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Inspired by this question about a fantasy World Tree, I thought I’d ask about the science fiction equivalent: a Dyson Tree. Dyson Trees are a living tree planted in a comet, which when fully grown is used as a space habitat.

The Terracide RPG includes Dyson Trees as part of the setting. They sound really cool in a visual and artistic sense, but my zoologist instincts are telling me that trees aren’t really designed to live in hard vacuum! For instance, to me a tree’s leaves look like flat, thin structures almost designed to radiate away heat and freeze solid, which won’t do the tree any good at all. To me a Dyson Saguaro Cactus seems a better shape!

However, my botany is minimal, so perhaps I’m missing something that Freeman Dyson thought of (I can’t track down his original description of Dyson Trees, so can’t check).

Is there any way to make Dyson Trees realistic enough to fit in with the rest of the (relatively hard sf) Terracide setting? What features would you have to genetically engineer into them? Why would someone choose to live in a space tree instead of a space station or asteroid colony (apart from for aesthetic reasons)?

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  • $\begingroup$ would Dyson trees for tourism with new strange animals be fine ?, because i don't see permanent residence by human due to lack of gravity. $\endgroup$ – Chinu Jul 27 '16 at 19:34
  • $\begingroup$ That's funny, because a zoologist wouldn't necessarily know anything about botany :-) $\endgroup$ – AndreiROM Jul 27 '16 at 19:34
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    $\begingroup$ The first mention of dyson trees would be in Dyson's lecture in Adelaide, South Australia, when he talked about the astrochicken too. The subject was combining genetic engineering,AI & solar-electric propulsion. IIRC, as I was there. The most likely text source is INFINITE IN ALL DIRECTIONS (1988). Page 287 refers to "the comet creeper, a warm-blooded vine which spreads like a weed over the surfaces of comets and keeps iself warm with super-insulating fur as soft as sable.' $\endgroup$ – a4android Jul 28 '16 at 5:15
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    $\begingroup$ Of course, I had to do some research.Growing trees in space is discussed in Chaper 21, "The Greening of the Galaxy," DISTURBING THE UNIVERSE (1979). Dyson imagines trees growing on carboneacous chondrite asteroids, next has them growing on the moons of the gas giants, on comets,and finally spreading out across the galaxy. To quote: "If it turns out that the black asteroids are the place, then we have millions of little worlds, conveniently accessible from Earth, where suitably programmed trees could take take root and grow in the soil as they find it. (to be continued) $\endgroup$ – a4android Jul 28 '16 at 5:26
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    $\begingroup$ [Quote continues]: With the trees will come other plants, and animals, and humans, whole ecologies in endless variety, each little world free to experiment and diversify as it sees fit." By black asteroids Dyson means carboneacous chondrite asteroids. Dyson didn't develop these concepts in technical detail. He called them images to stimulate thinking. One Dyson concept that has escaped attention is his image of space butterflies. Always surprising.Mr Dyson, always. $\endgroup$ – a4android Jul 28 '16 at 5:33
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Lets make the assumption that we are genetically modifying a tree from currently existing stock into some sort of incredible creature. Also, we will assume that photosynthesis would be the main energy source. So lets talk about some adaptations that you would genetically engineer.

Regarding the principles of tree operation, the leaf photosynthesis would not be able to occur in the normal fashion, because carbon dioxide is normally taken in through the leaves through stomate. So your tree will need to get carbon dioxide from somwhere else, and also exhaust the created oxygen somewhere else (i.e. not to space). This means the leaves should be sealed against the vacuum of space, preferably with a clear waxy film like some leaves already have. The trunk would also be sealed, and it shouldn't be too hard to make the necessary adaptation to the bark to accomplish this.

So for getting carbon dioxide and exhausting oxygen, the answer would be the root system. The roots already grab minerals and water, now they would have to absorb carbon dioxide as well. The roots could also exhaust oxygen. The danger here is that oxygen is highly reactive with alot of things, and can start fires. So all this exchange needs to happen in the roots, but the roots must be in something...like a comet.

Fortunately, comets are more or less the perfect material for feeding a tree. Our tree needs carbon dioxide, water, and a nitrogen source. Fortunately those are three of the most common comet materials (nitrogen being in ammonia). Mix those into a slurry held together by gravity and so far so good. The problem is that those three materials (carbon dioxide, water, ammonia) are not all accessible liquids at standard pressures. But at about 50 bar and ~275 K, all three materials would be liquids. 50bar is 5 MPa which is a lot of pressure, but not unbearable. For example, this is below the sustainable compressive, shear, and tensile pressure limits for several common hardwoods like ash, hickory, and oak.

