Robert Vernon Wagner

Observing the aftermath of recent impact events on the Moon tests models of impact frequency, surface change rates, and cratering physics. The Lunar Reconnaissance Orbiter Camera (LROC) Wide Angle Camera (WAC; 100-meter scale) images the whole Moon each month and has done so since 2010. Comparing images from two months under similar lighting conditions enables automated detection of surface changes. In fall 2025, a routine temporal comparison of WAC image sets revealed a new 222-meter-diameter crater that formed in spring 2024. This is the largest contemporary impact crater found in the Solar System and, according to current models, a once-in-132-year event. Later, a series of LROC Narrow Angle Camera (NAC) images provided high-resolution (meter-scale) photometric and topographic information. These images show that the crater exposed complex geology, inform current models of cratering mechanics, and document widespread surface changes extending more than 1000 crater radii.

Impact craters and subsequent secondary impacts from sparse distal ejecta alter the exposed lunar regolith and affect its maturity. Remotely sensed observations sample the upper few microns of regolith; therefore, our interpretations of the surface must account for alterations and localized churning from these impact events. We investigate several impact sites and examine the newly formed crater colors and photometric properties to gain insight into cratering mechanics and regolith alteration. Using temporal imaging, phase angle ratios, an empirical photometric function, and resolved Hapke parameter maps of the impact site, we map the exposure of immature material and identify distinct zones in the continuous ejecta layer that correspond to grain size or porosity differences. The proximal ejecta exhibit distinct high- and low-reflectance zones: color ratios indicate excavation of less mature material in the proximal high-reflectance zone, whereas the proximal low-reflectance zone is consistent with roughness and porosity changes in otherwise mature material. Furthermore, we identify distal reflectance rays that extend much farther (over 1000 crater diameters) than previous studies have measured or modeled. The absence of a corresponding visible color change in distal zones, coupled with phase-dependent contrast and Hapke inversions, indicates that distal darkening is dominated by increased photometric roughness from sparse particle impacts rather than deposition of compositionally distinct material. These results show that small impacts modify the lunar surface over much larger areas than previously recognized, reducing grain- and facet-level exposure times to space weathering and implying faster, more spatially extensive regolith gardening.

Airless bodies such as the Moon, Mercury, and Ceres have permanently shaded regions (PSRs) that can cold trap water ice. Mercury and Ceres have substantial ice deposits in their PSRs, but lunar water ice distribution remains uncertain because of sparse detections and limited data. Here, we assessed surficial water ice in lunar PSRs using high-resolution observations from ShadowCam onboard the Korea Pathfinder Lunar Orbiter. We used the high-reflectance and forward-scattering optical properties to search for water ice in lunar PSRs. We found no evidence of widespread water ice in PSRs at abundances above the detection limit of 20 to 30 wt % but could not rule out widespread low-content water ice. A few small locations with both high reflectance and forward-scattering behavior were observed, which could be consistent with >10 wt % ice. Future missions with low detection limits (<1 wt %) of water ice can test our findings.

The Lunar Reconnaissance Orbiter Camera (LROC) Narrow Angle Camera (NAC) and Korea Pathfinder Lunar Orbiter (KPLO) ShadowCam provide high-resolution (0.5–2 m per pixel) images of the Moon. These high-resolution images facilitate the creation of highly detailed controlled mosaics, which can be used for applications such as regional geomorphic maps, crater size-frequency distribution analysis, and mission planning. We establish the methodology used to produce most of our LROC NAC and ShadowCam regional controlled mosaics, conduct an analysis of the accuracy of our controlled mosaics, and discuss the utility of these products. This accuracy analysis includes a comprehensive analysis of the bundle adjustment results for both our LROC NAC and ShadowCam controlled mosaics and a comprehensive analysis of the positional accuracy of our LROC NAC controlled mosaics, with median positional offsets of our NAC controlled mosaics being <12 m in latitude and <5 m in longitude.

Exploration of the lunar poles is accelerating as multiple missions target these regions, with growing interest in studying the environment within permanently shadowed regions (PSRs)—areas at the poles that never receive direct sunlight. To prepare for these exploration activities within PSRs, we determined radiance levels in PSRs of various sizes and derived a conversion factor from ShadowCam radiance units to luminance, which is more suitable for evaluating human factors, as luminance accounts for the wavelength range to which humans are sensitive. Notably, during lunar summer, many PSRs reach luminance levels comparable to those of well-lit buildings for several Earth days each month, while peak winter lighting is typically up to six times dimmer, except in regions where regional shadows predominate and further decrease illumination. As a result, we do not expect artificial light to be needed for missions visiting PSRs during the summer peak lighting period, except for close inspection of samples. In contrast, in winter, diminished ambient lighting may require supplemental illumination for many tasks.

