Shackleton Crater Research Articles

Shape-from-Shading Derived DEMs from ShadowCam Images in Permanently Shadowed Regions at the Lunar South Pole: A First Look

Abstract. The lunar south pole, particularly its permanently shadowed regions (PSRs), has been the focus of future lunar exploration. The solar altitude angle at the lunar south pole is less than ∼ 2°, resulting in the PSRs not being directly illuminated and the possible existence of water ice in the PSRs due to the low temperatures. High-resolution digital elevation models (DEMs) in PSRs are crucial for future exploration missions and scientific research. However, existing image datasets (e.g., LROC NAC images) cannot penetrate the PSRs. Laser altimetry (e.g., LOLA) can measure the PSRs, but the DEMs derived from LOLA suffer from noises and interpolation defects. ShadowCam is a newly deployed camera onboard the Korea Pathfinder Lunar Orbiter, with a high imaging sensitivity. ShadowCam can capture the faint secondary illumination within PSRs, revealing previously indistinguishable topographic features in persistent darkness. Based on our existing Shape-from-Shading (SfS) pipeline for generating high-resolution DEMs from monocular images, we introduce a novel SfS approach that utilizes secondary illumination and reflectance to reconstruct pixel-wise high-resolution DEMs from ShadowCam images in PSRs. The approach consists of three steps: (1) modeling the secondary illumination on the target surfaces in PSRs based on the view factor; (2) optimizing a low-resolution LOLA DEM using the secondary illumination model; (3) refining the DEM to pixel-wise resolution based on SfS using the ShadowCam images. A test area (approximately 1 km × 1 km) within the PSR in the Shackleton crater near the lunar south pole is used for experimental evaluation. The results show that the DEM generated by the proposed approach is highly consistent with the direct LOLA measurements, particularly in small-scale topographic features such as crater floors and rims that are absent from the LOLA DEM. A first look at the results indicates that the proposed approach has great potential for generating high-resolution DEMs from ShadowCam images in PSRs, which can aid future exploration missions targeting the PSRs at the lunar south pole and support related scientific research on the water ice in the PSRs.

The Faustini Permanently Shadowed Region on the Moon

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.

Tectonics and Seismicity of the Lunar South Polar Region

The lunar south pole regions are subjected to global stresses that result in contractional deformation and associated seismicity. This deformation is mainly expressed by lobate thrust fault scarps; examples are globally distributed, including polar regions. One small cluster of lobate scarps falls within the de Gerlache Rim 2 Artemis III candidate landing region. The formation of the largest de Gerlache scarp, less than 60 km from the pole, may have been the source of one of the strongest shallow moonquakes recorded by the Apollo Passive Seismic Network. The scarp is within a probabilistic space of relocated epicenters for this event determined in a previous study. Modeling suggests that a shallow moonquake with an M w of ∼5.3 may have formed the lobate thrust fault scarp. We modeled the peak ground acceleration generated by such an event and found that strong to moderate ground shaking is predicted at a distance from the source of at least ∼40 km, while moderate to light shaking may extend beyond ∼50 km. Models of the slope stability in the south polar region predict that most of the steep slopes in Shackleton crater are susceptible to regolith landslides. Light seismic shaking may be all that is necessary to trigger regolith landslides, particularly if the regolith has low cohesion (on the order of ∼0.1 kPa). The potential of strong seismic events from active thrust faults should be considered when preparing and locating permanent outposts and pose a possible hazard to future robotic and human exploration of the south polar region.

Scientific objectives and payload configuration of the Chang'E-7 mission.

As the cornerstone mission of the fourth phase of the Chinese Lunar Exploration Program, Chang'E-7 (CE-7) was officially approved, and implementation started in 2022, including a main probe and a communication relay satellite. The main probe, consisting of an orbiter, a lander, a rover and a mini-flying probe, is scheduled to be launched in 2026. The lander will land on Shackleton crater's illuminated rim near the lunar south pole, along with the rover and mini-flying probe. The relay satellite (named Queqiao-2) will be launched in February 2024 as an independent mission to support relay communication during scientific exploration undertaken by Chang'E-4, the upcoming Chang'E-6 in 2024 and subsequent lunar missions. The CE-7 mission is mainly aimed at scientific and resource exploration of the lunar south pole. We present CE-7's scientific objectives, the scientific payloads configuration and the main functions for each scientific payload with its key technical specifications.

