Porous domes as wind noise filters for infrasound sensing on Mars

Abstract

The ability to detect infrasonic waves on Mars will enable further understanding of its environment. For example, infrasound arrivals from large storm systems, dust devils, and bolides can be used to understand source mechanisms and constrain impact statistics. The InSight microbarometer will measure the effect of ambient pressure fluctuations on seismometer data. It may also be able to detect infrasonic signals from distant sources, which, however, will be contaminated by wind noise. On Earth, infrasound stations use large-area spatial filters to reduce wind-noise contamination. These filters consist of long drilled pipes arranged radially around the sensor. Since this arrangement may not be easily deployable on Mars, we investigate the feasibility of tent-like porous domes, erected around the sensor, as wind-noise filters. Through theoretical modeling, we predict the power spectrum of wind pressure fluctuations at the center of the dome under Martian conditions. The results show that, as the porosity of the dome wall is lowered from 80% to 40%, a secondary wind-noise PSD peak is formed, moving from approximately 0.4 Hz–3 Hz, while the high-frequency “tail” (∼ 20 Hz) becomes stronger; low frequencies (f<0.1 Hz) show the typical characteristics of the energy-containing range. The porosity dependence shows promise in the potential to “adapt” the filter characteristics to various wind conditions. The research was supported by the Louisiana Space Grant Consortium (LaSPACE).