Fixing Planetoid Hulls
- Thread starter Jeff M. Hopper
- Start date
Lochlaber,
I'm beginning to understand why Dr. Constantine Thomas, an actual planetary scientist, no longer bothers to post here.
Follow Piper's links and read up on how planetoids form. I haven't the inclination and COTI hasn't the bandwidth to provide you with a primer on planetary formation, thermal metamorphasis, aqueous alteration, low-gee viscosity, chrondites, shattered micro-granules, and all the rest.
As for the old rhetorical question that, just because Traveller has fusion, jump drive, contragravity, and fill-in-the-blanks, why can't it also have triphibious monkeys with laser beams shooting out of their behinds, I'll leave that answer to you. If you're going to ask questions like that, plausible answers to other questions are merely a waste of time.
Have fun,
Bill
Actually, Bill, Lochaber is reflecting upon one of the biggest criticisms of planetology, one I happen to share:
So far, the number of systems observed similar to our own =1; to wit, our own. The number of systems provably NOT like our own: more than 100, and counting. The number of undocumented systems more than can be represented usefully.
Extrapolating from the Sol System is NOT science per se, even though it is based in science and the scientific method; the data set is too small. (Mind you, a 4 point study is interesting, and can be indicative, it's NOT reliable. Something most people publishing in education need to realize to cure their own cranio-rectal insertion.)
Likewise, to paraphrase some physicist on TV recently: simulations that show unexpected results don't prove the universe has hidden matter; it proves that the formulae match that theory that does suggest that.
It is a fundamental issue with planetology as extrapolation: None of it is valid YET other than there are a large fraction of main sequence stars with large, hot GG's inside the supposed GG formation limit, and that we have a small set of observed detailed data, which further local observation keeps revising, often with surprises.
We know that, of the known systems, ours is NOT a good model for them.
Of course, we can't yet find the systems that would be like our own.
This is not meant to diminish the efforts to collect the needed data. I applaud the efforts to get the needed data. I suggest, however, that extrapolations are not yet useful nor reliable, because those people are in the early stages of their work.
So far, the number of systems observed similar to our own =1; to wit, our own. The number of systems provably NOT like our own: more than 100, and counting. The number of undocumented systems more than can be represented usefully.
Extrapolating from the Sol System is NOT science per se, even though it is based in science and the scientific method; the data set is too small. (Mind you, a 4 point study is interesting, and can be indicative, it's NOT reliable. Something most people publishing in education need to realize to cure their own cranio-rectal insertion.)
Likewise, to paraphrase some physicist on TV recently: simulations that show unexpected results don't prove the universe has hidden matter; it proves that the formulae match that theory that does suggest that.
It is a fundamental issue with planetology as extrapolation: None of it is valid YET other than there are a large fraction of main sequence stars with large, hot GG's inside the supposed GG formation limit, and that we have a small set of observed detailed data, which further local observation keeps revising, often with surprises.
We know that, of the known systems, ours is NOT a good model for them.
Of course, we can't yet find the systems that would be like our own.
This is not meant to diminish the efforts to collect the needed data. I applaud the efforts to get the needed data. I suggest, however, that extrapolations are not yet useful nor reliable, because those people are in the early stages of their work.
B
Black Globe Generator
Guest
Bill, you say that like it's a bad thing.
(Lessee, that would be a 3kg gatherer, which attacks as a laser carbine minus two...)
To the extent that there are physical limitations of gravitational differentiation and chemical fractionation inherent in the formation of small bodies, Bill Cameron is right to suggest the classic Traveller interpretation of planetoid composition needs to be revamped. ("I kinna change th' laws o' physics, Cap'n!")
I share Lochlaber's concern about drawing absolute conclusions based on the study of one planetary system among billions, however. We have physical evidence for only one set of starting conditions - change those starting conditions and the results may look a bit different than what we see "here at home," even as the physical processes remain the same.
Thanks for the numbers, Robject.
What if you assumed a "pitcher and catcher" delivery instead of a constant tow? The pitcher could accelerate the hull towards the shipyard where a catcher would retrieve it (weeks, months or years later). Basic shaping and tunneling could be done in transit and the yard would receive the hull ready for systems installation.
If the catcher is the shipyard, the numbers for the pitcher would be about half, right?
That comes fairly close to the Cr100 tow fee from High Guard and the Cr400 nickel-iron price from Beltstrike.
Given the time it takes to produce a ship, it seems like this would be occasional work for an in-system tug rather than a full-time job.
