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Forcefields is a very interesting option for flight. You could have a brick like the Valkyrien, and sheath it in a light-scale forcefield in a perfect teardrop/aerofoil. Not beefy enough to count as an inv, but purely to interact with the air.

Hey presto, dead perfect lift in a way that modern planes can only dream of.

 Selym wrote:

 odinsgrandson wrote:
Now- I'm thinking that agriculture space stations are probably really inefficient. I mean, it is easy enough to bring the plant seeds into space, but you need a lot of soil- and that gets heavy and takes up a lot of room in shuttles.

On top of that, you need a lot of water for agriculture, and that gets REALLY heavy, really fast. Large amounts of water in space will be pretty damn expensive.

So much so that people have already been looking into mining water off of comets rather than shooting it into space

Hydroponics are specifically designed to not need soil, and just grow out of liquid solutions - it's in the name. And the water-carrying issue must have already been solved, otherwise long-term space habitation would be impossible in this setting. Water is incredibly plentiful on a galactic scale, and the IOM is no stranger to mass producing containers the size of battle-titans (otherwise they'd all be on Forgeworlds gathering dust).
At our current level of technology, here in M3, we're already pretty close to solving interstellar logistics (barring FTL, ofc). The IOM is so far beyond our level of technology that to think that spacelifting an entire agricultural ecosystem is beyond them is more an issue of Sci-Fi Writers Have No Sense Of Scale.

The only thing stopping them, imo, is their religious dogma. Which is probably not even the case in large areas of the IOM.

Even with hydroponics, you have issues with nutrient supply.

On earth, everything that is grown is supplied by the rotting poop of things that lived before. In a hydroponic lab, that rotting poop is supplied via a nutrient rich water. But in a orbiting space station, where food is grown and then exported out somewhere else, you are going to have to supply massive quantities of rotting life matter. Mass must be conserved. A 10trillion ton space station producing 1 trillion tons of food per year is going to need to be supplied by a trillion tons of nutrients and water ever year.
On a planet you dont need to supply the nutrients or the water, as they are created on planet so long as the scale of farming isnt too intense. So planetary production is going to be twice as efficient from a logistical standpoint.

A space station exporting a trillion tons of food will have incoming cargo vessels capable of importing a trillion tons of fertiliser.

A planet exporting that amount of produce will also have to import nutrients and stuff to replace the losses. Planets don't magically make matter any more than a space station. They just start with more

 Exergy wrote:

On earth, everything that is grown is supplied by the rotting poop of things that lived before.

Technically, it is decomposed and humified plant material (and dead bodies) that allows things to grow, not rotting poop
This means that a space station that uses soil and (artificial) sunlight rather than hydroponics could be self-sustaining as long as it only exports the edible parts of plants and leaves the remainder of the plant in place. Of course, intensive cultivation does drain nutrients faster than they can be replenished, but that could simply be solved by working with a system of crop rotation. A large enough facility would never have to import anything (except maybe stuff for the crew and such).

Basically, why go through all of the hassle of hydroponics when you can just ship a whole lot of dirt into space for plants to grow on?

 Iron_Captain wrote:

 Exergy wrote:

On earth, everything that is grown is supplied by the rotting poop of things that lived before.

Technically, it is decomposed and humified plant material (and dead bodies) that allows things to grow, not rotting poop
This means that a space station that uses soil and (artificial) sunlight rather than hydroponics could be self-sustaining as long as it only exports the edible parts of plants and leaves the remainder of the plant in place. Of course, intensive cultivation does drain nutrients faster than they can be replenished, but that could simply be solved by working with a system of crop rotation. A large enough facility would never have to import anything (except maybe stuff for the crew and such).

Basically, why go through all of the hassle of hydroponics when you can just ship a whole lot of dirt into space for plants to grow on?

Mass must still be conserved - if you remove the edible parts from the station, you're gonna get:

1] Station + Hydroponics + Plants + Food-material
2] Station + Hydroponics + Plants - Food-material

You've lost mass. Somehow, you'll have to put in however much you've sent out. This doesn't happen too much on Earth because we never take the "Food-material" out of our "Station". We just displace it temporarily.

Well, the funny thing is that most of the mass that plants are made of comes out of thin air. They pull CO2 out of the air and use the carbon as their primary building material. Energy comes from the sunlight. The soil is only needed for supplimental nutrients, which largely get recycled. Water is the other major component, but you can simply replace the water that leaves your system in the food with imported water.

So carbohydrates, the main food you'd get from plants, are basically made out of air and sunlight. The soil as far as mass doesn't make much of it at all.

So a massive space farm would have the following as its primary import needs,

Water to replace any that is leaving in the exported food. But this wouldnt be hard to get. Hydrogen and oxygen are very common on the galactic scale.

