A major part of what makes human space exploration extremely difficult is the infrastructure required to support the human body outside earth. It requires resources just to launch into space due to the added weight and resources needed to keep the body alive and comfortable. In contrast, it's far simpler and less expensive to send unmanned probes. For whatever reason, perhaps to stroke the collective ego of homo sapiens on earth, space exploration without humans is unsatisfactory. However, has a compromise been considered?

Instead of sending whole human bodies into space, why not just send human heads into space? A human head has less mass and requires less energy to support than a complete body. It requires a far smaller, more compact infrastructure to supply the brain with the proper nutrients and oxygen, making the size of the spacecraft as small as a probe.

If a noggin-only astronaut is unsatisfactory, the spacecraft can also carry the required dry materials to regenerate a full human body for the purposes of colonization. There's already some progress in tissue regeneration in the form of dry powders which can be reconstituted with water upon reaching the destination.

Processed Eggshell Membrane Powder Is a Promising Biomaterial for Use in Tissue Engineering Keeping Pig Brains Alive Outside the Body

  • $\begingroup$ AI (or whatever passes for it at the current level of tech) is likely to be cheaper, lighter, and easier to keep alive than biological matter. Space is harsh. $\endgroup$ Commented Aug 23, 2023 at 20:57
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    $\begingroup$ "It requires a far smaller, more compact infrastructure to supply the brain with the proper nutrients" - I mean, have you run the numbers on this? The human body is an amazingly complex device and much of it is devoted to exactly this kind of life support function. An artificial heart and lungs, sure, but then you have to think about the liver, kidneys, countless glands, bone marrow, the whole nervous system... $\endgroup$
    – Cadence
    Commented Aug 23, 2023 at 21:23
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    $\begingroup$ Makes it tough to push buttons though. $\endgroup$ Commented Aug 23, 2023 at 21:30
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    $\begingroup$ Where are you going to get the heads from? Also, we don't know how to do this, thank goodness. $\endgroup$ Commented Aug 24, 2023 at 1:26
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    $\begingroup$ Just how one would actually develop the envisioned technology in an ethical way completely escapes me. $\endgroup$
    – Jon Custer
    Commented Aug 24, 2023 at 22:09

1 Answer 1


You can't send humans into space without a life support system.

But you can't send a head into space without a life support system, either.

A body is the interface between the life support system and the head. There is no point in blowing oxygen at a disembodied head. You need lungs and circulatory system.

Likewise, the head is not very functional without end effectors. Hands and arms make dandy end effectors, especially since they are conveniently articulated with the respiratory/cardiovascular service module.

But you might make a good case for eliminating legs.

The novel 2001: Space Odyssey explored this whole concept. HAL 9000 was an AI which could operate a spaceship without humans.

The aliens which installed the monoliths had started as biologic organisms. They found a way to transfer their minds to spaceship computers, eliminating “wetware” and thus becaming sentient machines. Eventually they found a way to transfer their minds from electronics to light, eliminating their machine bodies and becoming pure energy. That’s what the tedious light show sequence in 2001: The Movie was all about.

I’m not sure what aliens did for end effectors at that point.

With progress in AI, I don’t think the wetware “brain in a bottle” stage is required. I suspect spacecraft with AI will soon get to the same point that fighter aircraft are: the presence of humans is a serious detriment to performance and endurance. Humans will go the way of vacuum tubes.

  • $\begingroup$ So you're saying it's impossible in the future to support full brain function artificially? The technology for doing it is far more plausible than sending whole humans into the void of space. I agree it's not as ideal. $\endgroup$
    – ATL_DEV
    Commented Aug 24, 2023 at 4:10
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    $\begingroup$ If you're just going to imagine fantastical future-tech then why not just copy a human mind into a computer and launch that? If we're making things up, we can make up anything we want to. $\endgroup$ Commented Aug 24, 2023 at 15:10
  • $\begingroup$ @DarthPseudonym That would be preferable, but we know next to nothing about how the brain encodes information and how to copy its information. This is far less technically further along than keeping a brain alive without a body. In fact, some organisms are already capable of doing so. $\endgroup$
    – ATL_DEV
    Commented Aug 25, 2023 at 1:10
  • $\begingroup$ In addition to supplying the "heads" with nutrients etc., for the heads to function a waste collection & disposal system would be needed to deal with cellular wastes. Our bodies have the kidneys & liver to do this. The organs with the torso are effectively the life support system for the brain. For humans to try to make a chemical plant that can do what the liver does would require a plant that would cover a huge area. Such a plant won't fit on a space ship. If the torso & arms are required then the legs may as well go along for the ride. In the interim to developing a HAL type AI system ... $\endgroup$
    – Fred
    Commented Aug 28, 2023 at 10:40
  • $\begingroup$ ... Blade Runner type replicants might be possible. $\endgroup$
    – Fred
    Commented Aug 28, 2023 at 10:41

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