Preliminary Characterization of Secondary Illumination at Shackleton Crater Permanently Shadowed Region from ShadowCam Observations and Modeling

Lunar permanently shadowed regions (PSRs) never see direct sunlight and are illuminated only by secondary illumination - light reflected from nearby topography. The ShadowCam imaging experiment onboard the Korea Pathfinder Lunar Orbiter is acquiring images of these PSRs. We characterize and discuss the nature of secondary illumination for the Shackleton PSR from ShadowCam radiance-calibrated images. We also use modeling to understand the magnitude and direction of the secondary illumination. Results from our analysis highlight the non-homogeneous, dynamic, and complex nature of PSR secondary lighting. Knowledge of the direction of the secondary illumination is crucial for reli-able interpretation of contrasts observed in ShadowCam images. This preliminary analysis of the floor of Shackleton crater from images acquired over multiple secondary illumination conditions does not reveal indications of exposed surface ice, even though temperatures are constantly below 110K.

Hidden morphology of Shackleton Crater, lunar South Pole

The article's goal is the detailed description of geomorphologic structures on the floor and interior walls of Shackleton Crater and a reconstruction of their formation histories.A Digital Elevation Model (DEM) with 20 m grid was constructed for the area around the crater based on Lunar Orbiter Laser Altimeter (LOLA) data. The DEM was analysed for slope steepness, Maximal Catchment Area (MCA) and four curvatures: maximal (kmax), minimal (kmin), horizontal (kh) and vertical (kv). Using this extensive set of Morphometric Variables (MVs) for the first time for a detail lunar DEM revealed unknown structures in permanently shaded areas.The previously identified large elevated structures “A" and “C" are attributed to landslides. “A" is related to a relatively large meteoroid impact that produced a recognisable crater on the exterior slope of Shackleton. “C" is associated with a landslide scar affecting the rim of Shackleton Crater directly above it. Structure “B” is not related to landsliding, but without of additional high-resolution geophysical data, its origin remains unclear.The low number of small impact craters on the steep slopes and sediment fields indicates ongoing surface erosion due to migration of unconsolidated fine grains and their deposition downslope. The foot slope zone is characterised by multiple accumulations of debris flows in the form of thin strips, identified as local landforms with kh > 0. On the surface of elevated structures “A”, “B” and “C” the map of kh reveals tree-like structures – erosion forms previously unknown in lunar geomorphology. These structures are formed by branching spurs characterised by several orders. The spurs are located relatively perpendicularly to the altitude isolines.The thickest (up to 120 m) slope deposits form a relatively flat area between the elevated structure “B" and the crater wall. These deposits should be of the greatest interest for future investigations searching for buried volatiles mixed with slope deposits.

Illumination conditions near the Moon's south pole: Implication for a concept design of China's Chang’E−7 lunar polar exploration

Volatiles including water on the Moon has been one of the most interesting scientific objects for decades. In this study, we systematically introduced a concept for China's Chang’E−7 (CE-7) lunar polar exploration mission which consists of five elements, the orbiter, lander, rover, and leaper, and one relay satellite. The orbiter will provide a high-resolution image preparing for landing site selection. We also proposed three phases for in-situ investigation after landing. (1) The rover and leaper will jointly investigate the sunlit area; (2) the leaper will explore cold traps; and (3) the leaper will fly back to the sunlit area and continue an extended exploration mission. An experimental penetrator launched by the lander will penetrate permanently shadowed crater walls for water ice detection. Data will be transmitted to Earth through the relay satellite due to the limited Earth visibility. We also calculated the illumination rate within a 15 × 15 km area that partially covers the Shackleton crater at a high spatial resolution of 20 m/pixel during lunar southern summer. Specifically, we compared two potential landing sites with accumulated illumination at different altitude levels, slopes, and distances to the target. We found that one part of the Shackleton crater rim can be a primary landing site for CE-7's both sunlit areas and cold trap explorations.

