NASA Ames Research Center and the Lockheed Martin Advanced Technologies Center have developed a rugged, low-resource neutron spectrometer instrument to characterize the near-surface hydrogen content of the lunar surface. This Neutron Spectrometer System (NSS) monitors local thermal and epithermal neutron rates to provide information about the depth-dependent distribution of hydrogen to depths of a few tens of cm. As of mid-2022, NSS is currently slated to fly on two NASA Commercial Lunar Payload Services (CLPS) missions; the Astrobotic Peregrine-1 lander to a near-side equatorial location, and the VIPER lunar rover to explore the polar terrain around Nobile crater. We report the results of a science calibration campaign that characterized the performance of the NSS sensors. These measurements were used to benchmark the accuracy of Geant4 radiation transport simulations that provide the energy- and angle-dependent neutron sensitivity of the NSS sensors. This information is a necessary input for converting NSS measurements of the thermal and epithermal neutron leakage flux to constraints on local hydrogen content in regions with otherwise known geochemical composition.

Colaprete, and Rick Elphic, KBR, NASA Ames Research Center, MS 245-3, Moffett Field, CA, USA (ara.nefian@nasa.gov),NASA Age and size characterization of Lunar craters plays a significant role in Lunar science as well as in mission planing. The first step in achieving this goal is building of a large scale, high accuracy crater detection system. Current methods in crater detection include both manual and automatic methods. While manual crater detection is impractical given the large amount of data made available by Lunar orbital missions, the accuracy of the automatic methods is often limited by the crater size, and by varying illumination conditions. The proposed fully automatic method has been tested successfully in Lunar Pole LRO-NAC imagery for craters down to 8m in diameter and captured in various illumination conditions.

Analyses of samples from the Apollo missions suggest that the Moon formed devoid of native water. However, recent observations by Cassini, Deep Impact, Lunar Prospector and Chandrayaan-1 indicate the existence of an active water cycle on the Moon. Here we report observations of this water cycle, specifically detections of near-surface water released into the lunar exosphere by the Neutral Mass Spectrometer on the Lunar Atmosphere and Dust Environment Explorer. The timing of 29 water releases is associated with the Moon encountering known meteoroid streams. The intensities of these releases reflect the convoluted effects of the flux, velocity and impact location of the parent streams. We propose that four additional detected water releases represent the signature of previously undiscovered meteoroid streams. We show that water release from meteoroid impacts is indicative of a lunar surface that has a desiccated soil layer of several centimetres on top of uniformly hydrated soil. We infer that the Moon is currently in the process of losing water that was either delivered long ago or present at its formation.

A major objective in the exploration of Mars is to test the hypothesis that the planet hosted life. Even in the absence of life, the mapping of habitable and uninhabitable environments is an essential task in developing a complete understanding of the geological and aqueous history of Mars and, as a consequence, understanding what factors caused Earth to take a different trajectory of biological potential. We carried out the aseptic collection of samples and comparison of the bacterial and archaeal communities associated with basaltic fumaroles and rocks of varying weathering states in Hawai'i to test four hypotheses concerning the diversity of life in these environments. Using high-throughput sequencing, we found that all these materials are inhabited by a low-diversity biota. Multivariate analyses of bacterial community data showed a clear separation between sites that have active fumaroles and other sites that comprised relict fumaroles, unaltered, and syn-emplacement basalts. Contrary to our hypothesis that high water flow environments, such as fumaroles with active mineral leaching, would be sites of high biological diversity, alpha diversity was lower in active fumaroles compared to relict or nonfumarolic sites, potentially due to high-temperature constraints on microbial diversity in fumarolic sites. A comparison of these data with communities inhabiting unaltered and weathered basaltic rocks in Idaho suggests that bacterial taxon composition of basaltic materials varies between sites, although the archaeal communities were similar in Hawai'i and Idaho. The taxa present in both sites suggest that most of them obtain organic carbon compounds from the atmosphere and from phototrophs and that some of them, including archaeal taxa, cycle fixed nitrogen. The low diversity shows that, on Earth, extreme basaltic terrains are environments on the edge of sustaining life with implications for the biological potential of similar environments on Mars and their exploration by robots and humans.

A critical goal to both science and exploration is to understand the form and location of lunar polar volatiles. The lateral and vertical distributions of these volatiles inform us of the processes that control the emplacement and retention of these volatiles, as well as helping to formulate in-situ resource utilization (ISRU) architectures. While significant progress has been made from orbital observations, measurements at a range of scales from centimeters to kilometers across the lunar surface are needed to generate adequate mineral models for use in evaluating the resource potential of volatiles at the Moon. VIPER is a solar and battery powered rover mission designed to operate over multiple lunar days, traversing several kilometers as it continuously monitors for subsurface hydrogen and other surface volatiles. In specific thermal terrain types, including permanently shadowed terrain and locales that permit near-surface ice stability, subsurface samples will be examined for volatile content using a one-meter drill. This talk will provide an overview of the VIPER mission which is scheduled for flight to the Lunar South Pole in December 2022.

We perform the first tests of various proposed explanations for observed features of the Moon's argon exosphere, including models of the following: spatially varying surface interactions; a source that reflects the lunar near‐surface potassium distribution; and temporally varying cold trap areas. Measurements from the Lunar Atmosphere and Dust Environment Explorer (LADEE) and the Lunar Atmosphere Composition Experiment (LACE) are used to test whether these models can reproduce the data. The spatially varying surface interactions hypothesized in previous work cannot reproduce the persistent argon enhancement observed over the western maria. They also fail to match the observed local time of the near‐sunrise peak in argon density, which is the same for the highland and mare regions and is well reproduced by simple surface interactions with a ubiquitous desorption energy of 28 kJ mol −1 . A localized source can explain the observations, with a trade‐off between an unexpectedly localized source or an unexpectedly brief lifetime of argon atoms in the exosphere. To match the observations, a point‐like source requires source and loss rates of ∼1.9 × 10 21 atoms s −1 . A more diffuse source, weighted by the near‐surface potassium, requires much higher rates of ∼1.1 × 10 22 atoms s −1 , corresponding to a mean lifetime of just 1.4 lunar days. We do not address the mechanism for producing a localized source, but demonstrate that this appears to be the only model that can reproduce the observations. Large, seasonally varying cold traps could explain the long‐term fluctuation in the global argon density observed by LADEE, but not that by LACE.

