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 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.