Author Topic: Worldships  (Read 6155 times)

Offline lamontagne

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Worldships
« on: 02/11/2017 07:12 PM »
A Worldship, as defined in the fundamental papers of Bond(2) and Martin(1) in the JBIS, is a type of Starship that can move from star to star carrying an complet autonomous biome, and capable of operating indefinitely.

In this it differs from a colony ship(3), that requires a viable destination to colonize, and can probably be much smaller.

Although the power requirements for this type of vehicle probably puts it far into the future, if ever, can the study of Worldships serve a useful purpose today in providing a simplified setting that allows us to think about the Earth, our present Worldship, and to imagine the solutions that need to be applied to maintain its viability?

I have joined a few documents and images to start the discussion.  The illustrated worldship is 15km long and 5km in diameter.  It carries 10 000 people and is part of a flotilla of 4.

Hope some people find this interesting.

Most of the theoretical work and discussions that led to these designs was carried out over three Workshops done at the TVIW, Tennessee Valley Interstellar Workshop.

1- Martin, A. R. "World Ships-Concept, Cause, Cost, Construction and Colonisation." Journal of the British Interplanetary Society 37 (1984): 243.
2-Bond, Alan, and A. R. Martin. "World Ships-AN Assessment of the Engineering Feasibility." Journal of the British Interplanetary Society 37 (1984): 254.
3-WORLD SHIPS – ARCHITECTURES & FEASIBILITY REVISITED
JBIS, Vol. 65, pp.119-133, 2012
Andreas M. Hein, Mikhail Pak, Daniel Pütz, Christian Bühler and Philipp Reiss
« Last Edit: 02/11/2017 07:35 PM by lamontagne »

Offline colbourne

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Re: Worldships
« Reply #1 on: 02/13/2017 06:05 AM »
Maybe the way to use World Ships is to look for an object already going in the required direction and then building a colony on that.
There are many stars and objects which have been pushed into strange high speed paths, probably by collisions of galaxies.
As these will need to maintain life for  possibly thousands of years , looking for a star with planets that has been pushed on to a path maybe the way to go.

Online Coastal Ron

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Re: Worldships
« Reply #2 on: 02/13/2017 06:39 AM »
It's certainly an interesting idea, and thinking about the requirements helps to identify (I hope) the path we need to take as we build our first rotating space stations.

I've been working on a design for a 1st generation rotating space station, so I've been giving a lot of thought to the various issues involved, but my assumption is that a 1st generation rotating space station would require a robust supply chain, which is not a surprise.  But I have been anticipating that there will be enough "land" available that some agriculture could be happen, which would decrease the amount of food supplies required.

As far as the Worldship goes though, based on the size you outlined it's going to require a lot of structural mass, which isn't a bad things considering the radiation shielding it would provide.  But that also means you would need to devote a lot of manufacturing resources to build such a fleet.

Even though they may be independent, and able to operate indefinitely, I would assume that taking in raw resources along their journey would still be a requirement since it would be impossible to not leak vital material along the journey, and some material may not be able to be recycled perfectly enough to keep from running out.  Which would require a fleet of service vehicles that would be needed for gathering the resources along the way.

Out of curiosity though, what would be the purpose of such vessels?  Why would the inhabitants, and their off-spring, want to spend all their lives traveling though space if it isn't to get to a destination?  Just curious what the thinking is...
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

Offline MickQ

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Re: Worldships
« Reply #3 on: 02/13/2017 07:46 AM »
Those with the vision and drive to see humanity as a multi planet species would be the type of people that would set out on such a voyage knowing that they and generations of their offspring would never set foot on a planetary body.   The threat of a planet killer asteroid on a highly probable collision course would be another incentive.  Or, if you are like me and think that this world is rapidly going down the toilet.

Just waiting for RAMA to break into orbit.

Offline mikelepage

Re: Worldships
« Reply #4 on: 02/13/2017 09:17 AM »
It's certainly an interesting idea, and thinking about the requirements helps to identify (I hope) the path we need to take as we build our first rotating space stations.

I've been working on a design for a 1st generation rotating space station, so I've been giving a lot of thought to the various issues involved, but my assumption is that a 1st generation rotating space station would require a robust supply chain, which is not a surprise.  But I have been anticipating that there will be enough "land" available that some agriculture could be happen, which would decrease the amount of food supplies required.

As far as the Worldship goes though, based on the size you outlined it's going to require a lot of structural mass, which isn't a bad things considering the radiation shielding it would provide.  But that also means you would need to devote a lot of manufacturing resources to build such a fleet.

Even though they may be independent, and able to operate indefinitely, I would assume that taking in raw resources along their journey would still be a requirement since it would be impossible to not leak vital material along the journey, and some material may not be able to be recycled perfectly enough to keep from running out.  Which would require a fleet of service vehicles that would be needed for gathering the resources along the way.

Out of curiosity though, what would be the purpose of such vessels?  Why would the inhabitants, and their off-spring, want to spend all their lives traveling though space if it isn't to get to a destination?  Just curious what the thinking is...

Perhaps the journey is the reward?  ::)

But seriously, my thinking, ever since coming up with the spiral space station concept (video below), is that any kind of interstellar Worldship will never be "complete".  They will set off on their journey with whatever minimum viable population/agriculture is, and by harvesting materials along the way, the ship size would grow as the colony does.

I actually tend to think that any Worldship that was truly successful might reach the "destination" star and have cause to wonder what was so great about planetary surfaces, anyway?  Go down a deep gravity well, only to deal with all this uncontrolled weather and seismic activity.  Why would you bother?  ::)


Offline Rei

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Re: Worldships
« Reply #5 on: 02/13/2017 10:34 AM »
That diagram is far too simplified. 

1) Enclosed biomes with plants trend toward instability, not stability - see Biosphere 2 as an example.  You need to be able to make everything that either humans, plants, or both need, in order to be able to account for deficiencies on one end, because sooner or later, they will arise.

2) Every process has consumables.  Every device has parts that can break or wear out.  You need to be able to make them.  Chemical production dependency chains can be long.  Just to pick a random example: look up Vectran, a popular fabric for space applications.  Start tracing back its dependencies all the way back to basic Sabatier synthesis.  Or worse, PBO (Zylon - popular for high temperature applications), or even worse, its amorphous relative PIBO.

Don't get me wrong, humanity will get there eventually.  Learning how to do this is a fundamental part of colonizing planets, meaning that colonization will inherently eventually lead to such "Worldships".  But it's no short road, and that diagram gives a misleading impression.
« Last Edit: 02/13/2017 10:35 AM by Rei »

Offline TakeOff

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Re: Worldships
« Reply #6 on: 02/13/2017 10:49 AM »
Out of curiosity though, what would be the purpose of such vessels?  Why would the inhabitants, and their off-spring, want to spend all their lives traveling though space if it isn't to get to a destination?  Just curious what the thinking is...
Because a free floating "world", purposely created for our best, could be made so very much more pleasant and productive than the Earth we happened to inherit from thoughtless rocks and plants. The question is rather why it would be interested in traveling to another planetary system, since life in the world ship is so much better than it could be on any planet, it might prefer orbiting and absorbing some high energy phenomena. Unless "other civilizations" are discovered and we follow our instinct to hunt or mate with anything that moves.


Quote
Out of curiosity though, what would be the purpose of such vessels?  Why would the inhabitants, and their off-spring, want to spend all their lives traveling though space if it isn't to get to a destination?  Just curious what the thinking is...
Eternal life! Human life time is increasing by X months every year now, and it is a long and accelerating trend. Biological engineering might be the thing that cracks the obstacle to human interstellar flight. If you live for ever you might not care much about spending a mere ten thousand years on the road in order to be honored as a great explorer or just to have a nice holiday.


Dying is getting old! I think we need to go beyond death in order to make interstellar progress, and it looks as if it is actually happening. Some social changes will come with eternal human individuals, but at least evolution we might replace by purposeful bio engineering. I'm just lamenting being one of the few last mortal generations of humans, after a string of tens of thousands. Like having a Lotto ticket identical to the eternally winning number, except for the last digit.
« Last Edit: 02/13/2017 11:02 AM by TakeOff »

Offline lamontagne

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Re: Worldships
« Reply #7 on: 02/13/2017 12:35 PM »
That diagram is far too simplified. 

1) Enclosed biomes with plants trend toward instability, not stability - see Biosphere 2 as an example.  You need to be able to make everything that either humans, plants, or both need, in order to be able to account for deficiencies on one end, because sooner or later, they will arise.

