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1. A Numerical Model of the SEIS Leveling System Transfer Matrix and Resonances: Application to SEIS Rotational Seismology and Dynamic Ground Interaction

Author

Brigitte Knapmeyer-Endrun, Lucile Fayon, M. Bierwirth, Pierre Delage, Cedric Schmelzbach, Sharon Kedar, Philippe Lognonné, Nicolas Verdier, William T. Pike, William B. Banerdt, S. Tillier, Naomi Murdoch, Raphaël F. Garcia, Foivos Karakostas, Kenneth Hurst, A. Kramer, Institut Supérieur de l'Aéronautique et de l'Espace - ISAE-SUPAERO (FRANCE), Institut de Physique du Globe de Paris (IPGP), Centre National de la Recherche Scientifique (CNRS)-Université de La Réunion (UR)-Université Paris Diderot - Paris 7 (UPD7)-IPG PARIS-Institut national des sciences de l'Univers (INSU - CNRS), University of Cologne, Max Planck Institute for Solar System Research (MPS), Max-Planck-Gesellschaft, Laboratoire Navier (navier umr 8205), Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS), Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Institut Supérieur de l'Aéronautique et de l'Espace (ISAE-SUPAERO), Centre National d'Études Spatiales [Toulouse] (CNES), Imperial College London, Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), and Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology in Zürich [Zürich] (ETH Zürich)

Subjects
Seismometer, Peak ground acceleration, 010504 meteorology & atmospheric sciences, Mars, 01 natural sciences, Transfer function, Regolith, symbols.namesake, [INFO.INFO-TS]Computer Science [cs]/Signal and Image Processing, Autre, 0103 physical sciences, medicine, Torque, Traitement du signal et de l'image, Rayleigh scattering, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, InSight, Stiffness, Astronomy and Astrophysics, Space and Planetary Science, Surface wave, symbols, Phase velocity, medicine.symptom, [SDU.OTHER]Sciences of the Universe [physics]/Other, Geology, Seismology
Abstract

International audience; Abstract Both sensors of the SEIS instrument (VBBs and SPs) are mounted on the mechanical leveling system (LVL), which has to ensure a level placement on the Martian ground under currently unknown local conditions, and provide the mechanical coupling of the seismometers to the ground. We 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 is implemented numerically and allows to estimate the effects of the LVL on the data recorded by the VBBs and SPs on Mars. The model is validated through comparison with the horizontal resonances (between 35 and 50 Hz) observed in laboratory measurements. These modes prove to be highly dependent of the ground horizontal stiffness and torque. For this reason, an inversion study is performed and the results are compared with some experimental measurements of the LVL feet’s penetration in a martian regolith analog. This comparison shows that the analytical model can be used to estimate the elastic ground properties of the InSight landing site. Another application consists in modeling the 6 sensors on the LVL at their real positions, also considering their sensitivity axes, to study the performances of the global SEIS instrument in translation and rotation. It is found that the high frequency ground rotation can be measured by SEIS and, when compared to the ground acceleration, can provide ways to estimate the phase velocity of the seismic surface waves at shallow depths. Finally, synthetic data from the active seismic experiment made during the HP3 penetration and SEIS rotation noise are compared and used for an inversion of the Rayleigh phase velocity. This confirms the perspectives for rotational seismology with SEIS which will be developed with the SEIS data acquired during the commissioning phase after landing.

Published
2018

2. Flexible Mode Modelling of the InSight Lander and Consequences for the SEIS Instrument

Author

Nicholas A Teanby, Robert Myhill, Daniel Alazard, Brigitte Knapmeyer-Endrun, Naomi Murdoch, Institut Supérieur de l'Aéronautique et de l'Espace - ISAE-SUPAERO (FRANCE), Max Planck Society (GERMANY), University of Bristol (UNITED KINGDOM), and Max-Planck-Institut für Sonnensystemforschung - MPS (GERMANY)

