Belter Settlments: Tunnels in Dwarf Planets

[Tom Kalbfus]

Ever stop to consider how a belter colony would look like on this asteroid? I think they would tunnel into it, and with 2.4% gravity, they could tunnel fairly deep Down to the Dwarf Planet's core in fact, but for habitation purposes the first 50 km down from the surface would probably suffice Imagine a tunnel dug in the surface 250 meters wide, down about 250 meters below the surface, the tunnel widens to 500 meters forming a spherical chamber, inside that chamber is a Bernal Sphere, it rotates twice a minute for gravity.

You may ask what about the artificial gravity generators in the traveller campaign? Well what do you think would happen if you could turn on a gravitational field underneath kilometers of rock, first they weigh very little under the natural gravity and suddenly they weigh thousands to millions of tons above your head, there is a chance that turning on a gravitational fields within a tunnel might trigger tunnel collapse, so Belters that live inside asteroids might decide to avoid artificial gravity fields and use spin gravity instead. Interesting thing, I worked out mathematically, if we had a series of shafts, each 50 kilometers deep, and with a Bernal Sphere for every kilometer of each shafts length, and a shaft placed one tenth of a degree from the next one covering the entire surface of this asteroid, we would have a surface area equal to one fifth the surface area of the Earth, almost the entire land area of our planet!

 

[phavoc]

For ships the deck plating itself provides the gravitational field. So, in theory, if you didn't put the same down on your rocky floors, you'd have zones of low-g between areas of gravity. Sure might make a mess of things!

I suppose, in theory, it should be possible to have localized gravity generators to provide that sort of thing. Would be interesting to see how they could apply it without making it spherical in nature. I suppose the grav plating has to be directional, otherwise if you had a multi-deck ship if you tossed a ball into the air it would "fall" towards the ceiling and remain there.

 

[Tom Kalbfus]

What do you think a belter colony would look like? Would it be O'Neillian or like something else?

 

[GypsyComet]

Ever stop to consider how a belter colony would look like on this asteroid?

I'm waiting for the mission to get some closer photos, but Ceres is a bit small to be classed as Size 1. This puts it in the Size "S" group, though at the large end of it.

Despite the really low gravity, I suspect Ceres and similar bodies would be settled in the same pattern as small planets. The difference is the shape. As Ceres is large enough to self-round, it is probably pretty solid, and even 1/20th of a G is better than microgravity. There is a "down". Would the inhabitants also put in artificial gravity? Probably. Only the oddballs are likely to play directional games with the artificial gravity, though. Plates can probably overcome the 0.05 G completely, but only Mad Gods and Wizards make dunge... habitats like that.

 

[Tom Kalbfus]

Ever stop to consider how a belter colony would look like on this asteroid?

I'm waiting for the mission to get some closer photos, but Ceres is a bit small to be classed as Size 1. This puts it in the Size "S" group, though at the large end of it.

Despite the really low gravity, I suspect Ceres and similar bodies would be settled in the same pattern as small planets. The difference is the shape. As Ceres is large enough to self-round, it is probably pretty solid, and even 1/20th of a G is better than microgravity. There is a "down". Would the inhabitants also put in artificial gravity? Probably. Only the oddballs are likely to play directional games with the artificial gravity, though. Plates can probably overcome the 0.05 G completely, but only Mad Gods and Wizards make dunge... habitats like that.

You have to ask why the belters are there? the surface of Ceres is relatively inhospitable, you can't breathe vacuum after all, Also a dome on the surface is more vulnerable to everything, solar flares, pirate attacks etc. Also surface settlements are 2 dimensional, a big advantage of a low gravity environment is its 3-dimesionality. Also 25% of Ceres is water by composition. I don't think belters would be mining water for export, they'll want what's under the water, therefore they will be digging tunnels, and tunnels make more sense on a low gravity world than strip mining. Strip mining involves removing a lot of stuff which isn't the stuff your trying to mine, and stripmining to the core of a dwarf planet isn't feasible, which means to take the whole dwarf planet apart! Tunneling is the only way to get to the core.

 

[GypsyComet]

25% of Ceres is water by composition. I don't think belters would be mining water for export, they'll want what's under the water, therefore they will be digging tunnels, and tunnels make more sense on a low gravity world than strip mining. Strip mining involves removing a lot of stuff which isn't the stuff your trying to mine, and stripmining to the core of a dwarf planet isn't feasible, which means to take the whole dwarf planet apart! Tunneling is the only way to get to the core.

