Years ago, I was tinkering around with the idea of an engineered life form which could survive the vacuum of space and be made into a starship. I have since given up on the idea, but curiosity is still there in case I find another use for the concept.

Setting aside the question of IF life can naturally occur in space since we are talking about engineered life forms, what would be a likely source of nutrition for space-faring, organic, lifeforms?

I'm imagining photosynthesis being a good start, but it needs a source of physical matter to provide sustenance, as well as something that can be turned into a means of propulsion.

Could the means to sustain and grow an organic life form be found within comets, asteroids, or stellar ice?

Note that the creatures are not intended for unassisted interstellar travel.

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    $\begingroup$ In general, it is best to wait a few days before accepting an answer. This allows all users, regardless of their time zone, to see and consider the question. Accepting early might discourage a better answer from a later user. $\endgroup$ – Frostfyre May 2 '17 at 12:30
  • $\begingroup$ Oh btw, I already answered, but this is more of a comment anyways: Are you aware that there are microbes living in space right now? On human-made objects? Is this something that you have in mind or are we really talking about macroscopic beasts? Some people see a virus as a lifeform - there you go. Don't need anything else, you have your space creature $\endgroup$ – Raditz_35 May 23 '17 at 13:34

Whatever form you need to provide it in will be driven by the technology of the synthetic biology of your craft. But your food chain needs a base! Where does the energy come from out between stars?

Given a source of energy, you will use the same synthetic biology tech / nanotechnology to harvest it. That is, if using solar power (which is not available far from the sun) you would have synthetic equivalents of algae or plants. That may need to be further processed to be a suitable and convienient food source, so you have a second life form. Likewise for storage.

The technology may not make the boundaries perfectly clear: e.g. in natural biology, grass stores energy from sunlight and cows eat stored dry hay, but microorganisms in the cow’s gut are part of the cow and only need to be considered by a vet if sick.

You may have flex fuel: different “algae” or at least different, modular, organelles for different energy sources.

For replacement atoms to handle maintainence, repair, and growth, comets are what you find out there. You'll build your structural components and machines using the elements that are available, so you'll design everything to ensure that comets are a good source of material.

You may still have rare elements that are needed in small amounts — these will have to be rationed carefully.

In general, you don’t need more atoms. You reuse those you have as you repair things. You need energy to tear down and rebuild arrangements of atoms.

  • $\begingroup$ My mistake, I forgot to state that they were not intended for unassisted interstellar travel. I also like the idea of them carrying symbiotic life aboard them to help process food. That, combined with the suspended animation suggested by Thorsten, gives me a good idea of the considerations I would need. $\endgroup$ – Arvex May 2 '17 at 1:19
  • $\begingroup$ They could gather their food from any source in their star system, store it, then set a course to a closer orbit around their star to gather energy to digest their food. $\endgroup$ – Arvex May 2 '17 at 1:22

Interstellar space does not allow active lifeforms.

The only thing space has is nothing, but for that it is extremely rich. Space is so mind-boggling empty that you could drift billion years around without meeting any celestial body at all.

So any kind of metabolism cannot take place because in this timespan anything will die. Other problems are the continous intake of high radiation by the solar wind and the extreme cold of space (or hotness if you are near a star). The vacuum will also remove any fluid or gaseous substance incorparated in the body over time.

The only possibility which allows organisms to survive space is a kind of suspended animation. Fungi are building spores which are extremely resilient to outer conditions, but need to meet a favorable environment to suspend hibernation. So your xenobiological life form must have this suspended animation mode with neglible metabolism to survive space and be also very light (microorganism) to survive reentry into an atmosphere/ground at cosmic velocites.

  • $\begingroup$ I like the idea of the suspended animation state. $\endgroup$ – Arvex May 2 '17 at 1:18
  • $\begingroup$ The point here is that his organism is "space-faring" and not at drift $\endgroup$ – Raditz_35 May 23 '17 at 8:44
  • $\begingroup$ @Raditz_35 The organism must be a microorganism to survive reentry, therefore no propulsion and no intelligent planning. $\endgroup$ – Thorsten S. May 23 '17 at 21:18


Food: Comets already contain amino acids and elements necessary for life as we understand it. Other sources are interstellar dust.

Energy: Photosynthesis, as you suggested, would work well near stars. It may be beneficial to metabolize cosmic radiation too.

