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At least 325 records · Page 18

SILVER: Surface Imaging for Lunar Volatiles, Resources, and Exploration

The Surface Imaging for Lunar Volatiles, Exploration, and Resources (SILVER) instrument is a proposed imaging investigation for the 2008 Lunar Reconnaissance Orbiter (LRO) mission. SILVER and its experienced Measurement Team will prepare for and support future lunar human exploration activities, especially landing site identification and certification on the basis of potential resources. SILVER combines a high-resolution pushbroom visible imaging channel (SILVER-HR) and a wide-field-of-view (45 deg) framing imaging channel (SILVER-WF). SILVER-HR will obtain a single-detector 6 km imaging swath of 12,228 pixels at 0.5 m/pixel to image greater than 100 sq km target areas from 50 km altitude, imaging greater than 15% the lunar surface during a 1 year nominal mission. SILVER-HR has excellent stray-light rejection and its imaging detector has selectable time delay integration (TDI) with up to 128 stages for extreme low-light sensitivity, permitting direct imaging of permanently shadowed polar regions in scattered sunlight or earthshine. SILVER-WF will obtain geodetic framing images in a 2048 x 2048 format at 20m/pixel, with 60% along-track overlap stereo for imaging context and for derivation of a global digital elevation model of meter-scale lunar topography.

Pappalardo, R. T.↗

Lunar Limb Observatory: An Incremental Plan for the Utilization, Exploration, and Settlement of the Moon

This paper proposes a comprehensive incremental program, Lunar Limb Observatory (LLO), for a return to the Moon, beginning with robotic missions and ending with a permanent lunar settlement. Several recent technological developments make such a program both affordable and scientifically valuable: robotic telescopes, the Internet, light-weight telescopes, shared- autonomy/predictive graphics telerobotic devices, and optical interferometry systems. Reasons for focussing new NASA programs on the Moon include public interest, Moon-based astronomy, renewed lunar exploration, lunar resources (especially helium-3), technological stimulus, accessibility of the Moon (compared to any planet), and dispersal of the human species to counter predictable natural catastrophes, asteroidal or cometary impacts in particular. The proposed Lunar Limb Observatory would be located in the crater Riccioli, with auxiliary robotic telescopes in M. Smythii and at the North and South Poles. The first phase of the program, after site certification, would be a series of 5 Delta-launched telerobotic missions to Riccioli (or Grimaldi if Riccioli proves unsuitable), emplacing robotic telescopes and carrying out surface exploration. The next phase would be 7 Delta-launched telerobotic missions to M. Smythii (2 missions), the South Pole (3 missions), and the North Pole (2 missions), emplacing robotic telescopes to provide continuous all-sky coverage. Lunar base establishment would begin with two unmanned Shuttle/Fitan-Centaur missions to Riccioli, for shelter emplacement, followed by the first manned return, also using the Shuttle/Fitan-Centaur mode. The main LLO at Riccioli would then be permanently or periodically inhabited, for surface exploration, telerobotic rover and telescope operation and maintenance, and support of Earth-based student projects. The LLO would evolve into a permanent human settlement, serving, among other functions, as a test area and staging base for the exploration, settlement, and terraforming of Mars.

Lowman, Paul. D., Jr.↗

Using the moon to probe the geomagnetic tail lobe plasma

We have detected the presence of plasma in the lobes of the geomagnetic tail from observations of magnetic induction in the moon forced by time variations of the earth's magnetotail lobe field. The magnitude of the moon's tangential electromagnetic transfer function when the moon is in the lobes of the geomagnetic tail is less than that when the moon is in the solar wind or geomagnetic tail plasma sheet. The tangential transfer function when the moon is in the magnetotail lobes decreases at frequencies above about 8 mHz due to finite wavelength effects. This shows that the waves in the magnetotail lobes which drive the lunar magnetic induction must have speeds far less than the speed of light and wavelengths comparable to the size of the moon.