An interesting game opportunity opens up if we accept it as “fact” that “Traveller” planetoid hulls do not form in “Earth-like” systems, and combine it with the “fact” that most systems are not Earth-like. A scout ship discovers a system not like ours, with no potential life-bearing worlds and completely unsuitable for human habitation. This system does, however, contain multiple shattered planets which has produced highly differentiated mineral deposits. This otherwise “worthless” system is a Belters dream and a potential source of limitless hulls. THAT is why the Imperium ships “ore” across interstellar distances.
Just a thought.
Arthur
Just a thought.
Arthur
The other major problem with planetoid hulls is that, regardless of whether nickel-iron asteroids are out there, all you're going to get out of a nickel-iron asteroid is a big chunk of nickel-iron, which is, well, underwhelming as a structural material. At best, you're talking about the equivalent of a big old chunk of wrought iron, which will result in a hull several times heavier than modern structural steel, let alone advanced structural materials available at Traveller tech levels.
Piper,
Sure they do. But, accept for the very large ones, they're NiFe in much the same way seawater can be said to be a salt body or a magnesium body or a gold body. Nickel and iron are present but they're mixed up among dozens of other materials in an undifferentiated mess.
In order for elements like nickle and iron in a planetoid to separate out into concentrations that may approach those found in earthbound ores, it requires large bodies that can retain heat for long periods so that thermal transformations and aqueous alterations can allow the subsequent viscosity differences to produce a differentiated body. Period.
Once the differentiation takes place, heavier materials like nickel and irong will be found at the planetoid's center or core while lighter materials make up the crust and/or mantle. Remember that bit because we'll get back to it.
Remember this too: out of the million plus planetoids in Sol's belt, the number of bodies large enough for that process to occur amount to less than a few dozen.
Yes, and their very size works against portions of their core being uncovered and released as independent bodies. And they'll still be 'nickel-iron' in concentrations that more resemble nickel-iron ores.
Your example of Vesta is the exception, not the rule. And the V-class planetoids and chrondites linked to Vesta's many collisions are olivine, not NiFe, which points to their origin in Vesta's crust-mantle and not Vesta's core.
Smaller bodies should be more numerous. It's also thermodynamically impossible for those smaller bodies to retain enough heat long enough to differentiate and produce NiFe in any meaningful concentrations. Numerous smaller planetoids does not equate numerous chances for planetoid hulls.
That is exactly what I'm proposing too; a very limited number of hulls. It will longer to find suitably sized planetoids of the right composition than just a few days and, as Anthony correctly points out, the chances that those planetoids will have the structural strength a hul requires is next to nil. I suggested ways around both those issues; i.e. 'carving' hulls out of larger, differentiated planetoids and 'smelting' hulls into tougher bodies of higher NiFe concentration. I've also pointed out that belts formed by shattered planets, instead belts made up of unformed planets like our own, should have an abundance of planetoid hulls thanks to the differentiation of the 'parent' planet.
Have fun,
Bill
Robject,
Prickly personality aside, you can't discount Dr. Thomas' science.
At JTAS I saw him craft in a matter of hours a plausible way for a planet with Antares canonical UWP to exist in orbit around the real Antares. His work on the supernova the posters at JTAS were inflicting on Antares was equally fascinating.
I had my problems with him, but the actual science he shared with us more than made up for any of that.
Have fun,
Bill
Personally, my response to this problem would be to totally ignore it.
The OTU, and almost any other universe that is recognisably "Traveller", clearly has physical laws that are noticeably different from our own.
Improbabilities and impossibilities are commonplace in Traveller, so why stress about this one?
The OTU, and almost any other universe that is recognisably "Traveller", clearly has physical laws that are noticeably different from our own.
Improbabilities and impossibilities are commonplace in Traveller, so why stress about this one?
TheEngineer
SOC-14 1K
Hi !
Generally I just can agree with alanb ...
Lochlaber, guess You have read some of the WIKI stuff or perhaps even other online resources.
Thanks to the internet you can access tons of PDFs from university astronomie lectures giving insights on recent knowledge.
The most specific text related to this topic is perhaps this one,
http://miami.uni-muenster.de/servlets/DerivateServlet/Derivate-1586/diss_merk.pdf
which -lucklily - is also in english language
Starting at the 1 km size (perhaps after 5-10 MY) "runaway growth" starts causing growth up to 100-300 km in around 20 MY.
Smaller asteroids (<15-50 km) are thought to keep their choatic inner structure, even if their inner temperatur might be 1000 degrees celsius as well.
If further growth could happen undisturbed everything could proceed, they "differentiate" and maybe those planetesimals form real planets. Bodies > 100 km are likely to have passed a dirrentiation process.
