[Zenzero]

Attempting to replicate a tail seems tangential to the purpose of the device. The human coccyx is a poor location to anchor anything given how the vertebrae are not equipped to handle force, and there is effectively zero musculature to support it. The harness on the back appears much more practical.

[barfbagginus]

Let's assume that for some reason attaching sensors/stimulatirs to the coccyx area lets us control tail like robots. Then the sensors could be attached in that area, and the actual tail could be mounted anywhere else, perhaps even remote to the astronaut's body.

I'm not sure that I buy that first assumption though. Measuring signals might be possible, and it might be possible to learn how to move the tail based on signals produced during conscious attempt to move the tail. But I don't see how it would be possible to send signals back to the brain.

[Zenzero]

That's an assumption that isn't rooted in anatomy. You need nerves to measure signals on. Look up the comparative anatomy of the human cauda equina vs that of a dog. Where you're thinking of plugging into the body, in a human you'd be left with the filum terminale, which is going to sorely disappoint if you are looking for nerve signals.

To get any meaningful spinal communication in this hypothetical scenario, you'd be looking higher up in the sacral region. Unless this hypothetical also includes some magic star trek technology, you'd be invasively implanting electrodes there, which sounds like a fantastic way to trigger fecal incontinence and chronic pain.

I get the fun idea of returning humans to our primate origins, but modern human anatomy has left us effectively nothing to work with. It's an anatomical dead end.

[neon5077]

Completely naïve guess, but maybe it'd make sense to tap into the hip muscles to hint the controller system what you want the tail to do. In zero g, a slight rotation in the pelvis won't cause too much movement, but I think it would feel fairly natural to trigger a tail swing with a hip motion.

I think the tail attached to the back might be physically awkward or impractical. After all, there's probably a good reason that all animals with prehensile tails have it attached to the pelvis. But then again, it may just be an artifact of it being an extended spine.

Unironically, I think this is a fantastic idea that might actually catch on if/when humans start spending extended time in zero g environments. Tails do have a lot of advantages for navigating and manipulating 3D space.

Unfortunately, I don't think we'll be able to actually solve the problems with this design until we're actually in space regularly.

[dreen]

Right, thanks for the proper information. I guess you need to go pretty far into our past to get to a tailed ancestor, quick google says its 25-30myam, pre-hominid monkeys. Back scratcher manufacturers aren't going out of business anytime soon.