Many upcoming lunar missions and payloads are targeting the south pole of the Moon, due to the volatiles potentially harboured in this region including ESA's PROSPECT instrument. PROSPECT is designed to sample the lunar regolith within the first meter of the surface and to analyse any volatiles found. Remote sensing methods and a range of datasets including thermal models, illumination models, LRO NAC images, LOLA DEMs and LRO NAC DEMs generated with shape-from-shading, were used to identify suitable areas for PROSPECT science within the south polar region (84-90 degrees S). Sites identified were down selected using a science matrix and scoring sites of interest based on if and how well the point of interest met the science requirements of PROSPECT. The highest scoring sites are presented and proposed to be ideal candidate landing sites for missions targeting the lunar south polar region, especially for missions that are interested in sampling volatiles, micro cold traps and Permanently Shaded Regions (PSRs). Understanding and sampling these colder areas within the south polar region will advance the understanding of volatiles within the lunar surface and volatile transfer.

The Lunar Flashlight cubesat mission was designed and flown to collect new data on the abundance and distribution of water ice frost in lunar permanently shadowed regions (PSRs) using active laser spectroscopy. Key advantages of active spectroscopy are that it can collect surface reflectance data in locations and conditions where passive spectroscopy cannot operate, specifically nightside locations where no indirect lighting is available, and in the deepest parts of PSRs where indirect lighting may be too faint for passive spectroscopy. Lunar Flashlight launched in 2022 but because of a propulsion system failure, did not make it to the Moon to conduct its science investigation. However, Lunar Flashlight proved to be an extremely successful technology demonstration mission, meeting or exceeding all its technology-focused mission goals, including demonstrating its instrument functionality. This paper describes the extensive ground and test campaigns to characterize the Lunar Flashlight laser reflectometer instrument and its planned utility for science observations, along with recommendations for future instrument design, development, verification, and use.

The 2009 Lunar CRater Observation and Sensing Satellite (LCROSS) impact mission detected water ice absorption using spectroscopic observations of the impact-generated debris plume taken by the Shepherding Spacecraft, confirming an existing hypothesis regarding the existence of water ice in permanently shadowed regions within Cabeus crater. Ground-based observations in support of the mission were able to further constrain the mass of the debris plume and the concentration of the water ice ejected during the impact. In this work, we explore additional constraints on the initial conditions of the pre-impact lunar sediment required in order to produce a plume model that is consistent with the ground-based observations. We match the observed debris plume lightcurve using a layer of dirty ice with an ice concentration that increases with depth, a layer of pure regolith, and a layer of material at about 6 m below the lunar surface that would otherwise have been visible in the plume but has a high enough tensile strength to resist excavation. Among a few possible materials, a mixture of regolith and ice with a sufficiently high ice concentration could plausibly produce such a behavior. The vertical albedo profiles used in the best fit model allows us to calculate a pre-impact mass of water ice within Cabeus crater of 5 +/- 3.0 x 10(11) kg and a mass concentration of water in the lunar sediment of 8.2 +/- 0.001 %wt, assuming a water ice albedo of 0.8 and a lunar regolith density of 1.5 g cm(-3), or a mass concentration of water of 4.3 ;+/- 0.01 %wt, assuming a lunar regolith density of 3.0. These models fit to ground-based observations result in derived masses of regolith and water ice within the debris plume that are consistent with in situ measurements, with a model debris plume ice mass of 108 kg.

We investigated the physical and spectral properties of potential dark mantling deposits (PDMDs) previously and newly identified on the SE limb of the Moon, near the craters Humboldt and Petavius. The goals of this investigation were to constrain the composition and mode of emplacement of these poorly studied deposits, to identify interdeposit variations, and to use these results to draw conclusions about regional and subsurface geologic processes. Our investigation involved an assessment of both the physical properties (size, texture, morphology) and spectral properties (albedo, absorption bands, color ratios) utilizing remote sensing data from multiple lunar orbital missions. We found that many of the SE Limb deposits previously identified as possibly pyroclastic in origin were likely effusively emplaced. However, we also identified several likely pyroclastic deposits, including three not previously mapped. We found that the volcanic deposits across the study area comprise three major spectral groups: one similar to Mare Fecunditatis, one similar to Mare Australe, and one similar to known glassy pyroclastic deposits elsewhere on the Moon. We conclude that volcanism across the SE limb was likely fed from at least two distinct magma source regions, and that the type and extent of surface expression of this volcanic activity was possibly influenced by regional variations in crustal thickness. Our documentation and analysis of the complex volcanic history in this region of the Moon supports ongoing efforts to develop increasingly detailed interpretations of the volcanic history of the entire Moon.

