"WindBorne told investigators its balloons are made from thin plastic film with no rigid structural components, and its ballast system uses low-density silica."
What about the instrument package the balloon was carrying? I suspect that's what...
Windbourne is being proactive by working on some remediation to lessen the potential of their balloons being hit by aircraft, as well as decreasing the damage they can do if hit - their blog describes much more detail and how they are working on...