Now for heat, space is cold, but vacuum is a pretty good insulator. One of the advantages of the tree's thicket of leaves is that much of the energy radiated out from the leaves in the infrared spectrum will immediately strike other nearby leaves and so not act as a net heat loss to the tree. I don't have enough information and math to say that this is sufficient, but if we combine a waxy insulating film and convective heat transfer from other warmer parts of the tree, then it could be possible to keeping water liquid as it transfers to the leaves.

Also of note for reducing heat loss, some trees like the fever tree can photosynthesize in their bark, so that would probably be a useful adaptation and could reduce the number of leaves needed. I imagine a tree like this would produce a thin layer of leaves facing the sun, and a moderately dense network of photosynthesizing branches supporting them, like this acacia.

As far as people living in this tree....yeah. That's the big problem. I don't see any answer to your last question (other than being space hippies).

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    $\begingroup$ Excellent answer. Of course space hippies will likely foul the tree, you really need space farmers or arbourists to maintain the tree in peak condition. $\endgroup$ – Thucydides Jul 28 '16 at 2:54
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    $\begingroup$ Well now, if you are talking about human "inhabitants", it is useful to remember that in the galaxy at large, organic materials are very rare compared to everything else. Also, it is conceivable that nomadic "asteroid harvesters" might exist who pull valuable minerals out of easily exploited asteroids. Say they also seed the belt with trees (that might even yield something like nuts or even fruits?) and when they circle back years later they get a nice supplement to their food stores and life support system. $\endgroup$ – JBiggs Jul 28 '16 at 14:59
  • $\begingroup$ I take back the nuts/fruits idea (and I think it found a big hole in our genetically modified space tree concept) -HOW do these trees possibly reproduce? I suppose they can't, since there is no way to transfer pollen. They would each have to be planted intentionally and would not yield anything as useful to mankind as nuts or fruits. $\endgroup$ – JBiggs Jul 28 '16 at 15:03
  • $\begingroup$ Fruit trees are not grown from seed. Orchard operators since prehistory have used vegetative propagation to 'clone' a tree from a piece of the original. Seeds are not necessary for this tree. $\endgroup$ – kingledion Jul 28 '16 at 15:31
  • $\begingroup$ please note that photosynthesis is an endothermic reaction, not exothermic; it subtracts from the heat received from solar radiation $\endgroup$ – taylor swift Jul 28 '16 at 19:05
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Form follows function.

Early nanotechnology of “growing” invented machines and materials will be based on and informed by the example of living cells, and will heavily borrow many of the nanoparts they use. So Earth examples of an equivalent such as mining landfills may in fact be heavily engineered plants and fungi.

But suppose they can’t get adapted/modified plant cells to work in space on an asteroid, at all. Later generations invent de nono a “cell” based on different materials that are capable of living in that environment.

Well, the deployment will still look like a tree! You would need a microscope and chemical tests to determine that it’s unrelated to Earth (natural) life. Form follows function. You will need roots to probe the comet and extract molecules of interest and transport them back using a vascular system. You will deploy solar panels on a branching hierarchy of beams in a manner to optimize the light gathering and the logistics of growing and maintaining them.

You will have structural members holding both major systems together.

The leaves may not be green, and will not be shaped to shed water, but the layout will strongly remind you of how tree canopies look! Everyone will call it a “tree”.

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Plants and animals right here on Earth have shown remarkable adaptability to extreme environments even to the point of microbes being sent into low Earth orbit list from Wikipedia Genetic engineering is in its infant stage, as is AI and robotics, even though we have come a long way, there appear to be huge leaps forward coming in the years ahead.

I believe power production should come from numerous sources. Space is not empty. It is full of a very plentiful and diverse array of usable materials that could be incorporated into such a ship. I think the ships could be programed here and sent far away to stellar nursery's as seedlings that are programmed to return here once they have fully matured like Salmon or other migratory creatures.

Once they have made the round trip and have powered up they may even have the kind of energy needed for near instantaneous travel by warping space with gravitational waves. The possibilities are truly endless!

Sketch of Dyson Tree

This is a rough Sketch of something I thought I came up with, but it is actually an idea that has been around for a long time. It is a genetically engineered plant designed for deep space travel and possibly colonization, that is called a Dyson Tree after the scientist that put forth the possibility of creating these things some time in the far future.

It is engineered to protect the occupants from the perils of space and provide them with the necessities for life as they travel to distant worlds throughout the cosmos. That is one tripping tree!

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