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Self-Gravitating Structures/Artificial Heavenly Bodies

Posted: Sun Apr 20, 2008 3:33 am
by shrinkshooter
Self-Gravitating Structures wrote:As orbital construction grows ever larger in scale, eventually the mass of a single installation is sufficient to appreciably self-gravitate. Where previously the microgravity environment was fundamental, designs must be rethought again, just as they were when originally moving surface activity into orbit. Rather than expanding endlessly in efficient regular patterns, the natural curved shapes of planetary bodies begins to emerge in artificial bodies as well. Advantages over surface construction are retained, however, as the artifical mass is designed and built with its purpose in mind.
Artificial Heavenly Bodies wrote:When roughly the mass of a small moon or larger, it is no longer suffient to conceive of what is wrought as a "structure", "station" or "ship". Rather, beyond this scale, the object becomes more like a heavenly body; its gravitational pull influences orbital motions, it may retain an thin atmosphere on its surface, and it may be orbitted by, rather than orbitting with, lesser structures. At even larger scales, entire planets may be built, or rebuilt, or even new stars may be formed and ignited, broadcasting the power and determination of their creators throughout the universe.
Something should be done with these. They're practically the same thing; the artificial bodies is perhaps larger in scale since it talks about an entire artificial planet being built, whereas the other tech implies something the size of an artificial moon. If construction continued on a "self-gravitating structure" it would eventually reach "artifical heavenly body" size. If someone does want to keep these techs separate, I suggest having this as one tech, doubly-researchable. Otherwise, this should most likely be combined into one tech.

Re: Self-Gravitating Structures/Artificial Heavenly Bodies

Posted: Sun Apr 20, 2008 7:18 am
by Tortanick
I'm not sure, it depends on just how big would a structure have to be before it creates its own gravity (anyone know?). If you need something the size of a small moon then yes, they're practically the same tech. If not then creating something the size of a moon or an entire planet probably deserves a separate tech to just a large spacestation and self gravitation structures should be modified to be more distinct.

If we get rid of one tech, keep artificial heavenly bodies, its cooler.

Re: Self-Gravitating Structures/Artificial Heavenly Bodies

Posted: Sun Apr 20, 2008 9:16 am
by shrinkshooter
Scientifically speaking, everything has gravitational pull. What the tech refers to is gravitational pull that is noticeably pulling on something as large as a human being (or whatever animal), as in you can tell that you're being pulled by something. In this case, yes, you would need something the size of a small moon (which is really just a lot of construction on an orbital structure). The self-grav sturctures tech talks about something so large it begins to take on the shape of a ball, which makes sense because a ball is the most energy-efficient shape and keeps everything in equilibrium.

You would be able to feel slight gravitational pull from something smaller than the moon in orbit around Earth, but it would still need to be pretty large. That's why I think they should be combined. What I think we should do (only if we want to replace the empty space left by the absence of self-gravitating structures) is probably have something like an artificial gravity tech or something of that sort, if we really want something gravity-oriented, although I'm not sure how well that would mesh with the tree.

Re: Self-Gravitating Structures/Artificial Heavenly Bodies

Posted: Sun Apr 20, 2008 10:23 am
by m_k
Tortanick wrote:I'm not sure, it depends on just how big would a structure have to be before it creates its own gravity (anyone know?).
The following calculations are by no means exact, but they should give a rough estimate of dimension. Lets say real gravity means if you jump up on the surface you won't be able to leave the gravitional pull of the structure (although you'll probably end up in an orbit). Calculating with someone reasonably trained, (75kg, ability to jump 1.5 meters up) this leads to an energy for the jump of about 75kg*1.5m*9.81m/s^2= 1100 joules. The potential energy of the gravitational field has to be at least that high. It is calculated by G*M*75kg/r, where G is constant, M is the mass of the structure and r the distance to it's center (the radius of the structure, if it is spherical), which leads to a mass/radius ratio of 2.2*10^11 kg/m. Assuming the structure is a sphere and is mostly empty space by design (constructing large solid objects in orbit isn't that interesting), it will have a density of let's say 100 kg/m^3, so it's mass will be 4/3*pi*r*100kg/m^3. With this we can now solve the whole equation leading to a radius of about 23 km and a mass of about 5*10^12 tons, which in my oppinion doesn't qualify as an artifical heavenly body yet.
The first problems in construction would probably even start at a lower scale, while we wouldn't even notice a gravitional pull of smaller size, millions of tons of still exert some force in it.
So I believe there is still a distinction between the two techs.

Re: Self-Gravitating Structures/Artificial Heavenly Bodies

Posted: Sun Apr 20, 2008 10:45 am
by Tortanick
True but now shrinkshooter got me thinking of it, the gist of the tech is basically "We now have gravity in our stations, but good design means we still get the benefits of no gravity" its also a bit of an odd progression:
Orbital construction: Redesign for no gravity.
Self-Gravitating Structures: Redesign for gravity
Controlled Gravity Architecture: Redesign for fully controlled gravity.

Is this really the best choice of tech for that slot? Its basically the first improvement we get to orbital construction, so any improved space-station design would fit. Since you require Metroplex Infrastructure for this tech (IE. your running out of space on the ground), something that implies that space stations are moving from specialised structures to a general replacement for ground based buildings would be a plus.

I think "Modular Orbital Design" (need better name) would probably do well. A quick and dirty sketch proposal.