Depends on the meaning of "export", and the extent of other belt communities. As a significant water source, Ceres may not be a mining community, but instead a watering hole and local "town". If a belter's choice for water restocks is Ceres, Jupiter, or Mars, Ceres may find a larger water market than you think. Export all the way to Earth for other than scientific purposes is unlikely, though.

As for tunneling, that will differ based on how Ceres is used in the long term. I'm a fan of Heinlein-style core-and-branch colonies for airless worlds, per "The Menace from Earth". You tunnel down to a point where the rock above you is providing the shielding you need, then you start a broad spiral downward, gradually hollowing out the interior of the spiral as common space (including the giant hanging garden/air plant) and digging homes, businesses and other facilities around the outside. At appropriate points side tunnels can start secondary spirals.

 

[Rick]

Once you hollow out the asteroid, presumably separating out the removed portion into raw materials and 'waste slag', why bother with an internal rotating cylinder or sphere? Why not fit thrusters to it and rotate the entire thing around it's centre of mass? As long as it is hollowed out into a cylindrical form, spun gravity should be fine.

 

[GypsyComet]

Mostly a matter of scale. Ceres is 590 miles across.

 

[Rick]

Mostly a matter of scale. Ceres is 590 miles across.

I see your point. Not a great candidate for a habitat. But, when hollowed out, a good candidate for a spaceport/secure berth. Put a couple of smaller ones (50-100 miles long in 3-4 cavern sections) nearby for spun habitats and you've got a Belt spaceport metropolis.

 

[Tom Kalbfus]

Mostly a matter of scale. Ceres is 590 miles across.

I see your point. Not a great candidate for a habitat. But, when hollowed out, a good candidate for a spaceport/secure berth. Put a couple of smaller ones (50-100 miles long in 3-4 cavern sections) nearby for spun habitats and you've got a Belt spaceport metropolis.

My point is you can't make Ceres into a single hollowed out rock, but you can carve many cavities in it. An Island One Space colony is a Bernal sphere 500 meters across, and it rotates 1.9 times per minute to simulate full gravity on its inside at the equator. The Bernal Sphere is held in place by a set of tracks built into the walls of the cavity it is held inside. The axis of its rotation is vertical, that is one of the Bernal Sphere's poles points downward, the other points upward. Each Bernal has a 250 meter wide hole cut around each Bernal pole, outside the South Pole is a tunnel 270 meters wide with a circular river of water 20 meters deep. The water flows around this cylindrical shaft once per minute. At the opening of the Bernal Sphere, the 250 meter wide hole, the simulated gravity is at one half that of Earth, The water flows once around the circular walls of the tunnel 0.95 times per minute, this means the gravity at the water surface is 0.126152 times that of Earth. About 1 km down the shaft is another Bernal Sphere, water piles up towards the bottom of the shaft, so the North Pole of that lower Bernal is smaller. About 500 meters above the uppermost Bernal Sphere is a dome at the surface of Ceres which holds in the shafts's atmosphere. At the midpoint of each water tunnel between Bernals are 4 20-meter wide tear drop shaped islands, each island is 90 degrees in a circle from its neighbor and rises 10 meters above the water surface, each island is 20 meters wide, with a horizontal tunnel entrace 10 meters wide, this forms a 6-way inter section with four 10-meter wise tunnels going north, south, east, and west, while the 250 meter wide water tunnel goes up and down. (The gravity is only 0.024 times that of Earth.) Water spirals down the shaft towards the Bernal below Water has to be pumped back up towards the top of the shaft. Some of the water flows through each Bernal. The shafts and the tunnels connects the atmospheres of each Bernal to each other. Basically all the tunnels and shafts are filled with breathable air. Each Shaft is 50 kilometers deep, and they are lined up in a North-South and East-West fashion from their neighbors along the surface of Ceres, each spaced one tenth of a degree apart, total surface area is one fifth that of the Earth's surface.

Below 50 km, tunneling becomes more difficult as the pressure builds, probably deeper tunnels are dug chiefly to extract minerals. I think Ceres in the Traveller setting probably has been tunneled out for a long time, the network of tunnels should be rather extensive. Who knows what's down there, some tunnels and passages might be forgotten. Perhaps some Solomani Rebels live down there having evades the Imperium for some time. There are a lot of possibilities.

