Numerical Verification of Full Waveform Inversion for the Chang'E-5
Lunar Penetrating Array Radar
Abstract
One of the scientific payloads of Chang’E-5 (CE-5), i.e., the lunar
penetrating array radar (LRPR), will carry out the in situ exploration
of the regolith structure and guide the drilling sampling process. To
evaluate the performance of the LRPR system, we present a multifrequency
full-waveform inversion (FWI) with the total variation (TV)
regularization constraint using simulated CE-5 LRPR data for imaging the
regolith structure and estimating the physical parameters (permittivity
and conductivity). The multifrequency FWI strategy is used to improve
the inversion resolution, which updates the low-frequency gradient for
the deep region and then increases the frequency range to update the
shallow region. The TV regular-ization constraint not only reduces the
gradient noise but also improves the inversion accuracy of local
structures. To evaluate the actual LRPR measurement scenario, we use the
actual source wavelet obtained from the LRPR instrument prototype in a
ground lab to replace the theoretical Ricker wavelet. The actual source
includes the effect of antenna radiation patterns and clutter noise from
the metallic lander. Two typical heterogeneous lunar regolith model
tests demonstrate that the proposed FWI scheme effectively reduces the
lander metal impact, provides a reliable way to estimate the lunar
regolith physical parameters and image the subsurface structures.