Atmospheric Seismology on Mars with InSight

Abstract:

InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) is a NASA Discovery Program mission that will place a single geophysical lander on Mars to study its deep interior. This mission is planned to be launched in March 2016, with first data return expected by the end of the year. Meteorological sensors onboard the lander will provide a continuous dataset of pressure, air temperature and wind speed and direction. The unprecedented sensitivity of the pressure sensor should allow catching signatures of a breath of infrasound sources from bolides to dust devils. In this presentation, we will show how acoustic and gravity waves propagation in the atmosphere of Mars, that is not only much more tenuous (~ 6 mbar) than the Earth atmosphere but also CO₂-rich and extremely windy. This demonstration will make use of acoustic ray tracing through an atmosphere modeled using the Mars Global Reference Atmospheric Model (MarsGram-2010) and also of the Spectral Element Method and normal modes summation for cross-benchmarking. In particular, the latter method allows the integration of dissipation processes due to viscosity and CO₂ relaxation. We will evaluate the maturity of the diverse numerical tools to model real Earth data, selected among ionospheric observations of chemical surface explosions, volcano eruptions and earthquakes. Eventually, we will investigate 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.