Subjects
Seismometer, 010504 meteorology & atmospheric sciences, Mars, 01 natural sciences, Signal, Regolith, Physics::Geophysics, 0103 physical sciences, Sensitivity (control systems), Aerospace engineering, 010303 astronomy & astrophysics, Seismology, 0105 earth and related environmental sciences, business.industry, Atmosphere, Mode (statistics), Optique / photonique, Astronomy and Astrophysics, Mars Exploration Program, Noise, Amplitude, Geophysics, Space and Planetary Science, Structural dynamics, Satellite, business, Geology
Abstract

We present an updated model for estimating the lander mechanical noise on the InSight seismometer SEIS, taking into account the flexible modes of the InSight lander. This new flexible mode model uses the Satellite Dynamics Toolbox to compute the direct and the inverse dynamic model of a satellite composed of a main body fitted with one or several dynamic appendages. Through a detailed study of the sensitivity of our results to key environment parameters we find that the frequencies of the six dominant lander resonant modes increase logarithmically with increasing ground stiffness. On the other hand, the wind strength and the incoming wind angle modify only the signal amplitude but not the frequencies of the resonances. For the baseline parameters chosen for this study, the lander mechanical noise on the SEIS instrument is not expected to exceed the instrument total noise requirements. However, in the case that the lander mechanical noise is observable in the seismic data acquired by SEIS, this may provide a complementary method for studying the ground and wind properties on Mars.

Published
2018

3. Near-Field Seismic Propagation and Coupling Through Mars’ Regolith: Implications for the InSight Mission

Author

Nicholas A Teanby, James Wookey, Robert Myhill, Naomi Murdoch, Institut Supérieur de l'Aéronautique et de l'Espace - ISAE-SUPAERO (FRANCE), University of Bristol (UNITED KINGDOM), and Département d'Electronique, Optronique et Signal - DEOS (Toulouse, France)

Subjects
Seismometer, Transfer coefficient, 010504 meteorology & atmospheric sciences, Attenuation, Mars, Astronomy and Astrophysics, Particle displacement, Mars Exploration Program, Atmospheric noise, 01 natural sciences, Regolith, Amplitude, Transfer coefficient Mars InSight, Autre, Space and Planetary Science, 0103 physical sciences, 010303 astronomy & astrophysics, Noise (radio), Seismology, Geology, 0105 earth and related environmental sciences, InSight
Abstract

NASA’s InSight Mission will deploy two three-component seismometers on Mars in 2018. These short period and very broadband seismometers will be mounted on a three-legged levelling system, which will sit directly on the sandy regolith some 2–3 meters from the lander. Although the deployment will be covered by a wind and thermal shield, atmospheric noise is still expected to couple to the seismometers through the regolith. Seismic activity on Mars is expected to be significantly lower than on Earth, so a characterisation of the extent of coupling to noise and seismic signals is an important step towards maximising scientific return. In this study, we conduct field testing on a simplified model of the seismometer assembly. We constrain the transfer function between the wind and thermal shield and tripod-mounted seismometers over a range of frequencies (1–40 Hz) relevant to the deployment on Mars. At 1–20 Hz the displacement amplitude ratio is approximately constant, with a value that depends on the site (0.03–0.06). The value of the ratio in this range is 25–50% of the value expected from the deformation of a homogeneous isotropic elastic halfspace. At 20–40 Hz, the ratio increases as a result of resonance between the tripod mass and regolith. We predict that mounting the InSight instruments on a tripod will not adversely affect the recorded amplitudes of vertical seismic energy, although particle motions will be more complex than observed in recordings generated by more conventional buried deployments. Higher frequency signals will be amplified by tripod-regolith resonance, probably reaching peak-amplification at $\sim 50$ Hz. The tripod deployment will lose sensitivity at frequencies $>50$ Hz as a result of the tripod mass and compliant regolith. We also investigate the attenuation of seismic energy within the shallow regolith covering the range of seismometer deployment distances. The amplitude of surface displacement decays as $r^{-n}$ , where $1.5 < n < 2$ . This exceeds the value expected for a homogeneous isotropic elastic halfspace ( $n \sim 1$ ), and reflects an increase in Young’s modulus with depth. We present an updated model of lander noise which takes this enhanced attenuation into account.

