General MegaStructures?

[Krikkitone]

I think the biggest problem with Vertical Megastructures is what happens when they fail. Hence, space elevator seems like a bad idea. With gravitics, I assume vertical megastructures would have powered grav supports spread throughout the structure (so the bottom is not holding up the top, the top is holding itself up so it won’t collapse onto the bottom)

 

[Spinward Flow]

Hence, space elevator seems like a bad idea. With gravitics

With gravitics, orbital elevator beanstalks become expensive boondoggle megaprojects. With gravitics, you don't need the space elevator structure at all ... just use a grav vehicle (lots of them!) instead.

One of the incredible downsides to orbital elevator beanstalks is that in order for them to function on an enduring basis, the orbital range that they sweep through MUST BE KEPT CLEAR. You basically can't have anything else floating around through the orbits that the orbital elevator beanstalk is sweeping through ... because ... Kessler Syndrome takes a lot of effort to clean up when you aren't willing to wait 10,000+ years for orbital debris to drag decay its way down into an atmosphere/impact onto a world surface. Building an orbital space elevator basically means losing ALL OF THE ORBITS that the space elevator spans through, because all other inertial orbits must "yield" to the space elevator as it sweeps through the sky around the world. The risk of collisions, at orbital velocities, is simply too great if you leave stuff "just lying around" in all of the orbits that the space elevator sweeps through ... and those collisions, if they occur, WILL NOT BE PRETTY.

So.
If you have a "pristine" clean orbital environment, you can build an orbital space elevator and push ALL inertial orbiting satellites OUT beyond the orbits that the space elevator sweeps through ... OR ... if you want to have satellite constellations in orbits closer than geosynchronous, you skip the orbital space elevator entirely and just go with space station and gravitic drive shuttlecraft. Guess which option is going to be easier on the world budget to operate and maintain.

 

[Condottiere]

I would say it's basically truck economics, versus railway, except you don't need to build highways.

It's also point to point, rather than hub and spoke.

However, you might have floating spaceports.

 

[Spinward Flow]

you might have floating spaceports.

For worlds that have oceans (and the tech level to build and maintain such facilities) going for an "offshore launch/touchdown point" makes a LOT of sense, especially on worlds that have energetic plate tectonics.

 

[atpollard]

Space Elevator: Just an observation that a Lunar Space Elevator can be built using TL6 steel cable (like a crane). It is only a “Megaproject” on Earth (1.0 Gee) surface gravity.

 

[atpollard]

I like the fact that standard Air is buoyant in dense atmospheres like Venus … so GO INFLATABLE AIRSHIP AGRICULTURE!

 

[kilemall]

Cordwainer Smith’s Earthport is definitely a megastructure.



The road winding down is its own megastructure, Alpha Ralpha Boulevard.

 

[Grav_Moped]

Boughene Station.

Boughene/Regina (SPIN 1904). One orbital station, 600,000 residents. (This is canon -- yes, almost all of them live on the Station.)

If everyone gets a 4Td stateroom and there's literally nothing else there (like power, fuel, grav, starport, and I don't know... food production?... it's 2.4 million displacement tons.

Almost 5 Tigress-class dreadnoughts. As housing.

Writers have no sense of scale.

 

[Condottiere]

I'd just park an asteroid in orbit.

Expand, or burrow, as necessary.

 

[Spinward Flow]

I'd just park an asteroid in orbit.

Expand, or burrow, as necessary.

But then it would have to be EVEN BIGGER!

Planetoid Hulls have a 20% "waste displacement" factor (in LBB5.80).
Buffered Planetoid Hulls have a 35% "waste displacement factor.

2.4 million / 0.8 = 3,000,000 tons
2.4 million / 0.65 = 3,692,308 tons

Granted, that's a "cheaper hull" than using a Metal Hull ... but still ...

A 216 meter diameter sphere has an internal volume of 42,213,400m³ ... which divided by 14m³ = 3,015,243 tons displacement ... sufficient for a Configuration: 8 (planetoid) hull containing 600,000 staterooms (and mostly NOTHING ELSE).

A 232 meter diameter sphere has an internal volume of 52,306,100m³ ... which divided by 14m³ = 3,736,150 tons displacement ... sufficient for a Configuration: 9 (buffered planetoid) hull containing 600,000 staterooms (and mostly NOTHING ELSE).

Almost 5 Tigress-class dreadnoughts. As housing.

Writers have no sense of scale.

From a COMBAT STARSHIP perspective, it sounds utterly ridonkulous ... since your starting point is in excess of 2.5 million tons!

But if you think of it in terms of needing to find a "1km diameter M-type Asteroid" ... that if spherical would have a volume of 523,599,000m³ ... which divided by 14m³ = 37,399,928 tons displacement ...

Good luck finding a Jump Tender for something in that displacement class ...
Maneuver drive-ing such a large displacement locally around a solar system (at very low acceleration over a very long time frame) in order to place it into a desired orbit elsewhere, however ... would be quite doable. EXPENSIVE ... but doable as a megaproject.

