Nasa Balloon

The main balloon has a starter balloon over it to hold it up, ( to protect the fabric), so helium can be pumped in.  A track load. Once the balloon is fairly full, the little starter or lifter balloon disappears. 
At about midday they suddenly let it go. The balloon is attached to the cargo with all the scientific equipment. during inflation, this was about 200 m to 300m to the side.  The earlier balloon has now gone round the antarctic area over 3 times.  Hard to appreciate the scale. Its BIG
High up the ballon expands to full size.