Lunar exploration is of significant importance in the development and utilization of in situ lunar resources, water ice exploration, and astronomical science. In recent years, ground-based radar (GBR) has gained increasing attention in the field of lunar exploration due to its flexibility, low cost, and penetrating capabilities. This paper reviews the scientific research on lunar exploration using GBR, outlining the basic principles of GBR and the progress made in lunar exploration studies. Our paper introduces the fundamental principles of lunar imaging using GBR and systematically reviews studies on lunar surface/subsurface detection, the dielectric properties inversion of the lunar regolith, and polar water ice detection using GBR. In particular, the paper summarizes the current development status of the Chinese GBR and forecasts future development trends in China. This review will enhance the understanding of lunar exploration results using GBR radar, systematically demonstrate the main applications and scientific achievements of GBR in lunar exploration, and provide a reference for GBR radar in future lunar exploration missions.

Early Mars is believed to have had extensive liquid water activity, which has now predominantly transitioned to a frozen state, with the majority of water stored in polar ice caps. It has long been deemed that the shallow subsurface of Mars' mid-to-low latitudes is devoid of liquid water. However, geological features observed at the Tianwen-1 landing site hint potential subsurface water. Our research indicates that the shallow subsurface at the Tianwen-1 landing site consists primarily of diluvium deposits containing liquid brine and brine ice, which exhibits diurnal thermal convection processes. Here we report the relationship between the loss tangent and temperature of materials within 5 meters depth of the subsurface at the Tianwen-1 landing site, as in-situ detected by high-frequency radar and climate station onboard the Zhurong rover. When the strata temperature exceeds ~ 240 K, the mixed brine ice transitions to liquid brine, significantly increasing the loss tangent from an average of ~ 0.0167 to a maximum of ~ 0.0448. This finding indicates the presence of substantial subsurface water in Mars' mid-to-low latitudes, influencing the shallow subsurface heat distribution and contributing to the current Martian hydrological cycle.

Small impact craters within the Martian north polar layered deposits (NPLDs) provide localized geomorphic records of surface modification within an ice-rich polar environment. We investigate a small crater in Mare Boreum using CTX and multi-temporal HiRISE imagery, HiRISE-derived topography, and regional constraints from MOLA, TES, GRS, SHARAD, and geological mapping. The crater retains a sub-circular planform but exhibits markedly subdued topographic expression, including attenuated rim relief and a shallow interior. HiRISE-derived topography indicates substantially reduced relief relative to fresh-crater morphometric expectations for a feature of comparable scale. The coexistence of a preserved planform and strongly attenuated relief indicates substantial cumulative post-impact modification. Multi-temporal HiRISE observations resolve the crater rim, interior, and illumination-sensitive surface features under broadly comparable seasonal conditions. Regional geological, thermophysical, geochemical, and radar observations constrain the broader ice-rich polar setting but do not resolve crater-scale composition, infill, or subsurface structure. The observed morphology is consistent with cumulative modification that may include depositional infilling, sublimation-related redistribution, rim degradation, and relaxation within the NPLDs, although the relative contributions of these processes cannot be uniquely determined from the available orbital observations.

The cosmos, replete with the elemental diversity of Earth, continues to cloak the existence of extraterrestrial life in mystery. Vital to the search for life is the identification of environments that can support biological processes. This review synthesizes current knowledge on the conditions necessary for life, with a special focus on extremophiles. These organisms, thriving under extreme conditions, illustrate the robust adaptability required for life beyond Earth. We examine the evolutionary adaptations on Earth to provide a framework for potential analogues on other celestial bodies. Importantly, this paper reports the initial identification of approximately three hundred three (∼ 303) sites on Mars as potential habitats intriguingly considered as potential Mars Cave Candidates (MCC) based on meticulous visual interpretations, and require detailed investigation to confirm their nature, whether as caves, other geological features, or craters. These investigations are currently ongoing, highlighting the dynamic and exploratory nature of Martian research. The findings are preliminary and serve to inform the development of robotic exploration strategies aimed at in-depth study of these environments, thereby advancing the astrobiological search for life. This review sets strategic directions for future research, aiming to refine our approach to uncovering where and how life could exist across the cosmos. By guiding future missions, both robotic and astrobiological, this work seeks to deepen our understanding of potential extraterrestrial habitats and to foster a systematic exploration of these promising sites.