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Old 08-16-2018, 06:37 AM   #11
Varyon
 
Join Date: Jun 2013
Default Re: Nuclear Powered Aliens

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Originally Posted by AlexanderHowl View Post
Biological fusion is not cold fusion, it is using organic ceramics and organic glasses to control a hot fusion reaction.
"Cold fusion," at least in the way I've always seen it used, refers to fusion with an incredibly low activation energy. The temperatures and pressures needed for a hot fusion reaction - such as powers the stars - are I believe well above what an organism could produce... or even survive.

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Originally Posted by Nereidalbel View Post
That said, it's likely that most systems will have at least one gas giant, and those are excellent sources of ionizing radiation. The Juno probe's 2 week trip around Jupiter was an estimated 20 million rads, which is probably enough of a dose to "feed" even their largest vessels (assuming you either rubber science things, or give them a racial Reduced Consumption).
If I opt to rubber science it, I'll probably have the bioships orbit gas giants from time to time, as well as incorporate radioactive sources into their bodies for a "trickle feeding" type effect to help sustain them between visits to the gas giants. I'm considering having their photosynthesis have roughly 10% efficiency (a brief bit of research indicates this is somewhere near the theoretical maximum for biological photosynthesis - or at least photosynthesis based around chlorophyll), so I'd probably give their radiosynthesis similar efficiency, which makes things even worse (one with human-like caloric requirements would need over 100 million rads per day). On the bright side, most of the malakim have lower caloric requirements than humans, because it's only a minority (one branch out of, at current count, 9) that have roughly human-level intelligence.
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Last edited by Varyon; 08-16-2018 at 06:43 AM.
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Old 08-16-2018, 06:45 AM   #12
AlexanderHowl
 
Join Date: Feb 2016
Default Re: Nuclear Powered Aliens

Nothing material can survive the temperatures of a fusion reaction, at 100 million K in does not matter what the reactor is made of if the fusion plasma touches the reactor wall, that is why they use magnetic fields for containment. A genetically engineered creature like a bioroid could use symbiotic bacteria to grow the components of a fusion reactor within it, using a process similar to the development of bug gems.
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Old 08-16-2018, 07:36 AM   #13
Nereidalbel
 
Join Date: May 2013
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Default Re: Nuclear Powered Aliens

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Originally Posted by Varyon View Post
I'm considering having their photosynthesis have roughly 10% efficiency (a brief bit of research indicates this is somewhere near the theoretical maximum for biological photosynthesis - or at least photosynthesis based around chlorophyll),
If you gene-splice your ships to use bacteriochlorophyll in addition to chlorophyll, you'll get a significant boost to energy production from sunlight alone.

As for converting ionizing radiation into food, melanin-containing fungi are actually pretty good at that.

If you can genetically engineer most of the biological inefficiencies from natural evolution, you can probably have bio-ships powered mostly by photosynthesis and radiosynthesis, with the occasional infusion of what amounts to fertilizer. In fact, that can be a pretty good way to handle biological waste from the life forms on board...
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Old 08-16-2018, 07:40 AM   #14
acrosome
 
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Default Re: Nuclear Powered Aliens

If your ships are going to be making food in any form that approaches what we are used to calling food, they will need more than "occasional fertilizer". Food is matter. So where is the mass coming from on a ship in space?

They will need some sort of bulk matter input, unless they are highly closed systems recycling waste products. (Which I guess could be what you all are trying to say, but then it would make more sense to call it a closed life-support system.) Even plants here on Earth take matter in from the ground and even more so in the form of carbon dioxide to get the carbon to make sugars.

Last edited by acrosome; 08-16-2018 at 08:56 AM.
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Old 08-16-2018, 09:04 AM   #15
Varyon
 
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Default Re: Nuclear Powered Aliens

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Originally Posted by AlexanderHowl View Post
Nothing material can survive the temperatures of a fusion reaction, at 100 million K in does not matter what the reactor is made of if the fusion plasma touches the reactor wall, that is why they use magnetic fields for containment. A genetically engineered creature like a bioroid could use symbiotic bacteria to grow the components of a fusion reactor within it, using a process similar to the development of bug gems.
So, what you're suggesting is that a human from a society that hasn't been able to make fusion into a reliable energy source would have the knowledge of how to build such and would also figure out how to make bacteria that would be able to build such a reactor inside of a living organism. Yeah, that's not happening in this setting.

