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A reconstruction algorithm for temporally aliased seismic signals recorded by the InSight Mars lander
  • +17
  • David Sollberger,
  • Cedric Schmelzbach,
  • Fredrik Andersson,
  • Johan O. A. Robertsson,
  • Nienke Brinkman,
  • Sharon Kedar,
  • Bruce Banerdt,
  • John Clinton,
  • Martin van Driel,
  • Garcia Raphael F.,
  • Domenico Giardini,
  • Matthias Grott,
  • Thomas Haag,
  • Hudson Troy L.,
  • Philippe Lognonné,
  • Jan ten Pierick,
  • William Thomas Pike,
  • Tilman Spohn,
  • Simon C. Stähler,
  • Peter Zweifel
David Sollberger
Institute of Geophysics, ETH Zurich

Corresponding Author:[email protected]

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Cedric Schmelzbach
ETH Zurich
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Fredrik Andersson
ETH Zurich
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Johan O. A. Robertsson
Institute of Geophysics, ETH Zurich
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Nienke Brinkman
Institute of Geophysics, ETH Zürich
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Sharon Kedar
JPL
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Bruce Banerdt
Jet Propulsion Laboratory
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John Clinton
Swiss Seismological Service
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Martin van Driel
ETH Zürich
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Garcia Raphael F.
Institut Supérieur de l'Aéronautique et de l'Espace, ISAE-SUPAERO
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Domenico Giardini
ETH Zürich
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Matthias Grott
DLR Institute for Planetary Research
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Thomas Haag
Institute of Geophysics, ETH Zürich
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Hudson Troy L.
Jet Propulsion Laboratory
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Philippe Lognonné
Université de Paris, Institut de physique du globe de Paris
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Jan ten Pierick
Institute of Geophyisics, ETH Zürich
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William Thomas Pike
Imperial College London
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Tilman Spohn
German Aerospace Center (DLR), Institute of Planetary Research
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Simon C. Stähler
Eidgenössische Technische Hochschule Zürich
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Peter Zweifel
Institute of Geophysics, ETH Zürich
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Abstract

The NASA InSight lander successfully placed a seismometer on the surface of Mars. Alongside, a hammering device was deployed that penetrated into the ground to attempt the first measurements of the planetary heat flow of Mars. The hammering of the heat probe generated repeated seismic signals that were registered by the seismometer and can potentially be used to image the shallow subsurface just below the lander. However, the broad frequency content of the seismic signals generated by the hammering extends beyond the Nyquist frequency governed by the seismometer's sampling rate of 100 samples per second. Here, we propose an algorithm to reconstruct the seismic signals beyond the classical sampling limits. We exploit the structure in the data due to thousands of repeated, only gradually varying hammering signals as the heat probe slowly penetrates into the ground. In addition, we make use of the fact that repeated hammering signals are sub-sampled differently due to the unsynchronised timing between the hammer strikes and the seismometer recordings. This allows us to reconstruct signals beyond the classical Nyquist frequency limit by enforcing a sparsity constraint on the signal in a modified Radon transform domain. Using both synthetic data and actual data recorded on Mars, we show how the proposed algorithm can be used to reconstruct the high-frequency hammering signal at very high resolution. In this way, we were able to constrain the seismic velocity of the top first meter of the Martian regolith.
Aug 2021Published in Earth and Space Science volume 8 issue 8. 10.1029/2020EA001234