Wood as a precious resource on spaceships

[Strato Incendus]

A lot of fictional examples of interstellar spaceships, be they generation ships or sleeper ships, have some sort of arboretum. However, those often just tend to be places for recreation, like a forest for joggers. Or, if the ship is transporting any animals, too, those might inhabit the arboretum.

For food supply, hydroponics generally seem to be the most efficient way to go, both in terms of resources and space on the ship. At the same time, though, that also erases the need to transport any soil for on-board acres and fields. And one would need to make quite a case to add all that additional mass to a spaceship.

On ships that need to produce everything themselves, anything made out of plastic or metal can theoretically be generated by smelting down something else. But what about materials you can’t simply smelt down?

Could this make wood the most precious resource on an interstellar ship? Even if it has an arboretum - cutting down as little as one tree would require an enormous justification, given the time it would take for a new tree to grow in its place.

Usually, people in stories about these interstellar travels worry about the ship not losing any of its oxygen and water. But at least water could be picked up from surrounding ice fields in space - of course, only if the ship slows down sufficiently, which is usually not an option for any type of colony ship. In stories where interstellar back-and-forth travel is more common, though, usually featuring some sort of Alcubierre-like warp drive, stopping somewhere to pick up ice seems like less of a problem.

But wood? That requires very specific surroundings to even grow somewhere on a planet, so finding a planet where you could cut down a tree in the first place already seems like quite a challenge.

 

[anorlunda]

Could this make wood the most precious resource on an interstellar ship? Even if it has an arboretum - cutting down as little as one tree would require an enormous justification, given the time it would take for a new tree to grow in its place.

Trees don't live forever. If they exist at all, they must grow, reproduce, and die.

You might open the horizon for plot storylines if you think of the the ship's mission time in terms of thousands or millions of human lifetimes. You may need to restructure the story along the lines of the James Michener novel "The Source" In that book, each chapter was at a different period in history and each had brand new characters.

 

[Algr]

It depends on the wealth of the people living in the interstellar ships. If the travelers are living in comfort, the difficulty of obtaining wood might turn it into a status symbol, marking those who can posses it as the upper class. If everyone is struggling to survive, however, then it would become valueless.

However if wood, (or paper) had some esencial function that could not be replaced, then the crew would have no choice but to devote resources to its creation and recycling. I'm not sure what that use might be though.

 

[Melbourne Guy]

Could this make wood the most precious resource on an interstellar ship?

It could...if you decide it does. If your tech includes atomic-level printers, wood needn't be any more precious than any other material, @Strato Incendus.

But wood? That requires very specific surroundings to even grow somewhere on a planet, so finding a planet where you could cut down a tree in the first place already seems like quite a challenge.

As does everything else! The biosphere is incredibly complex - and we're finding it more so with each new discovery - which most stories gloss over. Occasionally, I've read ones where exoplanets prove inimical to our biology, and they can be fun, but mostly it's assumed we'll figure out how to grow things elsewhere and authors just jump off with that (and readers too, an overburden of technical detail tends to drag unless you're reading the wordsmithing of a superior storyteller).

 

[Strato Incendus]

Thanks for your replies!

I guess the first step is to determine whether the ship would have an arboretum or not in the first place. For a “quick trip to the countryside”, joggers could already go to one of the two farm rings. Although the farmers might object to people jogging along their workplace.

The public ring, which has three decks, still has a lot of space for which I haven’t specified yet what it looks like. The entire third deck is one big gym, with separate courts for various different types of sports. The second floor has the canteen, the bar, and also the swimming pool, sauna, and tanning shop. The first floor however is currently just “the main hall”, where all the gatherings take place.

That said, even though the public ring already has a higher ceiling, that’s just a little over four metres per deck. If I extend the ring further inward in order to raise the ceiling, that would render this one ring heavier than the others. And the ship needs an equal number of rings spinning in both directions, otherwise it would spin around its own axis.

