DI024-0008
Insight Low Frequency Seismological Measurements: Environmental Noise Decorrelation And Applicability To Mars Internal Structure Refinement
Tuesday, 15 December 2020
Poster
Baptiste Pinot1, Raphael F. Garcia2, David Mimoun2, Laurent Pou3, Francis Nimmo4, Aymeric Spiga5, Philippe Henri Lognonné6, Donald J Banfield7, Leo Martire2, Naomi Murdoch8, Nicolas Compaire1 and W Bruce Banerdt9, (1)Institut Supérieur de l'Aéronautique et de l'Espace, Toulouse Cedex 04, France, (2)Institut Supérieur de l'Aéronautique et de l'Espace, DEOS/SSPA, Toulouse Cedex 04, France, (3)University of California Santa Cruz, Earth and Planetary Sciences, Santa Cruz, CA, United States, (4)University of California-Santa Cruz, Earth and Planetary Sciences, Santa Cruz, CA, United States, (5)Laboratoire de Météorologie Dynamique UPMC, Paris, France, (6)Université de Paris, Institut de physique du globe de Paris, CNRS, Paris, France, (7)Cornell University, Center for Radiophysics and Space Research, Ithaca, NY, United States, (8)Institut Supérieur de l’Aéronautique et de l’Espace, DEOS/SSPA, Toulouse, France, (9)NASA Jet Propulsion Laboratory, Pasadena, CA, United States
Abstract:
Since it successfully landed and deployed the SEIS package on the ground, the InSight mission has provided unprecedented combined seismological and meteorological data from the martian surface. While SEIS was primarily designed for measurements ranging from 0.01 Hz to 50 Hz, there are still signals of interest at lower frequencies, which can be used to constrain the internal structure of Mars. At long periods, the coupling between the ground and the atmosphere can be detected by the simultaneous measurements of the pressure sensors and of acceleration by the very broad band seismometers. Study of these long periods could improve the understanding of gravity waves and infrasounds. Detection of the atmospheric hum could yield information on the internal structure through the excitation of the normal modes of the planet. Another source of constraints on the internal structure, more specifically on the martian core radius and state, could come from the response of the planet to the tidal forcing of Phobos, at around a 5 hours period for the second degree tide.
In these lower frequency ranges, however, most of the energy recorded by the seismometers comes from the martian environment noise, which is either thermal noise, pressure noise or wind. This implies the development of data processing codes making use of the different auxilliary environment sensors, such as the temperature probes inside SEIS, to decorrelate those external influences from the seismic data.
This presentation explains the methods used for such a decorrelation of the SEIS measurements at low frequencies and shows the latest results of its implementation on long duration continuous records of InSight sensors. The study of the residuals leads to a discussion regarding the ability of those measurements to constrain Mars’ core and internal structure.
