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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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NASA NTRS2003

LSPECS: A Proposed Robotic Astronomy Mission to the Lunar South Polar Regions

This paper outlines a possible mission to emplace a robotic infrared/submillimeter wave interferometer array near the lunar south pole. This region has now been investigated by the Clementine and Lunar Prospector missions, and by Earth-based radar, and its topography and thermal environment are fairly well-known. The area would be exceptionally suitable for infrared/submillimeter astronomy because of the continually low temperatures, approaching that of liquid nitrogen (77K) in some places. The presence of ice has been inferred independently from Clementine and Lunar Prospector, providing another incentive for a south polar mission. A submillimeter spaceborne interferometer mission, Submillimeter Probe of the Evolution of the Cosmic Structure (SPECS) has been proposed by John Mather and others, covering the 40 - 500 micron region with 3 formation flying telescopes. The present paper proposes a lunar adaptation of the SPECS concept, LSPECS. This adaptation would involve landing 4 telescopes on the area north of Shackleton crater at zero degrees longitude. This is in nearly year round darkness but is continually radar visible from Earth. The landed payload of LSPECS would include a telerobotic rover, 4 three meter submm telescopes, a solar power array to be emplaced on the continually sunlit north rim of Shackleton crater, and an S-band antenna for data relay to Earth. Operation without the use of expendable cryogenics for cooling might be possible, trading long exposure time for instrument temperatures above that of liquid helium. The LSPECS would permit long-term study of an extremely wide range of cosmic and solar system phenomena in the southern celestial hemisphere. For complete sky coverage, a similar installation near the north pole would be required. The LSPECS site would also be suitable other types of observation, such as optical interferometry or centimeter wavelength radio astronomy. The lunar south pole is also of great interest because of its extensive ice deposits, which may represent cometary infall with pre-biotic compounds.

Lowman, Paul D., Jr.↗
NASA NTRS1988

The Lunar Orbital Prospector

The Moon is a body rich in natural resources and full of intriguing scientific questions, and it will most certainly play a central role in the growth of near-Earth and deep space ventures of the twenty-first century. The LOP mission is an example of one way to catalog the Moon's natural resources and to answer lunar science questions in parallel. In a realistic planetary exploration program, this mission must compete with other interesting planetary missions and therefore the LOP must be as low cost and adaptable as possible. This flexibility is reflected in the LOP's heavy design emphasis on modularity. The LOP mission can easily be expanded to include new technologies, and additional orbiters could be launched into lunar orbit to provide a constellation of remote-sensing platforms. This design thus projects a broad range of possibilities for continued lunar exploration in the next century.

Source record↗
NASA NTRS1999

Unusual Bow Shock and Magnetopause Locations During May 11-12, 1999

On May 11 and 12, 1999, when the solar wind proton density dropped to only about 3% of its nominal value, WIND and IMP 8 (and possibly Lunar Prospector) encountered the Earth's bow shock at unusually large distances. These observations, at 57-63 Re, correspond to the most distant crossings of the bow shock ever recorded. This paper will present observations from Interball-1 and Geotail, showing the bow shock near its nominal position, and from IMP 8 and WIND (and perhaps Lunar Prospector) crossing the bow shock at increasing radial distances. The bow shock is extremely weak by the time of its observation by WIND. However, a clear jump in both the magnetic field strength and solar wind bulk velocity is quite apparent, although with no significant changes in solar wind proton density. The nature of this dissipating shock will be discussed. Also, interball-1 has observed the magnetopause at an unusually large standoff distance. The observed motion of the magnetopause and bow shock will be compared with model predictions. This set of observations provide an excellent test case for the behavior of gas dynamic and MHD models under extreme conditions.

Szabo, Adam↗
NASA NTRS1999

Thorium Enrichment within the Procellarum KREEP Terrane: The Record in Surface Deposits and Significance for Thermal Evolution