Also, I still need somewhere to place the bridge - and that could be on the public ring, too. I always assumed it would be in the central trunk of the ship, and therefore not have any artificial gravity. The upside of that would be to have the bridge in a stable position, rather than rotating together with the rest, thereby constantly changing the point of reference. But having “standard” artificial gravity via rotation on the ship would make a lot of the scenes that take place there much easier. It would require me to slightly reinvent the ending of book 3, where somebody stays behind on the ship and sacrifices themselves so that the rest can leave for the planet (since all the rings unattach from the central trunk). But I could simply have that person move around the central trunk instead, where they have to start the unattaching process for each ring separately.

Hence, if there is an arboretum, since the ship already has two farm rings anyway, which rotate in opposite directions, I think it would make the most sense to extend the two farm rings further inwards, so that the mass of both rings remains about the same. In other words, then there would be two arboretums.

I can add up to 25 metres of ceiling height this way: The inner diameter of the rings is 500 metres. If I extend the farm rings further inwards, I raising the ceiling on the top floor by 25 metres on both sides of the ring would bring the inner diameter down to the magical number of 450 metres, or a radius of 225 metres. That’s the minimum radius needed to create 1 g of artificial gravity at no more than 2 rotations per minute, which is what’s still comfortable for humans.

Of course, most trees in actual forests get a lot higher than 25 to 30 metres. I could extend the ceiling even further - gravity on the ground of the arboretum floor would remain the same - but then gravity would decrease the further up you climb one of those trees. Which I guess some officers would have to do, if only in order to trim them.Now the question: Why would the ship designers do this? Why add all of this extra mass to the ship? Why put that much of the water supply into an on-board forest?

- The oxygen supply on board must probably be managed differently anyway - and the entirety of the hydroponics of the farm ring would most likely be involved in that already. Having the oxygen supply of the ship rely on the arboretum would make the entire mission just one on-board forest fire short of failing.

- The well-being of the crew is probably the main argument to have such a “park” on the ship. But the air on the arboretum floor wouldn’t necessarily feel much “fresher” than elsewhere. Sure, it might be nicer to jog around this ring than around the gym ring. But every quarter already has a private virtual-reality chamber to simulate any Earthen environment. These VR chambers have trackballs in the ground, so that it’s possible to run inside the chamber while remaining on the spot. Just like that, a user can switch from jogging through a forest to e.g. jogging along a beach in the blink of an eye. Without any of the added mass a real forest on board would bring with it.

- In terms of exporting fauna to the new planet (as invasive species), this is currently not part of the plan: All the meat on the ship is lab-grown, and the only animals on the ship are lab rats and mice for medical testing. So it’s not like we need an on-board forest for a bunch of boars and deer.
I could see the forest act as training grounds for the eventual settlers, though - a place to practice their survival skills (making a fire with stone-age methods etc.).
Then again, such survival skills would include hunting. Although the latter could probably be practiced in the VR chambers, too (like a form of ego shooter). After all, the pilots also have to use simulations to prepare for the eventual dismantling and landing of the ship parts, since they can’t practice the real procedure before the journey is complete.

- For wood supply, as you said, the main question is: What would that wood be needed for?
If wood is a precious resource for those who want it, because barely anything really needs to be made of it, this would mean it’s hard to build any musical instruments on board. The only ones available would be those that the original crew brought with them. Since the ship is supposed to export human civilisation, though, which includes culture, depending on your viewpoint of the mission, wood supply for musical instruments might even be essential to that mission.
Right now, since the ship in the current story wasn’t planned to have an arboretum yet, one of the musicians on board (who can only use software instruments so far) says the first thing he’ll do when landing on the planet is to cut down a tree and build a real guitar for himself. In other words, the absence of wood supply adds to his motivation.

- Even if there is an arboretum on the ship, cutting down a tree is easier said than done - especially once the ceiling of the arboretum floor gets higher than the width of the ring. Because then you can’t simply have the tree fall. Perhaps it would only be allowed to cut down the top half or top quarter of one first, before removing the rest.

 

[Melbourne Guy]

I guess the first step is to determine whether the ship would have an arboretum or not in the first place.

