My wife shared this picture with me today:

picture of a cartoon corgi doing the doggie paddle in space and moving forward

Adorable, but it got me thinking about that trope - swimming in space.

I've seen it before, mostly in cartoons and not live-action shows, the latter of which tend to have either more realistic space stations that astronauts pull themselves along on rails to get around in, or fictional artificial gravity.

My question then is three-part:

  1. Can a person actually 'swim' to get around in a real spacecraft?
  2. Could they do this in the vacuum of space? (Assuming they have proper space protection)
  3. Could a Pembroke Welsh Corgi on the ISS do a doggie paddle to get around?

You can sort of swim, but it would be very slow. The viscosity of air vs water is very low. Therefore the 'scoop' your hands or feet can get of the fluid, to propel it, and thus move you around would need to be much higher.

If you had fans (or 'wings') on your arms you would be more effective.

As for the corgi? Not likely, or at least very, very slowly.

You might be more effective inhaling with a wide open mouth slowly, then quickly exhaling through a small mouth in the direction opposite you wish to go.

  • 2
    $\begingroup$ Astronaut Dan Barry tried "swimming" in the ISS. It did not work. space.stackexchange.com/questions/18386/… $\endgroup$ – Organic Marble Mar 30 '18 at 18:34
  • $\begingroup$ @OrganicMarble: Nowhere in the text in the linked answer does Barry actually mention "swimming" - reading that text, it sounds more like he was trying to move by thrashing his limbs, which doesn't work even in water. Additionally, swimming through air would be quite slow, to the point where it would take quite a while to realise that you were, in fact, moving. $\endgroup$ – Vikki - formerly Sean Aug 16 '20 at 19:38
  • $\begingroup$ @Sean I guess it depends on your definition of "swimming". I am not as confident about how swimming in air would actually work as you seem to be. $\endgroup$ – Organic Marble Aug 16 '20 at 19:48

A person could swim. But that would take many, many effort to generate even a little of velocity. The viscosity of air is much lower than the viscosity of water. When you swim in water you are practically pushing the water away, creating a force that makes you go the direction you're swimming to.

Imagine this with air. You could simulate this yourself too: Standing on the bottom of a swimming pool and make a swimming movement with your arms and feel the effect of you pushing forward. Then try it in normal air, almost nothing would happen. Then again with a propeller it's a different story.

In the vacuum of space you can't do this of course. Since there's no mass to push away, nothing to swim in, nothing can make you push forward.

The Corgi in the ISS could theoretically do that. But, that would be more of an disappointment if you compare that with the moving picture. It would take a long time a little, so I don't think the dog will use that to move itself around.


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