The 5-band Clementine UVVIS data at similar to100 m/pixel were used to examine the compositions of 75 large and small lunar pyroclastic deposits (LPDs), and these were compared to representative lunar maria and highlands deposits. Results show that the albedo, spectral color, and inferred composition of most LPDs are similar to those of low-titanium, mature lunar maria. These LPDs may have consisted largely of fragmented basalt, with substantial components of iron-bearing malic minerals (pyroxenes, olivine) and smaller amounts (if any) of volcanic glass. Several smaller LPDs also show substantial highland components. Three classes of very large deposits can be distinguished from most LPDs and from each other on the basis of crystallinity and possible titanium content of their pyroclastic components. One class has spectral properties that are dominated by high-titanium, crystallized black beads (e.g., Taurus-Littrow), a second consists of a mixture of high-titanium glasses and beads with a higher glass/bead ratio (Sulpicius Gallus) than that of Taurus-Littrow, and a third has a significant component of quenched iron-bearing volcanic glasses (Aristarchus) with possible moderate titanium contents. Although areally extensive, these three classes of very large pyroclastic deposits compose only 20 of the 75 deposits studied (similar to27%), and eruption of such materials was thus likely to have been less frequent on the Moon. (C) 2003 Elsevier Science (USA). All rights reserved.

The program for lunar surface texture analysis with imaging polarimetry conducted at Observatoire de Paris included the large crater Langrenus near the lunar limb. When making the relevant observations, bright features were discovered near the Langrenus central peak. They appeared in both the photographic images and the polarigraphic images, on which they evolved simultaneously. Very few cases of so-called lunar transient phenomena have been reported in the past; they were diverse and controversial. Most of the visual apparitions were described as short-duration flashes. None of them were suggestive of the slowly evolving effect presently observaed. The brightness enhancements produced a simultaneous increase of polarized light. Such a dependance is not compatible with reflectivity variations at the solid surface of the Moon, which should associate brightness increases with polarization decreases. It does not agree with incandescence and with flashing discharges, which do not produce polarized light. Specular reflection on properly oriented relief slopes may increase the brightness and the polarization simultaneously, but the process can hardly explain the amplitude of the enhancments observed. Particles erupted by volcanic processes such as fire fountaining should leave after the active phases, a deposition of dark material at the lunar surface, which is not observed. It is clusters of hills made of a bright material that are present at the event emplacements. The simultaneous increase of brightness and of polarization is consistant with light scattering on clouds made of separated grains. Small bright highland soil grains may be levitated above the lunar surface by outgassing from the lunar interior. The events occurred at the border of a mare basin, near the central peak of a large crater, in a terrain presumed to be particularly fractured and fissured. The intense radon emanation that was measured around the site with the Apollo orbital instruments indicates gas release from the lunar interior, and supports the interpretation of the brightening events as soil grains levitated by the degassing. (C) 2000 Academic Press.

This paper deals with the problem of water permanence on the surface of the Moon Possible zones where water ice can survive are called cold traps (K. Watson, B. C. Murray, and H. Brown 1961, J. Geophys. Res. 66, 3033-3045). These are zones of the Moon permanently obscured where the temperatures are low enough to preserve ice far billions of years. In this work we developed a model for the topographic temperatures of complex craters whose shape was approximated by a capsized frustum of a circular right cone. Double-shaded areas were simulated by embedding a small hemispherical crater in the shadowed part of the previous one. Their temperatures were calculated using the R. R. Hedges, Jr. (1980, Proc. Lunar Planet. Sci. Conf. 11th, 2463-2477) model. First we verified that our results were in agreement with those of previous models. Our results confirm those obtained by J. R. Salvail and F. P. Fanale (1994, Icarus 111, 441-445), and in agreement with Hedges (1980), we found that the lowest temperatures are reached by Tycho-like craters that are the larger and shallower among the examined cases. When small craters are embedded in the shaded area of larger ones, their temperatures are low enough to preserve other volatiles like CO2 (Hodges 1980). In particular, if we consider double-shaded areas in Blot-like craters, the temperatures are lower than 103 K in a shell of almost 20 degrees around the poles, thus allowing the preservation of ices. For geometrical reasons a hemispherical crater embedded in the bottom of a Biot-like crater cold remain in the shadowed area for latitude values lower than those reached by an analogous crater embedded in Sosigene or Tycho-like craters. Therefore the latitudinal radius of polar frost caps could be greater than that predicted by previous models that did not consider double-shaded areas. However double shielding occurs in only a fraction of the secondary craters; therefore, in this case eventual deposits of ice would be of smaller dimensions compared with the case of primary shielding. Analysis of the Clementine radar data (S. Nozette, C. L. Lichtenberg, P. Spudis, R. Bonner, W. Ort, E. Malaret, M. Robinson, and E. hi. Shoemaker 1996, Science 274, 5292-5300) and the Lunar Prospector neutron spectrometer data seems to be consistent with the presence of water ice in very low concentrations across a significant number of craters, thus confirming the old hypothesis of Watson et ai. (1961). (C) 1999 Academic Press.