Moon’s Greatest Hits Since 2000 Misions to the Moon Mission Launch Date End Date Clementine 25 Jan. 1994 5 May 1994 Lunar Propsector 7 Jan. 1998 31 July 1999 SMART-1 27 Sept. 2003 3 Sept. 2006 Kaguya (SELENE) 14 Sept. 2007 10 June 2009 Chang’e 1 24 Oct. 2009 1 Mar. 2010 Channdrayaan-1 22 Oct. 2008 31 Aug. 2009 LRO 17 June 2009 STILL ACTIVE LCROSS 17 June 2009 9 Oct. 2009 ARTEMIS 20 July 2009* STILL ACTIVE Chang’e 2 1 Oct. 2010 April 2012 GRAIL 10 Sept. 2011 17 Dec. 2011 LADEE 6 Sept. 2013 17 Apr. 2014 Chang’e 3 1 Dec. 2013 STILL ACTIVE * Actual launch date = 17 Feb. 2007 as part of THEMIS mission. Date represents start of operations once three satellites arrived at the Moon Non-Representivity of Apollo Sites Lunar Terranes [Jolliff et al. (2000) JGR 105, 4197] • Apollo sites close to terrane boundaries. • Samples contain PKT signature.

• Apollo sample collection is not representative of the lunar compositional diversity.

Giguere et al. (2000) MaPS 35, 193 Lunar Topography

Kaguya (SELENE)

Chang’e-1 LRO (LOLA) Hi-Resolution Lunar Gravity GRAIL Gravity map, updating the Kaguya and Chang’E-1 gravity maps.

Kaguya: Namiki et al., (2009) Science 323, 900- 905. Free Air Chang’e-1: Yan et al. (2010) Advances in Space Bouger Research 46, 50-57. GRAIL: Zuber et al. (2013) Science 339, 668-672. Chang’E-1 Microwave Emission

Day

Night

Daytime (upper panel) and nighttime (lower panel)  maps of the 3 GHz channel, for −60° latitude 60° and −180° longitude 180°. Bright/dark show high/low values; in the daytime the maximum and minimum values of are 9 K and −10 K, respectively, while in the nighttime panel they are 7 K and −10 K. Chan et al. (2010) EPSL 295, 287-291. Global Neutron Maps 1˚ x 1˚ of fast neutron flux (in counts per second) from the lunar surface measured by LEND SHEN-N detector.

Litvak et al. (2012) J. Geophys. Res. 117 E00H22, doi:10.1029/2011JE003949 Reinterpretation of the Apollo Seismic Data Thinning of the nearside crust! Toksoz et al. (1972) Science 176, 1012-1016; (1974) Rev. Geophys. Space Phys. 12, 539-567): 60-65 km Khan & Mosegaard (2002) JGR 107, doi:10.1029/2001JE001658: 45 km Lognonné et al. (2003) Earth Planet. Sci. Lett. 211, 27-44: 30 km Chenet et al. (2006) Earth Planet. Sci. Lett. 243, 1-14: 31-38 km Wieczorek et al. (2013) Science 339, 671-675: 34-43 km Detection of the Lunar Core?

Weber et al. (2011) Science 331, 309-312 Evidence for a Liquid Lunar Core – Laser Ranging

Lunar rotation displays a strong source of dissipation which is compatible with a fluid core. Dissipation results suggest core radius of 352-374 km (20% of the lunar radius.

Williams et al. (2001) J. Geophys. Research 106, 27933–27968.

Williams et al. (2006) Advances in Space Research 37, 67-71. Rediscovery of Lunokhod 1 and Lunar Laser Ranging

LROC NAC images used to locate the lander and the rover. Lander identified by albedo anomaly and spacecraft identification. Rover located by(following the tracks.

Murphy et al. (2011) Laser ranging to the lost Lunokhod 1 reflector. Icarus 211, 1103-1108 Recent Volcanic Activity

“Recent” volcanic eruptions ~ 1 Ga.