Well, according to my most recent sources in our solar system the ongoing development of the area known as the asteroid belt is mainly prevented by Jupiter, how disrupted - and most likely still does - the ongoing agglomeration process by causing gravitational distortions and resonances, resulting in collisions of larger asteroids. Somehow Jupiter is indeed a shepard, but he keeps his sheep small.
So far, I found no source about the actual amount of differentiated asteroids or their leftovers in our belt. Most numbers deal with meteorites found on earth, but its pretty unclear how to correlate that to the composition of the belt.
Anyway almost any asteroid somehow "Traveller-usable" for shipbuilding could be considered to be a result of the collsions of a "big one".
The theories, that the belt is the rest of an unformed planet were dropped last century.
At least computer simulations show, that without a near jovian growth processes mainly driven by gravitation would go on ...
In MT you can use 80 % of a rocks volume for ships interior. Ok, thats just 20% as structure.
Has anybody checked this ?
Taking a spherical 38 kDton rock with a diameter of 100 m the hull strength would just be 3.5 m.
This thing is far from having anything like structural stability, even if it would be naturally melted iron.
Using my humble knowledge in structural mechanics tells me that a minimum 80 % of the asteroids mass should be used as structure.
If the 75 CR per Kl tunneling are also good for giving the missing stability thats really a deal
So IMHO thats a bit problematic regarding the design sequence...
Regarding the mining oppertunities in the belt I would consider, that because of the vast power generation abilities in Traveller the transportation and processing of metal containing stuff (even at low concentrations) in no longer a problem.
Perhaps even gold extraction from oceans could work, if the price for a kWh is only 1/1000 of today....
The real magic of Traveller lies within the vast amount a power available....even if the plant are inefficient ...
Regards,
TE
Generally I just can agree with alanb ...
Lochlaber, guess You have read some of the WIKI stuff or perhaps even other online resources.
Thanks to the internet you can access tons of PDFs from university astronomie lectures giving insights on recent knowledge.
The most specific text related to this topic is perhaps this one,
http://miami.uni-muenster.de/servlets/DerivateServlet/Derivate-1586/diss_merk.pdf
which -lucklily - is also in english language
The apparantly common view on planet creation is the aggregation of mmterial, starting on a level of molecular attraction, proceeding growth up to 1 km, keeping a non-rigid structure, that is capable to take and compensate punches of further "assimilate" impacting pieces. Depending on impacts energy local heating/mealting processes can occur.
Starting at the 1 km size (perhaps after 5-10 MY) "runaway growth" starts causing growth up to 100-300 km in around 20 MY.
Smaller asteroids (<15-50 km) are thought to keep their choatic inner structure, even if their inner temperatur might be 1000 degrees celsius as well.
If further growth could happen undisturbed everything could proceed, they "differentiate" and maybe those planetesimals form real planets. Bodies > 100 km are likely to have passed a dirrentiation process.
Well, according to my most recent sources in our solar system the ongoing development of the area known as the asteroid belt is mainly prevented by Jupiter, how disrupted - and most likely still does - the ongoing agglomeration process by causing gravitational distortions and resonances, resulting in collisions of larger asteroids. Somehow Jupiter is indeed a shepard, but he keeps his sheep small.
So far, I found no source about the actual amount of differentiated asteroids or their leftovers in our belt. Most numbers deal with meteorites found on earth, but its pretty unclear how to correlate that to the composition of the belt.
Anyway almost any asteroid somehow "Traveller-usable" for shipbuilding could be considered to be a result of the collsions of a "big one".
Er, AFAIK the belt in our solar system exists because its objects are kept small by shepard Jupiter.
The theories, that the belt is the rest of an unformed planet were dropped last century.
At least computer simulations show, that without a near jovian growth processes mainly driven by gravitation would go on ...
Honestly, even if I like the basic idea to use a rock as starship and given that there are plenty of rocks around to use them the Traveller way, this would not convince me as an engineer
In MT you can use 80 % of a rocks volume for ships interior. Ok, thats just 20% as structure.
Has anybody checked this ?
Taking a spherical 38 kDton rock with a diameter of 100 m the hull strength would just be 3.5 m.
This thing is far from having anything like structural stability, even if it would be naturally melted iron.
Using my humble knowledge in structural mechanics tells me that a minimum 80 % of the asteroids mass should be used as structure.
If the 75 CR per Kl tunneling are also good for giving the missing stability thats really a deal
So IMHO thats a bit problematic regarding the design sequence...