 

[Reynard]

Just so everyone know what Ceres is and what its properties are: http://en.wikipedia.org/wiki/Ceres_(dwarf_planet)

Yeah, this is a digit zero body with a diameter of 476km and a gravity of 0.029g. If you hollow at the rotational pole and create a cylinder within the stable racky core, you MIGHT use centrifugal force for artificial gravity though that would need to know the size of the habitat and the influence of the rock's natural rotation. Remember, hollowing it out removes some of the the core and mass that gives the rock gravity which can be a good thing so there's less counter effect on the rotational source. By the way, a sphere would suck! As you move away from the 'equator' gravity will go to nil quickly.

All this HIGHLY expensive construction is a bit moot unless you're there for a very good reason otherwise you slap a surface base on it or maybe burrow into the ice a bit for certain protective features. The place is ideal for scientific studies especially its possible water mantle and whether there may be water containing life. If it is indeed an ice covered rock, you have ice which is frozen water that can be mined and shipped as very large blocks to wherever water may be needed. Seems Earth could use some even today. Its rocky core could be more cheaply surface mined on its neighbors. In a Traveller universe with all the gas giants in out solar system, Ceres isn't worth using for fuel.

 

[Tom Kalbfus]

Just so everyone know what Ceres is and what its properties are: http://en.wikipedia.org/wiki/Ceres_(dwarf_planet)

Yeah, this is a digit zero body with a diameter of 476km and a gravity of 0.029g. If you hollow at the rotational pole and create a cylinder within the stable racky core, you MIGHT use centrifugal force for artificial gravity though that would need to know the size of the habitat and the influence of the rock's natural rotation. Remember, hollowing it out removes some of the the core and mass that gives the rock gravity which can be a good thing so there's less counter effect on the rotational source. By the way, a sphere would suck! As you move away from the 'equator' gravity will go to nil quickly.

All this HIGHLY expensive construction is a bit moot unless you're there for a very good reason otherwise you slap a surface base on it or maybe burrow into the ice a bit for certain protective features. The place is ideal for scientific studies especially its possible water mantle and whether there may be water containing life. If it is indeed an ice covered rock, you have ice which is frozen water that can be mined and shipped as very large blocks to wherever water may be needed. Seems Earth could use some even today. Its rocky core could be more cheaply surface mined on its neighbors. In a Traveller universe with all the gas giants in out solar system, Ceres isn't worth using for fuel.

It is easier to mine if the gravity is nearly zero, it is easier to dig into as well. You could dig deeper into Ceres than you could into a normal sized planet. It also makes for excellent armor. There is very little in a normal ship's armor that could blow up a dwarf planet. Even stuff which could lay waste to the surface of an earth-sized world, would hardly put a dent in a dwarf planet. Something at the center of Ceres, would be quite safe in fact from all the World's nuclear weapons. Dwarf planets make great hiding places as well, Remember the movie The Empire Strikes Back?. Now imagine a dwarf planet filled with an endless maze of tunnels and chambers. What if the Classice Traveller Ceres had such tunnels after thousands of years of tunneling and mining. Solomani Rebels could hide in those, I don't know what the Imperial Navy would do about it.

 

[Reynard]

I remember a long time ago there was mention how deadly meson guns are since they can be buried deep in a planet and still fire except....

They need surface arrays to operate. Find those and the entryways to the gun bunkers and you can nuke and bury them with ground troops. Same with some 'impenetrable' safe house in Ceres. Hopefully there should be no reason to make a ice mine such a valuable target.

 

[Tom Kalbfus]

I remember a long time ago there was mention how deadly meson guns are since they can be buried deep in a planet and still fire except....

They need surface arrays to operate. Find those and the entryways to the gun bunkers and you can nuke and bury them with ground troops. Same with some 'impenetrable' safe house in Ceres. Hopefully there should be no reason to make a ice mine such a valuable target.

Mesons are not good if you don't have sensors to detect your targets. If Such sensors existed, the rebels could have them too and detect the Imperial Warships as they approached and shoot them with their own meson guns. What is the range of a meson gun anyway? The Imperials would also need to know which cavern their enemy was hiding in, there is a lot of volume the rebels could be hiding in. Its even possible to dig to the core. Anyway the digging need not be done in modern times, it could have begun during the 21st century, so some of these tunnel could be quite ancient.

