This study revisits calculations using linear cascade theory (LCT) to estimate the relative importance of the ion-induced collisional sputtering yield (also referred to as knock-on, nuclear, or kinetic sputtering) and the ion-induced electronic sputtering yield. We focus on sputtering of Na from Mercury’s surface using data from the Mercury Surface, Space Environment, Geochemistry and Ranging (MESSENGER) mission. The updated nuclear and electronic sputtering yields for H and He solar wind ions at 1 keV amu ^−1 , respectively, are approximately an order of magnitude larger than the values calculated using LCT in M. A. McGrath et al. Compared to this earlier work, our study uses a factor of 10 larger Na surface fraction and a factor of 3 lower total atom surface density based on MESSENGER data that were not available when the McGrath et al. study was carried out. Additional differences are the use of new data more relevant to Mercury’s surface minerals for the nuclear and electronic stopping-power cross sections and the surface binding energies. For the conditions considered in this study, the nuclear sputtering yields calculated using LCT show good agreement with the values calculated using recent binary collision approximation models. We qualitatively compare estimates of the Na sputtering source rate to other source processes for Mercury’s exosphere, considering recent studies of the precipitating ion flux based on MESSENGER data. Future experiments that measure the yield and ejecta energy spectra for simulated Mercury surface conditions, along with advanced modeling of ion–surface interactions, are required to reduce uncertainties and support exospheric studies.

We revisit the importance of electron-stimulated Desorption (ESD) as a source of neutral sodium (Na) atoms and Na ^+ ions in Mercury’s exosphere and ionosphere. For the first time we have calibrated the ESD yield per electron as a function of electron energy in the energy range 100–950 eV. This calibrated yield per electron was convolved with the electron flux as a function of energy onto Mercury’s cusps to determine the average release rate of Na ^+ to the exosphere, using electron flux and cusp area estimates from a recent hybrid magnetosphere model. Given that previous work showed the ESD yields per electron of Na ^+ ions and neutral Na atoms are approximately equal, we compared the energy-weighted ESD release of Na ^+ to that deriving from micrometeoroid impact vaporization, photon-stimulated desorption, and ion sputtering. We conclude that ESD is not a significant source of neutral Na atoms or Na ^+ ions to Mercury’s exosphere.

Emission in Mercury’s exosphere observed from the ground and by spacecraft is produced by resonant scattering of sunlight. The process of resonant scattering changes the structure of the exosphere owing to the transfer of momentum between the incident photons and the scattering atoms, resulting in a net antisunward-directed force known as radiation pressure. The photon scattering rate (the so-called g -value) and the magnitude of radiation pressure depend strongly on both Mercury’s distance from the Sun and the radial velocities of the scattering atoms relative to the Sun. We discuss four effects of the changing g -value over a Mercury year that require a model capable of tracking the positions and speeds of exospheric constituents in order to properly interpret emission data: (1) variations in the escape flux of atoms, (2) variations in the ratio of atoms that escape Mercury in neutral versus ionized form, (3) difficulties in determining where material was ejected from the surface based on the locations of the emitting atoms in the exosphere, and (4) systematic uncertainties in interpreting the column density of emitting gas using a constant g -value versus a variable g -value that takes into account the radial motion of the atoms relative to the Sun.