Recent fumarolic eruptions; ~10 Ma? Ina depression in Lacus Felicitatis

Schultz et al. (2006) Nature, v. 444, p. 184-

Recent Volcanic Activity Aristarchus North Sosigenes Maclear-1 “IMPs” (Irregular Mare Patches) <100 Ga.

The irregular mare patches exhibit sharp, metre-scale morphology with relatively few superposed impact craters larger than ten metres in diameter. Crater distributions from the three largest

Unnamed Unnamed Unnamed irregular mare patches imply ages

Manilus-1 younger than 100 million years, based on chronology models of the lunar surface

Unnamed Unnamed

Braden S.E. et al. (2014) Nature Geoscience, v. 7, p. 787-791. Unnamed Unnamed Carrel-1

Images = 450 m across New Lunar Lithologies Rock Types not represented in the sample collection.

Pure Anorthosite: Kaguya (SELENE) New Lunar Lithologies Rock Types not represented in the sample collection.

Olivine, Orthopyroxene, and Mg-Spinel-rich lithologies (OOS)

Chandrayaan-: M3 Pieters et al. (2011) JGR, 116, E00G08; Pieters et al. (2014) American Min. 99, 1895-1910 Surface Volatiles on the Moon Volatile Deposits: Chandrayaan-1 (M3), LRO

Pieters et al. (2009) Science 326, 568-572

Hydrogen Deposits: LRO Mitrofanov et al. (2010) Science 330, 483-486

Cabeus Crater

OH/H2O 3µm adsorption Surface Volatiles on the Moon LCROSS Impact into Cabeus Crater

Colaprete et al. (2010) Science 330, 463-468. Schultz et al. (2010) Science 330, 468- 472. Surface Temperatures

Paige et al. (2010) Science 330, 479-482.

Bandfield et al. (2011) J. Geophys. Res. 116, E00H02, doi:10.1029/2011JE003866.

Bandfield et al. (2014) Icarus 231, 221-231.

PSRs are the coldest place in the Solar System. Ice Permafrost Around PSRs Neutron Suppression Regions (NSRs)are found in both permanently shadowed and illuminated areas, and they are not coincident with Permanently Shadowed Regions (PSRs).

Mitrofanov et al. (2012) J. Geophys. Res. 117 E00H27, doi:10.1029/2011JE003956. Radar Detection of Water-Ice Spudis et al. (2013) J. Geophys. Res. 118, 2016-2029. Fa & Cai (2013) J. Geophys. Res. 118, 1582- 1608. Spudis et al. (2010) Geophys. Res. Lett. 37, L06204, doi:10.1029/2009GL042259

High CPR inside and outside is consistent with blocks; High CPR inside only is consistent with water-ice. LRO/LAMP Evidence of Surface Water Frost in Lunar Polar Craters

LAMP’s nightside Lyman- α maps of the lunar poles show lower albedos (dark blue) in the Permanently Shaded Regions (PSRs), which is consistent with higher porosity surfaces in these regions.

Comparisons of star- illuminated surfaces at FUV wavelengths with a diagnostic water spectral signature (shortward and longward of 160 nm) indicate that PSRs such as Haworth crater (inset) are best explained by 1- 2% abundances of water frost right at the surface. LAMP provides the first indications of surface water frost in permanently shadowed polar craters Gladstone et al., “Far-Ultraviolet Reflectance Properties of the Moon’s Permanently Shadowed Regions,” J. Geophys. Res., 117, E00H04, doi:10.1029/2011JE003913, 2012. LRO LAMP detects H2O on lunar dayside Hendrix et al., "The Lunar Far-UV Albedo: Indicator of Hydrated Materials and Space Weathering," J. Geophys. Res., 117, E12001, doi:10.1029/2012JE004252, 2012 • LRO LAMP makes measurements of the surface of the moon at far- ultraviolet wavelengths morning afternoon • Small amounts of water are detected across the surface of the more hydration moon

• The H2O abundances are strongly correlated with surface temperature: - there’s more early in the day less hydration and late in the day, when the surface is cooler - there’s more at higher • The H2O is likely formed when solar wind latitudes, which receive less protons (H+) interact with surface molecules sunlight and are cooler containing oxygen - at warmer temperatures the • LAMP also detects H2O in permanently H2O “percolates” out of the soil shadowed polar regions Lunar Endogenous Volatiles

McCubbin et al. (2010) Proc. OH content of phosphates Nat. Acad. Sci. 107, 11223-11228.

