Building an Arcology

[robject]

From another topic (Igniting a Gas Giant) comes the excellent suggestion from Scott: build orbital arcologies in the hab zone. Attach them to planetoids. Build them from the asteroid belt. Etc.

With efficient fusion you can do wonders.

I reckon you could even produce a directed point-source of light with fusion. Voila, you don't need a star anymore.

So in Traveller, how big is an arcology? It's sort of a gargantuan starport, isn't it? Actually a starport is more like a spaceship than an arcology, isn't it? Or maybe it depends.

Easiest way to think about it: find a big honkin' planetoid and tunnel it out. Add power and life support, add a central section (or dome) with a fusion-powered point light source, and fill the rest of the space out with stuff. Docks for shuttles. Biomes (aka "fancy parks"), high-tech farms, living quarters, a small maneuver drive... and by small, I mean 0.1G, rules permitting, or 1G otherwise.

People need room. Say density is in indirect proportion to the average social standing of the population, maybe [ 50 + 200/SOC ]. So average people would fit in around 78 per square km... on a planet's surface.

What's a square km on a planet? Isn't it 1km x 1km x the atmospheric ceiling? Ouch. Even squeezing the space down to a cubic kilometer yields 78 people per 70 million displacement tons. Hey, they gotta live here all the time.

Okay, let's handwave that down to 1 person per 1 million dtons. Does sound a bit much, but on the other hand, it might not be too unreasonable.

So suppose you wanted a pop 4 planetoid -- say 50,000 people. That's a 50 billion ton planetoid. Now you see why I want a small maneuver drive? The Imperium just can't build them that big. A 6 G drive for a million ton vessel would push this rock at 0.00012 Gs, and only requires 60,000 dtons of fuel every month or so. Ye cats.

Okay, so we hollow out a 100 billion ton planetoid, and park it right next to a 100 billion ton chunk of ice. Most of our problems are solved. But it's still an amazing feat of engineering.

Implications for Starports

Notice that these guesstimations can be used to argue the general sizes of starports based on personnel support.

If arcologies need 1 million dtons per person, and starships need (roughly) 20 tons per person, then a starport is going to be somewhere in between.

But how big are starports? The saving feature is that they're probably not self-sufficient. They can have long-term support, but are expected to have supply lines from a mainworld or gas giant or wherever. In other words, they are not as big as an arcology, so supporting them with small craft is not a logistical impossibility.

They're also therefore cheaper. A typical starport with reasonable repair facilities is going to run you a billion credits -- which is nothing compared to a decent defense squadron.

So most of a starport is storage -- fuel, freight, drydock. The expensive part is the equipment and life support. In general, then, it seems like a starport might require 100 dtons of "people space" per fulltime personnel, and 10 dtons per expected visitor. And (I haven't thought this part through yet) maybe a ratio of 1 fulltime person per 1 visitor is a "reasonable" (i.e. convenient wild guess) staffing requirement.

So then, if your starport has, on the average, 100 visitors per week, then it ought to have 100 fulltime personnel (in a nice heirarchy), and have a "people space" volume of 110 x 100 = 11,000 dtons. Add to that fuel tankage, hangar space, freight holding storage, and whatnot.

So, can I justify 100 starport personnel?

Well, there's the guy in charge and five divisions (life support, engineering, drydock, service, and security). Each division has three shifts of 7 people each. Yup, easily 100 people. And at any given moment, 35 of them are on duty.

How about fuel? You'd probably need a depot that can hold 4 tons of fuel per ton of freight shipped as a rule of thumb (untested).

 

[TheEngineer]

Yep. Just think BIG

 

[Scott Martin]

Hi

There was a TAS article on constructing archologies (starting at tech/9) way back in the dawn of time.

I can also post some ISBN numbers for good books discussing this later this evening. There were a fair number published in the early '70s, and some included projected population densities. You're probably looking at a minimum of a few hundred square meters per person to a max of perhaps a hectare (10,000 m&sup2) per person.

The pocket empire I'm currently working on has no "habitable" planets but instead relies on extensive vaccum industry and artificial habitats. Incredibly poor ground troops (what is this "weather" of which you speak?) but *nasty* in space.

