Advances towards Balloon-based Seismic Studies on Venus

Seismology is essential for understanding a planet's interior structure and evolution. Earth, Moon, and Mars have all hosted seismic instruments on the surface, which have mapped seismic activity and provided insight into their interior. On Venus, high surface temperature and pressure present a difficult technological challenge to traditional seismology. In recent years, balloon-based seismology through the study of low-frequency seismo-acoustic signals (infrasound) has gained acceptance as a viable way to study seismic activity on Venus. Balloon-based barometers have the potential to detect and characterize atmospheric waves launched by venusquakes and volcanic eruptions while offering substantially longer instrument lifetimes in the Venus middle atmosphere, where temperature and pressure are significantly more benign (-10-100°C) as compared to the surface (>460°C). A balloon-based investigation of Venus quake and volcanic activity can also serve as a pathfinder for highly-targeted missions involving long-lived surface seismometers in the future. In addition, auxiliary data collected to discriminate seismic infrasound from other naturally occurring sources can contribute valuable in-situ data to study important atmospheric science questions on Venus.

In this presentation, we will showcase highlights from the last year and discuss progress achieved towards making the goal of balloon-based seismo-acoustic remote sensing a reality. Our results include the analysis of data from balloon flights over the aftershocks of the Ridgecrest earthquake sequence of July 2019, results from the "Glanes" experiment in France, where balloon-based infrasound was recorded from sub-surface chemical explosions to improve modeling capabilities, the development of a Venus balloon-grade atmospheric and infrasound seismology sensor, and a stratospheric proof-of-concept demonstration of the "vector infrasound aeroseismometer", which can eventually reduce the mass, power and deployment complexity of balloon-based infrasound sensors for seismology on Venus. Lastly, we discuss our progress towards deploying 120 balloon flights over the State of Oklahoma in the summers of 2021 and 2022 to detect and geolocate earthquakes and translate the measurements to detection limits in the atmosphere of Venus.