Designing a torque-less wind shield for broadband observation of marsquakes
Résumé
To perform seismic observations on Mars, reduction of the surface wind effect is necessary. In particular, ground tilt causes a serious problem for broadband seismic observations. Ground tilt is a seismic noise source, and it can be attributed to the torque of the wind shield. The torque brings about a difference in ground strain. Here, we report on an optimized torque-less wind shield to protect a seismometer from the wind, the design method, and an evaluation method for the background noise level. We have conducted wind tunnel tests and numerical simulations with several types of designs and obtained an effective shape to minimize the torque from the wind. The designed torque-less wind shield has lower ground tilt noise than typical-shape wind shields by one order of magnitude. This will enable us to achieve a more than 90% noise-free condition during an observation span, even for the most windy conditions on the Martian surface.