Seismo-Acoustic Waves Propagation in the Atmosphere of Mars during the InSight mission

Date: 4/25/2019

Time: 06:00 PM

Room: Fifth Avenue

InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) is a NASA Discovery Program mission that is placing a single geophysical lander on Mars to study its deep interior. This mission was launched in May 2018 and has landed successfully after a 6.5 months cruise on November 26. Meteorological sensors onboard the lander are designed to provide a continuous dataset of pressure, air temperature, wind speed and direction. The unprecedented sensitivity of the pressure sensor will allow catching signatures of a breath of infrasound sources from bolides to dust devils. e will highlight the specificities of acoustic waves propagation in the atmosphere of Mars, that is not only much more tenuous (~ 6 mbar) than the Earth atmosphere but also CO2-rich, sometimes dusty and extremely windy. We will make use of acoustic ray tracing and also of the Spectral Element Method and normal modes summation for cross-benchmarking. In particular, we show how dissipation processes due to viscosity and CO2 relaxation are taken into account. The effects of winds and dust on the propagation are also evaluated using parameters of the ambient atmosphere predicted during the lifetime of the mission (GCM) and at the location of the lander. We will finally discuss the efficiency of potential external sources to excite seismic waves to be sensed by the Insight seismometer SEIS and thus illuminating the interior of the planet.

Presenting Author: Lucie Rolland

Authors