Code: Select all

By uesing interchangeable station modules the construction and expansion of space stations becomes dramatically more efficient. As it becomes more common for society to expand into space purpose built unique stations are no longer an efficient investment. By building stations out of prefabricated modules it becomes cheep and simple to assemble stations without the expense of designing a new station, expanding an existing station becomes a simple task one simply attaches an additional module. In addition by constructing  modules in bulk large economies of scale are unlocked
Its just a quick job with little planning but it illustrates the idea. What do you think?

Geoff, if we're going down a dead end, care to say so?

Re: Self-Gravitating Structures/Artificial Heavenly Bodies

Posted: Sun Apr 20, 2008 5:29 pm
by shrinkshooter
Tortanick wrote:a bit of an odd progression:
Orbital construction: Redesign for no gravity.
Self-Gravitating Structures: Redesign for gravity
Controlled Gravity Architecture: Redesign for fully controlled gravity.

Is this really the best choice of tech for that slot? Its basically the first improvement we get to orbital construction, so any improved space-station design would fit. Since you require Metroplex Infrastructure for this tech (IE. your running out of space on the ground), something that implies that space stations are moving from specialised structures to a general replacement for ground based buildings would be a plus...Its just a quick job with little planning but it illustrates the idea. What do you think?
The logic you used is good, and had not even occurred to me. It's great that you saw that progression because I hadn't even noticed the asymmetry. I like what you've done, and I think it's a good idea. There is still a semi-roadblock though; just because we have self-grav things and artificial bodies doesn't mean they replace the orbital construction tech, which uses low-grav to manufacture things. It just means the tech compliments the others, so we have orbital construction with the other gravitating technologies.

But I do agree in that the slot could be better used. They aren't technically the same thing, but it's certainly a technicality. It's really just the same tech on a smaller scale, and like i said before, I don't think it should be a separate tech; it should be one tech that is doubly researchable.

Re: Self-Gravitating Structures/Artificial Heavenly Bodies

Posted: Mon Apr 21, 2008 7:29 pm
by Tortanick
I'm not sure where your coming from with "doublely researchable" at the moment neither tech do anything*, so we can simply replace either with whatever we think would work better.

* I don't think its possible to build a planet yet anyway?

Re: Self-Gravitating Structures/Artificial Heavenly Bodies

Posted: Sun May 11, 2008 11:04 am
by Chriss
I'd say these are two distinct technologies.

Self-Gravitating Structures has been sufficiently explained I think - a structure which is so big, that you have to consider the effects of gravitational pull when constructing it. But only for the station itself, it's statics and such things. Not for the rest of the system.

The difference in Heavenly Bodies is already in the description: "its gravitational pull influences orbital motions" - meaning you have to consider where to put your artificial heavenly body so that it will not alter the orbit of the other planets in the system. It is so big, with so much Gravity, that you have to consider the whole planetary system with all components when you want to build one. Otherwise, the whole planetary system would eventuelly collaps.

So Self-Gravitating Structures in my opinion is a prerequisite or so for really large stations. With the Artificial Heavenly Bodies, you can construct artificial planets. Maybe construct one (or more) Planets from Gas Giants and Asteroids, or change the Orbit of an existing planet (help with terraforming?).
Or, to take this one step further: With this, you can construct a Dyson sphere. :wink:

Re: Self-Gravitating Structures/Artificial Heavenly Bodies

Posted: Mon May 12, 2008 8:16 pm
by shrinkshooter
Chriss wrote:I'd say these are two distinct technologies...So Self-Gravitating Structures in my opinion is a prerequisite or so for really large stations. With the Artificial Heavenly Bodies, you can construct artificial planets.
Which means self-grav structures is also a prerequisite for artificial heavenly bodies. As I've already said, the only difference between the two techs is the difference in magnitude of the things being constructed. Other than that they're essentially the exact same thing. One is "take into account the gravitational pull from a really big station, like maybe a small moon" and the other is "take into account the gravitational pull of a really, REALLY big station, like maybe the size of a planet." If they were totally distinct, like you claim, then you should be able to construct artificial heavenly bodies without any connection to self-grav structures, which isn't possible because it doesn't make any sense. Building an artificial planet, but you don't know how to build a big station? It's like being able to build a real car without being able to assemble a model of it. No sense.

One tech is really just a bigger version of the other, so I was thinking that on the tech screen it could be the same tech, but able to be researched twice, the second time for the bigger version. No one has seemed to understand that yet.

Re: Self-Gravitating Structures/Artificial Heavenly Bodies

Posted: Mon May 12, 2008 10:14 pm
by Tortanick
I can understand the researched twice thing, I just think its a bit intelligent. Firstly the two techs are quite diffrent so they should have their own discriptions, icon and everything. Secondly its the only place in the entire tech tree currently proposed for something like this. Refinements are planned to be added, but I'd hardly think builing entire moons and planets is a refinement ;) and finally even if you have one tech researched twice, for game balance issues its two techs so it still takes up a slot that could be used on something else.

And while I agree it makes little sense if you can build a moon, but can't build a big station, but that doesn't mean you need a specific tech for it. It could just be pushed into the background, e.g. once stations start getting big the architects discover this problem, and fix it themselves without ever needing a massive government funded reaserach

If we can think of something that will fill that particular slot in the tech tree better I say drop self gravitating structures and put the new thing in, and yes, I do think that modular space stations would fit better because:
1) As history shows, modular design is a major improvement. Much more useful than just makeing things bigger.
2) Its a very down to earth sort of tech (I appreciate the irony), modular space stations rather showing that space is becoming more wondrous like Self Gravitating Structures dose the opposite, showing that space is becoming more and more part of daily life.