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Abstract:
In 2019, Chang’E-4 (CE-4) landed on the eastern floor of Von Kármán crater on farside of the Moon. The Yutu-2 rover of CE-4 mission carries a Lunar Penetration Radar (LPR) that is equipped with one transmitting and one receiving dipole antenna for 60 MHz, and one transmitting and two bow-tie receiving antennas for 500 MHz. LPR data acquired onboard the Moon Chang'E 4 mission rover Yutu-2 is used to quantify the attenuation within the regolith-dominated shallow subsurface on the Moon. The signal attenuation is estimated using a recently developed approach, based on the downshift of the centroid-frequency of the transmitted pulse, which is assumed to be a Ricker wavelet. In particular, the intrinsic attenuation, which is described in terms of the medium’s loss tangent, is retrieved from the back-scattered signals through a probabilistic inversion approach. In addition, the total energy loss (i.e., the sum of scattering and intrinsic losses), evaluated by the inverse quality factor is obtained from the linear fitting of the time amplitude decay. It is thus possible to separate the total loss to its composing components i.e., absorption and scattering terms. From the results, it appears that the intrinsic attenuation along the track is almost constant, while the total loss presents large variations, that are caused by both subsurface inhomogeneities and scatters. In addition, the average loss tangent and total loss are, and respectively.