Ah. I didn't realize that your question was about "the ship", @Strato Incendus. That might have been useful to include in the OP!

And the ship needs an equal number of rings spinning in both directions, otherwise it would spin around its own axis.

Is that true? Doesn't it just need equal mass? Does a small, dense, fast spinning flywheel could counter a larger, slower spinning ring?

Of course, most trees in actual forests get a lot higher than 25 to 30 metres.

You seem to think your world building is out of your control. What about they just don't plant tall tree species?

Even if there is an arboretum on the ship, cutting down a tree is easier said than done

Not really. Treeloppers already take down large trees in sections in urban environments, this would be no different. And as you noted, in your scenario there is reduced gravity in the upper canopy so that would make the job simpler.

 

[Strato Incendus]

Ah. I didn't realize that your question was about "the ship", @Strato Incendus. That might have been useful to include in the OP!

Yes, most questions I’m asking here are relevant for my ship, among others. But unless they’re specific to my ship, I try to phrase them more generally, so that others can chime in.

For example, most of the generation ships in Elite: Dangerous have arboretums, too - as dome-shaped structures on top of the decks in the ring, that is, along the inner circumference. I guess the reason they placed them there is so that the arboretums can have dome-shaped windows.

I don’t see why you would want an arboretum in space to have a ceiling window. In fact, my ship doesn’t have windows at all, only cameras on the outside and a bunch of screens on the inside that can pretend to be windows (by showing exactly what’s on the other side). But I would still place the arboretum on top of the decks, that is, at the innermost point of the rings - because this would allow me to raise the ceiling, as described.

That raises the question about the overall weight of this floor. At latest once the ship lands, and the sections of the rings turn into “buildings” on the surface, the arboretum would be on top of all the other floors. But the weight should already press down on the other decks while the ship is still in space, since the rings create 1 g. Only the angle of the force would be slightly different, namely tangential, rather than vertically down to the ground.

In short: Could I have an arboretum as the top floor - which also seems to be the case on all the generation ships from Elite: Dangerous - without that arboretum eventually crushing all the floors beneath it?

Is that true? Doesn't it just need equal mass? Does a small, dense, fast spinning flywheel could counter a larger, slower spinning ring?

I’ve tried that before, when my ship still only had five rings. But having an even number of rings, and then each of the rings that form a pair at equal mass, seems like the safer way to go. Otherwise there would probably have to be very strict limitations on how many people, and how much “stuff” in general, you could place on a given ring

You seem to think your world building is out of your control. What about they just don't plant tall tree species?

I guess the main kinds of trees they would plant would be such that can pay double-duty for food supply. Meaning: Apple and pear trees, various kinds of nuts, bananas, pineapples etc. Rather than having various kinds of needle trees just for the sake of it.

Not really. Treeloppers already take down large trees in sections in urban environments, this would be no different. And as you noted, in your scenario there is reduced gravity in the upper canopy so that would make the job simpler.

Fair point!

 

[Drakkith]

Of course, most trees in actual forests get a lot higher than 25 to 30 metres.

This is easily solved by planting shorter tree species or by trimming.

But the air on the arboretum floor wouldn’t necessarily feel much “fresher” than elsewhere. Sure, it might be nicer to jog around this ring than around the gym ring. But every quarter already has a private virtual-reality chamber to simulate any Earthen environment.

VR isn't real life though, and undoubtedly some people, perhaps most, will prefer to visit the real thing if it is available vs seeing a VR representation of it.

I could see the forest act as training grounds for the eventual settlers, though - a place to practice their survival skills (making a fire with stone-age methods etc.).
Then again, such survival skills would include hunting.

Unless your ship is absolutely massive then I can't see much hunting being done. A few hundred meters is enough room for only a handful of animals if they are deer sized or larger. The hunting skills you'd get from hunting animals in such a confined area would probably be limited to basic marksmanship and skinning. Tracking would be completely out of the question unless your forest goes on for several miles, with perhaps an exception for tracking wounded animals by blood trails.

