Infrasound noise mitigation on high altitude balloons

Abstract

Wind noise significantly limits the use of infrasound for remote sensing using ground-based sensors. Recently, there has been a surge in studies using high altitude balloons, termed heliotropes, to mitigate this problem. Since the balloon drifts with the wind there is minimal relative speed between the balloon and the local air. To resolve the direction of arrival from a signal, there must be sufficient separation between sensors. However, this separation increases the relative motion between the sensors and the local air. On Earth this has shown to have a weak dependence, but the use of such measurements are currently being considered as a means of exploring the interior of Venus. Vertical shear on Venus is between 5 and 10 m/s per km, which will create approximately 1 m/s of relative wind speed per 100 m of separation. Thus, the current work aims to identify wind noise reduction schemes for balloon based infrasound sensing on Venus using an Earth analog. This presentation will report on a variety of windscreen configurations examined, ground-based testing of the designs, and heliotrope flight testing of windscreens.