Limits on availability of planetoid hulls?

[Anonymous]

What are the guidelines people use for the availabilty of planetoid hulls for mass production?

It's obviously not an issue if you're building one, but what happens when you want to build a hundred, or a thousand ships?

Problems like "Would you get a quantity discount on the hull?" seem quite minor and easily sorted, but the question of "How many hulls can you obtain?" seems a much more major issue.

How many hulls can you get out of an asteroid belt?

If hulls have to shipped in from another system, what is the availabiliy of jump ships of the required size?

Most Traveller craft seem small but those are mostly adventure size ships. It seems likely to me that megacorporations and navies will have ships able to move loads in the hundreds of kilotons. The navy needs jump tugs to recover crippled ships, and a modern (real world) container ship carries, in Traveller terms about 30-35K d-tons of cargo: I assumed 12K TEU (containers) and the approximation of 6x2.5x2.5 meters per container, and 14 m3 per d-ton.

 

[FallingPhoenix]

A quick estimate for a 30,000 ton hull's length is somewhere close to 100 m if it's approximately spherical.

A quick internet search indicates there are estimated to be over 150 million asteroids over 100 m and in the inner solar system alone.

It seems likely that you'll have more asteroids than you could use in any given system for planetoid and buffered planetoid hulls.

 

[Reynard]

First, if you want to have a planetoid ship, you need an asteroid belt because the planetoids can't be jumped until processed and fitted. I don't see any limitation on the number of planetoid ship that can built except, as with normal ships, the limitations of personnel, budget and shipyard capacity. I've never hear restrictions on a structural type other than size which must be at least 3000 ton.

Why don't we see more PSs in Traveller? Looking in High Guard, if I'm reading it right, the tonnage is the disadvantage whereas a normal ship uses all the tonnage, a hollowed PS and Buffered PS only use 80% and 65% of available space respectively even if you do get automatic armoring. That could be a significant reason.

Other than that issue, I don't see systems with the resources, crew, facilities and budgets not making use of their asteroid fields for system defense. The saving in transport an hollowing could making building many ships possible. Monitors should be ideal.

 

[Galadrion]

For SDBs and monitors, planetoid hulls (buffered or not) are a good choice for several reasons - cheap, automatically armored (and can be more armored than anything else in space), there's some potential for camouflage (leaving aside the whole heat signature issue - come on, folks, it's a game!) As for availability, well, any system with an actual planetoid belt is going to a ready supply of suitable rocks. Even a system without such a belt is likely to have the local equivalent of an Oort Cloud, which, while less accessible, is going to provide vastly larger numbers of planetoids. (A lower percentage of nickel-iron ones, true, but in absolute terms? It's a game master's call, but for game purposes, you'd be more than justified in calling it a wash.)

The primary reason for not using planetoid hulls on a wholesale basis for military purposes is standardization - militaries want as much as possible standardized, for logistics purposes if nothing else. When all your SDB hulls are, by necessity, custom jobs, it's going to play hell with your support networks and supply solutions. But for the reasons listed above, some military organizations might well opt to tolerate the difficulties.

The main reason for civilian avoidance of planetoid hulls would relate to the purpose of the ship - most civilian starships are commercial in nature, and planetoid hulls are barred from planetary landings. That means you either carry subcraft (an added expense) or rely on local shuttles (another added expense, and not always available in any case).

*Shrug* Decisions such as these are always a matter of trade-offs. Personally, I think the military is a bit more likely to make use of planetoid hulls than civilians are - with the possible exception of pirates, who tend to be somewhat militaristic in mindset anyway, at least if they want to be successful.

 

[Reynard]

Problem with using a system Oort cloud would be a much greater overall cost for the distance to travel both to and from. Our own Oort cloud is 2 light years away whereas our asteroid belt center is a mere 2.7 AU. Fuel alone wouldn't justify the cost.

As to camouflage, it should be very possible. SDBs routinely go silent running as part of system defense especially in times of imminent attack whether it's in the protection of an ocean, floating in the clouds of a gas giant or drifting quietly at key locations. Planetoid hulls from 3000 ton SDBs to 50,000 ton monitors doing such duty should be an option especially messing with visual sensors compared to a shiny geometrically artificial shape.

 

[Anonymous]

First, if you want to have a planetoid ship, you need an asteroid belt because the planetoids can't be jumped until processed and fitted.

I couldn't find this rule. Where is it and what prevents planetoids being carried as cargo?

 

[Jeraa]

First, if you want to have a planetoid ship, you need an asteroid belt because the planetoids can't be jumped until processed and fitted.

I couldn't find this rule. Where is it and what prevents planetoids being carried as cargo?

Nothing prevents planetoids being carried as cargo, provided you have a cargo bay with the right dimensions to fit the planetoid.