Carbon. This would be the big thing. You'd need to add carbon, in the form of CO2, to your system. Again, a super common material. Easy to find in many forms, easily combustible to add to the air as carbon dioxide. The oxygen within your system would be completely self sustaining as well since you don't export any appreciable amount.

Trace minerals. Some minerals would leave your system in the food, so you would need to replace that. It could potentially be as simple as bringing human waste back from the planets you supply.

 Grey Templar wrote:
Well, the funny thing is that most of the mass that plants are made of comes out of thin air. They pull CO2 out of the air and use the carbon as their primary building material. Energy comes from the sunlight. The soil is only needed for supplimental nutrients, which largely get recycled. Water is the other major component, but you can simply replace the water that leaves your system in the food with imported water.

So carbohydrates, the main food you'd get from plants, are basically made out of air and sunlight. The soil as far as mass doesn't make much of it at all.

So a massive space farm would have the following as its primary import needs,

Water to replace any that is leaving in the exported food. But this wouldnt be hard to get. Hydrogen and oxygen are very common on the galactic scale.

Carbon. This would be the big thing. You'd need to add carbon, in the form of CO2, to your system. Again, a super common material. Easy to find in many forms, easily combustible to add to the air as carbon dioxide. The oxygen within your system would be completely self sustaining as well since you don't export any appreciable amount.

Trace minerals. Some minerals would leave your system in the food, so you would need to replace that. It could potentially be as simple as bringing human waste back from the planets you supply.

Not impossible. And human waste is not exactly rare. Any hive world would gladdly sell, literally well.. Poo... For money...

 jhe90 wrote:

Not impossible. And human waste is not exactly rare. Any hive world would gladdly sell, literally well.. Poo... For money...

What could be more grimdark that 40k? Victorian-era industries!

Do you sometimes have to eject the devil's mash potatoes?
Does it stink up your street when you do it?
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For just 5 Thrones a month, we will take your Hab-Cell's waste and send it all the way to a 3rd-satellite platform so you don't have to!

 Grey Templar wrote:
Well, the funny thing is that most of the mass that plants are made of comes out of thin air. They pull CO2 out of the air and use the carbon as their primary building material. Energy comes from the sunlight. The soil is only needed for supplimental nutrients, which largely get recycled. Water is the other major component, but you can simply replace the water that leaves your system in the food with imported water.

So carbohydrates, the main food you'd get from plants, are basically made out of air and sunlight. The soil as far as mass doesn't make much of it at all.

So a massive space farm would have the following as its primary import needs,

Water to replace any that is leaving in the exported food. But this wouldnt be hard to get. Hydrogen and oxygen are very common on the galactic scale.

Carbon. This would be the big thing. You'd need to add carbon, in the form of CO2, to your system. Again, a super common material. Easy to find in many forms, easily combustible to add to the air as carbon dioxide. The oxygen within your system would be completely self sustaining as well since you don't export any appreciable amount.

Trace minerals. Some minerals would leave your system in the food, so you would need to replace that. It could potentially be as simple as bringing human waste back from the planets you supply.

It is certainly possible to supply a space station with the materials needed to grow food.
The question is if it makes economic sense given that the IoM has a million worlds, most of which are undeveloped and suitable for farming. If it is cheaper/easier to just set up a farm on another planet than to build and supply a space station they will do that.
Energy cost also comes into it. On a hive world, there oculd be whole levels of hydroponic or aquaponic farms that grow food by adding artificial sunlight. At that point you have your nutrient supply and consumer on planet and your transportation and spoilage costs go to near zero, you just have to supply energy for the fake sunlight which might be cheaper than shipping poo out to the stars, collecting water and carbon and growing food with free sunlight on a space station.

I'd say the advantages of an agricultural orbital outweight the cost. 100% sunlight without the need for anything artificial, and the ability to load food into a spaceship in zero g rather than lug it all the way out of the planet's gravity well first, burning millions of tons of prometheum in the process. Plus, you can put one anywhere. In orbit above a hive world so you don't need to rely on warp transport for your food supply.

Given those massive advantages, the fact that the Imperium still uses agri-worlds and goes through all the rigmorole of transporting food off-world, i'd say it's exceedingly difficult for them to build agri-orbitals. Otherwise every Hive World would have one...

Hive Worlds are industrial wastelands with populations in the fives or tens of billions. Unless you have a 1:1 ratio of Agri to Hive worlds, you're going to need some supplements.

And what do you do when an Agri world gets taken/glassed/eaten?

 Ynneadwraith wrote:
I'd say the advantages of an agricultural orbital outweight the cost. 100% sunlight without the need for anything artificial, and the ability to load food into a spaceship in zero g rather than lug it all the way out of the planet's gravity well first, burning millions of tons of prometheum in the process. Plus, you can put one anywhere. In orbit above a hive world so you don't need to rely on warp transport for your food supply.