If wood is a precious resource for those who want it, because barely anything really needs to be made of it, this would mean it’s hard to build any musical instruments on board. The only ones available would be those that the original crew brought with them.

Almost every wood instrument can be made from an alternative material, and many modern instruments are predominately made out of metals anyways, so I doubt there'd be a lack of musical instruments as a result of lack of wood. And history has shown that in virtually every society people will make music using literally anything they can get their hands on, no matter how simple or seemingly out of place. If it can repeatedly make the same sound, it can be used for music.

Here's an incomplete list of the materials that musical instruments have been made out of over the centuries: wood, metal, clay, bone, hair, rock, glass, plastic, and more.

- Even if there is an arboretum on the ship, cutting down a tree is easier said than done - especially once the ceiling of the arboretum floor gets higher than the width of the ring. Because then you can’t simply have the tree fall. Perhaps it would only be allowed to cut down the top half or top quarter of one first, before removing the rest.

Luckily the ship has something that I don't have out in my back yard to help me trim my giant oak tree. A ceiling. Some kind of movable and suspended platform or scaffold could easily be set up to help cut the trees from the top down.

 

[Melbourne Guy]

I don’t see why you would want an arboretum in space to have a ceiling window. In fact, my ship doesn’t have windows at all,

That's because all those ships are based on Valley Forge, @Strato Incendus

In short: Could I have an arboretum as the top floor - which also seems to be the case on all the generation ships from Elite: Dangerous - without that arboretum eventually crushing all the floors beneath it?

Given it's science fiction, of course you can! Materials science will have of necessity progressed to the point that such structures will be sufficiently load bearing to allow this. And given the ship will presumably need to rotate to slow down, it probably wouldn't matter where the arboretum is located, the floors will need to support the load.

 

[hmmm27]

In Niven's Ringworld universe, humans (and others) bop around the galaxy in ships, which near-indestructible hulls are purchased from an alien species, then filled with homebuilt guts : engines, life-support, etc.

With that in mind, you could have the ship built of whatever : steel, carbon-fibre, etc. and the innards - bits that are only lightly or non-structural - made of wood.

But having an even number of rings, and then each of the rings that form a pair at equal mass, seems like the safer way to go.

Certainly easier on the audience, although working through a bit of a challenge can be enjoyable for the reader...

Of course, as is, with balanced rotational pairs, you could easily(ish) use differential precession to reorient the ship, without the need to spin the rings down/up, nor the waste of thruster mass.

 

[BillTre]

• In some place trees are grown commercially for wood. I believe that they use fast growing trees for this.
• Bamboo grows incredibly fast and is used for it wood. I have a friend who grows bamboo. From his well established plants (rhizomes) he can have a 2" shoot grow up to 40 feet high in a season.
• Wood may be growable in a lab dish.
• Trees can be genetically engineered, like a lot of other stuff. These techniques could be used to breed trees with the best combination of traits for your situation.

 

[AllanR]

bananas, pineapples

neither of these grow on trees (herb and shrub)

 

[Strato Incendus]

Here's an incomplete list of the materials that musical instruments have been made out of over the centuries: wood, metal, clay, bone, hair, rock, glass, plastic, and more.

Indeed, I've seen somebody on YouTube who turned his dead uncle's skeleton into an electric guitar. So much for our recent discussion of "not letting organic material go to waste on a spaceship"...

If you build an acoustic guitar out of metal, it will sound very different, probably closer to a Dobro (that's the instrument on the cover of "Brothers in Arms" from the Dire Straits).

But yes, probably most electric instruments would look like the "silent" kind of violin or guitar, meaning they only consist of an outer frame, which can be made from some artificial material. These instruments don't have a body and therefore aren't just even quiter than regular electric instruments (unamplified), but also even lighter.

Luckily the ship has something that I don't have out in my back yard to help me trim my giant oak tree. A ceiling. Some kind of movable and suspended platform or scaffold could easily be set up to help cut the trees from the top down.

Fair point!