Introduction: Na, Ar and He are some of the most abundant confirmed neutral species in Mercury’s exosphere. Whereas the source of He is from the solar wind (SW), the source of the Na is potentially due to sputtering from silicates on the Hermean surface (1, 2). As SW ions impact the surface, they deposit energy, leading to sputtered atoms from the substrate (3, 4). The yield and energy distributions of the sputtered atoms depends on the energy of the impacting ions and the composition of the impacted surface. Understanding the role SW ions play on surface sputtering of Mercury is critical to any exosphere model (3). The most common sputtering models use the binary collision approximation (BCA) and thus consider sputtering to be a result of binary collision cascades (5). These models can be used to predict the energy distribution and yield of sputtered atoms as a function of incoming ion type, energy, and impacting angle. A fundamental physical parameter for BCA models is the surface binding energy (SBE) of atoms in the substrate (6, 7). The SBE is a user defined value in SDTrimSP (8), a BCA sputtering simulation tool, and in the commonly referenced Thompson energy distribution of the sputtered atoms (9). Despite the clear importance of the SBE, its actual value is not well understood for many substrates. For single component substrates, the SBE is often approximated as the heat of sublimation for the substrate atoms (10). However, previous research has suggested that this approach can underestimate the SBE by 20-40% (7). More importantly for planetary science, there is no universal approach to estimating the SBE for multicomponent substrates where the Na is likely bonded to other atomic species. SDTrimSP recommends using the pure heat of sublimation of each atomic species as the SBE for sputtering from a compound, which is 1.1 eV for Na (8). However, this approach assumes that the SBE is independent of the bonds formed with the other atoms within the substrate. In contrast, Lammer et al. (12) predict a value between 2-2.65 eV but note that this is not well determined due to a lack of experimental data. Given that BCA methods rely on a user defined SBE, this can be a significant source of error for sputtering predictions. To address this issue, we have performed molecular dynamics (MD) simulations to better constrain the SBE of Na from silicates. We then consider the effect these modified inputs have on the predicted yield and energy distributions of sputtered Na due to SW impacts. Methods: MD simulations were conducted to determine the SBE of Na for various crystalline silicates: sodium metasilicate (Na2SiO3), sodium orthosilicate (Na4SiO4), and albite (NaAlSi3O8). An iterative method was used to determine the minimum energy needed to remove one Na atom completely from the substrate surface. Simulations were conducted using a many-body reactive potential that was previously shown to be suitable for a variety of sodium silicate crystals (13). BCA models were then used to determine how the resulting SBE values affected the predicted yield and energy distribution of sputtered Na. The commonly referenced Thompson distribution was used to determine the energy distribution vs. SBE. SDTrimSP was used to calculate the sputtering yield of Na vs. SBE. To capture the most common components of the SW, 1 keV H+ and He2+ impacts were simulated on sodium silicate surfaces. Results: The MD simulations yielded a range of SBEs from sodium silicates: 2.6 eV for sodium orthosilicate, 4.4 eV for sodium metasilicate, and 7.9 eV for albite. In contrast, the individual cohesive energy of pure Na is only 1.1 eV. Therefore, SBEs from a compound can be drastically different than their atomistic cohesive energies. These results show that the SBE of a specific atom is a function of the compound in which the atom is bound. The newly predicted Na SBE values were then used to determine the sputtering yield and energy distribution of the sputtered atoms using SDTrimSP and the Thompson energy distribution. We find that increasing the SBE from 1.1 to 7.9 eV had a significant effect on predicted energy distribution (Fig. 1). Therefore, the characteristics of sputtered atoms are highly dependent on the SBE used for the simulations. Similarly, the Na yield from albite was highly dependent on the Na SBE (Fig. 2). For example, the Na yield from albite for a 1keV H impact decreased by a factor of almost 15 when the SBE was increased from 1.1 eV to the SBE for Na from albite (7.9 eV). Overall, this study demonstrates that the SBE within in a compound can be significantly different than the monatomic cohesive energy. The results demonstrate the potential of MD to better understand and constrain these values, though laboratory measurements are still needed to benchmark these calculations. In summary, an accurate SBE is critical to obtaining realistic models of SW sputtering contribution to the Hermean exosphere.Fig 1. Normalized Energy distribution of sputtered Na atoms as a function of SBE\Fig 2. Sodium sputtering yield as a function of surface binding energy References:[1] McCoy TJ, et al. 2018. Mercury. View after MESSENGER, pp. 176–90 [2] McClintock WE, et al. Mercur. View after MESSENGER, pp. 371–406 [3] Killen RM, et al. 2001. J. Geophys. Res. Planets. 106(E9):20509–25 [4] Domingue DL, et al. 2014. Space Sci. Rev. 181(1–4):121–214 [5] Eckstein W, Urbassek HM. 2007. In Sputtering by Particle Bombardment, pp. 21–31. Springer [6] Stepanova M, Dew SK. 2001. J. Vac. Sci. Technol. A Vacuum, Surfaces, Film. 19(6):2805–16 [7] Yang X, Hassanein A. 2014. Appl. Surf. Sci. 293:187–90 [8] Mutzke A, et al. 2019 [9] Thompson MW. 1968. Philos. Mag.18(152):377–414 [10] Kelly R. 1986. Nucl. Instruments Methods Phys. Res. Sect. B Beam Interact. with Materials and Atoms. 18(1–6):388–98 [11] Leblanc F, Johnson RE. 2003. Icarus. 164(2):261–81 [12] Lammer H, et al. 2003. Icarus. 166(2):238–47 [13] Hahn SH, et al. 2018. J. Phys. Chem. C. 122(34):19613–24

Outgassing from materials, whether through the ascent/descent stages of lunar vehicles, airlock depressurizing, rover or astronaut suit outgassing, may cause an effect of unwanted accumulation of volatiles at the surface and exosphere. This is especially important at (or proximal) to permanently shadowed regions (PSRs) at the lunar poles. Herein, we provide estimates of expected outgassing from various human-landed objects on the Moon, including backpacks, airlocks, rovers, landers, trash and mining operations. Astronaut suits produce some level of oxygen outgassing (Helou et al., 2022), which may transport and condense in these PSRs, even in micro- cold traps (Glavin et al., 2010).We estimate the outgassing from drill mining and trash-to-gas conversion assuming a specific technology is operating. These outgassing systems can create local, temporary atmospheres in the vicinity (similar to 100 km radius) of the sources. The atmosphere may be particularly high within meters of the source. To obtain column densities for these temporary atmospheres, we first bracket ranges for the gas number loss as a function of time. We then derive the maximum distance traveled and the time the released molecules remain in the exosphere for a single ballistic hop, assuming the molecules are ejected from the surface of the object at its surface temperature. In some cases, such as the astronaut backpack and the rover, the temperature is that of the source. Given this information, an average and peak local exospheric density and column density can be estimated. We find that backpacks, airlock releases, and the Starship lander can create relatively high-density local atmospheres, with local near-lander outgassing water densities exceeding 10(7)/cm(3). This local water exosphere is over 10(6) times greater than the LADEE-derived lower limit of the natural water exosphere at similar to 3/cm(3). Thus, the anthropogenic temporary water exosphere will likely dominate the environment near the lander, making an assessment of the natural exospheric water environment difficult.

ReferencesLeblanc, F. et al., 2009. Short-term variations of Mercury's Na exosphere observed with very high spectral resolution. Geophys. Res. Lett. 36, 7.Mangano, V. et al., 2015. THEMIS Na exosphere observations of Mercury and their correlation with in-situ magnetic field measurements by MESSENGER, Planet. Space Sci. 115, 102-109.Potter, A. E., R. M. Killen and M. Sarantos. 2006. Spatial distribution of sodium on Mercury. Icarus 181, 1 -12.Potter, A. E., R. M. Killen and T. H. Morgan, 1999. Rapid changes in the sodium exosphere of Mercury. Planet. Space Sci. 47, 1441-1448.Potter, A. E. and T. H. Morgan, 1985. Discovery of sodium in the atmosphere of Mercury. Geophys. Res. Lett. 22, 3289-3292.Sprague, A. L. et al., 1998. Mercury sodium atmosphere enhancements, Radar bright spots, and visible surface features. Icarus 136, 60-68.

