How Big Can Starship Warden Really Be?

[Lucius]

For those who don't know or miss the reference:

 

"Warden" is the name of a huge "generation ship" in the game Metamorphosis Alpha. Different decks of the ship reproduced entire ecosystems such as forests, prairie, etc, so that upon reaching a planet suitable for colonization, a group of organisms from Earth could be introduced not as isolated species, but as an already functioning ecology. Needless to say, Humans were included as well.

 

I have several interrelated questions.

 

For those who have better grounding in the hard sciences than I do - what would be a minimum credible size to contain a living ecology capable of sustaining itself for generation after generation? One with room even for "apex predators" like lions, bears, and wolves, in sufficient numbers to guarantee reasonable genetic diversity?

 

For everyone - what would be a maximum size for such a generation ship that your suspension of disbelief would support? I'm positing that it was built in this solar system with local materials, plenty of rubber science allowed, with technology we could achieve in, say, the next five hundred or maybe one thousand years.

 

While we're at it, what kind of shapes do you all envision? I find myself picturing each ecosystem in a seperate gigantic sphere, all linked together, or possibly each as a rotating wheel (to generate gravity) linked by a common axle, neither of which is like the ship as presented in the game. If I did that, where can I find data on size and speed to simulate 1G?

 

Finally, what shape and especially what size do you see as maximizing fun? It's got to be big enough to support adventures, big adventures, lots of them.

 

Thank you for your input!

 

Lucius Alexander

 

The palindromedary notes that more questions may be forthcoming

[Rapier]

Re: How Big Can Starship Warden Really Be?

 

For those who have better grounding in the hard sciences than I do - what would be a minimum credible size to contain a living ecology capable of sustaining itself for generation after generation? One with room even for "apex predators" like lions' date=' bears, and wolves, in sufficient numbers to guarantee reasonable genetic diversity? [/quote']

 

Well, that's a complicated question. In the genre, it's not uncommon to have just such a vessel be little more than a few cubic miles. The larger the predator at the top of the food chain, the larger the space that would be needed.

 

I would be more likely to say that you are looking for something that is going to cover a few hundred square miles. Large predators need a LOT of food. IIRC, wolves have been known to roam something silly like 100 miles in a day. I would think that you would need a few days travels worth of distance to support an actual ecosystem.

 

For everyone - what would be a maximum size for such a generation ship that your suspension of disbelief would support? I'm positing that it was built in this solar system with local materials, plenty of rubber science allowed, with technology we could achieve in, say, the next five hundred or maybe one thousand years.

 

Max size? About the size of the moon.

 

While we're at it, what kind of shapes do you all envision? I find myself picturing each ecosystem in a seperate gigantic sphere, all linked together, or possibly each as a rotating wheel (to generate gravity) linked by a common axle, neither of which is like the ship as presented in the game. If I did that, where can I find data on size and speed to simulate 1G?

 

Spherical is definitely going to give you the easiest time. Everyone could live on the inside of the outer wall and spinning would provide gravity. The center of the ship is where cargo would be stored (zero-gravity makes moving stuff easy).

 

The calculations are fairly simple. I don't recall them off the exact top of my head, but I can find them without too much difficulty.

 

Finally, what shape and especially what size do you see as maximizing fun? It's got to be big enough to support adventures, big adventures, lots of them.

 

As above, I think go with a big hollowed out planet type. It's VERY in genre and certainly is easiest on the physics.

[sinanju]

Re: How Big Can Starship Warden Really Be?

 

For those who have better grounding in the hard sciences than I do - what would be a minimum credible size to contain a living ecology capable of sustaining itself for generation after generation? One with room even for "apex predators" like lions' date=' bears, and wolves, in sufficient numbers to guarantee reasonable genetic diversity? [/quote']

 

It would have to be huge! As already mentioned large predators need a very large territory. If they don't run in packs, they need space enough for a breeding population of solitary critters each with its own territory. Which means even MORE space needed.

 

For everyone - what would be a maximum size for such a generation ship that your suspension of disbelief would support? I'm positing that it was built in this solar system with local materials, plenty of rubber science allowed, with technology we could achieve in, say, the next five hundred or maybe one thousand years.

 

I think the moon is excessive. But definitely immense.

 

While we're at it, what kind of shapes do you all envision? I find myself picturing each ecosystem in a seperate gigantic sphere, all linked together, or possibly each as a rotating wheel (to generate gravity) linked by a common axle, neither of which is like the ship as presented in the game. If I did that, where can I find data on size and speed to simulate 1G?

 

Finally, what shape and especially what size do you see as maximizing fun? It's got to be big enough to support adventures, big adventures, lots of them.