The nearside-farside structural and compositional asymmetry of the Moon was recognized during the early days of Apollo and the suggestion was made that the migration of mantle melts to the nearside would have been favored by early Earth-Moon orbital dynamics and nonuniform planetesimal bombardment. Recent global geochemical mapping by Lunar Prospector has provided additional data, particularly in the Th distribution, that strongly supports the notion of global, preferential melt migration, which led in part to the development of the Procellarum KREEP Terrane (PKT) [2-5]. The surface distribution of Th was then reshaped by basin-forming impacts into the PKT, especially the Imbrium impact, which was the last and largest to strike in that region. The Imbrium event probably excavated material from a partially molten zone deep in the crust and delivered Th-rich ejecta Moon-wide. A fundamentally important but poorly understood aspect of the global Th distribution is the concentration of Th in the subsurface rocks of the PKT crustal section. For example, depending on what assumptions are made, the PKT crustal section, which is about 12% of the crust and only about 1.2% of the whole Moon, may contain as much as 40% of the Moon's entire Th budget. Such a distribution of Th and related heat-producing elements would have had a profound effect on melting, mixing, and the thermal evolution of the PKT and the underlying mantle. In this abstract, we examine the compositions of terra formations within the PKT and relate them to some of the Th-bearing rock types known from the Apollo samples. It appears that the existence of the PKT may be a unifying concept for a number of petrologic and geochemical observations. From the initial Lunar Prospector gamma-ray spectrometer data(-about 5 deg. resolution) and from the preliminary low-orbit data, there appears to be a number of relatively hotter "spots" within the PKT in terms of Th concentration. Some of the hotter spots correspond to intermediate-sized craters that penetrated volcanic flows and excavated Th-rich, submare material, such as Aristarchus, Aristillus, and Kepler. Other spots, however, correspond to surficial formations that constitute mainly rough topography associated with Imbrium ejecta or circum-Imbrium ring mountains and do not necessarily imply the presence of exposed KREEP basalts. The Fra Mauro Formation south of Copernicus toward the Apollo 14 site and regions of the Alpes Formation southwest of Copernicus in the vicinity of Reinhold lie within the most prominent hotspot; here them concentration is consistent with that found in the Apollo 14 soils (about 12-13 ppm) when the proportions of Fra Mauro Formation and mare basalt are considered. The area between Copernicus and Kepler and northwest of Copernicus in terra extending to the Carpathians is similarly enriched in Th. The Apennines from Eratosthenes toward the Apollo 15 site contain elevated Th concentrations, as does the northwestern quadrant of circum-Imbrium terra, especially between (but not including) La Condamine and Plato, and in the region northwest of the Jura mountains extending southward past Mairan to the Gruithuisen-Domes region. Within the main topographic rim of Imbrium, the Apennine Bench formation south of Archimedes appears to have relatively elevated Th concentration. Comparing the map of Th distribution to a digital-elevation map derived from Clementine altimetry, it appears that most of the areas richest in Th occur where the surface is elevated relative to the majority of PKT volcanic plains. Not all rough topography within the PKT has such elevated Th, however. Based on an analysis of the 5 deg. data, and using the calibration of, the mean Th concentrations for mainly volcanic-resurfaced terrain and rugged terrain are similar (about 5.5 ppm). This occurs in part because craters that penetrated mare basalt excavated Th-rich material. Even so, there appear to be extensive areas of volcanic resurfacing that have no obvious extrinsic source of Th-rich material, suggesting that the basalts, themselves, may contain as much as 5-6 ppm Th. High-FeO concentrations (18 to >20 wt%) indicate that these are not KREEP basalts but mare basalts. If so, this is surprising because most of the Apollo-sampled mare basalts have very low-Th (typically <2 ppm). A variety of Th-rich materials occur in the sample collection, particularly in the samples from the Apollo 12,14, and 15 sites. The most abundant Th-rich rock types are the mafic impact-melt breccias, which although found at all sites, are most abundant at Apollo 14, where they dominate the rock samples and make up some 40% of the rock particles in the soil. These have Th concentrations ranging up to about 30 ppm and averaging about 18 ppm. The Apollo 14 soils contain about 13 ppm Th, reflecting the high abundance of this melt-breccia component. At the nearby Apollo 12 site, the rocks consist mainly of mare basalts, and these have low-Th concentrations, mostly <1 ppm. Among the nonmare rocks, however, a few such as complex breccia 12013 contain a variety of evolved lithologies and represent potential sources of Th-rich components ranging from 17 to 50 ppm. A single fragment of KREEP basalt from the Apollo 12 soil contains about 50 ppm Th. Despite the identification of highly Th-enriched lithologic components at the Apollo 12 site, the soils there vary linearly in composition so as to extrapolate to a moderate Th KREEP-basalt component or a composition like that of the Fra Mauro formation as reflected by Apollo 14 soil (14 ppm Th at 10 wt% FeO). The nearby Lansberg Crater (39-km diameter) is a likely candidate to have delivered submare material such as buried Fra Mauro or Alpes material to the Apollo 12 site. Additional information contained in the original.