However, even as a Configuration: 9 (buffered planetoid) you would still have up to 24,309,953 tons displacement available ... at which point 2,400,000 tons dedicated to 600,000 staterooms suddenly turns into a mere 10% of the available habitat volume inside a "1km diameter M-type Asteroid" ...



For reference, the 16 Psyche asteroid is [best ellipsoid fit = 277 km × 238 km × 168 km] within the planetoid belt of the Terra system.

My point being that a "1km diameter M-type Asteroid" wouldn't even necessarily be that extraordinary or exceptional in terms of its size in astronomy terms, even in a star system lacking a Planetoid Belt. Such an object could presumably be found orbiting the trojan points of a gas giant (at L4 or L5) and maneuvered (with enough acceleration and time) into an L4/L5 position relative to a major moon of the same gas giant. Such a megaproject could easily take years (personally, I'd want a decade, minimum, just for the maneuvering phase) ... but is definitely something that would be within the budget of a megacorporation that wants to set up their own fiefdom somewhere and has the long term vision to execute such an endeavor. Initial capital outlays for such a megaproject would be ... astronomical ... but when you think in terms of building an outpost that will last for centuries(!), during which time it will (hopefully) generate sufficient economic revenue to "pay for itself" over a longer time horizon (say, a century or two) ... then such an investment ought to have long term payoffs that make the whole venture profitable (eventually).



A million tons here, a trillion credits there ... pretty soon we'll start talking in terms of real RU!

 

[Condottiere]

Just because the asteroid is parked there, doesn't mean it needs to be completely hollowed out.

That can be done as you need more space for business, manufacturing, warehousing, and/or traffic.

 

[TamsinP]

I imagine that Boughene station was built up over a very long period by adding modules as the workforce expanded. There's no reason why it would be spherical, a dispersed structure would be much more sensible.

As for the minimum size needed simply to house the population being the same size as 5 Tigress class dreadnoughts, why not? Would it be expensive to build? Yes. However, even at 10 times the size of 5 Tigresses it would probably be cheaper as there is no jump drive, little if any armour, and not much weaponry.

 

[kilemall]

But then it would have to be EVEN BIGGER!

Planetoid Hulls have a 20% "waste displacement" factor (in LBB5.80).
Buffered Planetoid Hulls have a 35% "waste displacement factor.

2.4 million / 0.8 = 3,000,000 tons
2.4 million / 0.65 = 3,692,308 tons

Granted, that's a "cheaper hull" than using a Metal Hull ... but still ...

A 216 meter diameter sphere has an internal volume of 42,213,400m³ ... which divided by 14m³ = 3,015,243 tons displacement ... sufficient for a Configuration: 8 (planetoid) hull containing 600,000 staterooms (and mostly NOTHING ELSE).

A 232 meter diameter sphere has an internal volume of 52,306,100m³ ... which divided by 14m³ = 3,736,150 tons displacement ... sufficient for a Configuration: 9 (buffered planetoid) hull containing 600,000 staterooms (and mostly NOTHING ELSE).

From a COMBAT STARSHIP perspective, it sounds utterly ridonkulous ... since your starting point is in excess of 2.5 million tons!

But if you think of it in terms of needing to find a "1km diameter M-type Asteroid" ... that if spherical would have a volume of 523,599,000m³ ... which divided by 14m³ = 37,399,928 tons displacement ...

Good luck finding a Jump Tender for something in that displacement class ...
Maneuver drive-ing such a large displacement locally around a solar system (at very low acceleration over a very long time frame) in order to place it into a desired orbit elsewhere, however ... would be quite doable. EXPENSIVE ... but doable as a megaproject.

However, even as a Configuration: 9 (buffered planetoid) you would still have up to 24,309,953 tons displacement available ... at which point 2,400,000 tons dedicated to 600,000 staterooms suddenly turns into a mere 10% of the available habitat volume inside a "1km diameter M-type Asteroid" ...



For reference, the 16 Psyche asteroid is [best ellipsoid fit = 277 km × 238 km × 168 km] within the planetoid belt of the Terra system.

My point being that a "1km diameter M-type Asteroid" wouldn't even necessarily be that extraordinary or exceptional in terms of its size in astronomy terms, even in a star system lacking a Planetoid Belt. Such an object could presumably be found orbiting the trojan points of a gas giant (at L4 or L5) and maneuvered (with enough acceleration and time) into an L4/L5 position relative to a major moon of the same gas giant. Such a megaproject could easily take years (personally, I'd want a decade, minimum, just for the maneuvering phase) ... but is definitely something that would be within the budget of a megacorporation that wants to set up their own fiefdom somewhere and has the long term vision to execute such an endeavor. Initial capital outlays for such a megaproject would be ... astronomical ... but when you think in terms of building an outpost that will last for centuries(!), during which time it will (hopefully) generate sufficient economic revenue to "pay for itself" over a longer time horizon (say, a century or two) ... then such an investment ought to have long term payoffs that make the whole venture profitable (eventually).