Surface water ice within lunar permanently shadowed regions (PSRs) could have an enhanced visible wavelength reflectance relative to lunar regolith. Moon Mineralogy Mapper (M³) infrared spectroscopic detections compose one data set previously interpreted as surface ice occurrences within the PSRs. Here we investigate the M³ water ice identifications at higher resolution with broadband visible-wavelength mosaicked images (60 m pixel scale) obtained by the ShadowCam instrument aboard the Korea Aerospace Research Institute Korea Lunar Pathfinder Orbiter. Individual M³ positive water ice detections show no radiance contrast with their surroundings. However, north polar PSRs with at least one M³ water ice detection have a ∼4.4× higher modal radiance than those lacking M³ water ice detections, although this cannot be definitively attributed to water ice. Our findings are consistent with previous estimates of ice abundance as being less than ∼30 wt%, resulting in contrast too small to be detected by the ShadowCam instrument.

The ShadowCam instrument on the Danuri spacecraft provides high-resolution views of shadowed portions of the Moon, which are illuminated by naturally scattered light from nearby sunlit terrain. The sensitive time-delay integration detector captures high signal-to-noise observations within the permanently shadowed regions and areas in shadow for part of the year. We characterized the geometric properties of the images, enabling accurate placement of observations within the lunar cartographic framework. This work describes the internal and external orientation parameters using laboratory observations and images collected during the cruise and commissioning phase of the mission. We identified a radial distortion in the cross-track direction from these observations, which is correctable during our standard calibration pipeline procedures. We also calculated the pointing of the camera relative to the spacecraft bus within ~0.001°. Using these models, corrections, and the initial ephemeris provided by the Korea Aerospace Research Institute, images can be aligned within 60 m on the surface (95% confidence interval). This calibration and a precise radiometric model will enable reliable interpretation of ShadowCam images and the development of future derived products, including precisely mapped mosaics and meter-scale digital elevation models.

Faustini crater (41 km diameter) hosts a large (664 km²) permanently shadowed region (PSR) with a high potential to harbor water-ice deposits. One of the 13 candidate Artemis III landing areas contains a portion of the crater rim and proximal ejecta. The ShadowCam instrument aboard the Korea Pathfinder Lunar Orbiter provides detailed images of the PSR within Faustini. We characterize the terrain and thermal environment within the Faustini PSR from ShadowCam images, Lunar Reconnaissance Orbiter thermal measurements and laser ranging, and thermal modeling. Our mapping revealed three distinct areas of the floor of Faustini based on elevations, slopes, and surface roughness. These units broadly correlate with temperatures; thus, they may be influenced by variations in volatile sublimation. Crater retention and topographic diffusion rates appear to be asymmetric across the floor, likely due to differences in maximum and average temperatures. Several irregular depressions and a pronounced lobate-rim crater are consistent with subsurface ice. However, differences in the thicknesses of deposited materials on the floor may also explain the asymmetry. Additionally, zones of elevated surface roughness across Faustini appear to result from overprinted crater ray segments, possibly from Tycho and Jackson craters. Mass wasting deposits and pitting on opposite sides of the crater wall may have resulted from the low-angle delivery of material ejected by the Shackleton crater impact event, suggesting that the Artemis III candidate landing region named “Faustini Rim A” will contain material from Shackleton.

The Lunar Reconnaissance Orbiter Camera (LROC) Narrow Angle Camera (NAC) images and their derived products make up one of the highest-resolution and most spatially accurate data sets available for the Moon, making them a crucial resource for planners of landed lunar missions. However, it is essential to understand the best uses for each data type and the limits on the accuracy and resolution of the data sets available. With this understanding, users can better interpret and communicate their results. In this paper, we describe what assumptions may be made about the accuracy of LROC NAC images and the various derived products created by the LROC team. NAC digital terrain models and their corresponding orthophotos have the best accuracy of all NAC products, usually better than 10 m horizontally, and should be used where available. Other controlled NAC products usually have accuracies better than 30 m. For areas without controlled products, we describe how to process NAC images to obtain coordinates with the highest possible accuracy. We also recommend best practices for data users interacting with LROC data through online map servers, such as QuickMap or Lunaserv, and for processing LROC data locally using the US Geological Survey Integrated Software for Imagers and Spectrometers.

Investigations that can be conducted at the Artemis III candidate landing regions will benefit from the knowledge of the thermal environment within permanently shadowed regions (PSRs). Within PSRs, secondary illumination controls the surface temperature, varying diurnally and seasonally, affecting the stability and concentration of volatiles cold-trapped within the PSRs. In this case study, we characterize the dynamic nature of secondary illumination at four PSRs that overlap five of the Artemis III candidate landing regions. Our analysis is based on secondary illumination model-generated images paired with PSR images acquired by ShadowCam on board the Korean Pathfinder Lunar Orbiter. We find that illumination and thermal conditions can change rapidly within the PSRs, and knowledge of time-variable secondary illumination can be decisive for the efficient design of investigations and sample collection operations at the PSRs.