14053,16 Water in Mare Basalt Sources: 2-5 ppm Liu et al. (2010) LPSC 41 Boyce et al. (2010) Nature 466, 466-469

14053,241 Lunar Endogenous Volatiles

Saal et al. (2008 Water in the Glass Parent Nature 454, 192-195) Magma: 260-745 ppm H2O

Apollo 15 Green Glass (VLT) Cl

F

Hauri et al. (2011) Science 333, 213-215

Melt Inclusions in Olivine S Lunar Endogenous Volatiles (Chandrayaan-1 M3 data) COMPTON BELKOVICH VOLCANIC COMPLEX Bhattacharya et al. (2013) Curr. Sci. 105(5), 685-691 Enhanced hydration at CBVC could have originated from the episodic events of eruption and effusion involving silicic magma. Chandrayaan-M3 Bhattacharya et al. (2015) CRATER THEOPHILUS Icarus 260, 167–173 High-resolution spectral and spatial data analyses of crater Theophilus revealed the presence of OH-bearing Exposures on its central peak in association with olivine- , spinel- and crystalline plagioclase- bearing lithologies. Lunar Endogenous Volatiles

Hejiu Hui, Anne H. Peslier, Youxue Zhang, and Clive R. Neal (2013) Water in lunar anorthosites and evidence for a wet early Moon. Nature GeoscienceLetters 6, 177-180 • FTIR analysis of Ferroan Anorthosites, samples of the primary lunar crust, show they contain significant amounts of water. • Results indicate the plagioclase contained ~6 ppm H2O. • These data allow an estimate of the initial water content of the lunar magma ocean to have been ~320 ppm. • Water in the final residuum (urKREEP) could have been 1.4 wt%. Lunar Endogenous Volatiles

Yang Chen, Youxue Zhang, Yang Liu, Yunbin Guan, John Eiler, Edward M. Stolper (2015) Water, fluorine, and sulfur concentrations in the lunar mantle. Earth & Planetary Science Letters 427, 37-46

• Analysis of volatiles in melt inclusions in 74220, 15421, 10020, 12008, 15016. • Results by Hauri et al. (2011) for 74220 are not anomalous. • Approximate constancy of volatile depletion in the Moon relative to the Earth explained by assuming that both acquired volatiles from a similar source or by a similar mechanism, but the earth was more efficient in acquiring the volatiles.

• The H2O, F and S concentrations in the primitive lunar mantle source to be similar to or slightly lower than those in terrestrial MORB mantle. Anhydrous Moon The Cl isotope composition of Apollo basalts & glasses have a range of isotopic values 25 times the range for Earth. Explained by volatilization of metal halides during eruption of a basalt containing H concentrations ~104 to 105 lower than those of Earth, implying that the lunar interior is essentially anhydrous.

Sharp et al. (2010) Science 329, 1050-1053.

Moon Discovery of “Lunar Pits” Mare Inginii Haruyama et al. (2009) Geophysical Research Letters, 36 L21206, doi:10.1029/2009GL040635 Robinson et al. (2012) Planetary & Space Science 69, 18-27.

50 m 50 meters Discovery of “Lunar Pits”

Wagner & Robinson (2014) Icarus 237, 52-60.

