During the recent return of Expedition 47 from the ISS, I noticed the main parachute of their Soyuz capsule pulsating. You can see it in [this video](https://www.youtube.com/watch?v=Mur7l2gxb2E#t=68m50):

"Flat":

[![enter image description here](https://i.stack.imgur.com/QurXS.png)](https://i.stack.imgur.com/QurXS.png)

"Domed":

[![enter image description here](https://i.stack.imgur.com/7KpVN.png)](https://i.stack.imgur.com/7KpVN.png)

My wife noted that it looks a little like a jellyfish, moments later I saw this [tweet by Alexander Gerst](https://twitter.com/Astro_Alex/status/744095384641867776):

> 
> The "jellyfish breathing" of the parachute feels like sitting in a small boat at sea. Not indicative of what is to come...
> 
> 
> 

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Is the parachute specifically designed to do this, if so - why? What benefits does it provide?

If it's not specifically designed to do this, and it's just a side effect of some other design constraint, what causes it to happen, and is it detrimental to the overall performance of the parachute at all? Perhaps all parachutes of this design/scale behave this way, and I've just never noticed it before?