Our understanding of the ion-sputtering contribution to the formation of exospheres on airless bodies has been hindered by the lack of accurate surface binding energies (SBEs) of the elements in the various mineral and amorphous compounds expected to be on the surfaces of these bodies. The SBE for a given element controls the predicted sputtering yield and energy distribution of the ejecta. Here, we use molecular dynamics computations to provide SBE data for the range of elements sputtered from plagioclase feldspar crystalline end members, albite and anorthite, which are expected to be important mineral components on the surfaces of the Moon and Mercury. Results show that the SBE is dependent on the crystal orientation and the element’s coordination, meaning multiple SBEs are possible for a given element. Variation in the SBEs among the different surface positions has a significant effect on the predicted yield and energy distribution of the ejecta. We then consider sputtering by H, He, and a solar wind mixture of 96% H and 4% He. For each of these cases, we derive best-fit elemental SBE values to predict the ejecta energy distribution from each of the (001), (010), and (011) cleavage planes. We demonstrate that the He contribution to the sputtering yield cannot be accounted for by multiplying the 100% H results by some factor. Lastly, we average our results over all three possible lattice orientations and provide best-fit elemental SBE values that can be easily incorporated into sputtering yield models.

This work assesses the potential of midsized and large human landing systems to deliver water from their exhaust plumes to cold traps within lunar polar craters. It has been estimated that a total of between 2 and 60 T of surficial water was sensed by the Lunar Reconnaissance Orbiter Lyman Alpha Mapping Project on the floors of the larger permanently shadowed south polar craters. This intrinsic surficial water sensed in the far-ultraviolet is thought to be in the form of a 0.3%–2% icy regolith in the top few hundred nanometers of the surface. We find that the six past Apollo Lunar Module midlatitude landings could contribute no more than 0.36 T of water mass to this existing, intrinsic surficial water in permanently shadowed regions (PSRs). However, we find that the Starship landing plume has the potential, in some cases, to deliver over 10 T of water to the PSRs, which is a substantial fraction (possibly >20%) of the existing intrinsic surficial water mass. This anthropogenic contribution could possibly overlay and mix with the naturally occurring icy regolith at the uppermost surface. A possible consequence is that the origin of the intrinsic surficial icy regolith, which is still undetermined, could be lost as it mixes with the extrinsic anthropogenic contribution. We suggest that existing and future orbital and landed assets be used to examine the effect of polar landers on the cold traps within PSRs.

In the coming decades, exploration of the lunar surface is likely to increase as multiple nations execute ambitious lunar exploration programs. Among several environmental effects of such activities, increasing traffic near and on the lunar surface will result in the injection of anthropogenic neutral gases into the lunar exosphere. The subsequent ionization of such anthropogenic neutrals in the lunar environment may contribute to and ultimately exceed the generation of ‘native’ lunar pickup ions, thereby altering the fundamental space plasma interaction with the Moon. To better understand these possible effects, we conducted plasma simulations of the solar wind interaction with the Moon in the presence of increasing ion production rates from an anthropogenic lunar exosphere. At ionization levels between 0.1 and 10 times the native lunar exospheric ion production rate, little to no changes to the solar wind interaction to the Moon are present; however, ionization levels of 100 and 1000 times the native rate result in significant mass loading of the solar wind and disruption of the present-day structure of the Moon’s plasma environment. Comparing to the planned Artemis landings, which are likely to contribute only an additional ∼10% of the native lunar exospheric ion production rate, we conclude that the Artemis program will have little effect on the Moon’s plasma environment. However, more frequent landings and/or continual outgassing from human settlements on the Moon in the more distant future are likely to fundamentally alter the lunar plasma environment.

We have measured the absolute doubly differential angular sputtering yield for 20 keV Kr+ impacting a polycrystalline Cu slab at an incidence angle of θi = 45° relative to the surface normal. Sputtered Cu atoms were captured using collectors mounted on a half dome above the sample, and the sputtering distribution was measured as a function of the sputtering polar, θs, and azimuthal, ϕs, angles. Absolute results of the sputtering yield were determined from the mass gain of each collector, the ion dose, and the solid angle subtended, after irradiation to a total fluence of ∼1 × 1018 ions/cm2. Our approach overcomes shortcomings of commonly used methods that only provide relative yields as a function of θs in the incidence plane (defined by the ion velocity and the surface normal). Our experimental results display an azimuthal variation that increases with increasing θs and is clearly discrepant with simulations using binary collision theory. We attribute the observed azimuthal anisotropy to ion-induced formation of micro- and nano-scale surface features that suppress the sputtering yield through shadowing and redeposition effects, neither of which are accounted for in the simulations. Our experimental results demonstrate the importance of doubly differential angular sputtering studies to probe ion sputtering processes at a fundamental level and to explore the effect of ion-beam-generated surface roughness.