Pits in Impact Melts

Pits in Mare Basalt Flows Organic Matter in Lunar Samples Carbonaceous matter on the surfaces of black pyroclastic beads, collected from Shorty crater during the Apollo 17 mission, represents the first identification of complex organic material associated with any lunar sample. It formed through the accretion of exogenous meteoritic kerogen from micrometeorite impacts into the lunar regolith. Thomas-Keprta et al. (2014) Geochim. Cosmochim. Acta 134, 1-15. Recent Lunar Tectonism

Watters et al. (2012) Nature Geosci. doi: 10.1038/NGEO1387 Recent Lunar Tectonism

Thrust faults forming lobate scarps known since Lunar Orbiter. LROC images show these are more widespread

Watters et al. (2010) Science 329, 936-940; Williams et al. (2013) JGR 118, 224-233 Recent Lunar Tectonism • Considered to be “young” - < 1 billion years old. • Lack of distributed large-scale lobate scarp thrust faults that express significant radial contraction argues against secular cooling of a completely molten early Moon.

Watters et al. (2010) Science 329, 936-940 Recent Lunar Tectonism

Lobate Scarps (5-29˚ slope; 0.6-21.6 km long; 20-410 m of shortening [S]). Small range of S consistent with a small amount of global contraction.

Banks et al. (2012) JGR 117, doi:10.1029/2011JE003907 Recent Lunar Tectonism Scarps crosscut impact craters with diameters as small as ~10 m, a lack of superposed craters, and graben depths as shallow as 1m suggest these pristine-appearing graben are less than 50 Myr old.

Watters et al. (2012) Nature Geosci. doi: 10.1038/NGEO1387 Recent Lunar Tectonism Thomas R. Watters, Mark S. Robinson, Geoffrey C. Collins, Maria E. Banks, Katie Daud, Nathan R. Williams, and Michelle M. Selvans (2015) Global thrust faulting on the Moon and the influence of tidal stresses. Geology 43, 851-854. • LROC images – 3200 lobate thrust fault scarps on the Moon. • Estimated to be <50 Ma and maybe actively forming today. • Non-random distribution consistent with late-stage global contraction. • Present-day tidal stresses potentially activate these thrust faults. • Possibly produce the enigmatic shallow moonquakes recorded by Apollo, some of which had body wave magnitudes ≥5.

Segment of Pasteur scarp crosscutting small-diameter impact craters Map of digitized locations of lobate scarps on the Moon Mascons

Paul K. Byrne, Christian Klimczak, Patrick J. McGovern, Erwan Mazarico, Peter B. James, Gregory A. Neumann, Maria T. Zuber, Sean C. Solomon (2015) Deep-seated thrust faults bound the Mare Crisium lunar mascon. Earth & Planetary Science Letters 427, 183-190.

GRAIL data, LROC WAC DTM, and finite element GRAIL free-air gravity anomaly modeling show that the map (to degree and order 320) deep-seated thrusts may for the interior of Mare Crisium. have been localized by the boundary between the super-isostatic mantle material and a sub- isostatic collar of thickened crust that resulted from basin formation and modification Tectonic landforms and shortly after impact. Other physiography of Mare Crisium. (a) mascons formed in a Structural map of the basin interior. (b) Color-coded elevation similar manner. map of the mare deposits. Higlands Composition

Athiray et al (2014), Planaetary and Space Science 104, 279 First direct detection of Na near Tycho ejecta Na abundance: 1-5 % Chandrayaan-1:C1XS X-ray Fluorescence data First PIXE measurement from the lunar surface Chandrayaan-1: C1XS • Particle Induced X- ray emission (PIXE) PIXE- Mg, Al, Si observed from the lunar surface

• Opens up an alternate method (to XRF) in order to map surface elemental abundances Narendranath et al (2014), Advances in Space Research 54, 1993 Discovery of an Ash Flow Caldera on the Moon COMPTON-BELKOVICH VOLCANIC COMPLEX (CBVC) Chauhan et al. (2015) Icarus, 253, 115-129

5 km Peculiar depositional feature Crystallization of the Lunar Magma Ocean W-Hf model of magma ocean crystallization must occur in less than 40 million years. Shearer C.K. and Newsom H.E. (2000) W-Hf isotope abundances and the early origin and evolution of the Earth-Moon system. Geochim. Cosmochim. Acta 64, 3599-3613.