Given those massive advantages, the fact that the Imperium still uses agri-worlds and goes through all the rigmorole of transporting food off-world, i'd say it's exceedingly difficult for them to build agri-orbitals. Otherwise every Hive World would have one...

Efficient but not planet scale production efichant.
For a smaller planet or vital military, research etc base there ideal.

But that does not fully translate to the efichancy of mass scale that a agri world has potential to produce.

 Selym wrote:
Hive Worlds are industrial wastelands with populations in the fives or tens of billions. Unless you have a 1:1 ratio of Agri to Hive worlds, you're going to need some supplements.

And what do you do when an Agri world gets taken/glassed/eaten?

The local hive worlds starve and then revolt.

 jhe90 wrote:

 Ynneadwraith wrote:
I'd say the advantages of an agricultural orbital outweight the cost. 100% sunlight without the need for anything artificial, and the ability to load food into a spaceship in zero g rather than lug it all the way out of the planet's gravity well first, burning millions of tons of prometheum in the process. Plus, you can put one anywhere. In orbit above a hive world so you don't need to rely on warp transport for your food supply.

Given those massive advantages, the fact that the Imperium still uses agri-worlds and goes through all the rigmorole of transporting food off-world, i'd say it's exceedingly difficult for them to build agri-orbitals. Otherwise every Hive World would have one...

Efficient but not planet scale production efichant.
For a smaller planet or vital military, research etc base there ideal.

But that does not fully translate to the efichancy of mass scale that a agri world has potential to produce.

Good point. I'm probably underestimating the sheer scale of an agri-world.

An orbital the size of Great Britain would be colossal. It would, however, be a speck on the surface of even an earth-sized agri-world, and we know that as far as planets go Earth is small fry.

 Ynneadwraith wrote:

 jhe90 wrote:

 Ynneadwraith wrote:
I'd say the advantages of an agricultural orbital outweight the cost. 100% sunlight without the need for anything artificial, and the ability to load food into a spaceship in zero g rather than lug it all the way out of the planet's gravity well first, burning millions of tons of prometheum in the process. Plus, you can put one anywhere. In orbit above a hive world so you don't need to rely on warp transport for your food supply.

Given those massive advantages, the fact that the Imperium still uses agri-worlds and goes through all the rigmorole of transporting food off-world, i'd say it's exceedingly difficult for them to build agri-orbitals. Otherwise every Hive World would have one...

Efficient but not planet scale production efichant.
For a smaller planet or vital military, research etc base there ideal.

But that does not fully translate to the efichancy of mass scale that a agri world has potential to produce.

Good point. I'm probably underestimating the sheer scale of an agri-world.

An orbital the size of Great Britain would be colossal. It would, however, be a speck on the surface of even an earth-sized agri-world, and we know that as far as planets go Earth is small fry.

Yeah. They have far less surface area. By many times. Ineffective way for a planet to be fed.
There great for keeping say a key remote naval base fed, supplying a large military base where regiments are readied for crusades, and gathered.
You need alot of food to keep and keep hundreds of thousands of crews, or millions of guardsmen at there rally stations. They consume alot of food and they also need it constantly.

They have a use. There ideal for key strategic uses such as that.
Or maybe one that orbits a deep space port or repair yard to feed its vast workforces, maybe even several.
Like deep space 9 was a major staging post for fedoration, they supply a large static space station many times size of the ramlies star forts.

Dang that's a cool idea for a story...

 Selym wrote:
Unless you have a 1:1 ratio of Agri to Hive worlds, you're going to need some supplements.

Not really.

If we turned Earth right now into an Agriworld, it could easily supply 4-5 Hive Worlds each with a few hundred million people. Earth has the potential to feed a LOT of people. The fear of us overpopulating Earth and not being physically capable of feeding everyone is, at this point, a complete myth. Earth, even only using a portion of the arable land, could easily feed many orders of magnitude more people than currently exist. It's just a matter of organization and land allocation. IE: not building cities or towns on land that can be farmed or grazed. And also being able to get food from where its grown to where its needed. Thats actually why people go hungry today, its not a lack of food production. Its that the food can't be taken to where the people are that need it.

But what a space station would have over an Agriworld would be location. You could build a hydroponics station anywhere. Agriworlds are stationary, and may not be where you want them.

So a single agriworld could supply many other planets with food. And it would be quite efficient since the agriculture would be organized on a planetary scale. Individual fields that are tens of thousands of square kilometers, tended by servitors who monitor the crop, and harvested by giant machines. Economies of scale on a level that we can't really comprehend.