Illumination and regolith temperature at China’s next candidate lunar landing site Shackleton crater

This study focuses on the illumination and temperature at China’s next lunar candidate landing site Shackleton crater. We used the NASA’s SPICE system to evaluate the terrain obscuration effect on real-time illumination; the resulting illumination map resembles previous studies, validating the methodologies used in our study. In addition, we estimated an accumulated illumination map for the period of likely rover movement. The map indicates the illuminated inner wall of the Shackleton crater is close to 27% of the whole, meaning that the rover will likely receive solar radiation during its movement. Using the real-time illumination and the distributed 1-D thermal diffusion model, we continuously evaluated the regolith temperature for more than 20 years to stabilize the temperature, and selected the temperature of the end time as the initial value used in a thermal study set for July 20, 2023 and May 8, 2027. Our results indicate the temperature in the permanent shadow region remains nearly constant, thus validating the stability of our estimated initial temperature. Our results also indicate that the surface temperature is more sensitive to transient illumination, but the subsurface temperature is more likely to be associated with the accumulated illumination. This difference indirectly implies that the conductivity of the lunar regolith is inefficient. The locations receiving more solar radiation show a temperature larger than the threshold (∼112 K) of ice stability. The permanently shadowed regions can be as cold as 25 K, and such extreme coldness is a hazard to the rover. There are suitable temperature locations which have a warm surface but cold subsurface to preserve water ice. To further ensure normal rover movement, we provided a map of suitable temperature sites and found that these locations exist not only in the Shackleton crater’s inner wall, but also outside the crater. We suggested four trade-off sampling sites with suitable temperatures and gradual slopes.

The Distribution and Accessibility of Geologic Targets near the Lunar South Pole and Candidate Artemis Landing Sites

Transformative lunar science will be driven by the accessibility, recovery, and return to Earth of geological specimens. Isolated boulders, rock exposures, and rocky craters at the lunar south pole all provide opportunities for geologic characterization and sampling of the lunar crust. Here, we present the results of orbital geological mapping of the region surrounding the south pole using Lunar Reconnaissance Orbiter Narrow Angle Camera images (0.5–2 m pixel−1). We mapped the distribution of isolated boulders (86,896), rocky craters (3556), and rock exposures (7553) around potential Artemis landing sites 001 and 004 (NASA 2020), which are within or near one of the Artemis III candidate landing regions. We found that boulder abundance decreases with increasing distance from the rim of Shackleton crater. From that correlation, we infer that most of the boulders and rock exposures near Shackleton were deposited as ejecta by the Shackleton impact, and by later the reworking of that material during smaller impact events. We additionally assessed the accessibility of the mapped features, and documented geologic targets located on shallow (<15°) slopes, including those on the Shackleton crater rim and on the “Connecting Ridge” between Shackleton and Henson crater. Such targets could be sampled by a future mission to the lunar south pole region. Our catalog of mapped features is made available to the lunar community.

Geomorphic map and science target identification on the Shackleton-de Gerlache ridge

Analogous to similar maps prepared in support of the Apollo missions, we produced a geomorphic map at a scale of 1:8000 of Artemis III Areas of Interest 001 and 004 on the Shackleton-de Gerlache ridge and the adjacent Shackleton crater rim to support future landed missions in the area. Using 1 m/pixel Lunar Reconnaissance Orbiter Narrow Angle Camera mosaics and 5 m/pixel topographic maps derived from Lunar Orbiter Laser Altimeter observations, we differentiated among ten units, all related to slope-controlled regolith processes or impacts, as well as among seven crater classes according to degradation state. Almost 85% of the map area outside of Shackleton crater are characterized by “elephant hide” textures at different intensities, which are mostly a function of the local slope angle. No signatures of the Shackleton ejecta blanket or a nearby Tycho ejecta ray were found in the morphology and crater statistics of our map area. We did, however, identify a potential lobate scarp and expanded on block detections by previous authors. We used our map to devise three consecutive traverse sequences named “Safe”, “Extended”, and “Increased risk”, which are each focused on maximizing sample yield and diversity to meet scientific objectives, while maintaining defined safety parameters. The three traverse sequences travel across respective maximum slopes of 10°, 15°, and 16°, have lengths of 3.6 km, 11.9 km, and 11.4 km, and each pass within sampling range of several block occurrences. The second traverse sequence “Extended” ends at a location with a direct line of sight into Shackleton crater, which would enable high-resolution observations using secondary illumination. The third traverse sequence “Increased risk” would conclude by reaching what might be a degraded Shackleton impact melt pond inside an adjacent, highly degraded crater. However, this sequence includes challenging illumination conditions and slopes up to 16° that warrant further investigations and hazard assessment. It should not be attempted until after key science questions are addressed during the preceding two traverse sequences. Based on their sizes, locations, and minor to moderate coverages by regolith, we interpret at least some of the blocks along each traverse sequence to be crustal fragments ejected during the Shackleton event or Shackleton rim material ejected by smaller craters. Thus, multiple locations along each traverse sequence provide the potential to not only investigate the unique south polar regolith, possible age signatures from Tycho, and potential volatiles in local micro-PSRs, but also the ages of Shackleton and the South Pole-Aitken basin.