Schubert, G.↗

Development of Radioluminescent Tritium Polymeric Material for High Visibility Applications

The Development of Radioluminescent Tritium Polymeric Material for High Visibility Applications effort investigates the nature and properties of materials consisting of tritium lights combined with various silicone adhesives. Physical, mechanical, and optical properties will be observed/measured, including their durability in the low earth orbit environment. Tritium or hydrogen-three is a radioactive isotope of hydrogen that emits beta particles as it undergoes a process called beta decay. A beta particle is a high-energy, high-speed electron (or positron) emitted from radioactive decay of an atomic nucleus. Because it is a gas, tritium must be bound to a material or encapsulated in a sealed glass container. The gaseous tritium can then be combined with a phosphor source which when struck with beta particles, fluoresces and emits light. Such a light source is referred to as a gaseous tritium light source (GTLS). A self-powered, radioluminescent tritium material capable of surviving multiple space environments has the potential to fulfill visibility requirements levied on space flight hardware and facilitate additional long term internal and external lighting needs such as for imaging, docking, tracking, and xEMU suits for lunar exploration on the moon.

Lauren Fisher↗

A Concept for Small, Remotely Operated, Coronagraph located at Small Observatory to Obtain Frequent Low-cost Remote Observations of the Lunar Exosphere and the Mercurian Tail

The sodium in the lunar exosphere is a marker species for studying the lunar exosphere because the element possesses two strong resonance transitions from the ground state whose wavelengths fall in the visible spectrum near 590 nm. Emissions at these wavelengths are thus, observable from Earth. Observations have shown that the exosphere responds in a complex way to the external processes (impact vaporization, sputtering, and photon stimulated desorption) that weather the lunar regolith to produce the sodium. Unraveling the sodium production allows us to study the processes that weather the regolith. Obtaining the extensive time sequence of observations required to unravel the sources of sodium using conventional observatories is impractical, and too expensive. Effectively imaging the lunar sodium exosphere dose to the Moon requires an off-axis rejection of scattered light that can only be obtained with a coronagraph. A related problem. the observation of the sodium tail of Mercury, can be addressed as well only by coronagraphic observations. We present here a concept for a small, rugged coronagraph sited at an observatory dedicated to remote robotic observing (the Winer Observatory in Sonoita Arizona) that can obtain the quality and quantity of lunar sodium observations needed to answer these questions. The design uses Commercial Off the Shelf Technology (COTS). If this facility is operational by 2013. the observations will be concurrent with the Lunar Atmosphere and Dust Environment Explorer (LADEE) mission.

Morgan, T. H.↗

U-Th-Pb, Rb-Sr, and Sm-Nd isotopic systematics of lunar troctolitic cumulate 76535 - Implications on the age and origin of this early lunar, deep-seated cumulate

The U-Th-Pb, Rb-Sr, and Sm-Nd isotopic systematics of four lightly leached residues of pristine, high-Mg, troctolitic cumulate 76535 were analyzed in order to determine their ages and magma sources. The data indicate that the cumulate was in isotopic equilibrium with a fluid or magma characterized by a high U-238/Pb-204 (mu) value of 600 at 4.236 Ga. Two and three stage Pb evolution calculations define even greater source mu values of about 1000, assuming low lunar initial mu values between 5 and 40 prior to about 4.43 Ga. These results are similar to mu values for KREEP sources and are also consistent with values from 78235, suggesting that at least some high-Mg suite rocks were derived from magma sources with high-mu values similar to KREEP, and support that idea that these rocks postdate primary lunar differentiation and formation of ferroan anorthosites.