Research Article| December 01, 2023 The Dust, Atmosphere, and Plasma at the Moon William M. Farrell; William M. Farrell NASA Goddard Space Flight Center 8800, Greenbelt Road, Greenbelt, MD, 20771 USA Search for other works by this author on: GSW Google Scholar Jasper S. Halekas; Jasper S. Halekas Department of Physics and Astronomy, University of Iowa, Iowa City, IA, 52242 USA Search for other works by this author on: GSW Google Scholar Mihaly Horányi; Mihaly Horányi Department of Physics,University of Colorado, Boulder, CO 80309, USA Search for other works by this author on: GSW Google Scholar Rosemary M. Killen; Rosemary M. Killen NASA Goddard Space Flight Center 8800, Greenbelt Road, Greenbelt, MD, 20771 USA Search for other works by this author on: GSW Google Scholar Cesare Grava; Cesare Grava Southwest Research Institute, 6220 Culebra Road, San Antonio, TX, 78238, USA Search for other works by this author on: GSW Google Scholar Jamey R. Szalay; Jamey R. Szalay Department of Astrophysical Sciences, Princeton University, Peyton Hall, 4 Ivy Lane, Princeton, NJ, 08544, USA Search for other works by this author on: GSW Google Scholar Mehdi Benna; Mehdi Benna NASA Goddard Space Flight Center 8800, Greenbelt Road, Greenbelt, MD, 20771 USA Search for other works by this author on: GSW Google Scholar Pamela E. Clark; Pamela E. Clark Department of Physics, Earth Science and Space Science Engineering, Morehead State University, 123 Lappin Hall, Morehead, KY, 40351, USA Search for other works by this author on: GSW Google Scholar Michael R. Collier; Michael R. Collier NASA Goddard Space Flight Center 8800, Greenbelt Road, Greenbelt, MD, 20771 USA Search for other works by this author on: GSW Google Scholar Anthony Colaprete; Anthony Colaprete NASA Ames Research Center, Space Science Division, Moffett Field, Mountain View, CA 94035, USA Search for other works by this author on: GSW Google Scholar Jan Deca; Jan Deca Laboratory for Atmospheric and Space Physics (LASP), University of Colorado, Boulder, CO 80309, USA Search for other works by this author on: GSW Google Scholar Richard C. Elphic; Richard C. Elphic NASA Ames Research Center, Space Science Division, Moffett Field, Mountain View, CA 94035, USA Search for other works by this author on: GSW Google Scholar Shahab Fatemi; Shahab Fatemi Department of Physics, Fysikhuset, plan 4, Linnaeus väg 24, FA419, Umeå Universitet, 901 87 Umeå, Sweden Search for other works by this author on: GSW Google Scholar Yoshifumi Futaana; Yoshifumi Futaana Swedish Institute of Space Physics, Bengt Hultqvists väg 1, 981 92 Kiruna, Sweden Search for other works by this author on: GSW Google Scholar Mats Holmström; Mats Holmström Swedish Institute of Space Physics, Bengt Hultqvists väg 1, 981 92 Kiruna, Sweden Search for other works by this author on: GSW Google Scholar Dana M. Hurley; Dana M. Hurley Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD, 20723, USA Search for other works by this author on: GSW Google Scholar Georgiana Y. Kramer; Georgiana Y. Kramer Planetary Science Institute, Tucson, AZ, 85719, USA Search for other works by this author on: GSW Google Scholar Paul R. Mahaffy; Paul R. Mahaffy NASA Goddard Space Flight Center 8800, Greenbelt Road, Greenbelt, MD, 20771 USA Search for other works by this author on: GSW Google Scholar Masaki N. Nishino; Masaki N. Nishino Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Yoshinodai 3-1-1, Chuo-ku, Sagamihara, Kanagawa, 252-5210, Japan Search for other works by this author on: GSW Google Scholar Sarah K. Noble; Sarah K. Noble Mary W. Jackson NASA Headquarters, 300 Hidden Figures Way SW., Washington, DC, 20546, USA Search for other works by this author on: GSW Google Scholar Yoshifumi Saito; Yoshifumi Saito Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Yoshinodai 3-1-1, Chuo-ku, Sagamihara, Kanagawa, 252-5210, Japan Search for other works by this author on: GSW Google Scholar Andrew R. Poppe; Andrew R. Poppe Space Sciences Laboratory, University of California, Berkeley, CA, 94720, USA Search for other works by this author on: GSW Google Scholar Kurt D. Retherford; Kurt D. Retherford Southwest Research Institute, 6220 Culebra Road, San Antonio, TX, 78238, USA Search for other works by this author on: GSW Google Scholar Xu Wang; Xu Wang Laboratory for Atmospheric and Space Physics (LASP), University of Colorado, Boulder, CO 80309, USA Search for other works by this author on: GSW Google Scholar Shoichiro Yokota Shoichiro Yokota Osaka University, Machikaneyama-cho, Toyonaka 560-0043, Japan Search for other works by this author on: GSW Google Scholar Author and Article Information William M. Farrell NASA Goddard Space Flight Center 8800, Greenbelt Road, Greenbelt, MD, 20771 USA Jasper S. Halekas Department of Physics and Astronomy, University of Iowa, Iowa City, IA, 52242 USA Mihaly Horányi Department of Physics,University of Colorado, Boulder, CO 80309, USA Rosemary M. Killen NASA Goddard Space Flight Center 8800, Greenbelt Road, Greenbelt, MD, 20771 USA Cesare Grava Southwest Research Institute, 6220 Culebra Road, San Antonio, TX, 78238, USA Jamey R. Szalay Department of Astrophysical Sciences, Princeton University, Peyton Hall, 4 Ivy Lane, Princeton, NJ, 08544, USA Mehdi Benna NASA Goddard Space Flight Center 8800, Greenbelt Road, Greenbelt, MD, 20771 USA Pamela E. Clark Department of Physics, Earth Science and Space Science Engineering, Morehead State University, 123 Lappin Hall, Morehead, KY, 40351, USA Michael R. Collier NASA Goddard Space Flight Center 8800, Greenbelt Road, Greenbelt, MD, 20771 USA Anthony Colaprete NASA Ames Research Center, Space Science Division, Moffett Field, Mountain View, CA 94035, USA Jan Deca Laboratory for Atmospheric and Space Physics (LASP), University of Colorado, Boulder, CO 80309, USA Richard C. Elphic NASA Ames Research Center, Space Science Division, Moffett Field, Mountain View, CA 94035, USA Shahab Fatemi Department of Physics, Fysikhuset, plan 4, Linnaeus väg 24, FA419, Umeå Universitet, 901 87 Umeå, Sweden Yoshifumi Futaana Swedish Institute of Space Physics, Bengt Hultqvists väg 1, 981 92 Kiruna, Sweden Mats Holmström Swedish Institute of Space Physics, Bengt Hultqvists väg 1, 981 92 Kiruna, Sweden Dana M. Hurley Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD, 20723, USA Georgiana Y. Kramer Planetary Science Institute, Tucson, AZ, 85719, USA Paul R. Mahaffy NASA Goddard Space Flight Center 8800, Greenbelt Road, Greenbelt, MD, 20771 USA Masaki N. Nishino Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Yoshinodai 3-1-1, Chuo-ku, Sagamihara, Kanagawa, 252-5210, Japan Sarah K. Noble Mary W. Jackson NASA Headquarters, 300 Hidden Figures Way SW., Washington, DC, 20546, USA Yoshifumi Saito Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Yoshinodai 3-1-1, Chuo-ku, Sagamihara, Kanagawa, 252-5210, Japan Andrew R. Poppe Space Sciences Laboratory, University of California, Berkeley, CA, 94720, USA Kurt D. Retherford Southwest Research Institute, 6220 Culebra Road, San Antonio, TX, 78238, USA Xu Wang Laboratory for Atmospheric and Space Physics (LASP), University of Colorado, Boulder, CO 80309, USA Shoichiro Yokota Osaka University, Machikaneyama-cho, Toyonaka 560-0043, Japan Publisher: Mineralogical Society of America First Online: 04 Dec 2023 Copyright © 2023 by the Mineralogical Society of AmericaMineralogical Society of America Reviews in Mineralogy and Geochemistry (2023) 89 (1): 563–609. https://doi.org/10.2138/rmg.2023.89.13 Article history First Online: 04 Dec 2023 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation William M. Farrell, Jasper S. Halekas, Mihaly Horányi, Rosemary M. Killen, Cesare Grava, Jamey R. Szalay, Mehdi Benna, Pamela E. Clark, Michael R. Collier, Anthony Colaprete, Jan Deca, Richard C. Elphic, Shahab Fatemi, Yoshifumi Futaana, Mats Holmström, Dana M. Hurley, Georgiana Y. Kramer, Paul R. Mahaffy, Masaki N. Nishino, Sarah K. Noble, Yoshifumi Saito, Andrew R. Poppe, Kurt D. Retherford, Xu Wang, Shoichiro Yokota; The Dust, Atmosphere, and Plasma at the Moon. Reviews in Mineralogy and Geochemistry 2023;; 89 (1): 563–609. doi: https://doi.org/10.2138/rmg.2023.89.13 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyReviews in Mineralogy and Geochemistry Search Advanced Search The topics of lofted dust, ejected atomic and molecular species, and plasma interactions at the Moon have made revolutionary strides since the last 'New Views of the Moon' review in 2006 (Jolliff et al. 2006). Specifically, in the last 13 years, there have been over a half-dozen spacecraft that are dedicated, wholly or in part, to the study of this neutral, ionized, and particulate atmosphere at the Moon. A key finding is that all three of these phenomena are inter-connected, and suggest the term 'exosphere' can be extended to particulates and surface-emitted plasma like reflected protons and exo-ions... You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