Nawotniak, D.S.S. Lim, S.S. Hughes, A. Sehlke, A. Brady, C. Cockell, S. Payler, A. Stevens, C. Haberle, R. Elphic, W.B. Garry, E. Gibbons, C. Borg, E. Sandmeyer, and the BASALT team. Department of Geoscience, Idaho State University, Pocatello, Idaho (kobsshan@isu.edu), NASA Ames Research Center, Moffett Field, CA, School of Geography & Earth Sciences, McMaster University, Hamilton, Ontario, Canada UK Centre for Astrobiology, The University of Edinburgh, Edinburgh, Scotland, Planetary Geodynamics Laboratory, Code 698, NASA Goddard Space Flight Center, Greenbelt, MD

The Inner Planets Panel of the Planetary Exploration Decadal Survey defined several science questions related to the origins, emplacement, and sequestration of lunar polar volatiles: 1. What is the lateral and vertical distribution of the volatile deposits? 2. What is the chemical composition and variability of polar volatiles? 3. What is the isotopic composition of the volatiles? 4. What is the physical form of the volatiles? 5. What is the rate of the current volatile deposition? A mission concept study, the Lunar Polar Volatiles Explorer (LPVE), defined a approximately $1B New Frontiers mission to address these questions. The NAS/NRC report, 'Scientific Context for the Exploration of the Moon' identified he lunar poles as special environments with important implications. It put forth the following goals: Science Goal 4a-Determine the compositional state (elemental, isotopic, mineralogic) and compositional distribution (lateral and depth) of the volatile component in lunar polar regions. Science Goal 4b-Determine the source(s) for lunar polar volatiles. Science Goal 4c-Understand the transport, retention, alteration, and loss processes that operate on volatile materials at permanently shaded lunar regions. Science Goal 4d-Understand the physical properties of the extremely cold (and possibly volatile rich) polar regolith. Science Goal 4e-Determine what the cold polar regolith reveals about the ancient solar environment.

SURFACE. J.L. Heldmann, D.S.S. Lim, A. Colaprete, W.B. Garry, S.S. Hughes, S. Kobs Nawotniak, A. Sehlke, C. Neish, G.R. Osinski, K. Hodges, A. Abercromby, B.A. Cohen, A. Cook, R. Elphic, H. Mallonee, A. Matiella Novak, E. Rader, D. Sears, H. Sears and the FINESSE and BASALT teams. NASA Ames Research Center Moffett Field, CA, Bay Area Environmental Research Institute, Petaluma, CA, NASA Goddard Space Flight Center, Greenbelt, MD, 4 Idaho State University, Pocatello, ID, Millennium Engineering, Moffett Field, CA, Western University, London, Ontario, Canada, Arizona State University, Tempe, AZ, Johns Hopkins University / Applied Physics Lab, Laurel, MD.

REMOTE FIELD/EVA TEAM. B. A. Cohen, D. S. S. Lim, K. E. Young, A. Brunner, R. E. Elphic, A. Horne, M. C. Kerrigan, G. R. Osinski, J. R. Skok, S. W. Squyres, D. Saint-Jacques, and J. L. Heldmann, NASA Marshall Space Flight Center, Huntsville AL 35812 (barbara.a.cohen@nasa.gov); NASA Ames Research Center; BAER Institute; CRESST/University of Maryland and NASA Goddard Space Flight Center; Arizona State University; University of Western Ontario; SETI Institute; Cornell University; Canadian Space Agency.

Resource Prospector is a lunar mission to investigate "strategic knowledge gaps" (SKGs) for in situ resource utilization (ISRU). The mission is proposed to land at one of the two poles where there are indication of enhanced volatile (hydrogen) concentrations. The landing site will be determined by the RP site-analysis team with input from broader lunar exploration community as being near traversable landscape that has a high potential of containing elevated concentrations of volatiles such as water while maximizing mission duration. A rover will host the Regolith and Environment Science and Oxygen and Lunar Volatile Extraction (RESOLVE) payload for resource mapping and processing. The instruments on the payload include a 1-meter drill, neutron spectrometer, a near infrared spectrometer, a drill operations camera, and a reactor with a gas chromatograph-mass spectrometer for volatile analysis. The concept of operations for the mission were tested during a field test in the fall of 2015. The path from the field test towards flight will be discussed as well as the current status of the instruments in the RESOLVE payload.

ODYSSEY NEUTRON SPECTROMETER DATA J. T. Wilson1, V. R. Eke1, R. J. Massey1, R. C. Elphic2, W. C. Feldman3, S. Maurice4 and L. F. A. Teodoro5, 1Institute for Computational Cosmology, Durham University, South Road, Durham. DH1 3LE, UK (j.t.wilson@durham.ac.uk), 2Planetary Systems Branch, NASA Ames Research Center, MS 245-3, Moffett Field, CA,94035-1000, USA, 3Planetary Science Institute, Tucson, AZ 85719, USA,4IRAP-OMP, Toulouse, France, 5BAER, NASA Ames Research Center, MS 245-3, Moffett Field, CA 94035, USA.