Zircon age of 4,4176 million years provides a precise younger age limit for the solidification of the lunar magma ocean. Nemchin A. et al. (2009) Timing of crystallization of the lunar magma ocean constrained by the oldest zircon. Nature Geosci. 2, 133-136.

The Moon formed from a high Sm/Nd terrestrial mantle prior to 4.45 Ga. The LMO completely crystallized by 4.44 Ga, and the sources of the high-Mg crustal rocks, KREEP and perhaps the low-Ti basalts were present in the lunar interior. Boyet & Carlson (2007) A highly∼ depleted moon or a non-magma ocean origin for the lunar crust? EPSL 262, 505-516. Crystallization of the Lunar Magma Ocean FAN age (60025) of 4,360 +/- 3 million years requires that either the Moon solidified significantly later than most previous estimates or the long-held assumption that FANs are flotation cumulates of a primordial magma ocean is incorrect. Borg L.E. et al. (2011) Chronological evidence that the Moon is either young or did not have a global magma ocean. Nature 477, 70-72.

The 176Lu–176Hf urKREEP model age = 4353 ± 37 Ma, which is concordant with the re-calculated Sm– Nd urKREEP model age of 4389 ± 45 Ma. The average of these ages, 4368 ± 29 Ma, represents the time at which urKREEP formed. Gaffney & Borg (2014) A young solidification age for the lunar magma ocean. GCA 140, 227-140 Modeling of Magma Ocean Crystallization New modeling techniques and approaches to the crystallization of the lunar magma ocean.

Elkins-Tanton et al. (2002) Re-examination of the lunar magma ocean cumulate overturn hypothesis: melting or mixing is required. EPSL 196, 239-249 Elkins-Tanton et al. (2011) The lunar magma ocean: Reconciling the solidification process with lunar petrology and geochronology. EPSL 304, 326-336. Elkins-Tanton & Grove (2011) Water (hydrogen) in the lunar mantle: Results from petrology and magma ocean modeling. EPSL 307, 173-179. Namur et al. (2011) Anorthosite formation by plagioclase flotation in ferrobasalt and implications for the lunar crust. GCA 75, 4998-5018. Elardo et al. (2011) Lunar Magma Ocean crystallization revisited: Bulk composition, early cumulate mineralogy, and the source regions of the highlands Mg-suite. GCA 75, 3024-3045 South Pole-Aitken Basin Impact Melt

Fresh crater central peaks inside SPA are commonly composed of an ultramafic assemblage dominated by Mg-rich orthopyroxene, suggesting a homogeneous layer buried under SPA that could be a relic of a gigantic impact melt pool produced by the SPA-forming impact. Nakamura et al. (2009) Ultramafic impact melt sheet beneath the South Pole–Aitken basin on the Moon. Geophys. Res. Lett. 36, L22202, doi:10.1029/2009GL040765.

Spectroscopic and geophysical constraints on the stratigraphy of SPA suggest a ~12.5 km thick layer of norite above ultramafic pyroxenite and dunite layers. impact melt differentiation can account for geophysical (non-zero crustal thickness) and geochemical (2 ppmTh) anomalies in SPA. Vaughn & Head (2014) Impact melt differentiation in the South Pole-Aitken basin: Some observations and speculations. Planet. Space Sci. 91, 101-106.

South Pole-Aitken Basin Impact Melt Modeling results indicate that noritic lithologies observed within SPA (e.g., central peaks of Bhabha, Bose, Finsen, and Antoniadi craters, as well as walls of Leibnitz and Schrödinger basins) could have formed from differentiation of the impact melt. Such locations represent potential destinations for collecting samples that can be analyzed to determine the age of the SPA impact. Additionally, potential remnants of the uppermost quenched melt may be preserved in gabbroic material exposed in “Mafic Mound.”