Deployment Method and Optimal Placement of Surface Beacon Navigation System for Co-located Lunar Landings

Lunar Space exploration is currently accelerating, and manned and unmanned missions to the Moon are planned by several space agencies and private companies in the coming 5–10 years. The construction of the Lunar Orbital Platform Gateway (LOP-G) and plans to establish a more permanent human presence on the Lunar surface will increase the landing frequency and require the capability to safely soft-land successive missions in near proximity to each other. The lunar South Pole is one of the preferred locations for surface exploration due to the discovery of volatiles in the permanently shadowed craters at the poles. However, landing on the lunar South Pole of the Moon is challenging due to the illumination and loss of Earth line-of-sight conditions combined with complex topography. The increased interest in co-located lunar landings concurrent with construction of lunar infrastructure and a challenging landing area warrants new approaches in navigation technology.In this paper we present a concept for a system of radio beacons installed around the Shackleton crater rim “SR1” landing site on the lunar South Pole. We present considerations for optimal placement of the radio beacons based on the specific landing site topography and quantify our finding with dilution of precision (DOP) calculations. We present a novel method for deploying the radio beacons as penetrators with embedded thermoelectric generators (TEGs) for autonomous power generation. We present findings on beacon survivability, penetration depth, spin-stabilization of the penetrators and maximal theoretical power generation.

Numerical modeling of the formation of Shackleton crater at the lunar south pole

The lunar south pole, on the rim of Shackleton crater, is the target for the next human landing on the Moon. We use numerical modeling to investigate the formation of that crater and the distribution of ejecta around the south pole. We find that a 1.5 km diameter asteroid with a chondrite-like composition, vertically impacting a gabbroic anorthositic target at 15 km/s, forms a crater morphologically similar to Shackleton. If the impact had a shallower 45-degree trajectory, the asteroid may have had a diameter of 1.75 km and velocity of 15 km/s or a diameter of 1.5 km and velocity of 20 km/s. Impact melt is generated during the impact, with most of the melt volume ponding on the crater floor. We introduce a water-bearing layer at various depths in the target and find that the burial depth of a volatile layer influences the final crater morphology and may explain the morphology of Shackleton.

Geologic context and potential EVA targets at the lunar south pole

The lunar south pole is being targeted for exploration, in part, because it contains topographical high points with >50% illumination needed for solar power. Additionally, the south pole is being targeted because it contains permanently shadowed regions (PSRs), which may sequester resources in the form of volatile materials. Geologically, the pole lies on the rim of ~21 km diameter Shackleton crater, which is located on the topographic rim of the ~2,500 km diameter South Pole-Aitken (SPA) basin, the largest and oldest basin on the Moon. To prepare for future missions, we conducted a photogeologic analysis of the walls, rim, and ejecta of Shackleton crater. Two types of underlying (target) terrains were identified. The impact penetrated and exposed (1) purest anorthosite (PAN) representative of primitive crust and (2) a layered terrain that is likely a series of impact ejecta deposits that stratigraphically cover the crystalline crust. Crew performing extravehicular activities (EVAs) near the south pole may be able to sample PAN; impact melt from Shackleton, SPA, and other pre-Nectarian and Nectarian-age impacts; and polar regolith, including material from small PSRs that may contain volatile components. The topography in the south polar region is dramatic, often producing slopes in excess of 15°, creating mobility challenges for astronauts during EVAs.