In the present decade and beyond, now 51 years after the last Apollo landing, the NASA Artemis human exploration program will offer abundant opportunities for heliophysics investigations from, by, and of the Moon from the vantage points of the lunar orbit and the surface. The Lunar Solar Occultation Explorer (LunaSOX) concept uses the lunar limb to occult the solar disk for high-resolution coronal observations at hourly, daily, to biweekly cadences from spacecraft either in the lunar orbit or at the surface. A 0.2 m diameter solar telescope in orbit with white light and narrow-band visible filters would provide arcsecond spectroscopic imaging of the low-to-high corona (1–10 R☉) with an upper limit of 10 –12 B☉ on the local scattered light background from lunar atmospheric dust, as compared to 10 –9 B☉ for Earth ground-based solar eclipse observations looking up through the atmosphere at totality. For eclipse observations from and by the Moon, there would be no significant atmospheric disturbances that otherwise limit seeing to arcsec resolution from Earth’s surface. The present eccentric orbits of the ARTEMIS P1 and P2 spacecraft are used as models for a 1 × 10 Rm orbit of LunaSOX to compute the times of solar eclipse intervals, up to 2 hours in duration between the east and west solar hemispheres at a daily cadence for coronal observations at 1–16 R☉ when the orbital aposelene is in anti-sunward directions. In a low-altitude circular orbit and from the surface, the observational cadences would, respectively, be hourly and biweekly. LunaSOX satellites also carrying in situ space environment instruments could integrate into a network of orbital platforms for space weather monitoring and communications relay to far-side surface lander and permanent base sites, e.g., for low-frequency radio cosmology and detection of exoplanet magnetospheres.