Premo, Wayne R.↗

Galileo photometry of Apollo landing sites

As of December 1992, the Galileo spacecraft performed its second and final flyby (EM2), of the Earth-Moon system, during which it acquired Solid State Imaging (SSI) camera images of the lunar surface suitable for photometric analysis using Hapke's, photometric model. These images, together with those from the first flyby (EM1) in December 1989, provide observations of all of the Apollo landing sites over a wide range of photometric geometries and at eight broadband filter wavelengths ranging from 0.41 micron to 0.99 micron. We have completed a preliminary photometric analysis of Apollo landing sites visible in EM1 images and developed a new strategy for a more complete analysis of the combined EM1 and EM2 data sets in conjunction with telescopic observations and spectrogoniometric measurements of returned lunar samples. No existing single data set, whether from spacecraft flyby, telescopic observation, or laboratory analysis of returned samples, describes completely the light scattering behavior of a particular location on the Moon at all angles of incidence (i), emission (e), and phase angles (a). Earthbased telescopic observations of particular lunar sites provide good coverage of incidence nad phase angles, but their range in emission angle is limited to only a few degrees because of the Moon's synchronous rotation. Spacecraft flyby observations from Galileo are now available for specific lunar features at many photometric geometries unobtainable from Earth; however, this data set lacks coverage at very small phase angles (a less than 13 deg) important for distinguishing the well-known 'opposition effect'. Spectrogoniometric measurements from returned lunar samples can provide photometric coverage at almost any geometry; however, mechanical properties of prepared particulate laboratory samples, such as particle compaction and macroscopic roughness, likely differ from those on the lunar surface. In this study, we have developed methods for the simultaneous analysis of all three types of data: we combine Galileo and telescopic observations to obtain the most complete coverage with photometric geometry, and use spectrogoniometric observations of lunar soils to help distinguish the photometric effects of macroscopic roughness from those caused by particle phase function behavior (i.e., the directional scattering properties of regolith particles).

Helfenstein, P.↗

Sulfur outgassing and in-gassing in lunar orange glass beads and implications for 33S “Anomaly” in the Moon

Our recent investigations have discovered inward diffusion (in-gassing) of moderately volatile elements (MVEs; e.g., Na, K and Cu) from volcanic gas into volcanic beads/droplets. In this work, we examine the distribution of sulfur in lunar orange glass beads. Our analyses reveal that sulfur exhibits a non-uniform distribution across the beads, forming “U” or “W” shaped profiles typical of in-gassing. A model developed to assess sulfur contributions from different sources (original magmatic sulfur versus atmospheric in-gassed sulfur) in the orange beads indicates that atmospheric sulfur in-gassed during eruption contributes approximately 9–24 % to the total sulfur content of an orange bead, averaging around 16 %. This in-gassed sulfur is derived from the eruption plume, where atmospheric sulfur could undergo photochemical reactions induced by UV light, leading to mass independent fractionation and a distinct sulfur isotope signature. Interestingly, a recent study discovered a small mass independent isotope fractionation of sulfur in lunar orange glass beads in drive tube 74002/1 and a lack of such mass independent isotope fractionation in black glass beads in the same lunar sample. This finding contrasts with sulfur in lunar basalts, which typically exhibit mass dependent fractionation. With our work, the observed mass independent fractionation signal in sulfur isotopes of orange beads can be attributed to the in-gassing of photolytic sulfur in the optically thin part of the eruption plume where UV light can penetrate. Using the sulfur isotope data of lunar orange beads, we estimate that the Δ33S value of atmospheric sulfur is approximately −0.18 ‰. Our study provides new insights into the complex dynamics of volatile elements in lunar volcanic processes, highlighting the role of in-gassing in shaping sulfur isotope signatures in volcanic glass beads.

Xue Su↗

Neural Radiance Fields for Shadow Removal and Relighting of Satellite Imagery

Multi-view stereo photogrammetric techniques have been conventionally utilized to generate Global Digital Elevation Models (GDEM) of planetary and lunar surfaces. However, these methods, relying on conventional feature detectors, are often subject to inaccuracies caused by changes in lighting conditions, including diffuse reflection and harsh shading. This has limited the ability of these methods to accurately reconstruct shadowed regions in orbital imagery, such as highly shaded urban areas and the permanently shadowed regions (PSRs) located in the lunar surface, which are critical targets for NASA's Artemis program. Neural Radiance Fields (NeRFs) offer a novel solution to these limitations by breaking away from traditional photogrammetric assumptions of ridged, opaque surfaces. NeRFs are capable of reconstructing 3D objects with variably transmissive properties, such as fluids, PSRs, and reflective surfaces. In this work, we demonstrate the robustness of NeRFs in generating high-fidelity 3D models of terrain from highly shaded orbital imagery acquired from small satellites in low earth orbit (LEO). Our results showcase the ability of NeRF to overcome the limitations of traditional photogrammetric methods and provide a promising solution for reconstructing complex scenes in challenging lighting conditions.