Tribocharging and electrical grounding of a drill in shadowed regions of the Moon

We present a first estimate of the triboelectric charging generated by a drill in Shackleton crater; a permanently shadowed region at the Moon’s south pole. The results depend upon the local plasma environment as well as material properties of the drill and lunar regolith. We show how in the dark plasma-poor regions, a high voltage can accumulate due to the negligible electrical grounding, leading to a potential hazard for explorers and their equipment. To mitigate this problem, two grounding solutions are described: (i) A sun-facing surface outside of the shadowed region and (ii) a portable UV ionization lamp. The two solutions are physically analogous, depleting charge by photo-ionization, and are predicted to both be relatively manageable to implement. We estimate the parameter requirements and discuss pros and cons for each method.

SELMA mission: How do airless bodies interact with space environment? The Moon as an accessible laboratory

The Moon is an archetypal atmosphere-less celestial body in the Solar System. For such bodies, the environments are characterized by complex interaction among the space plasma, tenuous neutral gas, dust and the outermost layer of the surface. Here we propose the SELMA mission (Surface, Environment, and Lunar Magnetic Anomalies) to study how airless bodies interact with space environment. SELMA uses a unique combination of remote sensing via ultraviolet and infrared wavelengths, and energetic neutral atom imaging, as well as in situ measurements of exospheric gas, plasma, and dust at the Moon. After observations in a lunar orbit for one year, SELMA will conduct an impact experiment to investigate volatile content in the soil of the permanently shadowed area of the Shackleton crater. SELMA also carries an impact probe to sound the Reiner-Gamma mini-magnetosphere and its interaction with the lunar regolith from the SELMA orbit down to the surface. SELMA was proposed to the European Space Agency as a medium-class mission (M5) in October 2016. Research on the SELMA scientific themes is of importance for fundamental planetary sciences and for our general understanding of how the Solar System works. In addition, SELMA outcomes will contribute to future lunar explorations through qualitative characterization of the lunar environment and, in particular, investigation of the presence of water in the lunar soil, as a valuable resource to harvest from the lunar regolith.

Illumination conditions at the lunar poles: Implications for future exploration

We produced 400 × 400 km Digital Terrain Models (DTMs) of the lunar poles from Lunar Orbiter Laser Altimeter (LOLA) ranging measurements. To achieve consistent, high-resolution DTMs of 20 m/pixel the individual ranging profiles were adjusted to remove small track-to-track offsets. We used these LOLA-DTMs to simulate illumination conditions at surface level for 50 × 50 km regions centered on the poles. Illumination was derived in one-hour increments from 01 January, 2017 to 01 January, 2037 to cover the lunar precessional cycle of 18.6 years and to determine illumination conditions over several future mission cycles. We identified three regions receiving high levels of illumination at each pole, e.g. the equator-facing crater rims of Hinshelwood, Peary and Whipple for the north pole and the rim of Shackleton crater, and two locations on a ridge between Shackleton and de Gerlache crater for the south pole. Their average illumination levels range from 69.5% to 82.9%, with the highest illumination levels found at the north pole on the rim of Whipple crater. A more detailed study was carried out for these sites as targets for a lander and/or rover equipped with solar arrays. For this purpose we assumed a lander with a structural height of two meters above the ground (height of the solar panels). Here average illumination levels range from 77.1% to 88.0%, with the maximum found at the ridge between Shackleton and de Gerlache crater on the south pole. Distances, sizes and slopes of nearby Permanently Shadowed Regions (PSRs) as a prime science target were also assessed in this case.