Published
2018

4. Geology and Physical Properties Investigations by the InSight Lander

Author

Sylvain Piqueux, Pierre Delage, William B. Banerdt, Ingrid Daubar, Nils Müller, Matthias Grott, Antoine Lucas, Tamara Gudkova, U. R. Christensen, Johan O. A. Robertsson, Don Banfield, Brigitte Knapmeyer-Endrun, T. Spohn, Suzanne E. Smrekar, Lucile Fayon, David Sollberger, Ralph D. Lorenz, Domenico Giardini, D. Kipp, G. Kargl, Matthew P. Golombek, Nicholas A Teanby, Sharon Kedar, B. Kenda, Ashitey Trebi-Ollennu, Raphaël F. Garcia, Ernst Hauber, Paul Morgan, Khaled Ali, Roy Lichtenheldt, Aymeric Spiga, Philippe Lognonné, Jason P. Marshall, Naomi Murdoch, David Mimoun, Cedric Schmelzbach, Joana Voigt, Constantinos Charalambous, Justin N. Maki, Veronique Ansan, William T. Pike, T. Nicollier, José E. Andrade, Mark P. Panning, Sebastien Rodriguez, Nicholas H. Warner, Institut Supérieur de l'Aéronautique et de l'Espace - ISAE-SUPAERO (FRANCE), Laboratoire de Planétologie et Géodynamique [UMR 6112] (LPG), Université d'Angers (UA)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique du Globe de Paris (IPGP), Centre National de la Recherche Scientifique (CNRS)-Université de La Réunion (UR)-Université Paris Diderot - Paris 7 (UPD7)-IPG PARIS-Institut national des sciences de l'Univers (INSU - CNRS), Département Electronique, Optronique et Signal (DEOS), Institut Supérieur de l'Aéronautique et de l'Espace (ISAE-SUPAERO), Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Institut Universitaire de France (IUF), Ministère de l'Education nationale, de l’Enseignement supérieur et de la Recherche (M.E.N.E.S.R.), Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), German Aerospace Center (DLR), Division of Engineering and Applied Science, California Institute of Technology, California Institute of Technology (CALTECH), School of Earth Sciences [Bristol], University of Bristol [Bristol], Interactions et dynamique des environnements de surface (IDES), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Deutsches Zentrum für Luft- und Raumfahrt (DLR), Jülich Centre for Neutron Science (JCNS - PGI, JARA-FIT), Peter Grünberg Institut, Max-Planck-Institut für Sonnensystemforschung (MPS), Max-Planck-Gesellschaft, Cornell University, Departments of Anesthesiology and Physiology and Biophysics, University of Alabama at Birmingham [ Birmingham] (UAB), UNS-CNRS-Observatoire de la Côte d'Azur, Géotechnique (cermes), Laboratoire Navier (navier umr 8205), Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS), Department of Mechanical Engineering [Imperial College London], Imperial College London, University of Arizona, Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), École normale supérieure - Paris (ENS Paris)-École normale supérieure - Paris (ENS Paris), University of Florida [Gainesville], Schmidt United Institute of Physics of the Earth [Moscow] (IPE), Russian Academy of Sciences [Moscow] (RAS), Departamento de Ecologia (CEAMISH), Universidad Autonoma del Estado de Morelos (UAEM), Institute of Geophysics [ETH Zürich], Department of Earth Sciences [ETH Zürich] (D-ERDW), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology in Zürich [Zürich] (ETH Zürich)-Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology in Zürich [Zürich] (ETH Zürich), Institut National Polythechnique Houphouet Boigny, California Institute of Technology (CALTECH)-NASA, Laboratoire de Planétologie et Géodynamique UMR6112 (LPG), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Nantes - Faculté des Sciences et des Techniques, and Université de Nantes (UN)-Université de Nantes (UN)-Université d'Angers (UA)