Caleb Ashmore Adams↗

Petrography and Geochemistry of Lunar Meteorite Miller Range 13317

Miller Range (MIL) 13317 is a 32-g lunar meteorite collected during the 2013-2014 ANSMET (Antarctic Search for Meteorites) field season. It was initially described as having 25% black fusion crust covering a light- to dark-grey matrix, with numerous clasts ranging in size up to 1 cm; it was tenta-tively classified as a lunar anorthositic breccia. Here we present the petrography and geochemistry of MIL 13317, and examine possible pairing relationships with previously described lunar meteorites.

Zeigler, R. A.↗

Shock compression and adiabatic release of a titaniferous mare basalt

A report is presented regarding the dynamic properties of a rock indigenous to the mare basins of the moon. The reported data were obtained in a study of sample 70215, a very titanium-rich basalt (58% pyroxene, 18% ilmenite, 15% plagioclase, 6% olivine, and 3% quartz by weight). This rock is probably representative of a class of the earliest mare-filling extrusive rocks which are exposed on the present lunar surface. Two series of experiments were performed. One set of experiments involved the measuring of Hugoniot and release adiabats to 15.7 GPa with a propellant gun apparatus. In the second set of experiments, a light-gas gun was employed to yield Hugoniot data at about 120 GPa and release states at about 90 GPa. Lunar basalt 70215 appears to be among the densest rocks in the present lunar sample collection, having a crystal density of 3.38 g/cu cm and a porosity of about 1.3%. The results of the experiments have important implications for both the degree of shock metamorphism expected for impact processes and the extent of ejecta transport on mare surfaces with high-titanium basalt composition.

Ahrens, T. J.↗

The Cl isotope composition and halogen contents of Apollo-return samples

Lunar mare basalts are depleted in F and Cl by approximately an order of magnitude relative to mid-ocean ridge basalts and contain two Cl-bearing components with elevated isotopic compositions relative to the bulk-Earth value of ∼0‰. The first is a watersoluble chloride constituting 65 ± 10% of total Cl with δ37Cl values averaging 3.0 ± 4.3‰. The second is structurally bound chloride with δ37Cl values averaging 7.3 ± 3.5‰. These high and distinctly different isotopic values are inconsistent with equilibrium fractionation processes and instead suggest early and extensive degassing of an isotopically light vapor. No relationship is observed between F/Cl ratios and δ37Cl values, which suggests that lunar halogen depletion largely resulted from the Moon-forming Giant Impact. The δ37Cl values of apatite are generally higher than the structurally bound Cl, and ubiquitously higher than the calculated bulk δ37Cl values of 4.1 ± 4.0‰. The apatite grains are not representative of the bulk rock, and instead record localized degassing during the final stages of lunar magma ocean (LMO) or later melt crystallization. The large variability in the δ37Cl values of apatite within individual thin sections further supports this conclusion. While urKREEP (primeval KREEP [potassium/rare-earth elements/phosphorus]) has been proposed to be the source of the Moon’s high Cl isotope values, the ferroan anorthosites (FANs) have the highest δ37Cl values and have a positive correlation with Cl content, and yet do not contain apatite, nor evidence of a KREEP component. The high δ37Cl values in this lithology are explained by the incorporation of a >30‰ HCl vapor from a highly evolved LMO.