NB that Imperial standard is to list the single "most important" planet in a system to get the UWP, so this may also explain the number of really crappy stars and planets that are listed.

Survey Officer: "So 'Dirtball Mine 2' is the most populous body in the system, with 60,000 sophonts?"

Diplomat: "No, it's just a mining colony. Archology 317 has a median population of over 200 million"

Survey Officer: "But that's not a naturally occurring body is it? I'm adding this systems UWP to our Imperial Records as D-231416-D"

Diplomat (protesting): "But we have over two dozen class "A" starports in the inner system alone!"

Survey Officer: "But none of them service natural bodies, do they?"

Just don't buy their man-portable military lasers: Salt lenses are a bad idea anywhere but space. They are quite cost effective and don't absorb many wavelengths useful for heating targets

Scott Martin

 

[parmasson]

What's a square km on a planet? Isn't it 1km x 1km x the atmospheric ceiling? Ouch. Even squeezing the space down to a cubic kilometer yields 78 people per 70 million displacement tons. Hey, they gotta live here all the time.

I can’t help but think that is way too much room per person. Economically speaking the arcology is not going to be independent. This is a massive undertaking and there must be a pressing military or economic need for it’s construction. I figure TL-15 is the only way to go assume that a lot of the space taken up on a planet’s surface like parking lots, sprawling single level farms, McMansions and 2 dton SUVs will simple not exist. I would think that personal space would be redefined and result in a different society. Average people might live in a 200 square foot space and count themselves lucky. Do you want the facility to produce all of its own food? It could but would it? How about manufacturing?

What I am getting at is why build the damn thing. If there is universe’s rchest deposit of mineral X nearby then factories will predominate, you get the point.

In addition keep in mind building times in Traveller. How long does it take to build a million ton starship? This facility will likely take decades to build and cost billions of MCr so it will be as small as it can be and still serve its purpose.


Oooooo . . . . Could you build a giant arcology on the end of a beanstalk orbiting a planet and have a really cool highport/startown in the same complex?

 

[mike wightman]

In an arcology your ceiling height only needs to be 3m

So an arcology with the same floor surface area as the Earth would be a 1.53x10^15m&sup3 box.

With a population of 5x10^9, that gives 306,000m&sup3 per person, or 21,857dt per person.

And I have no idea why I just calculated that

 

[Fritz_Brown]

No, Sigg, in a space station, it only needs to be 3m - in an arcology it will need to be high enough for trees, etc.

I would place the ecology part in the very center, with that artificial light source (yeah, you'd get that whole reverse horizon thing...). Then, I would place all the living spaces, factories, etc. (the architecture part) in concentrc spheres going out toward the hull - with the most industrial aspects closest to the hull.

You would need to calculate your volume based on a valume for each sophont to have their quarters, plus a certain amount of utility space per sophont, plus a surface area for x sophonts to be in the "park" at one time, then figure the volume for that sphere, then figure volume for each employed sophont's workspace (and the kids' schools, etc.). So four sets of calculations, really.

 

[Zutroi]

Originally posted by Sigg Oddra:
In an arcology your ceiling height only needs to be 3m

So an arcology with the same floor surface area as the Earth would be a 1.53x10^15m&sup3 box.

With a population of 5x10^9, that gives 306,000m&sup3 per person, or 21,857dt per person.

And I have no idea why I just calculated that

Sigg,

Don't forget Earth is ~70% water (and another good portion is otherwise 'uninhabitable' deserts and ice floes and the like...), so let's call it 6000 dtons per person. That is a persons living, working, shopping, food-growing and recreational space. Maybe we can drop the figure down somewhat, reducing 'shopping' space thru use of a data-net, and then downward still further by using 'outside' of the arcology for recreational space. Presumably TL 15 agriculture is more space-efficient than what we currently do (figure I heard is that 1/4 pound of ground beef took 2000 gallons of water to grow the fodder, water the cattle and process the beef, that's a lot of water tankage!), so again, let's substantially reduce the figure. I like Round Numbers - shall we put the figure down to 1000 dtons per occupant?