Regarding the mining oppertunities in the belt I would consider, that because of the vast power generation abilities in Traveller the transportation and processing of metal containing stuff (even at low concentrations) in no longer a problem.
Perhaps even gold extraction from oceans could work, if the price for a kWh is only 1/1000 of today....
The real magic of Traveller lies within the vast amount a power available....even if the plant are inefficient ...
Regards,
TE
Robject,
Prickly personality aside, you can't discount Dr. Thomas' science.
At JTAS I saw him craft in a matter of hours a plausible way for a planet with Antares canonical UWP to exist in orbit around the real Antares. His work on the supernova the posters at JTAS were inflicting on Antares was equally fascinating.
I had my problems with him, but the actual science he shared with us more than made up for any of that.
Have fun,
Bill </font>[/QUOTE]Smarts don't give license in my book. Period.
Jeff M. Hopper
SOC-14 1K
While we're talking about hauling the planetoids around for use as hulls...
Why not just start building the ship inside the planetoid hull while it is in transit to the main starport with the finishing being done once it reaches there?
How about using solar sails to move the rocks, they are slow but very efficient. Come to think of it, if you could design a "sailmaker" to manufacture low-grade solar sails from the slag created by the tunnelling you could make it pretty economical.
Why not just start building the ship inside the planetoid hull while it is in transit to the main starport with the finishing being done once it reaches there?
How about using solar sails to move the rocks, they are slow but very efficient. Come to think of it, if you could design a "sailmaker" to manufacture low-grade solar sails from the slag created by the tunnelling you could make it pretty economical.
far-trader
SOC-14 10K
Ya know, all this is just reinforcing my belief that planetoid hulls make no sense. I mean economically and practically. Even before, when they were plentiful and cheap I was never happy with using in them in most designs. The waste volume was just too big for the minimal armor trade off. Oh there were a couple designs that made good use of it, but they were the long exception rather than anything approaching a rule.
Now if the suitable material is even less common or downright rare that should raise the cost if it is in fact a valued commodity. And that will increase the time to find it when you decide you want a new rocky hull.
Then there's the transit time to get it to the shipyard before construction can even begin(1). Add the fusion tunnelling time and cooling time, and more cooling time if you're smelting the thing into a solid rock first.
This all leads to a big expense. Time is money. The shipyard wants their money to build it and the bank fronting your build wants that 20% down before they'll even give you the go ahead to stake the rock. And your ship won't be in service for a long time to start earning back that downpayment. And I'm not just talking about commercial ships here. Even the military has budget concerns to factor in.
While you're still making your rock into some kind of ship I'll be launching mine. And it'll almost always beat yours for economy and performance.
So it really doesn't matter IMTU if the suitable rocks are exceedingly rare and large, the only ones being used for such are likely to be hundred kiloton Monitors. And the space navies have already located and used the more easily found and accessible ones for just that purpose. In fact it's likely that no one even remembers how(2) to actually build the things and they just keep refitting the old rocks with new equipment.
(1) Nope, I don't think you can do any building until it arrives at the shipyard, unless you have a mobile shipyard, and that has got to cost more too, a lot more.
(2) Like with the Saturn rocket program, only instead of a couple decades we're talking a couple millenia. The art would have to be reinvented, probably with all kinds of false starts and problems.
Now if the suitable material is even less common or downright rare that should raise the cost if it is in fact a valued commodity. And that will increase the time to find it when you decide you want a new rocky hull.
Then there's the transit time to get it to the shipyard before construction can even begin(1). Add the fusion tunnelling time and cooling time, and more cooling time if you're smelting the thing into a solid rock first.
This all leads to a big expense. Time is money. The shipyard wants their money to build it and the bank fronting your build wants that 20% down before they'll even give you the go ahead to stake the rock. And your ship won't be in service for a long time to start earning back that downpayment. And I'm not just talking about commercial ships here. Even the military has budget concerns to factor in.
While you're still making your rock into some kind of ship I'll be launching mine. And it'll almost always beat yours for economy and performance.
So it really doesn't matter IMTU if the suitable rocks are exceedingly rare and large, the only ones being used for such are likely to be hundred kiloton Monitors. And the space navies have already located and used the more easily found and accessible ones for just that purpose. In fact it's likely that no one even remembers how(2) to actually build the things and they just keep refitting the old rocks with new equipment.
(1) Nope, I don't think you can do any building until it arrives at the shipyard, unless you have a mobile shipyard, and that has got to cost more too, a lot more.
(2) Like with the Saturn rocket program, only instead of a couple decades we're talking a couple millenia. The art would have to be reinvented, probably with all kinds of false starts and problems.
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