So I don't have a video or anything to show it, but I was able to get to the fallen 3.0 siva cluster by jumping into the huge flame pit in the middle of the felwinters social space. I decoded some engrams (including rare, legendary, sublime, and exotic), came back out, and saw the flame was twice as tall and had a purple tinge to it. I jumped in and it literally launched me right in front of the cluster on top of the tower. I haven't tried to recreate this, but decoding engrams was what I was doing immediately prior to seeing the flame and jumping into it. If this is already known, my bad. All I've seen about this cluster is jumping on a ship but that's just too much effort :P