 

[Reynard]

Check what we've found in our own solar system. Planetoids don't frequently form as nicely round balls so transports would need to be much larger than the desired rock. If you're really thinking about dragging large rocks to other system to be processed we're talking more expense. This is killing the cheapness normally associated with using PSs rather than a standard hull. Traveller tends to be generous with asteroid field so there's really no reason to have facilities where the source is.

 

[Condottiere]

Technically, two thousand and one tonnes.

Practically, as long as the planetoid maintains structural integrity, you could carve one up and use it like a jeep.

 

[Epicenter]

What are the guidelines people use for the availabilty of planetoid hulls for mass production?

How many hulls can you get out of an asteroid belt?

I don't really anyone would use planetoid hulls for mass production, as others have pointed out, even more than the size and shape of the planetoids, the consistency would ... inconsistent. You probably need a lot of nickel-iron in the planetoid, but you probably also want quite a bit of ice, but you need both of them in the right proportions and in the right places; while you could probably add a jacket of water ice later on, if a large vein of ice goes through the planetoid and is structural weakness, that makes it less appealing right there. That said, it might be possible to use lasers or something to fuse together several smaller planetoids to create a ship as well.

That said, if a navy wants a large number of planetoid hulls, I'd say the number of planetoids that would be suitable for building ships in is probably in the hundreds, perhaps the low thousands - effectively unlimited unless they've been doing it for a while.

For SDBs and monitors, planetoid hulls (buffered or not) are a good choice for several reasons - cheap, automatically armored (and can be more armored than anything else in space), there's some potential for camouflage (leaving aside the whole heat signature issue - come on, folks, it's a game!) .

I'm of the opinion that the cost savings of a planetoid hull is probably grossly overestimated in Traveller. In fact, I don't think there'd be any cost savings. Each planetoid ship would be close to a one-off design so each one would require it's own building plan "blueprint" - this would be pretty expensive. Then the cost and time to hollow out all the corridors, rooms, and similar areas; you don't want to totally hollow out the planetoid since that defeats much of the purpose of using a planetoid. Then you'd need to reinforce certain areas because of inherent weaknesses in the natural planetoid or just for added protection. You compare this to a shipyard built ship to a standard design where the blueprint is already done, industry-of-scale cost benefits for things like hull plating (while the internal fittings would be pretty much identical between both ships). I think in the end the cost of the two types of ships wouldn't really be that different.

I think the big advantage to a planetoid hull would be camouflage. If your planetoid ship is in the Life Zone (or closer) to its local star, the heat signature of the power source could be pretty easily hidden (especially if you're using some sort of aneutronic fusion or fuel cell system) simply from the sunlight hitting the ship's hull - just make sure it is in a stable orbit that doesn't threaten anything in-system otherwise it'd be pretty obvious. Similarly, a planetoid hull could probably hide around large gas giants and so on and play "shepherd moon" and mask lot of its heat signature if the gas giant is large enough to radiate heat on its own. In either case, having surface fittings that look decayed and abandoned (planetoid ships might deliberately have corridors that penetrate all the way through the planetoid open to space for instance) so that enemies that come into the system believe that the planetoid was once used for something but is now no longer used.

 

[Anonymous]

I'm of the opinion that the cost savings of a planetoid hull is probably grossly overestimated in Traveller.

I agree with respect to the price savings. It's probably not cheaper.

However, we are playing Classic High Guard, where there are some balance issues with the additional armor on planetoid hulls, and this makes them desirable tactically.

 

[Condottiere]

You can probably sculpt a planetoid to suit the appropriate tonnage range; you might even be able to weld on more to make up the weight.

 

[Epicenter]

I'm of the opinion that the cost savings of a planetoid hull is probably grossly overestimated in Traveller.

I agree with respect to the price savings. It's probably not cheaper.

Thinking about this, I do think that there are advantages to planetoid hull fabrication of starships:

Imagine a star system with moon and belt mining operations which doesn't have an A-class starport or even a B-class starport. News is that there's some war brewing; perhaps it's in some quasi-independent system between the Zhodani and the Imperium. They need some SDBs.

The subsystems for the planetoid SDBs (weapons, maneuver drives, and so on) could be reasonably easily purchased and transported.

The skills to build the ships exist in profusion in your system: Hollowing out the planetoid could be done by miners (they have the skills and equipment) and estimate its durability and reinforce it where necessary (mine geologists). The materials to reinforce such ships exist as well as mines require them.

Larger planetoids and moon mines might have work conducted in a shirt-sleeves environment; there'd be engineers in this case who have the skills to figure out the life support requirements and set up the necessary systems.

Semi-complete planetoid hull warships probably exist in profusion in the system; mined out or partially mined-out planetoids that have had their more valuable fractions (palladium group metals and so on) removed.