Hurwitz & Kring (2014) Differentiation of the South Pole–Aitken basin impact melt sheet: Implications for lunar exploration, J. Geophys. Res. Planets, 119, 1110–1133. Thickness of the Lunar Crust

The low-bulk lunar crustal density derived from GRAIL data allows construction of a global crustal thickness model that indicates that the Moon has an average crustal thickness between 34-43 km. In addition, the bulk refractory element composition of the Moon is not required to be enriched with respect to that of Earth.

Wieczorek et al. (2013) The crust of the Moon as seen by GRAIL. Science 339, 671- 675 Origin of the Procellarum Basin The spatial pattern of magmatic-tectonic structures bounding Procellarum is consistent with their formation in response to thermal stresses produced by the differential cooling of the province relative to its surroundings, coupled with magmatic activity driven by the greater-than-average heat flux in the region.

Andrews-Hanna et al. (2014) Structure and evolution of the lunar Procellarum region as revealed by GRAIL gravity data, Nature 514, 68–71. Origin of the Procellarum Basin

Low-Ca pyroxene can be formed during an impact by melting a mixture of crust and mantle materials or by excavating differentiated cumulates from the lunar magma ocean. The low-Ca pyroxene observed by the Kaguya spectral profiler are interpreted to be of impact origin.

The blue triangles and red crosses = Low-Ca pyroxene. Olivine-rich = green squares. Nakamura et al. (2014) Compositional evidence for an impact origin of the Moon’s Procellarum basin. Nature Geosci. 5, 775-778. Non-Destructive Recognition of Impact Melts Textures used through quantitative petrography to distinguish impact melts from pristine basalts. Crystal size distributions of olivine and plagioclase.

Method • Samples exhibit a variety of plagioclase CSD profiles. Focus on the steepest slopes (≤0.4 mm for olivine, ≥0.3 mm for plagioclase;) of CSDs.

• Calculate slope within this range only using size bins that show increasing population density.

• The intercept of the slope with the y-axis [ln(nO) or nucleation density] was calculated using the same data. Neal et al. (2015) GCA 148, 62-80 Impact Melt Ages

40Ar-39Ar ages have been obtained for 1– 3 mm sized rock fragments from Apollo 16 soil 63503 and chips from three rocks collected by Apollo 16 and Apollo 17 missions. The plateau age of 4.293±0.044 Ga obtained for impact melt rock 63503,13 represents the oldest known age for such a lithology. This age may represents the minimum age for the South Pole-Aitken (SPA) Basin.

Fernandes et al. (2013) The bombardment history of the Moon as recorded by 40Ar- 39Ar chronology, Meteorit. Planet. Sci, 48, 241-269. Impact Melts

• Impact melt deposits have been identified in small, simple impact craters (as small as 170 m diameter) within the lunar highlands. • Significant, visible impact melt deposits would not be expected in such small craters as most of the melt material would be ejected. • These small melt-containing craters represent near-vertical impacts in which the axes of melting and melt motion are essentially straight down. • Such craters also occur on the maria.

Plescia & Cintala (2012) Impact melt in small lunar highland craters. J. Geophys. Res., 117, E00H12, doi:10.1029/2011JE003941 Lunar Swirls • Despite having spectral characteristics of immaturity, the lunar swirls are not freshly exposed surfaces. • The swirl surfaces are regions of retarded weathering, while immediately adjacent regions experience accelerated weathering. • Weathering in the off‐swirl regions darkens and flattens the spectrum with little to no reddening, which suggests that the production of larger (>40 nm) nanophase iron dominates in these locations as a result of charged particle sorting by the magnetic field.