 

[Fritz_Brown]

So, if we go with 100,000 inhabitants (including children, homemakers, etc.) lets do some guesswork:

1. Only 10% of the population will be recreating in the ecology zone at one time. Lets say each person needs 20mx20m and we want trees that will grow 10-15m high (so a 20m "sky"). 33.5k m3 is the volume - using 14m3 per dTon, you get less than 2400dT, so lets round it to 2500dT to account for the dirt, etc.

2. Lets use standard starship rules for living space (since families will use common facilities and singles will probably double up bathrooms in their "apartments"). So, 100,000 x 4dT = 400,000dT.
(Ay-carumba! That's 160 times the ecology part! Central Park is ~1/900th of Metropolitan NY, so its OK, I guess.)

3. Utility space will include "farmland", hydroponics, waste disposal, water recycling, etc. Let's just say 100kdT for everything.

4. Workspace is a little trickier, as we could go lots of different ways. Plus, we already have space for homemakers and everybody that works in the utilities. If you assume some schooling at home (virtual classrooms), and some "telecommuting", lets just say 3mx3mx3m per worker and use a ratio of 1 worker for every 3 folks we've already accounted for: 25,000 folks times 2dT = 50kdT. (Edit: That's assuming office space... end edit)

To sum up: 25kdT + 400kdT + 100kdT + 50kdT = 575kdT for 100,000 people. You can throw in 25kdT for hangars, etc. and make it a nice round 600kdT!

 

[parmasson]

I errr . . . borrowed this to serve as the model for the structures you encounter on my high pop worlds 50+ billion IMTU.

http://www.tdrinc.com/ultima.html
Population: 1,000,000 people
Exterior surface area of building: 150,000,000 square feet
Enclosed volume: 53,000,000,000 cubic feet
Square footage: 1,500,000,000
Total enclosed acreage: 39,000 acres
Elevator speed: 20 feet per second (13 miles per hour) 9 minutes and 40 seconds to reach the top floor from the ground floor.
Dimensions: Height--10,560 feet; Diameter at the base--6000 feet; Number of stories--500;
Total Square Feet: Approximately 5,000,000 square feet

 

[archhealer]

Pack'em in like sardines, in a few generations all the ones who can't take it will have died or killed each other off anyhow.

 

[Scott Martin]

One of the better books (with real physics in it) would be "Colonies in Space" published in 1977 (of course that it had a start date for orbital construction of 1982...) T.A. Heppenheimer, ISBN 0-446-81-581-0.

Of course, it dates from before books had "exec summaries" so I may need to re-read it to get the volume for the space habitats: that said I'm pretty sure that it's WAY lower than Sigg's and may be lower than Fritz's too: pop density is similar to "Areas of France" Circa 1977, so in the ballpark of current central California pop densities.

Remember that you get to use sunlight for as many hours a day as you want, at intensities similar to the middle east, but with no water shortage issues: Agriculture is a LOT more productive than trying to grow grain in Ohio.

Other books with more fluff and less science are "The Space Enterprise" (name from memory) and "Mining the Sky" but I can't be bothered to pull the latter out to retrieve its ISBN info.

The "Stanford Torus" archology design (From Colonies in Space) is about 1 mile in raduis, and rotates at 1 RPM. It is designed to accomidate a population of 10,000 and includes Ag areas sufficient to be self supporting (sorry, get used to not eating Beef folks...)

Ag Archologies (Ehayup, that thar's Orbital Beef) are also covered, and a "bootstrap" development plan to build bigger and better colonies is covered. All payed for by something that's back in the news, orbital power satellites...

Scott Martin

 

[Golan2072]

Finally someone who's thinking like IMTU's Matriarchate. Planets are just... inefficient. Plus you have to waste resources on escaping a deep gravity well, you destroy a local ecology with your wastes, you spoil the surface with your wastes. Orbital life is better (all of these in the Matriarchate opinion, ofcourse

).

A good site for references for this thread is PERMANENT.