Subjects
Seismometer, 010504 meteorology & atmospheric sciences, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], Wind stress, Mars, 01 natural sciences, Wind speed, Seismic wave, [SDU.STU.PL]Sciences of the Universe [physics]/Earth Sciences/Planetology, Planetenphysik, 0103 physical sciences, Traitement du signal et de l'image, [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, 010303 astronomy & astrophysics, Dust devil, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, InSight, Raumfahrt-Systemdynamik, Physical properties, Leitungsbereich PF, Astronomy and Astrophysics, Geology, Geophysics, Mars Exploration Program, Surface materials, InSight Mars Geology Physical properties Surface materials, Regolith, [SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], Planetengeologie, Space and Planetary Science, Hesperian, [SPI.SIGNAL]Engineering Sciences [physics]/Signal and Image processing
Abstract

International audience; Although not the prime focus of the InSight mission, the near-surface geology and physical properties investigations provide critical information for both placing the instruments (seismometer and heat flow probe with mole) on the surface and for understanding the nature of the shallow subsurface and its effect on recorded seismic waves. Two color cameras on the lander will obtain multiple stereo images of the surface and its interaction with the spacecraft. Images will be used to identify the geologic materials and features present, quantify their areal coverage, help determine the basic geologic evolution of the area, and provide ground truth for orbital remote sensing data. A radiometer will measure the hourly temperature of the surface in two spots, which will determine the thermal inertia of the surface materials present and their particle size and/or cohesion. Continuous measurements of wind speed and direction offer a unique opportunity to correlate dust devils and high winds with eolian changes imaged at the surface and to determine the threshold friction wind stress for grain motion on Mars. During the first two weeks after landing, these investigations will support the selection of instrument placement locations that are relatively smooth, flat, free of small rocks and load bearing. Soil mechanics parameters and elastic properties of near surface materials will be determined from mole penetration and thermal conductivity measurements from the surface to 3–5 m depth, the measurement of seismic waves during mole hammering, passive monitoring of seismic waves, and experiments with the arm and scoop of the lander (indentations, scraping and trenching). These investigations will determine and test the presence and mechanical properties of the expected 3–17 m thick fragmented regolith (and underlying fractured material) built up by impact and eolian processes on top of Hesperian lava flows and determine its seismic properties for the seismic investigation of Mars’ interior.

Published
2018

5. Evaluating the Wind-Induced Mechanical Noise on the InSight Seismometers

Author

Philippe Lognonné, Naomi Murdoch, David Mimoun, Don Banfield, William B. Banerdt, Willian Rapin, Taichi Kawamuea, Raphaël F. Garcia, Centre National de la Recherche Scientifique - CNRS (FRANCE), Cornell University (USA), Institut de Physique du Globe de Paris - IPGP (FRANCE), Institut Supérieur de l'Aéronautique et de l'Espace - ISAE-SUPAERO (FRANCE), National Aeronautics and Space Administration - NASA (USA), Université de Paris Diderot - Paris 7 (FRANCE), Université Toulouse III - Paul Sabatier - UT3 (FRANCE), Université de La Réunion (FRANCE), California Institute of Technology - Caltech (USA), Institut national des sciences de l'Univers - INSU (FRANCE), Jet Propulsion Laboratory - JPL (Pasadena, USA), Département Electronique, Optronique et Signal (DEOS), Institut Supérieur de l'Aéronautique et de l'Espace (ISAE-SUPAERO), Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Institut de Physique du Globe de Paris (IPGP), Centre National de la Recherche Scientifique (CNRS)-Université de La Réunion (UR)-Université Paris Diderot - Paris 7 (UPD7)-IPG PARIS-Institut national des sciences de l'Univers (INSU - CNRS), Cornell Center for Astrophysics and Planetary Science (CCAPS), Cornell University, Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Cornell University [New York], Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), and Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SPI.OTHER]Engineering Sciences [physics]/Other, Seismometer, 010504 meteorology & atmospheric sciences, FOS: Physical sciences, Mars, 01 natural sciences, Regolith, Space exploration, Physics - Geophysics, Autre, 0103 physical sciences, Aerospace engineering, Baseline (configuration management), 010303 astronomy & astrophysics, Seismology, 0105 earth and related environmental sciences, Earth and Planetary Astrophysics (astro-ph.EP), Martian, business.industry, Atmosphere, Astronomy and Astrophysics, Mars Exploration Program, Mechanical noise, Geophysics (physics.geo-ph), Physics - Atmospheric and Oceanic Physics, Noise, Geophysics, Space and Planetary Science, Software deployment, Atmospheric and Oceanic Physics (physics.ao-ph), business, Geology, Astrophysics - Earth and Planetary Astrophysics
Abstract