That's because all those ships are based on Valley Forge, @Strato Incendus

Great to know, thanks! Even though this looks very cool, if I still try to keep at least the design of the ship as hard-science as possible, then any kind of windows that would allow radiation to get through are a huge no-no. I thought about filling the walls of the central pipe (the trunk around which the rings rotate) with water, so that moving through it would look like going through a tunnel at an aquarium. Of course, that would be a huge issue if one of the glasses broke - much more so than merely a water pipe inside a wall leaking a little.

In Niven's Ringworld universe, humans (and others) bop around the galaxy in ships, which near-indestructible hulls are purchased from an alien species, then filled with homebuilt guts : engines, life-support, etc.

With that in mind, you could have the ship built of whatever : steel, carbon-fibre, etc. and the innards - bits that are only lightly or non-structural - made of wood.

Well, Ringworld, as far as I've understood it, has a Dyson Ring as its setting, doesn't it? So taking that as a template for the rings on my ship would make them way too huge.

I'm currently reading David Ramirez's "The Forever Watch", in parallel to trying to finish Adam Oyebanji's "Braking Day" (the latter is really a drag for me!), and the Noah in "The Forever Watch" is similarly huge - with roads, multi-floor buildings and even railroad tracks inside the ship.

Sure, you're talking about space ships within the universe of Ringworld, but interactions with any kind of alien species are also a no-no for my crew. Well, unless they get to the destination planet... but they're arriving there in what are essentially pre-historic times.

Of course, as is, with balanced rotational pairs, you could easily(ish) use differential precession to reorient the ship, without the need to spin the rings down/up, nor the waste of thruster mass.

By "reorient the ship", do you mean having all rings rotate in the same direction in order to turn the ship around for braking? ;) We already considered that, and found that there are much easier solutions to turn the ship around its own axis.

Wood may be growable in a lab dish.

Drawing from the analogy to lab-grown meat here, mince is easer to grow in a dish than a steak. Rather, they would first have to grow the tissue and then use a 3D printer to shape the tissue into a stake, with multiple layers and such. For wood, this would mean that most things built out of it would be made out of plywood, rather than out of solid wood, I guess?

neither of these grow on trees (herb and shrub)

For the bananas, I was using the term "tree" very loosely here; I saw some images labelled as "forests of banana trees", even though these were as low in altitude as it gets.

For the pineapples, I guess I was just fooled by a bunch of people making images of pineapples they placed in trees and pretending they had grown there...

 

[hmmm27]

By "reorient the ship", do you mean having all rings rotate in the same direction in order to turn the ship around for braking? ;) We already considered that, and found that there are much easier solutions to turn the ship around its own axis.

<checks...> ah, brute force.

Have you considered unbolting the engine from the back then reattaching it, to the front ?

 

[AllanR]

Have you considered unbolting the engine from the back and reattaching it to the front ?

It does mean that you only have to have collision protection on one side instead of two. Also make radiation protection easier.

 

[Drakkith]

<checks...> ah, brute force.

Have you considered unbolting the engine from the back then reattaching it, to the front ?

I find putting it into reverse to be a much easier solution!

 

[Melbourne Guy]

Great to know, thanks! Even though this looks very cool, if I still try to keep at least the design of the ship as hard-science as possible, then any kind of windows that would allow radiation to get through are a huge no-no.

While it's dated, Silent Running is still a powerful movie, @Strato Incendus, and director Douglas Trumbull and cinematographer Charles Wheeler used the glass domes to terrific emotional effect. It's not an ideal design, but the final sequence tugs at the heart and a windowless ship could never have worked for that.

Drawing from the analogy to lab-grown meat here, mince is easer to grow in a dish than a steak. Rather, they would first have to grow the tissue and then use a 3D printer

3D printing has been done, but MIT recently fine tuned the method and conceptually works well in a scenario like yours (a more pop-sci article on the same work is here).

 

[Nik_2213]

If spun habitats, why not just have some multi-floor atriums for the tall trees etc ?? You'd need 'multiple' against failure modes...

Provided their access is pressure locked so an atrium cannot transfer smoke between levels, each tier could have balconies, planters etc etc, also allowing study of the canopy eco-system...