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Originally Posted by Nereidalbel View Post
If you gene-splice your ships to use bacteriochlorophyll in addition to chlorophyll, you'll get a significant boost to energy production from sunlight alone.
Plants rarely go above 2%, in spite of the roughly 10% maximum. I intended for them to incorporate some chlorophyll variants to make use of more of the electromagnetic spectrum to help them get to the roughly 10% value (which, to be fair, probably isn't quite the maximum for their photosynthesis compounds, but is about as high as I'm willing to go).

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Originally Posted by Nereidalbel View Post
As for converting ionizing radiation into food, melanin-containing fungi are actually pretty good at that.
I intended to have their radiosynthesis be based on that of the Chernobyl mushrooms (as I like to think of them), but didn't find any good numbers with a brief search.

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Originally Posted by Nereidalbel View Post
If you can genetically engineer most of the biological inefficiencies from natural evolution, you can probably have bio-ships powered mostly by photosynthesis and radiosynthesis, with the occasional infusion of what amounts to fertilizer. In fact, that can be a pretty good way to handle biological waste from the life forms on board...
Yeah, that's a lot of the idea.

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Originally Posted by acrosome View Post
They will need some sort of bulk matter input, unless they are highly closed systems recycling waste products. (Which I guess could be what you all are trying to say, but then it would make more sense to call it a closed life-support system.) Even plants here on Earth take matter in from the ground and even more so in the form of carbon dioxide to get the carbon to make sugars.
They are indeed highly closed systems, although there is some loss. While the larger bioships can't really function in atmosphere (at least, that's the current intent), they often get more matter from asteroids and similar.
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Old 08-16-2018, 09:35 AM   #16
Nereidalbel
 
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Default Re: Nuclear Powered Aliens

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Originally Posted by Varyon View Post
Plants rarely go above 2%, in spite of the roughly 10% maximum. I intended for them to incorporate some chlorophyll variants to make use of more of the electromagnetic spectrum to help them get to the roughly 10% value (which, to be fair, probably isn't quite the maximum for their photosynthesis compounds, but is about as high as I'm willing to go).
The 10% maximum would be for a plant that used all 7 (known) variants of chlorophyll. No reason you can't engineer that in your ships, honestly. Throw in the bacteriochlorophyll that can hit up to 70% efficiency, and your ships can at least hibernate if they need to be abandoned for some reason.

Even with high efficiency for solar power, that's only useful within a relatively short distance from the local star. You're still gonna need radiosynthesis and probably some form of matter digestion if you're going out as far as Jupiter.
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Old 08-16-2018, 11:31 AM   #17
Varyon
 
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Default Re: Nuclear Powered Aliens

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Originally Posted by Nereidalbel View Post
The 10% maximum would be for a plant that used all 7 (known) variants of chlorophyll. No reason you can't engineer that in your ships, honestly. Throw in the bacteriochlorophyll that can hit up to 70% efficiency, and your ships can at least hibernate if they need to be abandoned for some reason.
I didn't realize bacteriochlorophyll got to such efficiencies. At Jupiter-equivalent orbit in the human-inhabited systems (I'm not bothering to create the systems inhabited only by malakim, as human technology is currently incapable of reaching those... and the malakim located in such are by far in the minority), solar energy is around 92 W/m^2. A theoretical SM+0 bioship might have around 20 m^2 in exposed surface area with its wings fully spread and angled to catch as much sunlight as possible. That's around 1840 Watts, or just shy of 160 MJ in 24 hours. A GURPS adventurer needs to consume roughly 12.5 MJ (around 3000 kcal) daily, so even 10% efficiency would keep the bioship going, with some left behind. Considering consumption scales roughly with surface area, this relationship would scale up just fine for the actual bioships in question. If the crew members are 4 SM's smaller than the ship, for roughly 1/5th the consumption, the leftover 3.5 MJ would be enough to sustain nearly 1.5 of them, which is appropriate considering an SM+4 bioship would probably be a single seater fighter or similar.