2) Every process has consumables.  Every device has parts that can break or wear out.  You need to be able to make them.  Chemical production dependency chains can be long.  Just to pick a random example: look up Vectran, a popular fabric for space applications.  Start tracing back its dependencies all the way back to basic Sabatier synthesis.  Or worse, PBO (Zylon - popular for high temperature applications), or even worse, its amorphous relative PIBO.

Don't get me wrong, humanity will get there eventually.  Learning how to do this is a fundamental part of colonizing planets, meaning that colonization will inherently eventually lead to such "Worldships".  But it's no short road, and that diagram gives a misleading impression.

Any suggestion what could be added, while retaining readability?
I draw your attention two three grey boxes: Stores, recycling and industry, that I hope address some of criticism.  I guess I should add an arrow to supplement the stores from time to time, since the worldship is an open system, operating in an environment where asteroids and comets are likely to be the primary ressources, plus the fuel to drive the magic fusion drive.
I drew the diagram to better understand the water cycle, and I have covered, I think, the main elements.  But my ignorance knows no limits and I would love to improve the diagram.


Offline lamontagne

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Re: Worldships
« Reply #8 on: 02/13/2017 12:38 PM »
Maybe the way to use World Ships is to look for an object already going in the required direction and then building a colony on that.
There are many stars and objects which have been pushed into strange high speed paths, probably by collisions of galaxies.
As these will need to maintain life for  possibly thousands of years , looking for a star with planets that has been pushed on to a path maybe the way to go.
Another interesting possibility is to move from rogue planet to rogue planet.  The appear to be a number of these, with an average distance that might be as small as a light year apart.
If  the worldship can last, then colonies are perhaps not the best offspring for them.  Perhaps worlships build other worlships.

Offline lamontagne

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Re: Worldships
« Reply #9 on: 02/13/2017 12:43 PM »
Those with the vision and drive to see humanity as a multi planet species would be the type of people that would set out on such a voyage knowing that they and generations of their offspring would never set foot on a planetary body.   The threat of a planet killer asteroid on a highly probable collision course would be another incentive.  Or, if you are like me and think that this world is rapidly going down the toilet.

Just waiting for RAMA to break into orbit.
The children will not be highly motivated, though.  I's always a problem with visionary social projects.  The worlships need to find their justification in themselves, I believe.
I think these type of vehicles may be a natural consequence of the expansion of life, and may, if better technologies are not developed,  serve as a vector to move life beyond multiplanetary to interstellar.  But they are perhaps not the most likely way.  Don't really know, but am interested in opinions on this.

Offline lamontagne

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Re: Worldships
« Reply #10 on: 02/13/2017 12:47 PM »


I actually tend to think that any Worldship that was truly successful might reach the "destination" star and have cause to wonder what was so great about planetary surfaces, anyway?  Go down a deep gravity well, only to deal with all this uncontrolled weather and seismic activity.  Why would you bother?  ::)


There would probably be some people interested.  Planets are big and will probably appeal to some.
But it's unlikely, IMHO, that the worldship would be abandoned as a mere transportation device. 
I think an interesting coloray of the size of worldships is that the same technology can be used to make much smaller and faster ships (unless the drive, like our sun, has a minimal size)  so a worldship should never be the first somewhere...  and would probably be wise to send out scouts.


Offline JasonAW3

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Re: Worldships
« Reply #11 on: 02/13/2017 02:06 PM »
      As has already been stated, replenishment of consumables of all types, is a necessity for the Worldship concept to work.

      While some have suggested stopping to utilize various comets and asteroids, it occurs to me that an alternative, which also resolves an energy issue, as well as thrust, does exist, in theory.

      The Bussard Ramjet.

      This system has several advantages to most conceptual resource gathering systems for interstellar craft.

      1)  The electromagnetic ramscoop would not only gather free hydrogen from the interstellar medium, but also small debris, such as dust and micrometeroids, which could be harvested prior to going into the fusion constriction section of such a system.

      2)   Such a system would likely have an issue with carbon "coking" as hydrogen becomes fused into various heavier elements, up through carbon.  (Should the system ever fuse to iron, then the reaction would stop, and the decoking teams would be in a good deal of trouble as they haven't been doing their jobs!)  Obviously, the fusion torch would be periodically shutdown to remove and harvest the coke, as it would contain numerous useful elements that would likewise be created as fusion byproducts.

      3)   The Electromagnetic scoop would also act as a debris shield, preventing or reducing potential damage and frontal erosion for crafts moving at a significant fraction of the velocity of light.  Most debris encountered by these Worldships, will likely be of atomic or microscopic scales.  Such a system should be able to divert the majority of this debris, up to large pebbles, with the ramscoop.  Larger debris would require either a ceramic ablative shield, for intermediate sized impacts and erosion, or a slight object impact avoidance maneuver.  (Objects of dwarf planetary scale or larger would, of course, require a significantly larger OIAM).

      Overall, it seems the smaller the habitat, the more frequently resupply will be required.  This assumes a resource reserve proportional to the size of the habitat and population.  Planets in orbit around stars have a significant advantage as they would have a larger resource to population ratio compared to the hypothetical Worldships,

a)  They have a constant energy source, that requires no maintenance or refueling. (At least for several billion years)

b)  They have electromagnetic fields and atmospheric depth sufficient to mitigate most radiation damage.

c)  They also achieve a certain level of passive resupply from micrometeors, meteors and comets, falling into the atmosphere,

d)  They have a fairly stable biological recycling system already established, again, requiring little maintenance.

     Overall, Worldships will never be as efficient as actual planetary environments, but they can be made much more so with a sufficiently large and complex biosphere, and a high enough initial store of raw resources.
My God!  It's full of universes!

Offline Rei

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Re: Worldships
« Reply #12 on: 02/13/2017 02:08 PM »
Any suggestion what could be added, while retaining readability?
I draw your attention two three grey boxes: Stores, recycling and industry, that I hope address some of criticism.

That's like adding a box that says "technology".  It means nothing.

Quote
I guess I should add an arrow to supplement the stores from time to time, since the worldship is an open system, operating in an environment where asteroids and comets are likely to be the primary ressources

Huh?  I thought your point was ships that would be traveling between stars - a process that can take hundreds or even thousands of years for relatively short hops.  No stopping en route when you're doing semi-relativistic travel, if you can even find anything en route to stop at. 

Online guckyfan

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Re: Worldships
« Reply #13 on: 02/13/2017 03:16 PM »
I don't see worldships travelling at semi relativistic speeds. 1 or 2% of light speed is fully enough to go 10 or 20 light years.

I also don't see a need for replenishing on the way. Also no need for planets in the target system. Every sun should have at least an Oort Cloud with plenty of material to stock up and build new worldships before continuing the journey.

Offline lamontagne

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Re: Worldships
« Reply #14 on: 02/13/2017 03:54 PM »
Any suggestion what could be added, while retaining readability?
I draw your attention two three grey boxes: Stores, recycling and industry, that I hope address some of criticism.

That's like adding a box that says "technology".  It means nothing.

Quote
I guess I should add an arrow to supplement the stores from time to time, since the worldship is an open system, operating in an environment where asteroids and comets are likely to be the primary ressources

Huh?  I thought your point was ships that would be traveling between stars - a process that can take hundreds or even thousands of years for relatively short hops.  No stopping en route when you're doing semi-relativistic travel, if you can even find anything en route to stop at.
The ship stocks up every few hundred years, when it reaches stellar system.  It doesn't travel faster than 1% of the speed of light, and most of the time much more slowly.  I expect it to be continuous boost, because that has the lowest power requirements.  For the entire trip, it will encounter at most a few tonnes of dust, so I'm not counting on that.

It's a simplified graphic, do you expect me to illustrated the entirety of technical civilisation in a single diagram?  The main thing I want to show is the energy scales involved, in particular the tremendous power of even the most minimal drive system, the all importance of light in an ecosystem and the fact that it cannot exist without continuous intervention, that it is in fact an unstable and open system.  the vehicle itself is an unstable system; long rotating cylinders are inherently unstable. 

The ship ecosystem is much too small to be stable, but I expect it to have a certain inertia, than can help in its regulation.  There are no non technological mechanisms that I know of to replicate many of the larger scale parts of the Earth.  Lighting and geological processes for CO2 renewal come to mind.

I would be happy to improve the graphic.  I don't quite understand what you think is missing.