Rules concerning small-scale hydroponics and solar panels for LBB2 could be found in my document here; they could easily be adapted to HG.

 

[Maladominus]

So in Traveller, how big is an arcology? It's sort of a gargantuan starport, isn't it? Actually a starport is more like a spaceship than an arcology, isn't it? Or maybe it depends.

Have you read one of the JTAS issues (I forgot which number) that detailed the Arcologies of Azun? That article is a really good example of what arcologies can be in Traveller.

IIRC.... Azun's arcologies are basically 1 to 2 miles high gigantic towers. Think of the tallest modern Earth skyscraper, then make it even taller, and then triple its girth, and then give it a streamlined futuristic shape.... and you basically have an Azun arcology-city. A single one can house over a million citizens. Yes, I said millions! Azun is a relatively small tainted planet with a population in the tens of billions. The billions of Azunians have become urbanites crammed like sardines inside their cozy arcologies. The interiors of the giant arcologies can mimick sunlight, can mimick outdoor swimming pools, can mimick day and night cycles, etc. Majority of Azunians spend their entire lives living inside their arcology where they were born. Going outdoors is risky and not a popular thing to do.

It's a really well-written article, and I wish that JTAS would have written more of these articles dealing with arcologies and habitats.

 

[robject]

I remember Azun... that's a very early issue, isn't it? And these arcolgies are on a planet surface, so they get things like air (sort of) and food "for free". Plus, Azun sounds a little dystopian...

And Fritz -- 600kdt for 100,000 people is 6 dtons per person. That's starship density... well, probably less dense than that, since equipment will be a smaller percentage, but still, starships are crowded. "Normal" people generally spend a week on board...

And Sigg -- 3.0m is good for a room in a house, but it's probably not good for a biome.

I decided on a horribly large number because I suspect that there's lots of hidden spatial costs to raising a native population.

Kurega brought up the fact that an arcology can't be self-sufficient to be useful. He's probably right, but it can't rely on support the way a starship or starport does.

Ad absurdum: the death star. It's a sphere 60km in diameter (I think?). Most of its core, apparently, is machinery. That still leaves a significant crust. Anyone want to guess how many supply shuttles it would need for refuelling and meeting the needs of its population in the Traveller universe?

Too many.

As M.U.L.E. taught us, one reason for establishing any colonty is exploitation. That and the frontiering spirit, I suppose. But it's gotta be able to manage its own affairs. It can rely on critical freight for operations, but I bet those shipments won't be food and fuel. Not weekly, at any rate.

Bottom Line: I really wouldn't mind lowering the tonnage-per-person number, but I do think that arcologies are more like worlds than starships.

 

[robject]

Slaps own forehead This has already been done.

Biosphere 2 (http://www.bio2.com/) housed eight people under meagre and slowly deteriorating conditions for about 2 years. In my mind, that means it almost worked, and might work well as the kind of arcology I'm thinking of.

Those 3+ acres were in large, open structures (up to 30m tall) with lots of airspace. Additionally, there were two massive "lungs" by which air pressure could be regulated. The "life support" section, then, encompasses 304,000 cubic meters -- a bit over 22,000 dtons. For eight people, that works out to about 2750 dtons per person.

The 8 people were fed from a 0.2 hectare plot of land, using nutrient-rich foods only (useful stuff only!).

It took about 15 years to build, and (I think) cost about USD$150,000,000.

For the purpose of a game, I'd set a balancing relationship between self-sufficiency, volume, and supply requirements.

I'll assume a fixed construction time of ten years.

S = Supply requirements, in tons per week
V = Life support volume per person, in tons
P = Price, in MCr
"surface" means the arcology has some sort of planetary infrastructure to support it, by being on the surface of a world -- or even in orbit around it (assuming a developed infrastructure, that is).

S(surface) = (V - 2000) x 10
P(surface) = V/10

S(space) = (V - 3000) x 10
P(space) = V

Equipment and fuel volume would be added on to that.

There. That's better than 1mdt/person, isn't it? I was off by 3 orders of magnitude.