A million tons here, a trillion credits there ... pretty soon we'll start talking in terms of real RU!

The mechanism I had for the aforementioned Lagrange point Cities was processed lunar regolith, melted down and mixed with alloy by solar furnaces.

Worked out the financing too, which among other things has made the Scout Service partially Fish and Game wardens for genetic exploitation.

 

[Spinward Flow]

a dispersed structure would be much more sensible.

If you're building a space station and you don't have a suitably sized planetoid hull available for the job (always possible), then a Configuration: 7 (dispersed structure) metal hull does indeed make the most sense. Even better yet, you can "build it up" over time.

So if, for example, if we take the "40 year life expectancy" for most hulls as a reasonable depreciation point, for a population of 600,000 staterooms intended to last for 40 years, you would basically need to be (re)building ~15,000 stateroom blocks per year for 40 years. At the end of those 40 years, module blocks start "aging out" of service and get replaced by new ~15,000 stateroom blocks in a continuous cycle of rolling production. Presumably the depreciated asset modules would get recycled/munched to provide the necessary raw materials for the following generations of construction (reducing the need for mined resource inputs) and you can manage to keep the party going more or less indefinitely.

Building everything modular style like that in a rotating recycle/renew construction program that lasts indefinitely means that you only need to set up the production line and then just LET IT RUN. You don't have to build out everything all in one go (POOF! Instant Space Station!).

In point of fact, what would probably happen is something akin to having multiple production lines (3-4) each building out 5000 stateroom blocks worth of dispersed structure on a continuous rolling basis.

Mass produced housing for mass produced people (or words to that effect).

After that it's all just admin, once you've got the engineering dialed in and the design frozen.

 

[Talifon]

The road winding down is its own megastructure, Alpha Ralpha Boulevard.

With it's own theme song composed by electronic musician Ralph Lundsten from his 1979 album of the same name!

 

[Grav_Moped]

In point of fact, what would probably happen is something akin to having multiple production lines (3-4) each building out 5000 stateroom blocks worth of dispersed structure on a continuous rolling basis.

Which is why the place has a shipyard without significant starship construction capacity. They are kinda busy keeping the Station going with the "hull building" part of it. Repairs? Service? Sure.

But the whole idea seems to have been a minor setting backdrop detail, in a star-system where the really important stuff would happen elsewhere in the system. (Spoiler?)

Which means that when you're not using the scenario that makes the station merely a side-detail, and instead try to turn the station into a setting in and of itself... it gets interesting, and the logistics get complicated. (Accidental megastructure? Oops, there it is.)


Again, really well-written take on that scenario by Mongoose -- especially when viewed as a SF novel framed as an RPG scenario, rather than just a scenario -- but it can break the OTU, depending on the outcome. And I'd rather avoid that...

 

[TamsinP]

If you're building a space station and you don't have a suitably sized planetoid hull available for the job (always possible), then a Configuration: 7 (dispersed structure) metal hull does indeed make the most sense. Even better yet, you can "build it up" over time.

So if, for example, if we take the "40 year life expectancy" for most hulls as a reasonable depreciation point, for a population of 600,000 staterooms intended to last for 40 years, you would basically need to be (re)building ~15,000 stateroom blocks per year for 40 years. At the end of those 40 years, module blocks start "aging out" of service and get replaced by new ~15,000 stateroom blocks in a continuous cycle of rolling production. Presumably the depreciated asset modules would get recycled/munched to provide the necessary raw materials for the following generations of construction (reducing the need for mined resource inputs) and you can manage to keep the party going more or less indefinitely.

Building everything modular style like that in a rotating recycle/renew construction program that lasts indefinitely means that you only need to set up the production line and then just LET IT RUN. You don't have to build out everything all in one go (POOF! Instant Space Station!).

In point of fact, what would probably happen is something akin to having multiple production lines (3-4) each building out 5000 stateroom blocks worth of dispersed structure on a continuous rolling basis.

Mass produced housing for mass produced people (or words to that effect).

After that it's all just admin, once you've got the engineering dialed in and the design frozen.

I'd suggest that the cycle might even be over a longer period than 40 years; the duration of a ship mortgage is not the same as the life expectancy of a ship. In the case of an orbital station the life expectancy may be even longer than for a ship as it won't be subjected to the stresses and strains of 1g or more acceleration and jumps, nor will it have to endure atmospheric entry/exit and fuel skimming from as giants.

However, in the case of Boughene with a corrosive atmosphere I would expect the life expectancy of the vessels used to land harvesting teams to be much lower.

 

[Grav_Moped]

However, in the case of Boughene with a corrosive atmosphere I would expect the life expectancy of the vessels used to land harvesting teams to be much lower.

There's a whole thread on this... mind you, it's a slightly ATU version of the place because I screwed up the settings for TravellerWorlds while working on it, but pretty much everything carries over to the canon version.

And directly to this point, the folks on Boughene must have developed really advanced hull paint ..