Offline lamontagne

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Re: Worldships
« Reply #15 on: 02/13/2017 04:09 PM »
Despite its large size, the Worldship should be hit during the trip by a maximum of 1.3 tonnes of gas and 5 kg of dust, leading to the evaporation of approximately 1mm or less of shielding material(1).

The period inside a solar system would be much more risky.  The ship would be hit regularly by micrometeorites and would need to be repaired from time to time.

I don't really care about the drive.  If it is fusion, I would like it to be deuterium-deuterium, as this is relatively abundant and easier to do than deuterium tritium.  I just want to point out that it will create much more power than the ecosystem requires, over 10 000 times more power.  The people on the ship will have abundant energy resources.  Very, very abundant.  And will likely come from a civilisation that has the same energy abundance. 

1) Project Icarus: A Review of Local Interstellar Medium Properties of Relevance for Space Missions to the Nearest Stars
(Published in Acta Astronautica, 68, 691-699, 2011)Ian A. Crawford

Offline gospacex

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Re: Worldships
« Reply #16 on: 02/13/2017 04:10 PM »
      As has already been stated, replenishment of consumables of all types, is a necessity for the Worldship concept to work.

No, it is not a necessity. Earth does not need to replenish anything for 4.5 billion years already. All it needs is solar energy.

Worldship is, by definition, a ship large enough to have fully closed cycles for all materials, except energy sources (probably fission or fusion fuel).

Quote
      While some have suggested stopping to utilize various comets and asteroids

Some did not do the math to see how expensive it is to decelerate to be able to catch any such comet.

Quote
it occurs to me that an alternative, which also resolves an energy issue, as well as thrust, does exist, in theory.

      The Bussard Ramjet.

IIRC nobody yet posited a plausible method how exactly Bussard ramjet is supposed to fuse hydrogen. Protium fusion is HARD.

Offline lamontagne

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Re: Worldships
« Reply #17 on: 02/13/2017 04:18 PM »
A Worldship is going to be a lot more leaky than Earth, so new resources are probably required much faster.
I also think it is likely a worldship will be a system that needs to grow, and in a sense, reproduce, and that also requires resources.  I would expect one world ship to come in to a system, and a number of worldships to leave.
woldships are big on a technological scale, but tiny on a cosmic scale.

Although a bussard ramjet is a neat idea, it is not required for a worldship.  It adds another layer of complexity to what is already a (understatement coming here :-) complex system.


Offline gospacex

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Re: Worldships
« Reply #18 on: 02/13/2017 04:21 PM »
A Worldship is going to be a lot more leaky than Earth, so new resources are probably required much faster.

Indeed. Every few hundreds of years, it will need to stop in a suitable Oort Cloud :D

Offline cro-magnon gramps

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Re: Worldships
« Reply #19 on: 02/13/2017 04:58 PM »
A Worldship is going to be a lot more leaky than Earth, so new resources are probably required much faster.

Indeed. Every few hundreds of years, it will need to stop in a suitable Oort Cloud :D

why stop "in" the Oort Cloud
with thousands of years between stops
the technology they start with will not
necessarily be the ones they have even
with the first stop...

Cities in Flight, by James Blish might be a good primer to read...
"Hate, it has caused a lot of problems in the world, but it has not solved one yet." Maya Angelou
 Tony Benn: "Hope is the fuel of progress and fear is the prison in which you put yourself."

Offline lamontagne

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Re: Worldships
« Reply #20 on: 02/13/2017 05:12 PM »
A Worldship is going to be a lot more leaky than Earth, so new resources are probably required much faster.

Indeed. Every few hundreds of years, it will need to stop in a suitable Oort Cloud :D

why stop "in" the Oort Cloud
with thousands of years between stops
the technology they start with will not
necessarily be the ones they have even
with the first stop...

Cities in Flight, by James Blish might be a good primer to read...
I really liked Cities in Flight :-), probably some influence there :-)
Indeed.  the very concept of worldships requires that a number of technologies not happen:  no FTL, no inertialess propulsion, no uploading, no singularity, probably no hibernation (although it was neatly woven into the narrative of Aurora, by Kim Stanley Robinson).  BTW Aurora was too small.

Offline sghill

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Re: Worldships
« Reply #21 on: 02/13/2017 05:24 PM »
In light of this discussion, I thought I'd post the 1970's space art library from Ames Research Center.

Many of us grew up (sort of) dreaming about these stations....

Too many paintings (in poster quality resolution) to poster here, so just follow the link.

https://settlement.arc.nasa.gov/70sArtHiRes/70sArt/art.html

Bring the thunder Elon!

Offline lamontagne

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Re: Worldships
« Reply #22 on: 02/13/2017 09:38 PM »
In light of this discussion, I thought I'd post the 1970's space art library from Ames Research Center.

Many of us grew up (sort of) dreaming about these stations....

Too many paintings (in poster quality resolution) to poster here, so just follow the link.

https://settlement.arc.nasa.gov/70sArtHiRes/70sArt/art.html

These are great.  I also loved a national geographic article by Isaac Asimov, July 1976, the next frontier.  Paintings by Pierre Mion, about Oneil colonies.

https://www.flickr.com/photos/42665617@N07/sets/72157626987734175/

« Last Edit: 02/13/2017 09:41 PM by lamontagne »

Online Coastal Ron

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Re: Worldships
« Reply #23 on: 02/13/2017 09:51 PM »
[Perhaps the journey is the reward?  ::)

That's OK to say once the Worldship is built, but I can't see that as the primary reason for why someone or some group would provide the funding to build such an vessel (or the fleet of 4 for that matter).

Elon Musk's goal is to make humanity multi-planetary, and starting that by setting up a human colony on Mars.  That is a very specific goal, and Mars is a pretty well known commodity (i.e. better than any other known planet, though not anywhere as comfy as Earth).  So potential investors have, I think, enough information to make a decision on what to spend their money - and they may see their money going towards the potential survival of their progeny.

I'm just trying to imagine what the pitch would be to investors for a Worldship, and how many potential investors would be likely to buy into the vision.

Quote
But seriously, my thinking, ever since coming up with the spiral space station concept (video below), is that any kind of interstellar Worldship will never be "complete".  They will set off on their journey with whatever minimum viable population/agriculture is, and by harvesting materials along the way, the ship size would grow as the colony does.

The spiral space station design is interesting, but I'm not sure the structure is robust enough to scale up for human use.  The design seems to be limited by the strength of any one link, and when you scale that up it becomes problematic.  Just my $0.02, but I'm not a structural engineer.

As to a Worldship never being complete, that gets back to what the purpose of the vessel is, and what the inhabitants want it to be.  And depending on the design, they may not have the manufacturing capability to expand their vessels, or the design may not scale.  10,000 person communities on Earth don't have a lot of manufacturing capabilities that are independent of the global ecosystem.

Quote
I actually tend to think that any Worldship that was truly successful might reach the "destination" star and have cause to wonder what was so great about planetary surfaces, anyway?  Go down a deep gravity well, only to deal with all this uncontrolled weather and seismic activity.  Why would you bother?  ::)

That could happen.  But there needs to be a vision that investors buy into in order for the Worldship fleet to be built and launched in the first place, which could influence what their choices are.
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

Offline lamontagne

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Re: Worldships
« Reply #24 on: 02/13/2017 10:02 PM »
[Perhaps the journey is the reward?  ::)

That's OK to say once the Worldship is built, but I can't see that as the primary reason for why someone or some group would provide the funding to build such an vessel (or the fleet of 4 for that matter).

Elon Musk's goal is to make humanity multi-planetary, and starting that by setting up a human colony on Mars.  That is a very specific goal, and Mars is a pretty well known commodity (i.e. better than any other known planet, though not anywhere as comfy as Earth).  So potential investors have, I think, enough information to make a decision on what to spend their money - and they may see their money going towards the potential survival of their progeny.

I'm just trying to imagine what the pitch would be to investors for a Worldship, and how many potential investors would be likely to buy into the vision.

Quote
But seriously, my thinking, ever since coming up with the spiral space station concept (video below), is that any kind of interstellar Worldship will never be "complete".  They will set off on their journey with whatever minimum viable population/agriculture is, and by harvesting materials along the way, the ship size would grow as the colony does.

The spiral space station design is interesting, but I'm not sure the structure is robust enough to scale up for human use.  The design seems to be limited by the strength of any one link, and when you scale that up it becomes problematic.  Just my $0.02, but I'm not a structural engineer.