 

A vast cylinder tens of miles wide and many tens of miles long. It spins for gravity, but instead of concentric decks, there's ONE deck SPIRALING from the center out to the outer skin. Not a steep spiral, but definitely a spiral. Rivers would all run in the same direction (more or less, though they could wander) down to the bottom, then be pumped back to the center of the ship by extremely reliable plumbing. The ceiling would be one vast sheet of light panels, which could cycle on and off in rolling waves, so you'd have "dawn" as light began to filter from "upstream" before the lights overhead came on for full day, then went off, leaving only twilight as lights far around the curve of the "horizon" stayed on for a while. OR the whole ship could be on the same cycle as the lights cycle on and off gradually.

 

Gravity would vary considerably from fairly heavy gravity at the lowest level to zero g or microgravity near the center. But what can you do?

 

In any case, any such ship is going to be science fantasy. Realistically, by the time we could build any such vessel, we'll likely be able to grow all the animals from embryos stored at launch OR create them from raw materials using bio/nanotech anyhow. No need for a flying zoo.

[Lord Liaden]

Re: How Big Can Starship Warden Really Be?

 

Spherical is definitely going to give you the easiest time. Everyone could live on the inside of the outer wall and spinning would provide gravity. The center of the ship is where cargo would be stored (zero-gravity makes moving stuff easy).

 

The problem I see with a rotating sphere, is that it can only rotate along one axis. If centrifugal force gives you Earth-like gravity around the sphere's "equator," as you get closer to the "poles" the artificial gravity will be less as rotational speed slows.

 

A series of rings, or a spiral as sinanju suggests, would be more practical.

[Manic Typist]

Re: How Big Can Starship Warden Really Be?

 

...why can a sphere only rotate on one axis?

[austenandrews]

Re: How Big Can Starship Warden Really Be?

 

I'm intrigued by the spiral deck idea. Could you use the slope to offset some of the effects of Coriolis?

[Lucius]

Re: How Big Can Starship Warden Really Be?

 

...why can a sphere only rotate on one axis?

 

Possibly it could be made to rotate on more than one axis simultaneously, but that still would not generate a reliable 1 G gravity all over the inside surface.

 

Lucius Alexander

 

The palindromedary says: So you say you want a revolution?

[IndianaJoe3]

Re: How Big Can Starship Warden Really Be?

 

...why can a sphere only rotate on one axis?

 

I think that if you attempt to rotate a sphere around more than one axis, it is equivalent to rotating around a single axis which is the sum of the other axes. (Geometry was a long time ago.)

[Clonus]

Re: How Big Can Starship Warden Really Be?

 

...why can a sphere only rotate on one axis?

 

Have some mercy on your passenger's inner ears. Also you are kind of limited by the need to provide consistent thrust in one direction.

[Rapier]

Re: How Big Can Starship Warden Really Be?

 

Have some mercy on your passenger's inner ears. Also you are kind of limited by the need to provide consistent thrust in one direction.

 

Well, if we're going science fiction there might not actually be a requirement to have an external engine mount. You could use some kind of wavefront propulsion where the engine could be in the zero-g and generate the wavefront outside the ship. Anything is possible.

[Lucius]

Re: How Big Can Starship Warden Really Be?

 

While I'm at it:

 

For any of these variations, what would the "world" look like (feel like, etc) to the inhabitants?

 

Lucius Alexander

 

The palindromedary sings "so you say you want a revolution?"

[Rapier]

Re: How Big Can Starship Warden Really Be?

 

I think that if you attempt to rotate a sphere around more than one axis' date=' it is equivalent to rotating around a single axis which is the sum of the other axes. (Geometry was a long time ago.)[/quote']

 

I don't think that is the case. For closed system ease, I believe you can treat the two axes as being a single axis at the conjunction...but you are still rotating in two axes.

[zagman]

Re: How Big Can Starship Warden Really Be?

 

Cylinder, one axis of rotation with sufficient continuous gravity. 15miles long by 1mile radius. Roughly 47square miles and can have an external engine mount.

[phookz]

Re: How Big Can Starship Warden Really Be?

 

The continuous spiral idea is quite novel. It will be difficult to support the various climates with a single module. I would imagine rotating cilindars, one for each of the required climates, counter-rotating to prevent issues with torque.

 

As for size, tough to say. The sections would have to be quite large to support predators, but I suspect this could vary from climate locale to locale. If the sections had a 20 mile radius and were 2 miles wide you would have 251 square miles per section.

[Nyrath]

Re: How Big Can Starship Warden Really Be?

