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Since early 2019, the Lunar Penetrating Radar (LPR) onboard Chang'e‐4 (CE‐4)'s Yutu‐2 rover has been gathering data relating to the subsurface structure of the Von Kármán crater within the South Pole‐Aitken Basin (SPA) on the lunar farside. Low‐frequency radar data have the potential of carrying geological information of about 300 m worth of strata below the traversed path. Forty‐two days' data have revealed a bifurcated structure within the layered structure beneath the CE‐4 surveying area for the first time, affecting the overlying reflectors between 90 and 310 m. This study suggests that, based on the morphological characteristics, thickness, depth (timing sequence) and direction of the newly found structure, its origin might be linked to the deposition of ejecta from the Schrödinger impact. The local stratigraphy is interpreted as consisting of distinct geological layers, corresponding to the superposition of ejecta from different impact craters, paleo‐regolith, and basaltic lava flows. Plain Language Summary: A radar (the Lunar Penetrating Radar, or LPR), built to look at the rocks below the surface, is presently traveling across an area of the lunar farside onboard a rover, called Yutu‐2 sent by China to shed some light on the striking difference between the Earth‐facing side of the Moon and its farside. So far, the radar has revealed layered structures interpreted as distinct volcanic flows, thus helping to unravel their history. The rover has been surveying the floor of the Von Kármán crater inside one of the oldest and largest impact structures of the Moon, the South Pole‐Aitken (SPA) Basin. By analyzing 42 lunar days of data, we found a new layer with a hunched upper surface and a relatively flat bottom inserted into a multilayered structure. Based on the morphology, thickness, depth, and direction of the new feature, we argue that its source could represent the ejecta deposition from one of the ancient lunar impact basins: Schrödinger. The subsurface structure revealed by the radar shows a complicated geologic history on the farside including multiple lava eruption events, the deposition of ejecta from different impact craters and weathering layers that develop during the quiescent stage. Key Points: The CH‐1 Lunar Penetrating Radar data of Chang'e‐4 reveals ∼300 m deep subsurface stratigraphy of the lunar farsideA unique bifurcated structure that resembles an ejecta discontinuity affects the overlying and underlying strataThe geologic evolution of the Von Kármán crater and the ejecta layer might be connected to the Schrödinger basin [ABSTRACT FROM AUTHOR]

The current paper investigates the shallow layers of the lunar regolith at the Chang'E‐4 landing site. Four layers between 0 and 10 m were identified using lunar penetrating radar. Based on these outputs, a revised stratigraphic model is suggested for the post‐Imbrian ejecta at the Von Kármán crater. The layers were previously unseen due to the smooth boundaries between them. The revised model was inferred using an advanced hyperbola‐fitting scheme. Applying conventional hyperbola‐fitting to non‐homogeneous media results in errors and inaccuracies that are often wrongly assumed to be negligible. We propose a novel hyperbola‐fitting scheme that is, not constrained to homogeneous media and can be applied subject to any arbitrary one‐dimensional permittivity distribution. Via this approach, we can estimate the permittivity profile of an investigated area and detect layered structures that were previously transparent to electromagnetic waves due to the gradational dielectric properties at their interfaces. Plain Language Summary: The landing site of Chang'E‐4 is at the Von Kármán (VK) crater at the South Pole‐Aitken (SPA) basin. The SPA basin is the oldest and biggest basin on the Moon created at the early stages of its evolution by an impact that is, believed to have penetrated the lunar crust and uplifted materials from the top mantle. Understanding the geology and stratigraphy of the SPA basin can help us understand cratering processes and shed light on the evolution of the Moon. To that extent, ground penetrating radar (GPR) has been added to the payload of Yutu‐2 to investigate the stratigraphy of the Chang'E‐4 landing site. One drawback of GPR is that conventional processing methods fail to detect layers with smooth boundaries between them. Consequently, GPR data might give the false impression that an area is relatively homogenous, while in fact it might consist of numerous gradational layers representing a much more complex geological history. In the current paper, a novel interpretation tool is described, capable of detecting smooth transitions between layers. The proposed methodology revealed a previously unseen layered structure for the first ∼10 m of the VK crater. Key Points: We suggest a novel hyperbola‐fitting technique that assumes an arbitrary permittivity distribution with respect to depthThe proposed method is used to map the lunar regolith at the Chang'E‐4 landing siteA layered structure is revealed at the first 10 meters. A new stratigraphic model is suggested for the Von Kármán crater [ABSTRACT FROM AUTHOR]

The Chang'E‐4 (CE‐4) achieved the first successful soft landing on the floor of the Von Kármán crater located in the northeast of the South Pole‐Aitken (SPA) basin on the Moon. Here, through analysis and processing of the dual‐channel lunar penetrating radar (LPR) data, the shallow regolith structure and deep geological strata below the landing site are exposed. The high‐frequency data (CH‐2, 500 MHz) show that the Von Kármán crater underwent remodeling because of ejecta from multiple craters within a thickness of 40 m. Under the surface fine‐grained regolith, superpositions among these crater materials and mare basalt units establish shallow regolith stratigraphic sequences. The low‐frequency data (CH‐1, 60 MHz) show a deep stratigraphic structure to the depth of 360 m that indicates the previous geological evolution history of the Von Kármán crater. The LPR results provide an important scientific basis for understanding the geological history of the far side of the Moon. Plain Language Summary: The Chang'E‐4 (CE‐4) landed in the Von Kármán crater, which is located on the far side of the Moon. The lunar penetrating radar (LPR) loaded on the Yutu‐2 rover can be used to determine the shallow lunar regolith structure and deep geological strata of the Von Kármán crater. In this article, first, different processing procedures focused on the two channels of LPR data (CH‐1 and CH‐2) are designed, and clear radar images that can be used to explain the underground structure of the Von Kármán crater are obtained. The radar images are then combined with previous geological information to reveal the subsurface geological structure of the Von Kármán crater. The Von Kármán crater underwent various geological processes, including basaltic magmatism, ejecta coverage, and the interaction of volcanic eruptive clastics and lava. The regolith layer on the surface has a thickness of more than 10 m, and below the regolith layer is a multilayer formed by the ejecta material of surrounding impacts, which is as thick as more than 30 m. Underneath are three basalt magma covers. Key Points: The CH‐2 LPR data reveal that the landing site underwent remodeling because of ejecta from multiple craters within a thickness of 40 mThe CH‐1 LPR data provide the deep stratigraphic structure within 360 m, including more than three basalt magma activitiesThe LPR data demonstrate that the Von Kármán crater was landscaped by various geological processes [ABSTRACT FROM AUTHOR]