Granted, this is assuming a bioship is going to have similar caloric requirements as a human scaled to the same size. They'll actually have much lower basal metabolic rates (less energy need be spent getting up to temperature, as space is a pretty good insulator, and they don't need to burn energy to sustain oversized brains), but much higher active caloric needs (their "aether flukes" burn through a lot of energy), which will probably work out to overall higher caloric requirements. Additionally, interstellar travel requires them to travel all the way out to the system's termination shock (which in-setting is simply called the helioshock), which is going to be somewhere around 18x further from the sun than the Jupiter-equivalent, and then requires them to travel through hyperspace where there's no solar radiation to rely on, so they'll need radiosynthesis - and/or a very large store of fat or similar - to make it through all that.

...

I think I have my sort-of-rubber-science explanation. In the systems of interest, the primary gas giant has incredibly high radiation levels, resulting in any of its moons that lack atmosphere having high concentrations of radioactive elements - notably, they tend to have an abundance of Plutonium-238. One of the malakim forms, the Lachporim, is a specialized digger and bioconcentrator of a variety of useful elements, including Plutonium-238. It shares this with other malakim, and they use its decay energy to supplement their rations. As Plutonium-238 produces around 0.57 W/g, with 10% efficiency a malakim with a 3000 kcal daily requirement would require somewhere around 2 kg to avoid needing to eat. They'll actually have a good deal less than this, of course, as they do still need to eat. Also, any energy that isn't converted into usable calories is going to be waste heat, which could be problematic with only 10% efficiency. On the bright side, the malakim probably don't need to "waste" any food calories on staying warm, as their internal plutonium reserves handle that for them.

The bioships themselves tend to "park" in a highly-radioactive orbit around the gas giant to store energy (likely as fat or similar) from time to time. This is particularly common following travel through hyperspace, as that tends to deplete their reserves.
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Old 08-16-2018, 11:52 AM   #18
AlexanderHowl
 
Join Date: Feb 2016
Default Re: Nuclear Powered Aliens

I would like a citation on the 70% efficiency for bacterial photosynthetic efficiency because from what I have read in my research on biofuels for energy policy bacteria are less efficient than plants. If it was not the case, every biofuel scheme would be using bacterial photosynthesis rather than plant photosynthesis because bacteria are easier to grow than plants. Honestly, if bacterial photosynthesis was that efficient, plant life would have never evolved because bacteria would have filled all of the available aquatic niches long before plants first formed.

If you do not have fusion, you are not going to survive in deep space with anything short of superscience. The fission reactors in Spaceships should be considered superscience because they are orders of magnitude cheaper and lighter than in real life. In Spaceships, they have a 300 MW reactor for $30M and 450 metric tons at TL8 when, in real life, it is $3B and 4500 metric tons at TL8. At TL8, high energy fission is far from reality for spacecraft, and the only vehicles that can really use it are nuclear powered aircraft carriers and the like. Of course, if you use superscience force fields, you can probably create a fission reactor like that found in Spaceships.
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Old 08-16-2018, 11:53 AM   #19
Nereidalbel
 
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Default Re: Nuclear Powered Aliens

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Originally Posted by Varyon View Post
I didn't realize bacteriochlorophyll got to such efficiencies.
Considering the biomes it's used in, it kind of HAS to be that efficient, just for the bacteria to survive. Conveniently enough, the wavelengths of light it can produce bio-available energy from don't overlap with chlorophyll, which is good for your ships.

If your ship and crew can hibernate, that also cuts down on the requirements to survive a trip to the point where a jump to hyperspace can be made, and a short trip to either the inner planets of a system or a nebula full of organic compounds would provide caloric needs to travel through hyperspace.
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