Fig. 6
adapted from ejected blocks around fresh impact craters (Krishna and Kumar 2016). The blocks have an assigned relative permittivity of 7.5 and thicknesses of ~ 0.35 m. The width of the cavity is assumed to be ~ 4 m here, and its height is set to ~ 3 m. Small irregularly shaped rocks are added at the bottom of the cavity. Multilayered structures are implanted within the shallow regolith, as shown in Fig. 4. The background relative permittivity is cited from the empirical equation of the Apollo core samples (Carrier et al. 1991). b Simulated radargram based on the model shown in panel a. c Annotated phase reversals in the simulated radargram, and the positive and negative amplitudes of the echo patterns are shown in green and red, respectively. d and e are the observed radargram and annotated phase reversals, respectively
Comparison between the observed radargram and that derived from a more realistic regolith model that contains a subsurface cavity. a A complex yet still simplified subsurface cavity model in lunar regolith. Blocks supporting the subsurface cavity have shapes