Example General Products builds Gusekke, a space arcology for 1 million people. Deciding to skimp a bit on volume, it assumes 1000 dt per person, for a total life support area of 1 billion dtons. This section costs 1 billion credits.

Gusekke will have to import 20,000 dtons of goods per week.

So, let's cut that number in half. A 2000-dton-per-person arcology needs 10,000 tons of freight per week. A 3000-ton-per-person arcology, which is what I'm sort of aiming at, would require only incidental cargoes.

 

[robject]

Playing around with the starport rules of thumb... suppose I take one of my biggest traffic runs -- where hundreds of thousands of tons of traffic pass through the port weekly. Mora, or Rhylanor, or Sylea might qualify here. What's the size of that starport?

Assume: 100,000 dt freight per week
Assume: 25,000 passengers per week

Life support space: 110 x 25,000 = 2.75 million tons
Cargo handling space: 200,0000 dt

So, total volume for the biggest starport IMTU is perhaps around 3 million tons. This is a combined highport + downport volume, I suspect, with additional acreage for landing pads and/or parkbays on the ground. There might be a significant fuel depot, as well...

On the other hand, a small orbital port could see 10 tons and 2 passengers per week. That would make it perhaps 250 dtons in size, with maybe 50 tons (or less) of fuel storage.

 

[parmasson]

Because of the cost of construction this settlement would be placed at a VERY desirable location meaning that a trade classification of “Rich” would not be out of the question. Since there would be no habitable planets nearby the place could be net exporter of food to nearby rockballs and asteroid outposts. Yeah the grain from a garden world is good but isn’t it Cr300,000 (that is $849,000 in 2005 terms IIRC) per dton! At that price the food slurry and soybars form the station start to look quite economical.

So bulk up on some more agro space and cargo capacity to make a fortune!

(edit) This will be a spinning arcology right? Think of all the millions of Cr that could be saved by not having to wire up AG allover the place. Just look at the cost of personal gravitics.

 

[mike wightman]

Biosphere 2 didn't have the advantage of fusion power generation, but at the same time didn't involve any industrial production

IMHO to qualify for the title arcology, the building has to be entirely self sufficient in both food and local industry.

Take a look at how Gateway was built in the Lords of Thunder issue of MegaTraveller Digest.

 

[robject]

Kurega: I didn't even think of spin. I automagically assumed antigrav, just like on TL9+ spaceships... maybe I'd figure AG into the cost, and then give a price break for spin colonies.

Very clever idea, building an arcology to support a vast in-system mining concern.

Sigg: I'd allow a small measure of dependency, but it would have to have goods worth trading to balance out that dependency. Traveller arcologies are likely to be owned, so are built according to the whims of the owner(s).

 

[Fritz_Brown]

And, of course, we are talking about two "different" things at the same time: arcologies and space arcologies. I don't think I'd want to spin a plain old arcology....

Yeah, if you are talking a planetside arcology, you can reduce the size by taking out grav tech, spaceship hangars, waste disposal.... (You really do not want giant blue icicles sticking out from your space arcology...

)

I think 6dT per person is a little tight, robject. But 1000dT is unbelievable! Remember that a huge amount of our atmosphere is wasted space if you are in an enclosed structure - its primarily there to protect us from deadly stuff in outer space (BSD does that in Traveller! ).

I screwed up on the ecology space calculations, BTW. I didn't calculate from the surface area requirement to find a radius, I just used the 20m radius I was contemplating. Using the numbers I used previously (10% of 100,000 at any one time, using 20mx20m each), I now get pretty close to 100kdT just for the park, with almost a 70m radius.

If you up the usage to 25% and up the area to 30m by 30m, you get (a bit closer to robjects numbers): 225kdT and a radius of 90m. And, you really only need 9km2 - about 3 times the size of Central park! How many people are jammed into Manhattan, again? (Answer: 1.5million in only 85km2 total!) I'm thinking my numbers for a space arcology make sense.

Also, robject, a large park with green trees and a "sun" makes a big difference when otherwise living in apartments/dorms/condos. Now, if you want to make things like shopping spaces in the park section, we're going to need a bigger ball of rock....