helium ball

[skilliyay]

looking for educated guesses here:

would it be possible to build a helium ball no larger than a beach ball that would float indefinately at rtp, using gas retaining materials?

admittedly a toughy without doing the math, but any ideas?

[JustSia]

No, either due to diffusion or effusion.

S

[skilliyay]

but I read somewhere about zero-permeability materials, or would these be too heavy?

[Gef]

Probably misunderstood the question but many party balloons are not much bigger than a beach ball and rise quite well. I know the helium will leak out eventually but if cost was not a problem then I'm sure that a totally impervious cover could be made.

[jake-the-peg]

I think not quite yet.

The problem is that Helium will diffuse through most materials. I know NASA is interested in "Aerobots" (do a google search) which obviously require this sort of technology.

Contracts seem to have been awarded for ultra low permeability materials using impregnation with carbon nanotubes but I can't see any specific details regarding how low they've managed to get the permeability down to.

[skilliyay]

very interesting thanks jake