As to a Worldship never being complete, that gets back to what the purpose of the vessel is, and what the inhabitants want it to be.  And depending on the design, they may not have the manufacturing capability to expand their vessels, or the design may not scale.  10,000 person communities on Earth don't have a lot of manufacturing capabilities that are independent of the global ecosystem.

Quote
I actually tend to think that any Worldship that was truly successful might reach the "destination" star and have cause to wonder what was so great about planetary surfaces, anyway?  Go down a deep gravity well, only to deal with all this uncontrolled weather and seismic activity.  Why would you bother?  ::)

That could happen.  But there needs to be a vision that investors buy into in order for the Worldship fleet to be built and launched in the first place, which could influence what their choices are.

The question of motive is fundamental and not very clear.  Rather like space colonization in general.
My idea on this is that these would be preceded by space colonies, and build by societies used to live in space colonies.  If the asteroid belt ever gets a little crowded, then colonies might invest into moving to the Oort cloud, and from there it's not that much of a stretch to moving first to rogue planets and finally to other stars.

The drive needs to be fairly cheap to operate.  That is why I like deuterium, that is simple to mine, and carries its own energy, as opposed to anti matter that requires a humongous production facilities.






Offline spacenut

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Re: Worldships
« Reply #25 on: 02/13/2017 10:06 PM »
I could see O'Neal colonies around our solar system.  They would use the moon, Mars, moons of Jupiter and Saturn for resources, as well as the asteroid belt.  The O'Neal colonies would need resources to build new colonies, make replacement parts, etc.  That way, people could avoid the gravity wells and atmospheres to overcome landing and launching.  The only landing and launching could be raw materials and mining equipment.  Moons and asteroids without atmospheres might be better for raw material accessibility.  An O'Neal colony could be accessed in space, zero g, in their center sections on the ends. 

Offline mikelepage

Re: Worldships
« Reply #26 on: 02/14/2017 04:48 AM »
Would recommend this documentary on Thorium and molten salt reactors to anyone here who hasn't seen it.  I came across it a couple weeks ago - I didn't intend to watch the whole thing, but it drew me in :)  It's very well presented, and makes the case for Thorium nuclear in space.  The levels of Thorium on the moon and Mars do make me think this is a viable solution for having energy when we go beyond the range where solar power is useful.

Suffice to say, any kind of worldship is going to need serious power, and Thorium MSR is a concept that already has proof-of-principle demonstration.

https://www.youtube.com/watch?v=0BybPPIMuQQ&feature=youtu.be

Perhaps the journey is the reward?  ::)

That's OK to say once the Worldship is built, but I can't see that as the primary reason for why someone or some group would provide the funding to build such an vessel (or the fleet of 4 for that matter).

Elon Musk's goal is to make humanity multi-planetary, and starting that by setting up a human colony on Mars.  That is a very specific goal, and Mars is a pretty well known commodity (i.e. better than any other known planet, though not anywhere as comfy as Earth).  So potential investors have, I think, enough information to make a decision on what to spend their money - and they may see their money going towards the potential survival of their progeny.

I'm just trying to imagine what the pitch would be to investors for a Worldship, and how many potential investors would be likely to buy into the vision.
(snip)
The question of motive is fundamental and not very clear.  Rather like space colonization in general.
My idea on this is that these would be preceded by space colonies, and build by societies used to live in space colonies.  If the asteroid belt ever gets a little crowded, then colonies might invest into moving to the Oort cloud, and from there it's not that much of a stretch to moving first to rogue planets and finally to other stars.

Because we can.

I don't mean to be trite with that.  If you think about what a species has to go through to get to the stage where they have so much excess energy to play with that they can even contemplate trying to escape the gravity well of their home planet, much less do it enough times to transport up the extra mass required for that initial beachhead required to live in space, you start to realise how exceptional "because we can" is, as a statement.

Life has been on the planet for ~4 billion years, with photosynthetic cyanobacteria for most of that.  These became the source of our fossil fuel industry of today, for which we have arguably used as much as half of them, or will have soon, in the last 250 years or so, and will probably continue using them at our current rates for some time to come.  The sun will expand through Earth's orbit in only another 4 billion years or so.

Which means that in the entire history of Planet Earth (past and future), we humans, in this ~200 year window, are probably the only species on the planet that will ever be able to say "we can".

My personal opinion is that settling Mars isn't actually enough.  Even supposing we set up a full million-person colony on Mars, if the ships that move us through space fail to become self-sufficient in their own right, any catastrophe that destroyed, say, the ability to launch/manufacture such ships, would just leave Earth and Mars, trying to survive independently.  Sure, two is better than one, but for long term survival, you'd still have to put your money on Earth.  It's only if the ships which go between worlds become fully independent and self-sufficient colonies in their own right: true "worldships" that we hedge against planetary catastrophes. 

If those ships go interstellar, that becomes a hedge against solar system-level catastrophes, which we know will happen in 4 billion years, but could also happen at any time in the form of nearby gamma ray bursts, supernovae, etc, or even something as mundane as an influenza pandemic.

Offline Katana

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Re: Worldships
« Reply #27 on: 02/14/2017 05:29 AM »
A colony on a small asteroid with low gravity could be fully lifted to space as a worldship.
If colonization of Mars could happen, colonization of asteroids is straightforward.
Pressurized and shielded hab on Mars is already virtually pressurized and shielded hab in vacuum.

That's OK to say once the Worldship is built, but I can't see that as the primary reason for why someone or some group would provide the funding to build such an vessel (or the fleet of 4 for that matter).

Elon Musk's goal is to make humanity multi-planetary, and starting that by setting up a human colony on Mars.  That is a very specific goal, and Mars is a pretty well known commodity (i.e. better than any other known planet, though not anywhere as comfy as Earth).  So potential investors have, I think, enough information to make a decision on what to spend their money - and they may see their money going towards the potential survival of their progeny.

I'm just trying to imagine what the pitch would be to investors for a Worldship, and how many potential investors would be likely to buy into the vision.

Offline Nascent Ascent

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Re: Worldships
« Reply #28 on: 02/14/2017 05:44 AM »
Back in the early 1960s there was a book entitled Beyond Tomorrow.  About the future of spaceflight through the lens of those optimistic days.  A relative of mine, Roy Scarfo did the artwork and I remember his depiction of a hollowed out asteroid way back then. I believe well before Rama.  You can see many of the illustrations here..

http://www.royscarfo.com/

http://www.allentium.com/playground/royscarfo_site/index.cfm?section=visions&fuse=prints

http://www.allentium.com/playground/royscarfo_site/main.cfm?section=visions&fuse=prints&id=33

http://www.allentium.com/playground/royscarfo_site/main.cfm?section=visions&fuse=prints&id=34
« Last Edit: 02/14/2017 05:45 AM by Nascent Ascent »
“Why should we send people into space when we have kids in the U.S. that can’t read”. - Barack Obama

Offline Rei

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Re: Worldships
« Reply #29 on: 02/14/2017 01:41 PM »
I don't see worldships travelling at semi relativistic speeds. 1 or 2% of light speed is fully enough to go 10 or 20 light years.

That is what I would call "semi-relativistic speeds".

Quote
I also don't see a need for replenishing on the way.

My whole point is that closed ecosystems are not anywhere nearly as simple as presented on that graph.  They tend to inherently go out of balance unless you're talking something the size of a planet that has a lot of inertia going for it.  Meanwhile, every system has consumables / needs maintenance over time. 

Think of it like battery chemistry.  You have a given set of reactions on charging and discharging.  On charge, certain compounds change into others, and on discharge they change back.  Why doesn't any battery chemistry last forever?  Because of side reactions. No process proceeds perfectly.  Eventually everything ends up locked up somewhere where it's not participating in the desired reactions, and you're out of luck.

I already mentioned Biosphere 2 as a concrete example, and recommend reading about it.  Or for a more mechanized example, look at hydroponics recycling.  In a basic hydroponics system, you add in every mineral your plants need at appropriate levels and monitor electrical conductivity, to see how much of the minerals plants have taken out of solution.  You then add minerals back until EC is restored to the original levels.  Good, right?  Nope.  The pH will swing badly and eventually kill your plants.  Okay, so  you monitor pH too and add in various nutritive acids and bases as well as EC monitoring, and now you're good, right?  Nope.  After a while the various anion and cations go all out of balance, and ultimately kill your plants. Attempts to close the loop have gone so far as to burn all plant matter at high temperatures, creating a mix of oxides and hydroxides with all of the cations, then dissolving them in manufactured acids to restore the anions (mainly nitric, since nitrates are the most in demand).  Guess what?  That doesn't work either.  The only way to keep the solution in balance is to do ion-by-ion analysis, such as with mass spec, and add them ion-by-ion (such as taking your incineration outputs and running them through fractional crystallization).