Jolliff, B. L.↗
NASA NTRS2011

Lunar Ion Transport Near Magnetic Anomalies: Possible Implications for Swirl Formation

The bright swirling features on the lunar surface in areas around the Moon but most prominently at Reiner Gamma, have intrigued scientists for many years. After Apollo and later Lunar Prospector (LP} mapped the Lunar magnetic fields from orbit, it was observed that these features are generally associated with crustal magnetic anomalies. This led researchers to propose a number of explanations for the swirls that invoke these fields. Prominent among these include magnetic shielding in the form of a mini-magnetosphere which impedes space weathering by the solar wind, magnetically controlled dust transport, and cometary or asteroidal impacts that would result in shock magnetization with concomitant formation ofthe swirls. In this presentation, we will consider another possibility, that the ambient magnetic and electric fields can transport and channel secondary ions produced by micrometeorite or solar wind ion impacts. In this scenario, ions that are created in these impacts are under the influence of these fields and can drift for significant distances before encountering the magnetic anomalies when their trajectories are disrupted and concentrated onto nearby areas. These ions may then be responsible for chemical alteration of the surface leading either to a brightening effect or a disruption of space weathering processes. To test this hypothesis we have run ion trajectory simulations that show ions from regions about the magnetic anomalies can be channeled into very small areas near the anomalies and although questions remain as to nature of the mechanisms that could lead to brightening of the surface it appears that the channeling effect is consistent with the existence of the swirls.

Keller, J. W.↗
NASA NTRS2012

Solar Wind Electron Interaction with the Dayside Lunar Surface and Crustal Magnetic Fields: Evidence for Precursor Effects

Electron distributions measured by Lunar Prospector above the dayside lunar surface in the solar wind often have an energy dependent loss cone, inconsistent with adiabatic magnetic reflection. Energy dependent reflection suggests the presence of downward parallel electric fields below the spacecraft, possibly indicating the presence of a standing electrostatic structure. Many electron distributions contain apparent low energy (<100 eV) upwardgoing conics (58% of the time) and beams (12% of the time), primarily in regions with non-zero crustal magnetic fields, implying the presence of parallel electric fields and/or wave-particle interactions below the spacecraft. Some, but not all, of the observed energy dependence comes from the energy gained during reflection from a moving obstacle; correctly characterizing electron reflection requires the use of the proper reference frame. Nonadiabatic reflection may also play a role, but cannot fully explain observations. In cases with upward-going beams, we observe partial isotropization of incoming solar wind electrons, possibly indicating streaming and/or whistler instabilities. The Moon may therefore influence solar wind plasma well upstream from its surface. Magnetic anomaly interactions and/or non-monotonic near surface potentials provide the most likely candidates to produce the observed precursor effects, which may help ensure quasi-neutrality upstream from the Moon.

Solar↗
NASA NTRS2018

Instrumentation for Lunar Volatile Analysis

Understanding the available lunar resources is key to incorporating their availability into exploration architectures. Previous lunar missions have provided insight into the potential resources on the moon as an initial step enabling in-situ resource utilization (ISRU). Orbiting missions, such as Clementine and Lunar Prospector, have mapped the lunar polar region and found enhanced hydrogen signals on kilometer-scale resolution. The Lunar Crater Observation and Sensing Satellite (LCROSS) mission provided the first direct measurement of water ice in a permanently shadowed region. Future missions will provide ground truth data to measure and quantify lunar volatiles.One approach to exploration capitalizes on commercial partnerships for Class D risk aware missions. Partnerships with commercial partners enable rapid design cycles, leveraging the investment of the commercial industry in instrument development. Modified Commercial off the Shelf (COTS) hardware can be utilized to enhance capabilities in exploration missions. The hardware under development at the Kennedy Space Center for availability within the Commercial Lunar Payload Services opportunities capitalizes on modified COTS, enabling an aggressive delivery schedule and low-cost development. The modified hardware has been integrated and tested in a thermal vacuum environment, with final flight modifications currently in work. The use of a modified COTS instruments will be discussed for space applications.

