Infrasound Detection from Zero Pressure Solar Balloons

Infrasound is generated from a multitude of sources ranging from earthquakes and volcanoes to thunderstorms and waves on the ocean. Due to these phenomena, the range for sources in infrasound can be a useful tool for identifying and characterizing a planet's interior structure and atmospheric behavior. The vertical ground motion of seismic waves launches infrasonic acoustic waves into the atmosphere and the resulting excited waves propagate upward. The amplitude of waves increases with height owing to conservation of momentum, because the atmosphere is rarefied exponentially with height. Multiple detectors allow cross correlation to triangulate location of the source. Infrasound travels long distances in the atmosphere and can be used on a solar balloon for remote sensing on alien planets like Venus. Venus is chosen as an ideal planet for this type of testing because the surface of Venus is so inhospitable to landers (surface temp > 460°C). Whereas the middle atmosphere of Venus is much more hospitable (0-100°C) making remote sensing with balloons an easier challenge than a lander. The downside to the wide range of these sources is that it requires a large data set to help characterize which infrasound source we are receiving. To be able to demonstrate suitability for the aerial seismology ideal, additional data sets are needed. This is done by a continuous balloon campaign that is taking place from June to the end of September 2021 over the seismogenic zone in Oklahoma, where multiple balloon launces a week will take place. We will discuss the flight system, instrumentation, and details of the campaign design.