Soil doesn't stay in balance.  Air doesn't stay in balance.  Pollinators don't stay in balance.  Nothing stays in balance unless you make it.  The Earth only stays in balance because it's so utterly massive that it takes a long time for things to change in a relevant manner, during which time species can adapt, and because species have adapted to the Earth over the course of billions of years.  None of this applies to a small isolated biosphere.  Ultimately, whatever aspect you're talking about, something vital ends up getting broken down or locked up somewhere inaccessible over time.  Even the structure of the ship can do this - in Biosphere 2, for example, the carbon dioxide ended up becoming locked up in the concrete of the greenhouse.

In space you have to be able to make everything.  Which means incredibly long dependency chains. It's not a trivial task. That doesn't mean it's not a task worth working on - it absolutely is.  Not does it mean that it's unachievable - it absolutely is. But graphs that credit things to generic terms like "industry" bring nothing to the table.  The concept isn't even new; it's called a generation ship and it's been around for ages; Goddard proposed it in 1918. 

I'm just trying to figure out what is being proposed that's new here.

Online guckyfan

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Re: Worldships
« Reply #30 on: 02/14/2017 04:32 PM »
Soil doesn't stay in balance.  Air doesn't stay in balance.  Pollinators don't stay in balance.  Nothing stays in balance unless you make it.  The Earth only stays in balance because it's so utterly massive that it takes a long time for things to change in a relevant manner, during which time species can adapt, and because species have adapted to the Earth over the course of billions of years.  None of this applies to a small isolated biosphere.

That's why it is a good idea to start on Mars and not start with a O'Neill space habitat. A nearly closed circle ecology is needed but some losses are permissible because there are still resources around. After a few hundred years the knowledge will be gained to make a nearly closed circle ecology with minimal losses that enables O'Neill habitats. Add another few hundred years of experience and improved propulsion a worldship can be sustained for a few hundred years until it reaches another sun to replenish its resources.

Offline envy887

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Re: Worldships
« Reply #31 on: 02/14/2017 05:09 PM »
I don't see worldships travelling at semi relativistic speeds. 1 or 2% of light speed is fully enough to go 10 or 20 light years.

That is what I would call "semi-relativistic speeds".

You can for all practical purposes ignore relativity at those speeds. There's no noticeable length contraction or time dilation.

Offline lamontagne

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Re: Worldships
« Reply #32 on: 02/15/2017 01:52 AM »
I don't see worldships travelling at semi relativistic speeds. 1 or 2% of light speed is fully enough to go 10 or 20 light years.

That is what I would call "semi-relativistic speeds".

Quote
I also don't see a need for replenishing on the way.

My whole point is that closed ecosystems are not anywhere nearly as simple as presented on that graph.  They tend to inherently go out of balance unless you're talking something the size of a planet that has a lot of inertia going for it.  Meanwhile, every system has consumables / needs maintenance over time. 

Think of it like battery chemistry.  You have a given set of reactions on charging and discharging.  On charge, certain compounds change into others, and on discharge they change back.  Why doesn't any battery chemistry last forever?  Because of side reactions. No process proceeds perfectly.  Eventually everything ends up locked up somewhere where it's not participating in the desired reactions, and you're out of luck.

I already mentioned Biosphere 2 as a concrete example, and recommend reading about it.  Or for a more mechanized example, look at hydroponics recycling.  In a basic hydroponics system, you add in every mineral your plants need at appropriate levels and monitor electrical conductivity, to see how much of the minerals plants have taken out of solution.  You then add minerals back until EC is restored to the original levels.  Good, right?  Nope.  The pH will swing badly and eventually kill your plants.  Okay, so  you monitor pH too and add in various nutritive acids and bases as well as EC monitoring, and now you're good, right?  Nope.  After a while the various anion and cations go all out of balance, and ultimately kill your plants. Attempts to close the loop have gone so far as to burn all plant matter at high temperatures, creating a mix of oxides and hydroxides with all of the cations, then dissolving them in manufactured acids to restore the anions (mainly nitric, since nitrates are the most in demand).  Guess what?  That doesn't work either.  The only way to keep the solution in balance is to do ion-by-ion analysis, such as with mass spec, and add them ion-by-ion (such as taking your incineration outputs and running them through fractional crystallization).

Soil doesn't stay in balance.  Air doesn't stay in balance.  Pollinators don't stay in balance.  Nothing stays in balance unless you make it.  The Earth only stays in balance because it's so utterly massive that it takes a long time for things to change in a relevant manner, during which time species can adapt, and because species have adapted to the Earth over the course of billions of years.  None of this applies to a small isolated biosphere.  Ultimately, whatever aspect you're talking about, something vital ends up getting broken down or locked up somewhere inaccessible over time.  Even the structure of the ship can do this - in Biosphere 2, for example, the carbon dioxide ended up becoming locked up in the concrete of the greenhouse.

In space you have to be able to make everything.  Which means incredibly long dependency chains. It's not a trivial task. That doesn't mean it's not a task worth working on - it absolutely is.  Not does it mean that it's unachievable - it absolutely is. But graphs that credit things to generic terms like "industry" bring nothing to the table.  The concept isn't even new; it's called a generation ship and it's been around for ages; Goddard proposed it in 1918. 

I'm just trying to figure out what is being proposed that's new here.
Nothing is new.  I'm not proposing anything.  I'm just exploring the idea a bit, revisiting a classic, if you want. 

I think people forget just how powerful a worldship is, and I expect that power could be used in interesting ways to help the ship survive.

I am annoyed by stories where agrarian societies live on  broken down worldship and have no idea where they are.  I agree that worldships are incredibly complex.  I've read Kim Stanley Robinson Aurora, that describes in excruciating detail how these ships can/would go wrong.

I think it would be interesting to determine if there is a size that is large enough that the stability can be a few thousand years.  And if reaching a solar system after a trip could provide sufficient ressources to enable the worldship to rejuvenate itself.  I would have though that small Islands, for example, provide examples of working ecologies that could be applied to worldships.

There is the whole social side of things that would be fun to explore as well. 

I also think it would be interesting to determine that the worldship is unworkable.

I am mainly an illustrator; I would like to improve what I draw, and am limited in what I can do on my own as my ignorance it vast and limitless.

Offline mikelepage

Re: Worldships
« Reply #33 on: 02/15/2017 06:32 AM »
I also find this topic interesting, but I do think the illustrations earlier in the thread are unworkable.  Mainly it's those vast internal chambers where only the circumference is used.  It's an insane waste of pressurised space, and my mind immediately jumps to nightmarish scenarios of what a large chamber like that looks like when an explosive decompression occurs. 

Much more realistic to have an interconnected set of smaller chambers, and nature has already shown us how to do this.  This is where the spiral space station concept came from in the first place:




Quote
My thinking, ever since coming up with the spiral space station concept (video below), is that any kind of interstellar Worldship will never be "complete".  They will set off on their journey with whatever minimum viable population/agriculture is, and by harvesting materials along the way, the ship size would grow as the colony does.

The spiral space station design is interesting, but I'm not sure the structure is robust enough to scale up for human use.  The design seems to be limited by the strength of any one link, and when you scale that up it becomes problematic.  Just my $0.02, but I'm not a structural engineer.

Interesting that this was your impression, but I probably should have prefaced that video with the pic of the nautilus shell above. Far from being weak, the log spiral is one of the strongest natural structures that exist.

The only modification is to make it a dual-log spiral, so as to allow it to stay balanced while spinning. Here's a different (earlier) depiction of the concept, a cross section of a series of solid chambers, rather than a framework for inflatables.



Each segment covers 30 degrees of the circumference, but includes an increase in radius and width by a factor of ~1.031 (or more exactly, a 1.2x increase in size over 180 degrees).  Your first stage of construction is to build out until you reach a radius that supports 1xg, and then the spin rate will slow down as the radius grows ever larger.

Of course this means that the "prime" real estate is towards the circumference, and with a range of lower g areas towards the axis.  I also like to imagine that one of the two spirals would be isolated as agriculture/botanical garden, while the other one would be living space/workshops (although no special need to stick to this, since each segment will be isolated by airlock from those pro-spin, anti-spin, above and below).  Construction of the ever bigger segments would occur close to the axis and then be lowered down via crane to be installed in place.

