Comment Battery life (Score 2) 51
I read another article on this (possible on The Register), and one of the shortfalls of the project as it turned out (i.e. going further than expected) seemed to be the lack of battery power for the transponder for attempts at a longer journey.
I wonder how much a nicely paired up solar panel would upset the lift/weight balance on a high altitude balloon, and whether it would be able to charge the batteries well enough to power a transponder over a longer trip.