The SEIS (Seismic Experiment for Interior Structures) instrument onboard the InSight mission to Mars is the critical instrument for determining the interior structure of Mars, the current level of tectonic activity and the meteorite flux. Meeting the performance requirements of the SEIS instrument is vital to successfully achieve these mission objectives. Here we analyse in-situ wind measurements from previous Mars space missions to understand the wind environment that we are likely to encounter on Mars, and then we use an elastic ground deformation model to evaluate the mechanical noise contributions on the SEIS instrument due to the interaction between the Martian winds and the InSight lander. Lander mechanical noise maps that will be used to select the best deployment site for SEIS once the InSight lander arrives on Mars are also presented. We find the lander mechanical noise may be a detectable signal on the InSight seismometers. However, for the baseline SEIS deployment position, the noise is expected to be below the total noise requirement >97% of the time and is, therefore, not expected to endanger the InSight mission objectives., 32 pages, 16 figures

Published
2017

6. Estimations of the Seismic Pressure Noise on Mars Determined from Large Eddy Simulations and Demonstration of Pressure Decorrelation Techniques for the Insight Mission

Author

Taichi Kawamura, Balthasar Kenda, Philippe Lognonné, Aymeric Spiga, William B. Banerdt, Naomi Murdoch, David Mimoun, Centre National de la Recherche Scientifique - CNRS (FRANCE), Institut de Physique du Globe de Paris - IPGP (FRANCE), Institut Supérieur de l'Aéronautique et de l'Espace - ISAE-SUPAERO (FRANCE), National Aeronautics and Space Administration - NASA (USA), Université de Paris Diderot - Paris 7 (FRANCE), Université Pierre et Marie Curie, Paris 6 - UPMC (FRANCE), Université de La Réunion (FRANCE), California Institute of Technology - Caltech (USA), Ecole Normale Supérieure de Paris - ENS Paris (FRANCE), Ecole Polytechnique (FRANCE), Ecole des Ponts ParisTech (FRANCE), Institut national des sciences de l'Univers - INSU (FRANCE), Département Electronique, Optronique et Signal (DEOS), Institut Supérieur de l'Aéronautique et de l'Espace (ISAE-SUPAERO), Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École des Ponts ParisTech (ENPC)-École polytechnique (X)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Centre National de la Recherche Scientifique (CNRS)-Université de La Réunion (UR)-Université Paris Diderot - Paris 7 (UPD7)-IPG PARIS-Institut national des sciences de l'Univers (INSU - CNRS), and École normale supérieure - Paris (ENS Paris)-École normale supérieure - Paris (ENS Paris)

Subjects
Seismometer, 010504 meteorology & atmospheric sciences, FOS: Physical sciences, Mars, Surface pressure, 01 natural sciences, Regolith, Physics::Geophysics, Physics - Geophysics, 0103 physical sciences, Pressure, 010303 astronomy & astrophysics, Decorrelation, Astrophysique, Seismology, 0105 earth and related environmental sciences, Earth and Planetary Astrophysics (astro-ph.EP), Atmospheric pressure, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Atmosphere, Astronomy and Astrophysics, Mars Exploration Program, Geodesy, Pressure sensor, Geophysics (physics.geo-ph), Physics - Atmospheric and Oceanic Physics, Amplitude, Geophysics, 13. Climate action, Space and Planetary Science, Atmospheric and Oceanic Physics (physics.ao-ph), Geology, Noise (radio), Astrophysics - Earth and Planetary Astrophysics
Abstract

