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Geophysical observations of Phobos transits by InSight
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  • Simon C. Stähler,
  • Rudolf Widmer-Schnidrig,
  • John-Robert Scholz,
  • Martin van Driel,
  • Anna Magdalena Mittelholz,
  • Kenneth Hurst,
  • Catherine L. Johnson,
  • Mark T Lemmon,
  • Ralph D. Lorenz,
  • Philippe Henri Lognonné,
  • Nils T Mueller,
  • Laurent Pou,
  • Aymeric Spiga,
  • Donald Banfield,
  • Savas Ceylan,
  • Constantinos Charalambous,
  • Domenico Giardini,
  • Francis Nimmo,
  • Mark Paul Panning,
  • Walter Zürn,
  • William Bruce Banerdt
Simon C. Stähler
Eidgenössische Technische Hochschule Zürich

Corresponding Author:[email protected]

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Rudolf Widmer-Schnidrig
Black Forest Observatory, Institute of Geodesy, Stuttgart University, Heubach 206, D-77709 Wolfach, Germany
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John-Robert Scholz
Max Planck Institute for Solar System Research, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
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Martin van Driel
ETH Zürich
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Anna Magdalena Mittelholz
The University of British Columbia
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Kenneth Hurst
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
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Catherine L. Johnson
University of British Columbia
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Mark T Lemmon
Space Science Institute
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Ralph D. Lorenz
Johns Hopkins University Applied Physics Lab
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Philippe Henri Lognonné
Institut de Physique du Globe de Paris et Université de Paris Diderot
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Nils T Mueller
German Aerospace Center (DLR), Institute of Planetary Research
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Laurent Pou
Dept. of Earth and Planetary Sciences, University of California Santa Cruz, Santa Cruz, CA 95064, USA
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Aymeric Spiga
Sorbonne Université (Faculté des Sciences)
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Donald Banfield
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Savas Ceylan
ETH Zurich
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Constantinos Charalambous
Imperial College London
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Domenico Giardini
ETH Zürich
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Francis Nimmo
University of California, Santa Cruz
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Mark Paul Panning
Jet Propulsion Laboratory, California Institute of Technology
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Walter Zürn
Black Forest Observatory (Schiltach), Universities Karlsruhe/Stuttgart
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William Bruce Banerdt
Jet Propulsion Laboratory
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Since landing on Mars, the NASA InSight lander has witnessed 8 Phobos and one Deimos transit. All transits could be observed by a drop in the solar array current and the surface temperature, but more surprisingly, for several ones, a clear signature was recorded with the seismic sensors and the magnetometer. We present a preliminary interpretation of the seismometer data as temperature induced local deformation of the ground, supported by terrestrial analog experiments and finite-element modelling. The magnetic signature is most likely induced by changing currents from the solar arrays. While the observations are not fully understood yet, the recording of transit-related phenomena with high sampling rate will allow more precise measurements of the transit times, thus providing additional constraints for the orbital parameters of Phobos. The response of the seismometer can potentially also be used to constrain the thermo-elastic properties of the shallow regolith at the landing site.
16 Oct 2020Published in Geophysical Research Letters volume 47 issue 19. 10.1029/2020GL089099