Captain, J.↗
NASA NTRS2015

Resource Prospector: Mission Goals, Relevance and Site Selection

Over the last two decades a wealth of new observations of the moon have demonstrated a lunar water system dramatically more complex and rich than was deduced following the Apollo era. Observation from the Lunar Prospector Neutron Spectrometer (LPNS) revealed enhancements of hydrogen near the lunar poles. This observation has since been confirmed by the Lunar Reconnaissance Orbiter (LRO) Lunar Exploration Neutron Detector (LEND) instrument. The Lunar Crater Observation and Sensing Satellite (LCROSS) mission targeted a permanently shadowed, enhanced hydrogen location within the crater Cabeus. The LCROSS impact showed that at least some of the hydrogen enhancement is in the form of water ice and molecular hydrogen (H2). Other volatiles were also observed in the LCROSS impact cloud, including CO2, CO, an H2S. These volatiles, and in particular water, have the potential to be a valuable or enabling resource for future exploration. In large part due to these new findings, the NASA Human Exploration and Operations Mission Directorate (HEOMD) have selected a lunar volatiles prospecting mission for a concept study and potential flight in CY2020. The mission includes a rover-borne payload that (1) can locate surface and near-subsurface volatiles, (2) excavate and analyze samples of the volatile-bearing regolith (up to 1 meter), and (3) demonstrate the form, extractability and usefulness of the materials.

Moon↗
NASA NTRS2005

A Thorium-rich Mare Basalt Rock Fragment from the Apollo 12 Regolith: A Sample from a Young Procellarum Flow?

In this abstract, we report on the composition, mineralogy and petrography of a basaltic rock fragment, 12032,366-18, found in the Apollo 12 regolith. Age data, collected as part of an investigation by Barra et al., will be presented in detail in. Here, only the age dating result is summarized. This rock fragment garnered our attention because it is significantly enriched in incompatible elements, e.g., 7 ppm thorium, compared to other known lunar basalts. Its mineral- and trace-element chemistry set it apart from other Apollo 12 basalts and indeed from all Apollo and Luna basalts. What makes it potentially very significant is the possibility that it is a sample of a relatively young, thorium-rich basalt flow similar to those inferred to occur in the Procellarum region, especially northwestern Procellarum, on the basis of Lunar Prospector orbital data. Exploiting the lunar regolith for the diversity of rock types that have been delivered to a landing site by impact processes and correlating them to their likely site of origin using remote sensing will be an important part of future missions to the Moon. One such mission is Moonrise, which would collect regolith samples from the South Pole-Aitken Basin, concentrating thousands of rock fragments of 3-20 mm size from the regolith, and returning the samples to Earth.

Jolliff, B. L.↗
NASA NTRS1999

Man-Made Debris In and From Lunar Orbit

During 1966-1976, as part of the first phase of lunar exploration, 29 manned and robotic missions placed more than 40 objects into lunar orbit. Whereas several vehicles later successfully landed on the Moon and/or returned to Earth, others were either abandoned in orbit or intentionally sent to their destruction on the lunar surface. The former now constitute a small population of lunar orbital debris; the latter, including four Lunar Orbiters and four Lunar Module ascent stages, have contributed to nearly 50 lunar sites of man's refuse. Other lunar satellites are known or suspected of having fallen from orbit. Unlike Earth satellite orbital decays and deorbits, lunar satellites impact the lunar surface unscathed by atmospheric burning or melting. Fragmentations of lunar satellites, which would produce clouds of numerous orbital debris, have not yet been detected. The return to lunar orbit in the 1990's by the Hagoromo, Hiten, Clementine, and Lunar Prospector spacecraft and plans for increased lunar exploration early in the 21st century, raise questions of how best to minimize and to dispose of lunar orbital debris. Some of the lessons learned from more than 40 years of Earth orbit exploitation can be applied to the lunar orbital environment. For the near-term, perhaps the most important of these is postmission passivation. Unique solutions, e.g., lunar equatorial dumps, may also prove attractive. However, as with Earth satellites, debris mitigation measures are most effectively adopted early in the concept and design phase, and prevention is less costly than remediation.

Johnson, Nicholas L.↗
NASA NTRS2017

Application of CFS to a Lunar Rover: Resource Prospector (RP)