International audience; The atmospheric pressure fluctuations on Mars induce an elastic response in the ground that creates a ground tilt, detectable as a seismic signal on the InSight seismometer SEIS. The seismic pressure noise is modeled using Large Eddy Simulations (LES) of the wind and surface pressure at the InSight landing site and a Green’s function ground deformation approach that is subsequently validated via a detailed comparison with two other methods: a spectral approach, and an approach based on Sorrells’ theory (Sorrells,Geophys. J. Int. 26:71–82, 1971; Sorrells et al., Nat. Phys. Sci. 229:14–16, 1971). The horizontal accelerations as a result of the ground tilt due to the LES turbulence-induced pressure fluctuations are found to be typically ∼ 2–40 nm/s2 in amplitude, whereas the direct horizontal acceleration is two orders of magnitude smaller and is thus negligible in comparison. The vertical accelerations are found to be ∼ 0.1–6 nm/s2 in amplitude. These are expected to be worst-case estimates for the seismic noise as we use a half-space approximation; the presence at some (shallow) depth of a harder layer would significantly reduce quasi-static displacement and tilt effects. We show that under calm conditions, a single-pressure measurement is representative of the large-scale pressure field (to a distance of several kilometers), particularly in the prevailing wind direction. However, during windy conditions, small-scale turbulence results in a reduced correlation between the pressure signals, and the single-pressure measurement becomes less representative of the pressure field. The correlation between the seismic signal and the pressure signal is found to be higher for the windiest period because the seismic pressure noise reflects the atmospheric structure close to the seismometer. In the same way that we reduce the atmospheric seismic signal by making use of a pressure sensor that is part of the InSight Auxiliary Payload Sensor Suite, we also the use the synthetic noise data obtained from the LES pressure field to demonstrate a decorrelation strategy. We show that our decorrelation approach is efficient, resulting in a reduction by a factor of ∼ 5 in the observed horizontal tilt noise (in the wind direction) and the vertical noise. This technique can, therefore, be used to remove the pressure signal from the seismic data obtained on Mars during the InSight mission.

Published
2017

7. The Noise Model of the SEIS Seismometer of the InSight Mission to Mars

Author

William B. Banerdt, Philippe Lognonné, Naomi Murdoch, David Mimoun, K. Hurst, William T. Pike, Jane Hurley, T. Nebut, Centre National de la Recherche Scientifique - CNRS (FRANCE), Institut de Physique du Globe de Paris - IPGP (FRANCE), Institut Supérieur de l'Aéronautique et de l'Espace - ISAE-SUPAERO (FRANCE), National Aeronautics and Space Administration - NASA (USA), Université de Paris Diderot - Paris 7 (FRANCE), Université de La Réunion (FRANCE), California Institute of Technology - Caltech (USA), Imperial College London (UNITED KINGDOM), Institut national des sciences de l'Univers - INSU (FRANCE), and Science and Technology Facilities Council - STFC (UNITED KINGDOM)

Subjects
Seismometer, Operation planning, Martian, 010504 meteorology & atmospheric sciences, Noise model, Bandwidth (signal processing), Astronomy and Astrophysics, Mars Exploration Program, Seismic noise, 01 natural sciences, On board, InSight SEIS, Planetary science, Autre, 13. Climate action, Space and Planetary Science, 0103 physical sciences, 010303 astronomy & astrophysics, Geology, 0105 earth and related environmental sciences, Remote sensing, Mars environment
Abstract

The SEIS (Seismic Experiment for Interior Structures) instrument on board the InSight mission to Mars is the critical instrument for determining the interior structure of Mars, the current level of tectonic activity and the meteorite flux. Meeting the performance requirements of the SEIS instrument is vital to successfully achieve these mission objectives. The InSight noise model is a key tool for the InSight mission and SEIS instrument requirement setup. It will also be used for future operation planning. This paper presents the analyses made to build a model of the Martian seismic noise as measured by the SEIS seismometer, around the seismic bandwidth of the instrument (from 0.01 Hz to 1 Hz). It includes the instrument self-noise, but also the environment parameters that impact the measurements. We present the general approach for the model determination, the environment assumptions, and we analyze the major and minor contributors to the noise model.

Published
2017

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