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Ultra-wideband SAR Tomography on asteroids
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  • Oriane Gassot,
  • Alain Hérique,
  • Wenzhe Fa,
  • Jun Du,
  • Wlodek Kofman
Oriane Gassot

Corresponding Author:oriane.gassot@univ-grenoble-alpes.fr

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Alain Hérique
French National Centre for Scientific Research (CNRS)
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Wenzhe Fa
Peking University
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Jun Du
Peking University
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Wlodek Kofman
Institute of Planetology and Astrophysics, Grenoble, France
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Our knowledge of the internal structure of asteroids is currently indirect and relies on inferences from remote sensing observations of surfaces. However, it is fundamental for understanding small bodies’ history and for planetary defense missions. Radar observation of asteroids is the most mature technique available to characterize their inner structure, and Synthetic Aperture Radar Tomography (TomoSAR) allows 3D imaging by extending the synthetic aperture principle in the elevation direction. However, as the geometry of observation of small asteroids is complex, and TomoSAR studies have always been performed in the Earth observation geometry, TomoSAR results in a small body geometry must be simulated to assess the methods’ performances. Different tomography algorithms can be adopted, depending on the characteristics of the problem. While the Frequency Domain Back Projection (FDBP) is based on the correction of the Fourier transform of the received signal by an ad-hoc function built from the geometry of study, it can only retrieve the true position of the scatterers when applied along with ray-tracing methods, which are unreliable in the case of rough asteroid surfaces. Meanwhile, the Compressive Sensing (CS) is based on the compressive sampling theory, which relies on the hypothesis that few scatterers lie in the same direction from the subsurface. The CS can be used to retrieve the position of the scatterers, but its application in the small body geometry is questioned. Thus, both performances of the FDBP and the CS in a small body geometry are demonstrated, and the quality of the reconstruction is analyzed.
Aug 2021Published in Radio Science volume 56 issue 8. 10.1029/2020RS007186