I originally thought the steel cables from the outer truss support ring (the part that looks like a roller coaster) to the roof would hold the inner ring up as well as holding up the PTFE/ETFE material to be used to cover the inner part of the new roof. I thought the bubbles on the PTFE/ETFE material were going to be formed by steel cables attached to the material that ran to the outer truss support ring. Like Olympic Stadium in Montreal.
But it looks like that isn't the case. It looks like the bubbles are pre-formed. Interesting.