  • $\begingroup$ So do you know how far apart comets are and that they are not giant chunks of protein ready to be eaten? $\endgroup$ – Raditz_35 May 23 '17 at 8:45
  • $\begingroup$ @Raditz_35 the distance between comets is not of importance to the question. In case you are concerned, I am well aware that they are separated by great distances. The question was asking for sources if nutrients that an artificial life form could make use of, which in that case comets are rich in them. And while not loaded in protein per say, the precursors to them are found on the surface. $\endgroup$ – Joe Kissling May 23 '17 at 13:22
  • $\begingroup$ So let's agree to disagree on the word "likely". The thing is your answer could be misleading to someone who doesn't know much about stuff in general. The couple of amino acids are not a viable food source anyhow unless we are talking microbes here $\endgroup$ – Raditz_35 May 23 '17 at 13:32
  • $\begingroup$ @Raditz_35 That's what the link is for. $\endgroup$ – Joe Kissling May 23 '17 at 13:40
  • $\begingroup$ Link or no link, I don't think you would recommend that a hungry person on earth should simply lick his mobile phone because the bacteria on top of it contain some degree of amino acids? $\endgroup$ – Raditz_35 May 23 '17 at 13:54

Questions of food sources for engineered life form to live in space depend purely on the level of technology used in engineering such beings.

If you have advanced technology enough, then you have strange living metal beings that can use any ambient energy sources to sustain themselves. Such beings could have organs that operate much like fission and fusion reactors to both provide energy, but as well give the ability for this entity to create elements it needs with these nuclear reactions.

If the level of technology is less advanced, then you have clearly more biological looking beings that rely for energy sources more commonly used by living beings on our planet.


I will still call them space-ships unless you explicitly state that you are asking about giant floating balloons that do nothing but exist in space which wouldn't make an exciting story tbo. If you ask me, if the organism moves - it is a space-ship of some kind.

Forget natural food sources. Space is a giant void, in order to move in it you need some kind of repulsion and there is just no way that you can even reach the next body as a biological organism without simply losing too much water and burning too much energy (unless you want to go really slow and arrive someplace a billion years later). And then if you arrive at one of these bodies, well, your food source will be embedded in ice and rock that most likely just turning them into something of value for your organism consumes more energy than what you get out of it. Photosynthesis is also out of the question. I'm not saying you cannot harvest solar energy, but photosynthesis is extremely inefficient and not something you want for your living spaceship but rather for a tree that doesn't move.

So here are my suggestions:

First of all, unless you go into crazy sci-fi where the mind and the physical universe melt, stop having your organism move on its own. Not that you said anything like that, but I think it is implied. Give them inanimate engins like any space-ship would. Then they can use fuel like hydrogen or helium (which you will find a lot in a planetary system - basically on any gas giant) at the temperatures required for whatever process you desire. And do not feel bad about this, even today living humans are part machine for medical reasons - it should become much more common in the future. No more farting out to move, use a real engine is the motto here.

Second, your organism needs to be fed or have a super slow metabolism. A super slow metabolism is not the right answer since the advantages of a biological space-thing would be completely lost (unless you want "technically alive" - if so then state so). So just feed them. Check out the movie "The Matrix". They have a slime there that provides you with everything you need. I think the space-ship would eat such slime.

So you asked for the most likely food sources, I think they are fuel for the non-biological parts and "regular food" from planets for the rest. No sane civilization would build a comet-eating fart-ship that needs to drink water by the moon-load.


I think you need to go another route to come nearer to an answer. If you want to know which food sources would be possible you'd first need to specify:

  1. What exactly should this creature be able to do?
  2. How could that be accomplished?
  3. What energy does each function / all functions together consume?
  4. Why is it preferable to accomplish it in an organic way? And which synergy effects might different organic functions produce? Which might they produce in cyborg setting?

Regarding (1) Possible functions

  • Provide an inner breathable atmosphere / complex life support
  • Provide food, water and light for symbiotic life forms inside and make waste management
  • Organic Computing (e.g. for route calculations, managing life support, managing communication)
  • Senses (which ones? radio transmission, radar, sonar, laser?)
  • communication with the symbiotic life forms inside (pilots?)
  • impulse

You might also need to specify what functions the symbiotic life forms inside should accomplish:

  • piloting - chosing targets
  • medical skills in case the creature gets sick
  • maintainance in case the biosphere inside is out of balance

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