Technology development for the ExaVolt Antenna (EVA) suborbital ultra-high energy particle observatory

We describe technology development for the ExaVolt Antenna (EVA) mission, a planned ultra-high energy (UHE) particle observatory under development for NASA's suborbital super-pressure balloon program in Antarctica. The design is based on a novel application of toroidal reflector optics which utilizes a super-pressure balloon surface, along with a feed-array mounted on an inner membrane, to create an ultra-large radio antenna system with a synoptic view of the Antarctic ice sheet below it.