Online guckyfan

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Re: Worldships
« Reply #34 on: 02/15/2017 09:19 AM »
O'Neill cylinder type structures would not be a model for a worldship. Those are designed for using incoming natural sunlight. A worldship would use completely artificial light as there is no sun near. So it could have a large number of concentric volumes. It would not be sensitive to hits as they could be compartmentalized.

Assuming that people adjust well to martian gravity, 60% of the radius at least could be habitats. The 40% inward would represent only a quite small percentage of the total volume. That area could house plants. As ISS tests prove there are plants that don't mind even microgravity. A worldship could grow by stretching the cylinder or by adding another shell outward. Outward would have more gravity or it needs to spin slower which would reduce gravity in existing shells.

Online high road

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Re: Worldships
« Reply #35 on: 02/15/2017 10:29 AM »
Soil doesn't stay in balance.  Air doesn't stay in balance.  Pollinators don't stay in balance.  Nothing stays in balance unless you make it.  The Earth only stays in balance because it's so utterly massive that it takes a long time for things to change in a relevant manner, during which time species can adapt, and because species have adapted to the Earth over the course of billions of years.  None of this applies to a small isolated biosphere.

That's why it is a good idea to start on Mars and not start with a O'Neill space habitat. A nearly closed circle ecology is needed but some losses are permissible because there are still resources around. After a few hundred years the knowledge will be gained to make a nearly closed circle ecology with minimal losses that enables O'Neill habitats. Add another few hundred years of experience and improved propulsion a worldship can be sustained for a few hundred years until it reaches another sun to replenish its resources.

That's why it's a good idea to start by gradually upgrading a space station in LEO. Extracting resources to produce consumables and equipment with a limited lifetime (that's everything) requires a scale that is already far beyond our current activities in space. Better to postpone that until the station/colony grows to that scale by itself. ;-)

Offline Katana

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Re: Worldships
« Reply #36 on: 02/15/2017 02:58 PM »
Soil doesn't stay in balance.  Air doesn't stay in balance.  Pollinators don't stay in balance.  Nothing stays in balance unless you make it.  The Earth only stays in balance because it's so utterly massive that it takes a long time for things to change in a relevant manner, during which time species can adapt, and because species have adapted to the Earth over the course of billions of years.  None of this applies to a small isolated biosphere.

That's why it is a good idea to start on Mars and not start with a O'Neill space habitat. A nearly closed circle ecology is needed but some losses are permissible because there are still resources around. After a few hundred years the knowledge will be gained to make a nearly closed circle ecology with minimal losses that enables O'Neill habitats. Add another few hundred years of experience and improved propulsion a worldship can be sustained for a few hundred years until it reaches another sun to replenish its resources.

That's why it's a good idea to start by gradually upgrading a space station in LEO. Extracting resources to produce consumables and equipment with a limited lifetime (that's everything) requires a scale that is already far beyond our current activities in space. Better to postpone that until the station/colony grows to that scale by itself. ;-)
Or EML2 space station + ARM mining.

Offline lamontagne

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Re: Worldships
« Reply #37 on: 02/16/2017 01:13 AM »
O'Neill cylinder type structures would not be a model for a worldship. Those are designed for using incoming natural sunlight. A worldship would use completely artificial light as there is no sun near. So it could have a large number of concentric volumes. It would not be sensitive to hits as they could be compartmentalized.

Assuming that people adjust well to martian gravity, 60% of the radius at least could be habitats. The 40% inward would represent only a quite small percentage of the total volume. That area could house plants. As ISS tests prove there are plants that don't mind even microgravity. A worldship could grow by stretching the cylinder or by adding another shell outward. Outward would have more gravity or it needs to spin slower which would reduce gravity in existing shells.
There is a problem with concentric volumes if they are used for agriculture.  In such a case, each floor receives an average of 250 W/m2 via lighting.  But as there are floors above and bellow there is no way to remove this heat. The bottom floor of a 4 floor structure would receive 1000 W/m2 of heat and be unlivable.
The answer to this problem is to add cooling, and to remove the heat as fast as it is added.  So your vessel will end up with radiators and pipes and systems to remove heat.  Kalplana 1 is an interesting space colony design that addressed this problem.
In fact, the soil and ship wall are so insulating that it is impossible to remove the heat directly through radiation.  So even a single wall worldship required extra cooling and radiators, as per the image joined.

The space even a single floor of habitation provides is colossal.  For the 5km x 15 km ship, 230 km of habitation, at 100m2 per person, is space for over 2 million people.  As the biome will have difficulty more than a few tens of thousands, you would need to create much denser and much more artificial food production facilities, that risk breaking down sooner.  But the ship inhabitants would have the power to run them if they decided to go that route.

There is also the question of the mass of the floors. There may not be all that much gain in having dozens of floors, versus having one enclosed area. Rather like a sheet on a bed vs a folded sheet in the cupboard, it has the same area, and the same mass but it is more compact. If there is one thing that is not expensive in space, it is volume...
I agree the unused gas in the middle of the vehicle can be seen as a waste; that is why the design I have is more of an extended torus, and the center is filled with fuel, stores, and zero g spaces.




Offline lamontagne

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Re: Worldships
« Reply #38 on: 02/16/2017 01:19 AM »
O'Neill cylinder type structures would not be a model for a worldship. Those are designed for using incoming natural sunlight. A worldship would use completely artificial light as there is no sun near. So it could have a large number of concentric volumes. It would not be sensitive to hits as they could be compartmentalized.

Assuming that people adjust well to martian gravity, 60% of the radius at least could be habitats. The 40% inward would represent only a quite small percentage of the total volume. That area could house plants. As ISS tests prove there are plants that don't mind even microgravity. A worldship could grow by stretching the cylinder or by adding another shell outward. Outward would have more gravity or it needs to spin slower which would reduce gravity in existing shells.
I think stacking rings is the way to go.

Offline cro-magnon gramps

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Re: Worldships
« Reply #39 on: 02/16/2017 03:02 PM »
http://www.cbc.ca/news/technology/toronto-student-s-space-colony-design-wins-nasa-contest-1.821777
I was reminded of this by your mention of layered rings. As has been mentioned, this might be a useful interim step...

To the left side of the news article is a link to a detailed pdf (11mb) of the student's project...

Gramps
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Offline lamontagne

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Re: Worldships
« Reply #40 on: 02/17/2017 03:39 AM »
http://www.cbc.ca/news/technology/toronto-student-s-space-colony-design-wins-nasa-contest-1.821777
I was reminded of this by your mention of layered rings. As has been mentioned, this might be a useful interim step...

To the left side of the news article is a link to a detailed pdf (11mb) of the student's project...

Gramps

You can see all of the design for this contest here:
https://settlement.arc.nasa.gov/Contest/

As well as many excellent ressources (Actually, pretty much all available ressources!!) from this page:
http://space.alglobus.net/

The contest has been running for 20 years, and produced some great models.  I think its run by Al Globus.

These are all a little bit small for Worldships though, and usually dependent on solar power.

Offline Vultur

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Re: Worldships
« Reply #41 on: 02/17/2017 06:37 AM »
I don't think the closed cycle problem for worldships would be terribly bad - usually they are discussed in the context of a few centuries, maybe a couple of thousand years at most.

Biosphere 2 is not a good example of the difficulties because it was designed terribly. Some of this may be hindsight, but there were some decisions that should have been obviously stupid at the time (desert next to rainforest next to ocean in 3 acres... right  ::) ... ) And in general they thought too much in terms of 'copying Earth's ecosystem' rather than in terms of processes. IMO even with what they knew at the time the oxygen issues could have been avoided if it was seriously analyzed in terms of cycles/processes. But the thinking behind Biosphere 2 was often not terribly scientific.

We could do far better.

Also, while Earth is big, some ecosystems on Earth are pretty isolated. Not completely, sure, but things like black smoker vent communities are largely disconnected from the global photosynthesis-driven ecology, at least on "short" (<100k years) time scales.

So there's no reason to think that small ecological systems inherently collapse. (Energy input from the Sun - EDIT: or chemicals from within the Earth - means it's not a closed system, so entropy needn't increase.) A worldship wouldn't have sunlight, but a fusion reactor would serve the same purpose.
« Last Edit: 02/17/2017 06:38 AM by Vultur »

Offline KelvinZero

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Re: Worldships
« Reply #42 on: 02/18/2017 06:38 AM »
Just wanted to insert my pet idea of converting dwarf planets to ocean worlds under protective eggshells of ice.

