Description: The Flight Test of a Balloon-borne Aeroseismometer project will develop direction-finding capabilities for balloon-borne infrasound sensors. Researchers will install two infrasound/accelerometer packages on a Stratollite balloon from World View Enterprises two Cyclone Balloon Systems from Raven Aerostar and direct the balloons to the vicinity of ground explosions. This will test the efficacy of the team’s balloon seismometer method for potential use in detecting seismic activity on Venus. Infrasound investigations on Venus and other planetary bodies could uncover valuable information about the planets’ interior structures. Problem Statement The primary challenge of balloon-borne infrasound sensors is the lack of direction finding. Since pressure measurements are scalar values (not vector values like seismometers, for example) sensors on a single balloon cannot determine the azimuth of arrival. The consequences of this are twofold: 1) difficulty in distinguishing true far field waves from local noise (e. g. turbulence) and 2) lack of constraint on possible source regions for an incident signal. However, a serendipitous measurement taken on a coupled infrasound/accelerometer payload on the 2016 High Altitude Student Platform (HASP) indicates that the balloon itself is set in motion by even very small acoustic waves impacting the envelope. As a result, the entire flight system can be leveraged as a pendulum seismometer; the resulting motion can be captured using accelerometers and thus provide direction of arrival information for incident acoustic waves. Technology Maturation The instrumentation is presently at a TRL of 4/5, and at the conclusion of the project would achieve a TRL of 6.

Benefits: This balloon aeroseismometer technology has important implications for interplanetary exploration. With robust and precise acoustic sensing capabilities, researchers could explore bodies like Venus that are otherwise inhospitable to human investigation. This would benefit NASA missions, the commercial space industry, and other government agencies. Future Customers • NASA New Frontiers missions to Venus, Jupiter, and Titan • Terrestrial infrasound monitoring • Acoustic waves from bolides, severe storms, and clear air turbulence