We have simulated the sodium (Na) exosphere of Mercury to show how the exosphere is affected by the assumed surface binding energy (SBE) of Na in the sputtered component. We constrained ion precipitation onto the surface using distributions for the cusp regions that are consistent with measurements by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging Fast Imaging Plasma Spectrometer instrument. We have simulated sputtering with SBEs of 0.27, 2.6, 4.4, and 7.9 eV, with the lowest value commonly used in exosphere models and the highest from recent molecular dynamics calculations for the Na-bearing feldspar end-member, albite. A gradual change in the exosphere is seen as the yield decreases and the ejecta energy increases with increasing SBE. We describe the corresponding exosphere source functions for ion sputtering (IS), as well as for the previously studied processes of micrometeoroid impact vaporization and photon-stimulated desorption (PSD), along with their release energy distributions and spatial distributions. We have summed the contributions of the various source processes to explain how and when the different sources can be distinguished by observations. The modeled exosphere scale heights range from 72 km for PSD to over 1000 km for IS using a SBE of 7.9 eV. We find that the processes responsible for generating Mercury's Na exosphere are separable by measuring line-of-sight column densities tangent to the planet at various altitudes and positions around the planet. Our initial results are consistent with the Na being sputtered from a high-SBE material such as feldspar, which has been predicted to be abundant on the Mercury's surface.

Rosemary M. Killen , Liam S. Morrissey , Matthew H. Burger , Ronald J. Vervack, Jr. , Orenthal J. Tucker , and Daniel W. Savin 1 NASA Goddard Space Flight Center, Planetary Magnetospheres Laboratory, Code 695, Greenbelt, MD 20771, USA; rosemary.killen@nasa.gov 2 NASA Goddard Space Flight Center/Catholic University, Washington, DC 20005, USA 3 Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA 4 Johns Hopkins Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723, USA 5 Columbia Astrophysics Laboratory, Columbia University, MC 5247, 550 West 120th Street, New York, NY 10027, USA Received 2023 March 14; published 2023 April 28

Introduction: Solar wind, which comprises high energy hydrogen ions, continuously strikes the lunar surface, which is rich in oxygen. This presents an opportunity for hydroxylation - the creation of OH on lunar soil. Both OH and H2O have been detected on the lunar surface, with some variability in abundance throughout the lunar day. It is important to understand how space weathering contributes to the production and proliferation of hydrogen-bearing resources such as water within the lunar environment.OH shows a distinct absorption feature in the infrared (IR) at ~3 µm-1 that can be readily studied. Fourier Transform Infrared (FTIR) Spectroscopy is a fast and accurate way to detect changes in the infrared spectra of lunar soil. Previous studies have examined the changes in IR spectra of amorphous silica and olivine, as well as lunar soil before and after hydrogen irradiation. However, the evolution of the OH band and other IR features has not been studied during hydrogen radiation itself. It is especially important to not expose the samples to terrestrial air, which will contaminate the samples with water. Method and Results: We present FTIR spectra on Apollo-era soil samples obtained simultaneously with high energy hydrogen plasma irradiation, similar to the solar wind. Samples are first prepared by baking under vacuum to drive off any surface water. Samples are also brought through thermal cycling and heated to 400K (lunar dayside maximum temperature) in-situ, and changes in their IR spectra are reported. Comparisons between Apollo samples with different minerology and with a control of crushed SiO2 are also provided. Results show broad but distinct growths in the 3 µm-1 absorption band for lunar samples compared to a sharper peak for SiO2. Since the samples are not exposed to terrestrial water during measurements, the evidence of hydroxylation presented is likely due to hydrogen irradiation.

A latitudinal and radial study of the lunar sodium exosphere has been performed utilizing observations made from two different methods: (1) observations made at targeted altitudes using a Fabry-Perot Spectrometer (FPS) and (2) observations made from a coronagraph. The FPS observations made from the National Solar Observatory McMath-Pierce Solar Telescope, Kitt Peak, Arizona and the coronagraph observations were made at the Winer Observatory, Sonoita, Arizona. A small subset of the high resolution FPS observations were made concurrently with coronagraph measurements. Measured linewidths and linewidth-derived temperatures from FPS observa-tions were compared to temperatures derived from the coronagraphic intensity altitude profiles, with FPS linewidth-derived temperatures shown to be consistently lower. We suggest that the coronagraph method samples a velocity distribution perpendicular to the FPS's LOS, while the FPS samples a velocity distribution tangential to the lunar limb (i.e., along the FPS LOS). We also suggest that the coronagraph measurements may be more sensitive to the escaping population of atoms as the population close to the surface is not observed. The concurrent FPS measurements sit below the occulting disk of the coronagraph and measure the atoms closer to the surface. Furthermore, both the FPS linewidth-derived temperatures and the coronagraph scale heights show an increase towards high latitudes, an effect which is attributed to particle transport and/or contributions from a source like meteoroid impact vaporization. FPS linewidths decrease as a function of altitude, a result confirmed through a simulation of velocity distributions from nonthermal source mechanisms. And, finally, Linewidths are largest when looking over the dawn/dusk terminator. These results will enable improved characterization of the sources for the lunar sodium exosphere.

Future exploration efforts of the Moon, Mars, and other bodies are poised to focus heavily on persistent and sustainable survey and research efforts, especially given the recent interest in a long-term sustainable human presence at the Moon. Key to these efforts understands a number of important processes on the lunar surface for both scientific and operational purposes. We discuss the potential value of in situ artificial substrate witness plates, powerful tools that can supplement familiar remote sensing and sample acquisition techniques and provide a sustainable way of monitoring processes in key locations on planetary surfaces while maintaining a low environmental footprint. These tools, which we call Biscuits, can use customized materials as wide ranging as zircon-based spray coatings to metals potentially useable for surface structures, to target specific processes/questions as part of a small, passive witness plate that can be flexibly placed with respect to location and total time duration. We examine and discuss unique case studies to show how processes such as water presence/transport, presence and contamination of biologically relevant molecules, solar activity related effects, and other processes can be measured using Biscuits. Biscuits can yield key location sensitive, time integrated measurements on these processes to inform scientific understanding of the Moon and enable operational goals in lunar exploration. While we specifically demonstrate this on a simulated traverse and for selected examples, we stress all groups interested in planetary surfaces should consider these adaptable, low footprint, and highly informative tools for future exploration.