If you have mastered fusion power (even primitive fusion power such as building and detonating H-bombs) and you live under the ice and dump your waste heat there this would happen sort of naturally.

That makes an entire world your self-repairing gas tank. You could make a world-ship from that, easy.

It doesn't solve issues of gravity for health, but there are many different ways to solve that and also to just avoid the problem by adapting your inhabitants. This is a world. You could have all these solutions and experiments going on at once. Spinning habitats above and below the ice. Different variations of humans living side by side, or some on the surface and some living many kilometers down under crushing pressures.

Moving even a dwarf planet obviously would require massive engineering, but you can start small with little colonies and just grow. You are not going to worry about moving the thing until it is entirely converted and does not itself contain new territory in its own right. It is basically a deathstar with huge fusion powerplants at that point.

Online MikeAtkinson

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Re: Worldships
« Reply #43 on: 02/18/2017 10:12 AM »
Maybe the way to use World Ships is to look for an object already going in the required direction and then building a colony on that.
There are many stars and objects which have been pushed into strange high speed paths, probably by collisions of galaxies.
As these will need to maintain life for  possibly thousands of years , looking for a star with planets that has been pushed on to a path maybe the way to go.
Another interesting possibility is to move from rogue planet to rogue planet.  The appear to be a number of these, with an average distance that might be as small as a light year apart.
If  the worldship can last, then colonies are perhaps not the best offspring for them.  Perhaps worlships build other worlships.

Even better is the Oort cloud, perhaps a billion objects bigger than 20 km in diameter, although mainly made of ices, objects that size would contain millions of tonnes of metals. It is quite possible for a worldship to replicate at these larger Oort cloud objects (there are 3 orders of magnitude more smaller objects in the Oort cloud that could be used for refueling and replenishment.

The larger objects would average about 0.002 light-years (about 130 AU) apart
So a world ship travelling at under 0.002% of the speed of light (no exotic propulsion necessary) could hop from object to object, visiting a new one every 100 years or so, replicating into a swarm over thousands of years.

Offline chalz

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Re: Worldships
« Reply #44 on: 02/24/2017 06:20 AM »
Just wanted to insert my pet idea of converting dwarf planets to ocean worlds under protective eggshells of ice.

If you have mastered fusion power (even primitive fusion power such as building and detonating H-bombs) and you live under the ice and dump your waste heat there this would happen sort of naturally.

That makes an entire world your self-repairing gas tank. You could make a world-ship from that, easy.

It doesn't solve issues of gravity for health, but there are many different ways to solve that and also to just avoid the problem by adapting your inhabitants. This is a world. You could have all these solutions and experiments going on at once. Spinning habitats above and below the ice. Different variations of humans living side by side, or some on the surface and some living many kilometers down under crushing pressures.

Moving even a dwarf planet obviously would require massive engineering, but you can start small with little colonies and just grow. You are not going to worry about moving the thing until it is entirely converted and does not itself contain new territory in its own right. It is basically a deathstar with huge fusion powerplants at that point.
Love this idea. The ocean could be used as reaction mass to get the planet moving. Couple of kilometres off the top would be a vast volume and (having not done the maths) would give a small but useful velocity. Perhaps to slingshot off the 'birth' star for more speedl.

It interests me how the people would evolve on such a world. In some ways it seems to be the opposite of the 'make life interplanetary' mantra since you effectively isolate yourself. Unless you pointed yourself at a destination star, just wandering aimlessly seems an odd way to start a journey. Or perhaps that is over-analysing since the Earth is 'wandering aimlessly' but nobody worries about it.

Offline gospacex

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Re: Worldships
« Reply #45 on: 02/24/2017 03:51 PM »
Just wanted to insert my pet idea of converting dwarf planets to ocean worlds under protective eggshells of ice.

If you have mastered fusion power (even primitive fusion power such as building and detonating H-bombs) and you live under the ice and dump your waste heat there this would happen sort of naturally.

That makes an entire world your self-repairing gas tank. You could make a world-ship from that, easy.

It doesn't solve issues of gravity for health, but there are many different ways to solve that and also to just avoid the problem by adapting your inhabitants. This is a world. You could have all these solutions and experiments going on at once. Spinning habitats above and below the ice. Different variations of humans living side by side, or some on the surface and some living many kilometers down under crushing pressures.

Moving even a dwarf planet obviously would require massive engineering, but you can start small with little colonies and just grow. You are not going to worry about moving the thing until it is entirely converted and does not itself contain new territory in its own right. It is basically a deathstar with huge fusion powerplants at that point.
Love this idea. The ocean could be used as reaction mass to get the planet moving. Couple of kilometres off the top would be a vast volume and (having not done the maths) would give a small but useful velocity.

Well, this does not seem to work. Even with a huge Isp of 0.1c, I'm getting very pessimistic numbers. For example, if 1% of the worldship launch mass is used up as reaction mass, I get below 300 km/s velocity.

Online sanman

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Re: Worldships
« Reply #46 on: 02/25/2017 08:50 AM »
How about converting a comet or a Kuiper Belt object to do something vaguely similar?

When you're already farther out in the Kuiper Belt or the Oort Cloud, how much benefit does that give you on escape velocity?

Offline KelvinZero

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Re: Worldships
« Reply #47 on: 02/25/2017 09:57 AM »
Well, this does not seem to work. Even with a huge Isp of 0.1c, I'm getting very pessimistic numbers. For example, if 1% of the worldship launch mass is used up as reaction mass, I get below 300 km/s velocity.
If you want to compete with those extreme machines that carry most of their mass in specialised nuclear fuel, then the endpoint of your processing of your worldship would have to pretty much be one of those extreme machines.

What you could get with a percent of your mass is probably a much tidier Oort cloud. I have heard estimates there might be 10,000 dwarf planets out there, but spread over a huge range. Maybe you want them all in a ring or closer to home or something.

You could also just diffuse through the galaxy. One of the problems of the Fermi paradox is that you don't need to postulate any significant speed at all. Just opportunistic hopping to passing worlds should have allowed colonisation of the entire galaxy by now, if any race had achieved open ended expansion.

Someone probably could produce a good estimate for the plausible ISP of a fusion engine that uses water both for it's fuel and propellant mass. It is not going to be as good as a vehicle carrying specialised fuel. And nothing beats exploiting the sun somehow: lasers around the sun, or mass itself projected from the sun at great velocity. If your goal is huge speed in something the size of a world, I think you probably want to exploit the sun somehow.

For my worldship, I was more just thinking along the lines of a world that has the resources to sustain life for million of years and is not bound to this solarsystem. Rather than setting out on a mission to another star, the question is more how far it would have to travel to encounter another similar sized rock to colonise.

Another question that interests me is what sort of nucleosynthesis is plausible starting with not much more than a ball of ice. If you are just endlessly detonating H-bombs in the core or somewhere would you end up producing other useful elements? Or would you use up the tiny fraction of deuterium in the ice and then not really be able to do anything with the rest?

Offline Paul451

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Re: Worldships
« Reply #48 on: 02/28/2017 12:38 AM »
Eternal life! Human life time is increasing by X months every year now, and it is a long and accelerating trend.

Actually, in the US, in the last year with solid stats, 2015, the trend went backwards for the first time in decades. And the last several years have added just one net day to the average lifespan.

Long before that, the productive human lifespan hadn't extended in decades. Even in countries with longer lifespans, they've only lengthened the "last decade", as it were, rather than delaying it. We are only adding more senescence rather than more "life".



As has already been stated, replenishment of consumables of all types, is a necessity for the Worldship concept to work.
No, it is not a necessity. Earth does not need to replenish anything for 4.5 billion years already. All it needs is solar energy.

Actually it does, the most fertile parts of Earth are areas that deposit sediment eroded from recent uplift. The "new" material may come from inside the Earth (along with recycled crust), but that is an entire planet's worth of "storage" of new elements. Something that a much more mass-efficient Worldship would lack.

(Mass of the Earth = ~6e24kg. Even if 1/10th of 1% is considered of use, and spread out over 4.5 billion years, that's 1.3 billion tonnes of material per year available for consumption. "Sometimes quantity has a quality all of its own.")

((Of course, with 7 billion humans, that's around 190 kilograms per person per year. There's some natural recycling within the biological ECLSS, of course, but we may perhaps be exceeding our personal allotment a little.))