Resource Prospector (RP) is a lunar mission sponsored by NASA's Advanced Exploration Systems (AES) division, that aims to study in-situ resource utilization (ISRU) feasibility and technologies on the surface of the moon. The RP mission's lunar surface segment includes a rover equipped with with a suite of instruments specifically designed to measure and map volatiles both at the surface and in the subsurface. Of particular interest is the quantity and state of volatiles in permanently shadowed regions. To conduct the mission, ground system operators will remotely drive the rover, directing it to waypoints along the surface in order to achieve measurement objectives. At selected locations, an onboard drill will be deployed to collect material and obtain direct measurements of the subsurface constituents. RP is currently planned for launch in 2022. RP is managed at NASA Ames Research Center. The RP Rover is being designed and developed by NASA Johnson Space Center (JSC) in partnership with NASA Ames. NASA Kennedy Space Center (KSC) is responsible for the Honeybee drilling system and science payload. In order to better understand the technical challenges and demonstrate capability, in 2015 the RP project developed a rover testbed (known as RP15). In this mission in a year, a rover was designed, developed, and outfitted with science instruments and a drill. The rover was operated from a remote operations center, and operated in an outdoor lunar rock yard at Johnson space center. The study was a resounding success meeting all objectives. The RP Rover software architecture and development processes were based on the successful Lunar Atmosphere and Dust Environment Explorer spacecraft. This architecture is built on the Core Flight System software and an interface to Matlab/Simulink auto-generated software components known as the Simulink Interface Layer (SIL). The application of this lunar satellite inspired framework worked well for the rover application, and is currently being planned for the mission. This presentation provides an overview of the architecture and processes, and describes some of the changes and challenges for the rover application.

RP↗
NASA NTRSDate not supplied

Lunar Payloads to Constrain Exospheric Water through the NASA M-STAR program

Our understanding of water cycles on the Moon has significantly enhanced recent observations by Chang E-5, Lunar Prospector, and Chandrayaan-1 missions indicating the existence of an active water cycle on the Moon. In a new partnership between Delaware State University (DSU) and NASA Goddard Space Flight Center, enabled through the NASA’s M-STAR (MUREP Space Technology Artemis Research) program, we are developing low mass and power lunar rover payloads to enable long-duration human exploration missions. Payload technologies include wavelength modulation absorption spectroscopy to simultaneously detect water (H16OH) and isotopes (H16OD) in the (6700 nm) mid-infrared region using a closed path in compact Herriot cell optical design and wavelength modulation spectroscopy, and (2) Laser-induced breakdown spectroscopy (LIBS) to simultaneously detect and correlate water isotopes with characteristics elemental composition of lunar regolith. Due to the airless atmosphere of the Moon, we will utilize Artificial intelligence (AI) and Machine learning (ML) approaches to discriminate spectral interference with instrument drifts and correlate mid-IR trace gas profile with LIBS spectral information. This partnership will initiate a STEM engagement space program, e.g., Lander and CubeSat payload technology development for students and the next-generation NASA workforce for future lunar and Mars missions. DSU, a Historically Black University, prides itself in its proven excellence in teaching and research. It enrolls a diverse population of students (~5000) traditionally underrepresented in STEM disciplines. DSU has established itself at the forefront of optics and photonics research that transcends multidisciplinary fields of earth sciences, environmental, defense, and biomedical sensing applications.

water cycles↗
NASA NTRS2003

The Moon Beyond 2002

Over a hundred lunar scientists met in the clear mountain air of the Taos Ski Valley, September 12-14, 2002, to share their discoveries and, most importantly, their questions about the composition, geological evolution, and future exploration of the Moon. The wealth of data from the Clementine and Lunar Prospector missions, coupled with continued study of lunar samples, has led lunar scientists to pose sophisticated questions about the Moon. Because of the Moon's central role in planetary science, answers to these questions will help us understand the other rocky bodies in the Solar System. A fascinating array of missions is planned, including orbiting spacecraft and sample-return missions. Human habitation of the Moon may not be far beyond.

Taylor, G. Jeffrey↗
NASA NTRS2014

The Miniature Radio Frequency Instruments (Mini-RF) Global Observations of Earth's Moon

Radar provides a unique means to analyze the surface and subsurface physical properties of geologic deposits, including their wavelength-scale roughness, the relative depth of the deposits, and some limited compositional information. The NASA Lunar Reconnaissance Orbiter's (LRO) Miniature Radio Frequency (Mini-RF) instrument has enabled these analyses on the Moon at a global scale. Mini-RF has accumulated 67% coverage of the lunar surface in S-band (12.6 cm) radar with a resolution of 30 m/pixel. Here we present new Mini-RF global orthorectified uncontrolled S-band maps of the Moon and use them for analysis of lunar surface physical properties. Reported here are readily apparent global- and regional-scale differences in lunar surface physical properties that suggest three distinct terranes, namely: a (1) Nearside Radar Dark Region; (2) Orientale basin and continuous ejecta; and the (3) Highlands Radar Bright Region. Integrating these observations with new data from LRO's Diviner Radiometer rock abundance maps, as well Clementine and Lunar Prospector derived compositional values show multiple distinct lunar surface terranes and sub-terranes based upon both physical and compositional surface properties. Previous geochemical investigations of the Moon suggested its crust is best divided into three to four basic crustal provinces or terranes (Feldspathic Highlands Terrane (-An and -Outer), Procellarum KREEP Terrane, and South Pole Aitken Terrane) that are distinct from one another. However, integration of these geochemical data sets with new geophysical data sets allows us to refine these terranes. The result shows a more complex view of these same crustal provinces and provides valuable scientific and hazard perspectives for future targeted human and robotic exploration.