Research Article| December 01, 2023 Surface Volatiles on the Moon Dana M. Hurley; Dana M. Hurley Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, Maryland 20723, U.S.A. dana.hurley@jhuapl.edu Search for other works by this author on: GSW Google Scholar Matthew A. Siegler; Matthew A. Siegler Planetary Science Institute, 1700 E Fort Lowell Rd STE 106, Tucson, Arizona 85719, U.S.A. msiegler@psi.edu Search for other works by this author on: GSW Google Scholar Joshua T. S. Cahill; Joshua T. S. Cahill Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, Maryland 20723, U.S.A. joshua.cahill@jhuapl.edu Search for other works by this author on: GSW Google Scholar Anthony Colaprete; Anthony Colaprete NASA Ames Research Center, Moffett Field, California 94035, U.S.A. anthony.colaprete-1@nasa.gov Search for other works by this author on: GSW Google Scholar Emily Costello; Emily Costello Hawai'i Institute of Geophysics and Planetology, University of Hawaii at Manoa, Honolulu, Hawai'i 96822, U.S.A. ecostello@higp.hawaii.edu Search for other works by this author on: GSW Google Scholar Ariel N. Deutsch; Ariel N. Deutsch NASA Ames Research Center, Moffett Field, California 94035, U.S.A. ariel.deutsch@nasa.gov Search for other works by this author on: GSW Google Scholar Richard C. Elphic; Richard C. Elphic NASA Ames Research Center, Moffett Field, California 94035, U.S.A. richard.c.elphic@nasa.gov Search for other works by this author on: GSW Google Scholar Wenzhe Fa; Wenzhe Fa Institute of Remote Sensing and GIS, Peking University, Beijing 100871, China wzfa@pku.edu.cn Search for other works by this author on: GSW Google Scholar Cesare Grava; Cesare Grava Southwest Research Institute, 220 Culebra Road, San Antonio, Texas 78238, U.S.A. cesare.grava@swri.org Search for other works by this author on: GSW Google Scholar Paul O. Hayne; Paul O. Hayne Astrophysical and Planetary Sciences, 2000 Colorado Avenue, University of Colorado, Boulder, Colorado 80309, U.S.A. paul.hayne@colorado.edu Search for other works by this author on: GSW Google Scholar Jennifer Heldmann; Jennifer Heldmann NASA Ames Research Center, Moffett Field, California 94035, U.S.A. jennifer.heldmann@nasa.gov Search for other works by this author on: GSW Google Scholar Amanda R. Hendrix; Amanda R. Hendrix Planetary Science Institute, 1700 E Fort Lowell Rd STE 106, Tucson, Arizona 85719, U.S.A. ahendrix@psi.edu Search for other works by this author on: GSW Google Scholar Andrew P. Jordan; Andrew P. Jordan Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Morse Hall, 8 College Road, Durham, New Hampshire 03824, U.S.A. a.p.jordan@unh.edu Search for other works by this author on: GSW Google Scholar Rosemary M. Killen; Rosemary M. Killen NASA Goddard Space Flight Center, 800 Greenbelt Rd, Greenbelt, Maryland 20771, U.S.A. rosemary.killen@nasa.gov Search for other works by this author on: GSW Google Scholar Rachel L. Klima; Rachel L. Klima Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, Maryland 20723, U.S.A. rachel.klima@jhuapl.edu Search for other works by this author on: GSW Google Scholar Georgiana Kramer; Georgiana Kramer Planetary Science Institute, 1700 E Fort Lowell Rd STE 106, Tucson, Arizona 85719, U.S.A. gkramer@psi.edu Search for other works by this author on: GSW Google Scholar Shuai Li; Shuai Li Hawai'i Institute of Geophysics and Planetology, University of Hawaii at Manoa, Honolulu, Hawai'i 96822, U.S.A. shuaili@hawaii.edu Search for other works by this author on: GSW Google Scholar Yang Liu; Yang Liu National Space Science Center, Zhongguancun Nanertiao 1, Beijing, 100190, China yangliu@nssc.ac.cn Search for other works by this author on: GSW Google Scholar Paul G. Lucey; Paul G. Lucey Hawai'i Institute of Geophysics and Planetology, University of Hawaii at Manoa, Honolulu, Hawai'i 96822, U.S.A. lucey@higp.hawaii.edu Search for other works by this author on: GSW Google Scholar Erwan Mazarico; Erwan Mazarico NASA Goddard Space Flight Center, 800 Greenbelt Rd, Greenbelt, Maryland 20771, U.S.A. erwan.m.mazarico@nasa.gov Search for other works by this author on: GSW Google Scholar Yvonne Pendleton; Yvonne Pendleton NASA Ames Research Center, Moffett Field, California 94035, U.S.A. pendletonyvonne@gmail.com Search for other works by this author on: GSW Google Scholar Michael Poston; Michael Poston Southwest Research Institute, 220 Culebra Road, San Antonio, Texas 78238, U.S.A. michael.poston@swri.org Search for other works by this author on: GSW Google Scholar Parvathy Prem; Parvathy Prem Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, Maryland 20723, U.S.A. parvathy.prem@jhuapl.edu Search for other works by this author on: GSW Google Scholar Kurt D. Retherford; Kurt D. Retherford Southwest Research Institute, 220 Culebra Road, San Antonio, Texas 78238, U.S.A. kretherford@swri.edu Search for other works by this author on: GSW Google Scholar Micah Schaible Micah Schaible