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A Comodulation Analysis of Atmospheric Energy Injection Into the Ground Motion at InSight, Mars

Charalambous, C. and Stott, Alexander E. and Pike, W. T. and McClean, J. B. and Warren, T. and Spiga, Aymeric and Banfield, D. and Garcia, Raphaël F. and Clinton, J. and Stähler, S. and Navarro, S. and Lognonné, Philippe and Scholz, J.‐R. and Kawamura, T. and van Driel, M. and Böse, M. and Ceylan, S. and Khan, A. and Horleston, A. and Orhand‐Mainsant, Guénolé and Sotomayor, L. M. and Murdoch, Naomi and Giardini, D. and Banerdt, William Bruce A Comodulation Analysis of Atmospheric Energy Injection Into the Ground Motion at InSight, Mars. (2021) Journal of Geophysical Research: Planets, 126 (4). ISSN 2169-9097

(Document in English)

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Official URL: https://doi.org/10.1029/2020JE006538


Seismic observations involve signals that can be easily masked by noise injection. For the NASA Mars lander InSight, the atmosphere is a significant noise contributor, impeding the identification of seismic events for two-thirds of a Martian day. While the noise is below that seen at even the quietest sites on Earth, the amplitude of seismic signals on Mars is also considerably lower, requiring an understanding and quantification of environmental injection at unprecedented levels. Mars’ ground and atmosphere are a continuously coupled seismic system, and although atmospheric functions are of distinct origins, the superposition of these noise contributions is poorly understood, making separation a challenging task. We present a novel method for partitioning the observed signal into seismic and environmental contributions. Atmospheric pressure and wind fluctuations are shown to exhibit temporal cross-frequency coupling across multiple bands, injecting noise that is neither random nor coherent. We investigate this through comodulation, quantifying the synchrony of the seismic motion, wind and pressure signals. By working in the time-frequency domain, we discriminate between the different origins of underlying processes and determine the site's environmental sensitivity. Our method aims to create a virtual vault at InSight's landing site on Mars, shielding the seismometers with effective postprocessing in lieu of a physical vault. This allows us to describe the environmental and seismic signals over a sequence of sols, to quantify the wind and pressure injection and estimate the seismic content of possible marsquakes with a signal-to-noise ratio that can be quantified in terms of environmental independence. Finally, we exploit the relationship between the comodulated signals to identify their sources.

Item Type:Article
Audience (journal):International peer-reviewed journal
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Institution:Université de Toulouse > Institut Supérieur de l'Aéronautique et de l'Espace - ISAE-SUPAERO (FRANCE)
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Deposited On:07 Jan 2022 13:06

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