Kramer et al. (2011) J. Geophys. Res., 116, E04008, doi:10.1029/2010JE003669 Lunar Swirls

Lunar swirls are high-albedo arkings on the Moon that occur in both mare and highland terrains; their origin remains a point of contention. Here, we use data from the LRO Diviner Lunar Radiometer to showthat the swirls are formed as a result of deflection of the solar wind by local magnetic fields. Glotch et al. (2014) Formation of lunar Reiner Gamma formation, located at 7.5N 59.0W swirls by magnetic field standoff of the solar wind. Nat. Comm. 6:6189 | DOI: 10.1038/ncomms7189. Our results show that cometary impacts entrain the finest fraction of lunar soil grains (<10 µm) over regional scales (~100–1000 km), produce large masses of vaporized material, and likely generate trans- ient magnetic fields that could exceed the Earth’s surface field strength by a factor of 104. This combination of processes is consistent with a mechanism to generate lunar swirls. Syal & Schultz (2015) Cometary impact effects at the Moon: Implications for lunar swirl formation Icarus 257, 194-206. Lunar Swirls • Lunar swirls are unusually bright lunar features. Their origin has been debated since their identification in the 1960s • LRO data are used to constrain their surface properties and explain their origin • Swirls show no difference in 50 km 20 km surface texture, but do show differences in the amount of space weathering relative to their Space weathered surroundings surroundings • These data suggest that swirls are formed by the deflection of the solar wind by intense local Less space weathered swirls magnetic fields that shield the surface from the darkening effects of the solar wind LRO Data of lunar swirls (LROC image on top, Diviner Glotch, T. D. et al. Formation of lunar swirls by composition maps on bottom). Left frames show the classic magnetic field standoff of the solar wind. Reiner Gamma swirl on the nearside, right frames the Van de Nature Communications 6:6189 doi: Graff swirl on the farside. Magenta features are optically 10.1038/ncomms7189 (2015). immature, signifying less exposure to the solar wind. First Global Maps of Hapke Parameters from LRO • Hapke parameters have a physical meaning related to the interaction of light with the surface. The parameters vary based on the optical thickness and grain shape irregularity, albedo (w,

top right),and grain size distribution (hS, bottom right). • LRO’s stable orbit and the repeated global coverage (>50 times) by the LRO Wide Angle Camera (WAC) coupled with the high resolution LRO-generated topography enables the derivation of the Hapke parameters for nearly the entire Moon -- a first for any planetary body. • Parameter maps highlight previously unobserved variations in certain parameters (right, bottom), which highlight physical differences in how the regolith is formed and evolves over geologic time. Two of the five derived parameter maps showing variations in surface albedo (w, top) and the scale of the opposition effect • Observations closer to the poles lack adequate (hs, bottom) which is related to the distribution of grain sizes in coverage and will be measured during LRO’s the regolith. Map is centered on the lunar farside and extends second extended mission. from 70º North to 70º South. Sato, H., M. S. Robinson, B. Hapke, B. W. Denevi, Bottom Line: we’re learning how the regolith and A. K. Boyd (2014), Resolved Hapke parameter on airless bodies works in ways we’ve never maps of the Moon J. Geophys. Res. Planets 119, been able to do before! 1775–1805, doi:10.1002/2013JE004580. Charging of Regolith in PSRs

• Data from CRaTER on LRO was used to develop the first model predictions for dielectric charging of regolith on an GCRs & SEPs airless body. • Charged particles from GCRs and SEPs penetrate and charge the regolith. • Areas of permanent shadow near the lunar poles are susceptible to enhanced charging because the regolith these areas are extremely cold (< 100 K – from Diviner data). The above illustration shows a permanently • Regular, high energy dielectric shadowed region of the moon undergoing breakdown events may cause subsurface sparking (the "lightning bolts"), which ejects vaporized material from the increased breakdown of the surface. Subsurface sparking occurs at a depth regolith within areas of permanent of about one millimeter.

shadow Model outputs using GCR fluxes measured by Jordan, A. P., T. J. Stubbs, J. K. Wilson, N. CRaTER (left, top). The charge density due to A. Schwadron, H. E. Spence, and C. J. the accumulation of protons builds with accumulating GCR flux (second row). As the Joyce (2014), Deep dielectric charging of charged lay develops the surface (solid line) regolith within the Moon's permanently and interior (dashed) electric fields (third row). shadowed regions, J. Geophys. Res. The divergent electric fields builds the interior 119, doi:10.1002/2014JE004648. current density, dissipating the charged layer Planets (bottom row).