Things that would go inside the canopy:

UVC LEDs and any necessary supports
Back up parachute in case canopy bursts
Radar reflector
Pressure sensor (in case of leaks)

But all the above sterilised by UVC from outside before flight! (That way, leaks don't jeopardise sterility - only flight time)

Ahhh - here's something interesting, a bit like the Travelling Salesman Problem:
You have one LED in the middle of a big spherical balloon
You have one LED travelling up and down a cylinder balloon
At what given combination of radius and power does one sterilise quicker than the other?

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