Offline Paul451

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Re: Worldships
« Reply #49 on: 02/28/2017 12:45 AM »
Just wanted to insert my pet idea of converting dwarf planets to ocean worlds under protective eggshells of ice.
If you have mastered fusion power (even primitive fusion power such as building and detonating H-bombs) and you live under the ice and dump your waste heat there this would happen sort of naturally.
That makes an entire world your self-repairing gas tank. You could make a world-ship from that, easy.

In that scenario, I don't think you'd be trying to make World-ships, they'd just be Worlds. Settlements. Smaller "torch-ships" (assuming fusion) would move between them for trade, migration, etc, but I doubt they'd move the Worlds themselves (other than a minor tweak, perhaps, to match orbits with important trade or cultural partners.)

That's why I prefer asteroid colonisation as a "next step" rather than either Martian colonisation or O'Neill colonies. If there is anything that allows an asteroid settlement to pay for itself, then it will be a naturally expanding, self-reinforcing, self-"replicating" system. You only need a way in, that one first profitable settlement, and then by definition you already have sufficient technology to colonise the entire inner solar system. Each improvement in technology after that, faster ships, better power generation, tighter ECLSS, etc, not only improves the viability of existing settlements, but expands the limits that people can reach in the outer solar system. Over time, you get vast eco-systems of settlements, creating massive redundancy and resilience. But all paying for itself as it goes, like human expansion across Earth, with no grand Vision required to keep it going.

By the time you've reached the Kuiper Belt, the vast bulk of the economy will be independent of Earth. No further input from Earth is required for the process to continue expanding into the Oort Cloud (and, if technology permits that, beyond.)

(Colonising Mars, OTOH, emphasises technology needed to colonise Mars. Which is going to be unique to Mars. There's no natural expansion of capability, technology, and resources to settle anywhere else in the solar system; other then the systems of transport to/from Earth, which will tend to stay focused on Earth, rather than optimise for space-to-space transit. O'Neill colonies seem even worse.)

...
The ocean could be used as reaction mass to get the planet moving. [...]
In some ways it seems to be the opposite of the 'make life interplanetary' mantra since you effectively isolate yourself. Unless you pointed yourself at a destination star, just wandering aimlessly seems an odd way to start a journey.

Any multi-generational Worldship capable of reaching another star system has the technology necessary to not need to enter the star system, only brush against the occasional resources of an Oort Cloud. (This is the case whether it's a Worldship or the incremental outward settlement described above.) The bulk of human civilisation will exist outside heliopause, with no reason to approach any closer. Hence it doesn't matter which way you're going.

Offline KelvinZero

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Re: Worldships
« Reply #50 on: 03/03/2017 11:27 AM »
Just wanted to insert my pet idea of converting dwarf planets to ocean worlds under protective eggshells of ice.
If you have mastered fusion power (even primitive fusion power such as building and detonating H-bombs) and you live under the ice and dump your waste heat there this would happen sort of naturally.
That makes an entire world your self-repairing gas tank. You could make a world-ship from that, easy.

In that scenario, I don't think you'd be trying to make World-ships, they'd just be Worlds. Settlements. Smaller "torch-ships" (assuming fusion) would move between them for trade, migration, etc, but I doubt they'd move the Worlds themselves (other than a minor tweak, perhaps, to match orbits with important trade or cultural partners.)
Yeah I think we will keep finding ways to avoid moving large masses: eg uploaded personalities, nanoscale replicating probes..

It is something I don't worry about much because so many possibilities arise after we have some self sufficient colonies. Get to that point and some future humanity will sort this all out. No need to worry about those sorts of details now.

I think in the far future there might be reasons to get large masses moving at large velocites but it would be a permanent thing. You would never stop at your destination. You might drop nano probes as you fly by but there is so much effort getting to that velocity, such wasted effort stopping, so much advantage from keeping that velocity.

Offline lamontagne

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Re: Worldships
« Reply #51 on: 03/05/2017 06:54 PM »
Just wanted to insert my pet idea of converting dwarf planets to ocean worlds under protective eggshells of ice.
If you have mastered fusion power (even primitive fusion power such as building and detonating H-bombs) and you live under the ice and dump your waste heat there this would happen sort of naturally.
That makes an entire world your self-repairing gas tank. You could make a world-ship from that, easy.

In that scenario, I don't think you'd be trying to make World-ships, they'd just be Worlds. Settlements. Smaller "torch-ships" (assuming fusion) would move between them for trade, migration, etc, but I doubt they'd move the Worlds themselves (other than a minor tweak, perhaps, to match orbits with important trade or cultural partners.)
Yeah I think we will keep finding ways to avoid moving large masses: eg uploaded personalities, nanoscale replicating probes..

It is something I don't worry about much because so many possibilities arise after we have some self sufficient colonies. Get to that point and some future humanity will sort this all out. No need to worry about those sorts of details now.

I think in the far future there might be reasons to get large masses moving at large velocites but it would be a permanent thing. You would never stop at your destination. You might drop nano probes as you fly by but there is so much effort getting to that velocity, such wasted effort stopping, so much advantage from keeping that velocity.
It's pretty hard to resupply at high velocity.  The interstellar medium is ressource poor, to say the least.
An intriguing notion is the possibility of hopping from rogue planet to rogue planet.  This would allow a worldship to move much more slowly, but still find ressources to resupply itself and would be a rather natural extension of Oort cloud comet hopping.  I would expect a worldship to tend to reproduce each time it came into contact with a planet or solar system, just a outlet for growth and to keep the possibility of leaving the vehicle open.  It seems like a natural extension of how life already operates.
In a sense the worldship is an organism, carrying happy little symbiotes in the shape of humans :-)

Offline qraal

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Re: Worldships
« Reply #52 on: 03/05/2017 07:35 PM »
Dandridge Cole called them 'Macrolife'. Seems fitting.

Offline llanitedave

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Re: Worldships
« Reply #53 on: 03/06/2017 01:44 AM »
Just wanted to insert my pet idea of converting dwarf planets to ocean worlds under protective eggshells of ice.
If you have mastered fusion power (even primitive fusion power such as building and detonating H-bombs) and you live under the ice and dump your waste heat there this would happen sort of naturally.
That makes an entire world your self-repairing gas tank. You could make a world-ship from that, easy.

In that scenario, I don't think you'd be trying to make World-ships, they'd just be Worlds. Settlements. Smaller "torch-ships" (assuming fusion) would move between them for trade, migration, etc, but I doubt they'd move the Worlds themselves (other than a minor tweak, perhaps, to match orbits with important trade or cultural partners.)
Yeah I think we will keep finding ways to avoid moving large masses: eg uploaded personalities, nanoscale replicating probes..

It is something I don't worry about much because so many possibilities arise after we have some self sufficient colonies. Get to that point and some future humanity will sort this all out. No need to worry about those sorts of details now.

I think in the far future there might be reasons to get large masses moving at large velocites but it would be a permanent thing. You would never stop at your destination. You might drop nano probes as you fly by but there is so much effort getting to that velocity, such wasted effort stopping, so much advantage from keeping that velocity.
It's pretty hard to resupply at high velocity.  The interstellar medium is ressource poor, to say the least.
An intriguing notion is the possibility of hopping from rogue planet to rogue planet.  This would allow a worldship to move much more slowly, but still find ressources to resupply itself and would be a rather natural extension of Oort cloud comet hopping.  I would expect a worldship to tend to reproduce each time it came into contact with a planet or solar system, just a outlet for growth and to keep the possibility of leaving the vehicle open.  It seems like a natural extension of how life already operates.
In a sense the worldship is an organism, carrying happy little symbiotes in the shape of humans :-)

By that point in evolution, I suspect the descendants of humans would have long since ceased retaining the shape of humans.
"I've just abducted an alien -- now what?"

Offline lamontagne

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Re: Worldships
« Reply #54 on: 03/06/2017 01:38 PM »
Dandridge Cole called them 'Macrolife'. Seems fitting.
Very interesting reference.  I read Beyond Tomorrow about 25 years ago, in a public library in a small town way up north called Rouyn-Noranda, where I was the first person to take out the book in over a decade.  And was amazed by how much had been anticipated.

The only technical point I would like to raise about asteroids as starships is that I believe the ideas of mr. Cole had evolved by the time he wrote his last works, and that the final versions of the asteroid starships were built from metal asteroids expanded into shells using mirrors and steam pressure.  So the rocky outside look used in the illustrations would have been replaced by bright shiny stainless steel surfaces.  I don't recall seeing any visual expression of this though.

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