School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332, U.S.A. mjschaible@gatech.edu Search for other works by this author on: GSW Google Scholar Author and Article Information Dana M. Hurley Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, Maryland 20723, U.S.A. Matthew A. Siegler Planetary Science Institute, 1700 E Fort Lowell Rd STE 106, Tucson, Arizona 85719, U.S.A. Joshua T. S. Cahill Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, Maryland 20723, U.S.A. Anthony Colaprete NASA Ames Research Center, Moffett Field, California 94035, U.S.A. Emily Costello Hawai'i Institute of Geophysics and Planetology, University of Hawaii at Manoa, Honolulu, Hawai'i 96822, U.S.A. Ariel N. Deutsch NASA Ames Research Center, Moffett Field, California 94035, U.S.A. Richard C. Elphic NASA Ames Research Center, Moffett Field, California 94035, U.S.A. Wenzhe Fa Institute of Remote Sensing and GIS, Peking University, Beijing 100871, China Cesare Grava Southwest Research Institute, 220 Culebra Road, San Antonio, Texas 78238, U.S.A. Paul O. Hayne Astrophysical and Planetary Sciences, 2000 Colorado Avenue, University of Colorado, Boulder, Colorado 80309, U.S.A. Jennifer Heldmann NASA Ames Research Center, Moffett Field, California 94035, U.S.A. Amanda R. Hendrix Planetary Science Institute, 1700 E Fort Lowell Rd STE 106, Tucson, Arizona 85719, U.S.A. Andrew P. Jordan Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Morse Hall, 8 College Road, Durham, New Hampshire 03824, U.S.A. Rosemary M. Killen NASA Goddard Space Flight Center, 800 Greenbelt Rd, Greenbelt, Maryland 20771, U.S.A. Rachel L. Klima Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, Maryland 20723, U.S.A. Georgiana Kramer Planetary Science Institute, 1700 E Fort Lowell Rd STE 106, Tucson, Arizona 85719, U.S.A. Shuai Li Hawai'i Institute of Geophysics and Planetology, University of Hawaii at Manoa, Honolulu, Hawai'i 96822, U.S.A. Yang Liu National Space Science Center, Zhongguancun Nanertiao 1, Beijing, 100190, China Paul G. Lucey Hawai'i Institute of Geophysics and Planetology, University of Hawaii at Manoa, Honolulu, Hawai'i 96822, U.S.A. Erwan Mazarico NASA Goddard Space Flight Center, 800 Greenbelt Rd, Greenbelt, Maryland 20771, U.S.A. Yvonne Pendleton NASA Ames Research Center, Moffett Field, California 94035, U.S.A. Michael Poston Southwest Research Institute, 220 Culebra Road, San Antonio, Texas 78238, U.S.A. Parvathy Prem Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, Maryland 20723, U.S.A. Kurt D. Retherford Southwest Research Institute, 220 Culebra Road, San Antonio, Texas 78238, U.S.A. Micah Schaible School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332, U.S.A. dana.hurley@jhuapl.edu joshua.cahill@jhuapl.edu rachel.klima@jhuapl.edu parvathy.prem@jhuapl.edu msiegler@psi.edu ahendrix@psi.edu gkramer@psi.edu anthony.colaprete-1@nasa.gov ariel.deutsch@nasa.gov richard.c.elphic@nasa.gov jennifer.heldmann@nasa.gov pendletonyvonne@gmail.com ecostello@higp.hawaii.edu shuaili@hawaii.edu lucey@higp.hawaii.edu wzfa@pku.edu.cn cesare.grava@swri.org michael.poston@swri.org kretherford@swri.edu paul.hayne@colorado.edu a.p.jordan@unh.edu rosemary.killen@nasa.gov erwan.m.mazarico@nasa.gov yangliu@nssc.ac.cn mjschaible@gatech.edu Publisher: Mineralogical Society of America First Online: 04 Dec 2023 Copyright © 2023 by the Mineralogical Society of AmericaMineralogical Society of America Reviews in Mineralogy and Geochemistry (2023) 89 (1): 787–827. https://doi.org/10.2138/rmg.2023.89.18 Article history First Online: 04 Dec 2023 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Dana M. Hurley, Matthew A. Siegler, Joshua T. S. Cahill, Anthony Colaprete, Emily Costello, Ariel N. Deutsch, Richard C. Elphic, Wenzhe Fa, Cesare Grava, Paul O. Hayne, Jennifer Heldmann, Amanda R. Hendrix, Andrew P. Jordan, Rosemary M. Killen, Rachel L. Klima, Georgiana Kramer, Shuai Li, Yang Liu, Paul G. Lucey, Erwan Mazarico, Yvonne Pendleton, Michael Poston, Parvathy Prem, Kurt D. Retherford, Micah Schaible; Surface Volatiles on the Moon. Reviews in Mineralogy and Geochemistry 2023;; 89 (1): 787–827. doi: https://doi.org/10.2138/rmg.2023.89.18 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyReviews in Mineralogy and Geochemistry Search Advanced Search Discovery of water in lunar samples and on the lunar surface has opened a new chapter in lunar exploration. In addition to their potential utility, water and other volatile compounds can record a vast amount of information about the evolution of the Moon and migration of material throughout the Solar System. This chapter centers on volatile species (H2O, OH, CO2, Ar, etc.) identified and theorized in the upper microns to meters of the lunar surface. While volatiles are generally thought of as residing within the cold, permanently shadowed regions (PSR) near the lunar poles, volatiles also... You do not have access to this content, please speak to your institutional administrator if you feel you should have access.