The goal here is neutral buoyancy when in gravity so that it behaves as though there were no gravity. Put a bag of water in water and it floats like the rest of the water, gravity or no.
Neutral buoyancy is achieved with very specific densities. You can either make the astronaut buoyant, or you can make the poop, but not both at the same time.
Neutral buoyancy is achieved with very specific densities. You can either make the astronaut buoyant, or you can make the poop, but not both at the same time.