Ultra‐Wideband SAR Tomography on Asteroids. Issue 8 (24th August 2021)

• Record Type: Journal Article
• Authors: Gassot, Oriane; Herique, Alain; Fa, Wenzhe; Du, Jun; Kofman, Wlodek
• Is Part Of: Radio science. Volume 56:Issue 8(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-08-24
• Subjects: asteroids -- Synthetic Aperture Radar -- SAR tomography -- simulation; Radio meteorology -- Periodicals; Radio wave propagation -- Periodicals; 621.38405
• DOI: 10.1029/2020RS007186
• Languages: English
• ISSNs: 0048-6604

Abstract

Abstract: 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 of their interior. However, as the geometry of observation of small asteroids is complex, and TomoSAR studies have always been performed in the Earth observation geometry, its results in a small body geometry must be simulated to assess the methods' performances. We adopt here two different tomography algorithms and evaluate their performances in our geometry by assessing the resolution and the difference between the scatterer's position and its retrieved position. The first method, the Frequency Domain Back Projection (FDBP) is based on correcting the Fourier transform of the received signal by a phase function built from the geometry. While it can provide a good resolution, a bias remains in the imaged scatterer's position. Meanwhile, Compressive Sensing (CS) relies on the hypothesis that few scatterers lie in the same direction from the subsurface. Its application in the small body geometry is studied, which results in a slightly impoverished resolution but an improved localization of the scatterer. Key Points: High‐Frequency Radar (HFR) is an UWB Synthetic Aperture Radar (SAR) developed to retrieve the 3D structure of the first 10 m of an asteroid's subsurface SAR Tomography (TomoSAR) is crucial to improve the resolution in the vertical direction In the specific asteroid geometry, simulations are necessary the assess the performances of the TomoSAR algorithms