Spatial seismologic instrumentation: transfer function of the 6 axes InSight seismometer and development of an picometric displacement sensor by interferometry
Séminaires Planétologie et Sciences Spatiales
522, bât. Lamarck
I will defend my thesis next April, 17th. This seminar will be a first version of this presentation (45min) which will be corrected with your comments. The understanding of the Solar System formation and its evolution is deeply connected to the knowledge of the planet interior structures. In situ studies with seismometers are therefore crucial to probe the internal structure and composition of the telluric planets. Indeed, SEIS (Seismic Experiment for Interior Structure) will land on Mars in 2018 (NASA InSight mission). Its both types of sensors (VBBs and SPs) are mounted on the LVL (a mechanical leveling system) for which the purpose if twofold: ensure a level placement of the sensors on the Martian ground and provide the mechanical coupling of them to the ground. In this thesis, I developed a simplified analytical model of the LVL structure in order to reproduce its mechanical behavior by predicting its resonances and transfer function. This model will also allow to estimate the elastic properties of the landing site regolith and determine the phase velocity of surface waves. Today, new projects are also considered for a seismic return on the Moon. Indeed, the Apollo seismometers had a good resolution in ground displacement but were however unable to detect all the lunar seismic signal. During this thesis, I worked on the development of an optical readout prototype for planetary seismometers, based on the use of gravitational waves detectors’ technology. The objective is to improve the sensitivity of InSight VBBs by 2 orders of magnitude. These two different works will be presented.