On the Nature of the Impactor That Formed the Shackleton Crater on the Moon

The present paper attempts to assess the characteristics of the impactor that formed the Shackleton crater, located at the south pole of the Moon. The crater’s morphometric parameters were analyzed based on the data of the Lunar Orbiter Laser Altimeter aboard the Lunar Reconnaissance Orbiter. Conclusions were drawn regarding the possible range of the impact angle and the parameters of the transient crater, such as depth and volume. The thickness of ejecta deposits on the transient crater rim and the volume of these deposits at a certain distance from the crater rim were assessed. These assessments enabled determining the type and characteristics of impactors (velocity, density, size, and impact angle) that could have formed the Shackleton crater. It was shown that the Shackleton crater could have been formed by an impact of a low-velocity (3 km/s) comets with diameter 4–4.5 km, chondrite or achondrite with a diameter of 2 km at a 45°–50° angle, whose velocity did not exceed 6 km/s, as well as stony–iron or iron–nickel impactors with a 1–2 km diameter for stony–iron asteroids and 1–1.5 km for iron–nickel asteroids. The impact velocity of stony–iron impactors, according to the authors’ calculations, can reach 12 km/s. The impact velocities of iron–nickel asteroids range from 6 to 9 km/s. The impactor’s substance mass that could have remained in the crater after it was formed was assessed.

Optimized traverse planning for future polar prospectors based on lunar topography

To fully understand the extensive collection of remotely sensed polar observations by the Lunar Reconnaissance Orbiter and other recent lunar missions, we must acquire an array of ground-truth measurements. A polar rover can sample and assay potential polar resources both laterally and at shallow depths. To identify ideal, least-energy traverses for such a polar prospecting mission, we developed a traverse planning tool, called R-Traverse, using a fundamental wheel–regolith interaction model and datasets from the Lunar Reconnaissance Orbiter Camera, Lunar Orbiter Laser Altimeter, and Diviner Lunar Radiometer Experiment. Using the terramechanics model, we identified least-energy traverses at the 20 m scale around Shackleton crater and located one traverse plan that enables the rover to remain illuminated for 94.4% of the lunar year. By incorporating this path planning tool during mission planning, the feasibility of such a mission can be quantified.

Identification of surface hydrogen enhancements within the Moon’s Shackleton crater

Bulk surface hydrogen enhancements have been identified within the Moon’s Shackleton crater. Using an analysis of fast and epithermal neutron data from the Lunar Prospector mission, the permanently shadowed region (PSR) within this crater has a surface concentration of 0.72±0.13wt.% water equivalent hydrogen (WEH). In contrast, hydrogen enhancements within other polar PSRs such as Cabeus are likely buried under more than 10cm of hydrogen-poor regolith. Subsurface hydrogen absent a surficial counterpart implies an episodic delivery mechanism. The burial depth suggests the epoch of hydrogen deposition was at least 100myr ago if impact gardening is the dominant mechanism for volatile transport to depth. Shackleton crater’s surface enhancement may be related to its thermal environment, ∼30K warmer than other south pole PSRs, in which thermal processes control the vertical migration of hydrogen within Shackleton but inhibit migration in colder regions. One sentence summaryEnhanced bulk surface hydrogen concentrations have been identified within Shackleton crater, giving insights into volatile delivery and transport processes within permanently shadowed regions at the Moon’s poles.

Enhanced hydrogen at the lunar poles: New insights from the detection of epithermal and fast neutron signatures

The Lunar Prospector (LP) and Lunar Reconnaissance Orbiter (LRO) orbital neutron spectroscopy data sets represent a unique comprehensive multimission lunar resource. A rigorous statistical approach has been used to (re)analyze neutron data from both missions to provide new details regarding the relationships between the individual detector data sets, as well as a new evaluation of enhanced hydrogen deposits at the lunar poles. Using the multimission epithermal neutron data set, we find water ice distributed broadly across the poles, but showing evidence for a dependence on topographical features. A footprint averaged water equivalent hydrogen (WEH) abundance of 106 ± 11 ppm at each pole, with maxima of 131 and 112 ppm at the north and south poles, respectively, is derived from the epithermal neutron data. We also report the first definitive detection of a fast neutron signature consistent with an enhanced hydrogen hypothesis. These data suggest a highly localized distribution, consistent with Shackleton Crater, corresponding to a footprint averaged WEH abundance of 194 ± 11. If confined to this crater, this abundance yields a localized deposit of ∼0.7% WEH. Details of the analysis approach are presented along with spatial distribution maps showing the intriguing enhanced hydrogen deposits at the lunar poles.