 

To calculate the spin required for gravity, there are a couple of on-line calculators

http://www.artificial-gravity.com/sw/SpinCalc/SpinCalc.htm

http://www.talisiorder.ca/worldbuilding/spingrav.php

 

The equations are here

http://www.projectrho.com/rocket/rocket3u.html

[phookz]

Re: How Big Can Starship Warden Really Be?

 

Nyrath is to Star HERO as Killer Shrike is to Fantasy HERO. To be fair, Atomic Rocket / Project Rho isn't system specific, but it is just an amazing wealth of knowledge.

 

Have to spread rep around yadda yadda.

[Ian Mackinder]

Re: How Big Can Starship Warden Really Be?

 

I also like the spiral floor idea.

 

Need to consider ceiling heights in the habitat area(s). Higher ceilings mean more volume used for basically empty space, but also means ample room for things that fly or are just very very tall. Or for things that can fly AND are very very tall.

[Lucius]

Re: How Big Can Starship Warden Really Be?

 

I also like the spiral floor idea.

 

Need to consider ceiling heights in the habitat area(s). Higher ceilings mean more volume used for basically empty space, but also means ample room for things that fly or are just very very tall. Or for things that can fly AND are very very tall.

 

Not many things fly AND are very very tall.

 

That "empty space" may be desirable if one wants a more "natural" in-ship "climate" although there may be ways to simulate weather on less atmosphere.

 

Lucius Alexander

 

The palindromedary expresses gratitude to all who contribute to the discussion.

[austenandrews]

Re: How Big Can Starship Warden Really Be?

 

"Natural" will be compromised in any case. Anything close to a realistic ecosystem will be impossible except on the smallest scales. You'll never actually have enough space and food chain for a herd of elephants or a pride of lions to roam and feed the way nature intended. You probably won't have the luxury of allowing Andean condors to soar as they do in the wild. It'll have to be a simulation however you slice it, a high-tech zoo enclosure. You'll probably see (or even engineer) a reduction in the size of the animals, in the same way large species tend to shrink on islands.

[Ian Mackinder]

Re: How Big Can Starship Warden Really Be?

 

Not many things fly AND are very very tall..

 

Plainly, you have never seen the ... mutations some Referees come up with thanks to the magic of high radiation, low gravity and a really sick imagination.

[Markdoc]

Re: How Big Can Starship Warden Really Be?

 

Using the handy calculators Nyrath provided and going with the idea of multiple rotating cylinders, a short stubby cylinder 30 kilometers in radius and 60 kilometers long would give you about 170,000 square kilometers. Plenty of space for an earthlike environment, and plenty of space for a functioning environment, even for top predators with a little fudging on the weather and a rotational speed which isn't too outrageous. But even that would take just 2 days hard slog to walk across and less than a couple of weeks to walk right around ...

 

cheers, Mark

[Ian Mackinder]

Re: How Big Can Starship Warden Really Be?

 

Using the handy calculators Nyrath provided and going with the idea of multiple rotating cylinders, a short stubby cylinder 30 kilometers in radius and 60 kilometers long would give you about 170,000 square kilometers. Plenty of space for an earthlike environment, and plenty of space for a functioning environment, even for top predators with a little fudging on the weather and a rotational speed which isn't too outrageous. But even that would take just 2 days hard slog to walk across and less than a couple of weeks to walk right around ...

 

cheers, Mark

 

All the more reason to go for multiple levels or the spiral floor, or combinations thereof.

[DusterBoy]

Re: How Big Can Starship Warden Really Be?

 

Personally, I'd go with a really big asteroid with an antimatter drive with an acceleration of about 1g to provide gravity and a lighting system set up to provide "day and "night".

[Nyrath]

Re: How Big Can Starship Warden Really Be?

 

Personally' date=' I'd go with a [i']really[/i] big asteroid with an antimatter drive with an acceleration of about 1g to provide gravity and a lighting system set up to provide "day and "night".

Well, except that would be a problem in a spacecraft that lost its crew generations ago.

 

If there is no crew, a spinning spacecraft would still spin for hundreds of years.

 

If there is no crew, an antimatter drive accelerating for hundreds of years would eventually suffer a failure in the containment tanks, resulting in the entire ship being vaporized in a matter-antimatter explosion.

[austenandrews]

Re: How Big Can Starship Warden Really Be?

 

Using the handy calculators Nyrath provided and going with the idea of multiple rotating cylinders, a short stubby cylinder 30 kilometers in radius and 60 kilometers long would give you about 170,000 square kilometers. Plenty of space for an earthlike environment, and plenty of space for a functioning environment, even for top predators with a little fudging on the weather and a rotational speed which isn't too outrageous. But even that would take just 2 days hard slog to walk across and less than a couple of weeks to walk right around ...

 

cheers, Mark

I'm not following your math. Are you talking about fifteen cylinders in a row?