 

[Rikki Tikki Traveller]

A Planetoid Belt is NOT required to get these hulls. Even without the Asteroid Belt in our solar system, there are still millions of asteroids (at least hundreds of thousands in the right tonnage range for discussion) that are not associated with our planetary belt. All of the Gas Giants have asteroid moons (heck, even Mars has two), and they all have a clump of asteroids at their Trojan Points.

Even if you assume that the majority of the asteroids everywhere in our system originated in the Asteroid Belt (Mars' moons almost definitely did), the formation of a planetary system is a very messy time and there is always going to be a LOT of debris left over that will take many billions of years to clean up (if it ever does).

Also remember that the majority of asteroids/Planetoids are going to be rocky (silacate or carbonate), Icy (if in the Outer System) and only the rarest Metallic asteroids are going to be usable as ship hulls. But, even in the most sparse system, that should still be thousands of potential hulls.

 

[Reynard]

Traveller editions have addressed asteroid belts differently but, like the proficiency of 'earth-like' worlds, system belts are often generous. even still, here's a description of our real belt:

"About half the mass of the belt is contained in the four largest asteroids: Ceres, Vesta, Pallas, and Hygiea. The total mass of the asteroid belt is approximately 4% that of the Moon, which is significantly less than that of Pluto and roughly twice that of Pluto's moon Charon (whose diameter is 1200 km).

Ceres, the asteroid belt's only dwarf planet, is about 950 km in diameter, whereas Vesta, Pallas, and Hygiea have mean diameters of less than 600 km. The remaining bodies range down to the size of a dust particle. The asteroid material is so thinly distributed that numerous unmanned spacecraft have traversed it without incident."

Yeah, belts aren't necessarily homes to infinite hulls. We assume though there's enough for reasonably sized fleet and squadrons of SDBs. Luckily Traveller also makes asteroid belts fairly frequent in solar systems.

Then there's the resources and facilities to build these ships. MgT High Guard states the planetoid costs to be transported to a facility to shape and outfit. That will be a specialized shipyard with equipment and trained personnel that know how to carve out and shape the interior as a ship rather than just a ball of rock crudely gutted for resources with little are for structural integrity and efficiency of space. If the operation is solely for PSs then the shipyard will be located in or near the belt. Time to dig out your copy of Space Stations. Having a yard that is tailored to PS building need to be cost efficient. Are there enough masses out there to justify the cost of the yard compared to a regular yard for standard hulls? Dropping a yard near a belt might also need to include defenses to protect it as well as the expense of defenses around the primary world. So far, all these can factor in to why we don't see lots of PSs or their facilities.

One thing to consider is the system whose primary 'homeworld' is, in fact, an asteroid belt. That means starport and shipyard facilities will be at or near the belt even when there may be actual world(s) in the system too. That suggests there is something special about the belt and not always only mining. Scouts discovered a large source of PS worthy asteroids?

Now that it's been suggested here, I need to take some iconic example of Traveller ships 3000 tons and up and redo as PSs for comparison of cost and design.

 

[Anonymous]

There is a lot of rock in an asteroid belt.

My maths needs to be checked.

Earth system asteroid belt is 3.6x10^21 kilograms (wikipedia)

3000kg/m3 density for asteroid (wikipedia).

1.2x10^18 m3 / 14.0 / 1000 = 8x10^13 dtons?

Classic Traveller Battleship is 200-500 ktons, lets say they are 200K and you get 5 per MTon (10^6).

8x5=40 so 40x10^7 ships (400 million battleships)?

This assume 100% utilisation. If we have even 1% of usable rocks, we still have 4,000,000 battleships?

In Classic, even a large sector fleet would have a few dozen battleships at most.

So we need some sort of limit, or some reason to explain why not everything is a planetoid. I am not sure "refuelling" is the answer.

 

[Reynard]

From my quotation, how much of an asteroid belt is usable size planetoids and how much is dust that probes pass through with ease?

Also remember PSs are automatically unable to use gas giants to refuel even down to the 3000 ton ships. I have a feeling many, if not most, Highports aren't good at servicing PSs directly.

 

[Anonymous]

From my quotation, how much of an asteroid belt is usable size planetoids and how much is dust that probes pass through with ease?

That's what I have been asking since the first question of this thread

 

[Reynard]

Best answer (to me) is whatever it takes for a campaign and adventures. Justify having a class A shipyard in a system with an asteroid belt that specializes in PSs. Depending where the mainworld is, the referee could describe to the players sensors picking up a massive planetoid in their vicinity on a slowing trajectory towards the massive shipyard where several other rocks of varying sizes are being attended to in a hive of activity. As they approach the actual starport, they get a spectacular view of various PSs docked nearby standing out by the aft engine ports and cargo airlocks on the surface with formation lights alerting traffic to their presence.

One my be your next adventure.

 

[Condottiere]

I'm surprised no one doesn't build battle-rider squadrons around them, because I'm configuring the Solomani Navy to having lots of tenders around capable of transporting one or more very large planetoids interstellar distances.