The Moon↗

Electroluminescence Imaging: A Quantitative Characterization Technique to Measure Dust Occlusion of Solar Cells

Electroluminescence (EL) imaging is a qualitative characterization technique that is typically used to identify cracks, corrosion, and other defects in solar cells. It consists of imaging a cell under forward bias, where the solar cell emits photons due to radiative electron-hole pair recombination. Over the past few years, our team has expanded this into a quantitative technique with the help of image processing. We have primarily used this method to investigate lunar dust occlusion of solar cells and arrays. Lunar dust accumulation on solar cells is a major concern because it directly limits light accessible to the cell, decreasing power output. Many teams are working to develop dust mitigation technology to protect these arrays on the surface of the Moon, but thoroughly characterizing their efficacy is important to ensure their success prior to launch. Here, we present EL as a quantitative characterization technique to observe dust coverage on solar cells that, when coupled with IV performance measurements, can offer unique insights into how dust coverage impacts power output. Quantitative electroluminescence imaging works by running EL images through an image processing script that first grayscales the image then plots a histogram of the brightness of each pixel. On its own, it does not offer much insight into a solar cell’s performance. However, when comparing images to a baseline pristine, undamaged, or uncoated solar cell, it can quickly provide information about the impacts of surface contaminants or damage to the cell. Here, we present a case study where quantitative EL is used to measure the efficacy of dust mitigation technology for flexible solar arrays and discuss the lessons learned about dust mitigation, testing with lunar simulant, and this characterization technique.

photovoltaics↗

Apollo lunar rendezvous

Lunar module rendezvous with command and service module by coelliptic sequence establishing standard lighting and relative position and velocity for final approach

Alexander, J. D.↗

Apollo lunar rendezvous

Lunar module rendezvous with command and service module by coelliptic sequence, establishing standard lighting and relative position and velocity for final approach

Alexander, J. D.↗

Smart Structures for Vibration Control on Long-Term Space Exploration and Habitation Missions

The current vision for space exploration focuses on human missions to the Moon, Mars, and beyond. To support these goals, it is certain that new vehicles and intermediate bases will be developed, whether that means simply re-direction of the ISS as a "mission research facility" or construction of a lunar base. Since these facilities are expected to be constructed from inherently light-weight materials, this work examines some of the potential sources of vibration and noise as well as means for controlling these vibrations. Many of the operating components within these facilities, such as pumps, fans, and motors, will produce vibrations during operation. These vibrations become structure in which they are housed. Resonances can impact acoustic noise levels and noise quality within the environment, possibly affecting crew health and productivity. For long-term missions in particular, it is expected that crew members will spend significant portions of their time restrained in the structure, such as in seats. As a result, the general health and well-being of the crew can be improved by limiting the harmful effects of human exposure to long-term audible and tactile vibration input. Besides the human factor, this work also examines some operational considerations in which vibrations play an important role. Vibrations can impact the environment for science and in-situ manufacturing research within these vehicles. Since a benign vibratory environment is beneficial for most types of science experiments, there is a need for various forms of vibration control. Because the operational characteristics of a vehicle can change during a long-term mission, it is further expected that the characteristics of many of the vibratory excitations will change with time. Consequently, the form of vibration control needed to improve overall habitability and usefulness of the vehicle or element for exploration missions will rely to some degree on the vibration control system's ability to adapt. To address these needs, this work also examines the development and use of smart materials to tune the dynamic characteristics of the structure in a passive sense. One prime example is the use of an adaptive electrical shunt connected to a piezoelectric patch in order to provide tuned passive vibration damping. The work also examines the use of active vibration control, such as by applying power to that same piezoelectric patch. The overall goal is to examine the use of smart structures that can react to the environment thereby improving the overall living, working, and learning environment for these long-term missions.

Gattis, Christy B.↗

Initial Petrographic Analysis of Apollo 17 73002 Continuous Core Thin Sections Using QEMSCAN Mapping Techniques

In 1972, the Apollo 17 mission landed in the Taurus-Littrow Valley located in the southeastern edge of Mare Serenitatis [1].During EVA 2at Station 3,a double drive tube was used to collect a sealed core sample (73001/2)of the upper~70cm of the lunar regolith[2-4].The core was taken from the surface of the light mantle deposit, found at the base of the South Massif [3]. For nearly 50 years, the sealed core samples have remained unopened. This study is part of the Apollo Next Generation Sample Analysis (ANGSA) initiative to analyze the continuous thin sections from the Apollo 17 drive tubes opened in 2019[5-7].

QEMSCAN↗