energy of 1.3E12 J, which is not a small number at all.  And the angular momentum is about 1.3E13 kg*m^2*s, which is also very large.  If you're launching your projectiles from the outer edge of the cylinder at 3000 m/s, you'll need to fire approximately 1.7E7 kg, with a total energy in the projectiles of 7.7E13J. 

The trouble is that you need something rather uniform (both in shape and density) or else it will wobble and that is a "bad thing" in general.  I'm not sure it would make a lot of sense to go to the effort of this...as opposed to hollowing one out as a temporary work space/living quarters.  Grav plates simplify the issue.

Theoretically, you could make it work so long as you have a definite long axis to the body.  However, balance would make it better.