Radar observations↗
NASA NTRS2012

NASA's Lunar Polar Ice Prospector, RESOLVE: Mission Rehearsal in Apollo Valley

After the completion of the Apollo Program, space agencies didn't visit the moon for many years. But then in the 90's, the Clementine and Lunar Prospector missions returned and showed evidence of water ice at the poles. Then in 2009 the Lunar Crater Observation and Sensing Satellite indisputably showed that the Cabeus crater contained water ice and other useful volatiles. Furthermore, instruments aboard the Lunar Reconnaissance Orbiter (LRO) show evidence that the water ice may also be present in areas that receive several days of continuous sunlight each month. However, before we can factor this resource into our mission designs, we must understand the distribution and quantity of ice or other volatiles at the poles and whether it can be reasonably harvested for use as propellant or mission consumables. NASA, in partnership with the Canadian Space Agency (CSA), has been developing a payload to answer these questions. The payload is named RESOLVE. RESOLVE is on a development path that will deliver a tested flight design by the end of 2014. The team has developed a Design Reference Mission using LRO data that has RESOLVE landing near Cabeus Crater in May of2016. One of the toughest obstacles for RESOLVE's solar powered mission is its tight timeline. RESOLVE must be able to complete its objectives in the 5-7 days of available sunlight. The RESOLVE team must be able to work around obstacles to the mission timeline in real time. They can't afford to take a day off to replan as other planetary missions have done. To insure that this mission can be executed as planned, a prototype version of RESOLVE was developed this year and tested at a lunar analog site on Hawaii, known as Apollo Valley, which was once used to train the Apollo astronauts. The RESOLVE team planned the mission with the same type of orbital imagery that would be available from LRO. The simulation team prepositioned a Lander in Apollo Valley with RESOLVE on top mounted on its CSA rover. Then the mission simulation began as the operations team's consoles came alive with data and images. They executed the mission just like the real mission with lunar communications delays and limited bandwidth and a realistic remote mission control room. This paper will describe the RESOLVE payload in detail and describe the results of the mission simulation in Hawaii.

Larson, William E.↗
NASA NTRS2002

A Miniature Mineralogical Instrument for In-Situ Characterization of Ices and Hydrous Minerals at the Lunar Poles

Lunar missions over the past few years have provided new evidence that water may be present at the lunar poles in the form of cold-trapped ice deposits, thereby rekindling interest in sampling the polar regions. Robotic landers fitted with mineralogical instrumentation for in-situ analyses could provide unequivocal answers on the presence of crystalline water ice and/or hydrous minerals at the lunar poles. Data from Lunar Prospector suggest that any surface exploration of the lunar poles should include the capability to drill to depths of more than 40 cm. Limited data on the lunar geotherm indicate temperatures of approximately 245-255 K at regolith depths of 40 cm, within a range where water may exist in the liquid state as brine. A relevant terrestrial analog occurs in Antarctica, where the zeolite mineral chabazite has been found at the boundary between ice-free and ice-cemented regolith horizons, and precipitation from a regolith brine is indicated. Soluble halogens and sulfur in the lunar regolith could provide comparable brine chemistry in an analogous setting. Regolith samples collected by a drilling device could be readily analyzed by CheMin, a mineralogical instrument that combines X-ray diffraction (XRD) and X-ray fluorescence (XRF) techniques to simultaneously characterize the chemical and mineralogical compositions of granular or powdered samples. CheMin can unambiguously determine not only the presence of hydrous alteration phases such as clays or zeolites, but it can also identify the structural variants or types of clay or zeolite present (e.g., well-ordered versus poorly ordered smectite; chabazite versus phillipsite). In addition, CheMin can readily measure the abundances of key elements that may occur in lunar minerals (Na, Mg, Al, Si, K, Ca, Fe) as well as the likely constituents of lunar brines (F, Cl, S). Finally, if coring and analysis are done during the lunar night or in permanent shadow, CheMin can provide information on the chemistry and structure of any crystalline ices that might occur in the regolith samples.

Sarrazin, P.↗