 

[Reynard]

You're right about a warship can fire back with their own mesons but they need to know where a target is within a large body as opposed to targeting a relatively tiny ship. That's the other advantage. The difference is a starship's sensor arrays aren't the ultimate Achilles Heel to their firepower. Find the planetary sensors plus their entry points and you can blind their uber weapon while making the planet their tomb. Ceres is worst because it's so very tiny compared to a planet and targeting most gun emplacements and the infrastructure is almost as easy as a starship.

Seriously, don't make a vulnerable object a valuable target. (Guns of Navarone).

 

[Tom Kalbfus]

You're right about a warship can fire back with their own mesons but they need to know where a target is within a large body as opposed to targeting a relatively tiny ship. That's the other advantage. The difference is a starship's sensor arrays aren't the ultimate Achilles Heel to their firepower. Find the planetary sensors plus their entry points and you can blind their uber weapon while making the planet their tomb. Ceres is worst because it's so very tiny compared to a planet and targeting most gun emplacements and the infrastructure is almost as easy as a starship.

Seriously, don't make a vulnerable object a valuable target. (Guns of Navarone).

Do the Imperial have a weapon which can blow up a Dwarf Planet? If they don't know where precisely their enemy target is within the dwarf planet, they don't know where to fire their meson gun. Now as Traveller is one of the more realistic role playing games, I don't imagine they have a Death Star, do they?

Another possibility is perhaps a jump could be made from the center of the Dwarf Planet since gravity would cancel out there. Now just imagine the possibilities, if there was a cave at the dead center, they could jump from there to some other Star System and pick up weapons, and then Jump back to the center of Ceres since space is flat at the center of Ceres, the gravity of the Dwarf planet cancels out there.

 

[Reynard]

Read where I stated Plan B in the event of anti-ship mesons. If you can't find it, you look for it's surface sensors and entry points. Doesn't take a Death Star just Intel, a ground team and the ordinance to take those points out. (Adventure hint!)

As to jumping into the interior of a planetary body, go read the Traveller rules again. I'll wait.

But since we're almost out of time today, Jumps are not always accurate especially to within a few tens of meters.

 

[Tom Kalbfus]

Read where I stated Plan B in the event of anti-ship mesons. If you can't find it, you look for it's surface sensors and entry points. Doesn't take a Death Star just Intel, a ground team and the ordinance to take those points out. (Adventure hint!)

As to jumping into the interior of a planetary body, go read the Traveller rules again. I'll wait.

But since we're almost out of time today, Jumps are not always accurate especially to within a few tens of meters.

Sensors can be very small, and Ceres is huge! And a tunnel system can have more than one exit. Well maybe Jumping into it may be hard, but jumping out is a possibility, it is of course an optional rule, so rules lawyers can get off my back.

 

[atpollard]

For a Belter colony, inflate a Kevlar balloon and start to spin it (I like the portable fuel bladder since anything that will safely hold liquid hydrogen is more than strong and tight enough.)
Mine the asteroid for what you want and spray the molten slag over the Kevlar balloon.
When the cooling shell is thick enough to block the background radiation (probably a few meters), move in.

 

[heron61]

For a Belter colony, inflate a Kevlar balloon and start to spin it (I like the portable fuel bladder since anything that will safely hold liquid hydrogen is more than strong and tight enough.)
Mine the asteroid for what you want and spray the molten slag over the Kevlar balloon.
When the cooling shell is thick enough to block the background radiation (probably a few meters), move it.

That's an excellent plan for most asteroids (pretty much anything under 100 km in any dimension), because we now know that smaller asteroids are little more than piles of rubble that have been compacted together, but not sufficiently to become fully solid, so surface mining would be awesome, but tunneling would be difficult and dangerous.

However, larger asteroids like Vesta and Ceres are solid bodies with different layers due to internal heating. Digging into them would be like digging into the same sort of rock on Earth. You'd want to line tunnels to keep them air tight, but mine by digging a tunnel, start digging the next one, spray the previous tunnel with something to make it air tight, install fittings and grav plates, and you've got a pretty nice habitation.