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Finding SEIS North on Mars: Comparisons between SEIS sundial, Inertial and Imaging measurements and consequences for seismic analysis
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  • Denis Savoie,
  • Andy Richard,
  • Marc Goutaudier,
  • Philippe Henri Lognonné,
  • Kenneth Hurst,
  • Justin N. Maki,
  • Matthew P. Golombek,
  • Martin van Driel,
  • John Clinton,
  • Eleonore Stutzmann,
  • David Mimoun,
  • William Bruce Banerdt,
  • Nathan Robert Williams
Denis Savoie
Observatoire de Paris
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Andy Richard
Palais de la decouverte
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Marc Goutaudier
Palais de la decouverte
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Philippe Henri Lognonné
Institut de Physique du Globe de Paris et Université de Paris Diderot

Corresponding Author:[email protected]

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Kenneth Hurst
Jet Propulsion Laboratory
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Justin N. Maki
Jet Propulsion Laboratory, California Institute of Technology
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Matthew P. Golombek
California Institute of Technology/JPL
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Martin van Driel
ETH Zurich
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John Clinton
Swiss Seismological Service
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Eleonore Stutzmann
Institut De Physique Du Globe De Paris
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David Mimoun
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William Bruce Banerdt
Jet Propulsion Laboratory (NASA)
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Nathan Robert Williams
Jet Propulsion Lab
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In this paper, we present the results obtained in the determination of the true North direction on Mars by using a gnomon on the InSight mission and compare the measurements with either the North determination from the Inertial Measurement Unit and Imaging analysis. The obtained measurement has been use to populate the SEIS orientation information in the archived SEIS data. Images taken during December 2018 and January 2019 allows to determine the gnomon shadow position and length over a target. By calculating the Sun local coordinates using planetary ephemeris VSOP87, the images are used to estimate the true North direction on the landing site. By using eight different images, we obtain the true North direction with an accuracy up to $2.5^{\circ}$, which is confirmed by the IMU and Imaging analysis. The true North direction is also confirmed by an image taken near local noon, when the sun crosses the meridian. The North determination precision is then discussed in view of the seismic determination of the back-azimuth.
Mar 2021Published in Earth and Space Science volume 8 issue 3. 10.1029/2020EA001286