PPS23-01

Room:A02

Time:May 25 14:15-14:30

High permittivity regions in Oceanus Procelluram and Mare Imbrium found by SELENE(Kaguya)
KUMAMOTO, Atsushi1∗ ; ISHIYAMA, Ken1 ; OSHIGAMI, Shoko2 ; HARUYAMA, Junichi3 ; GOTO, Yoshitaka4
1

Tohoku University, 2 National Astronomical Observatory of Japan, 3 JAXA/ISAS, 4 Kanazawa University

Introduction: The effective permittivity of the lunar surface material is important for discussion of their composition andporosity. Based on the Maxwell-Garnett mixing model, the bulk density of the lunar surface materials can be derived from theireffective permittivity by using the following equation [Fa and Wieczorek, 2012]: ρ [g/m3 ] = 4.61 (εr - 1) / (εr + 2). Bulk densityof the lunar surface material depends on the abundances of voids and heavy components such as ilmenite. The dataset obtainedby Lunar Radar Sounder (LRS) onboard SELENE (Kaguya) [Ono et al., 2010] enables us to perform global high-resolution
mapping of the lunar surface permittivity because the observation was performed from the polar orbiter at an altitude of about
100 km, and in a frequency range around 5 MHz where thermal emissions is negligible. We should note that the echo powers
from the lunar surface depends not only on the permittivity but also on the roughness of the lunar surface. As for the roughness,
we can use SELENE Digital Terrain Model (DTM) based on Terrain Camera (TC) observation [Haruyama et al., 2008]. We cantherefore calculate expected echo powers by applying Kirchhoff Approximation (KA), and compare them with observed echo
powers in order to determine the effective permittivity.
Analyses Method: The global distributions of the intensity of the off-nadir surface echo in a frequency range of 4 - 6 MHz in an
incident angle range from 10 to 20 degrees were derived from the SELENE/LRS dataset. The median of off-nadir echo intensities
were derived in 360 x 180 areas of 1 degree (longitude)x 1 degree (latitude). In addition, we have derived the global distributionof the surface roughness parameters. The RMS height ν can be derived from the SELENE TC/DTM. If we assume the self-affine
surface model, the roughness parameters H and s can be obtained by the least square fitting: ν = s ∆xH in a baseline length ∆x
range from 30 m to 3 km. The off-nadir surface echo power was then calculated by using the radar equation. Assuming KA,
the backscattering coefficient in the radar equation can be obtained from the roughness parameters H, s [Bruzzone et al., 2011].
In calculation of the expected echo powers, we have to assume some effective permittivity also. We compared the observed andcalculated echo powers with changing effective permittivity assumption, and determined the most plausible effective permittivity.
Results: By applying the analysis method mentioned above, we could obtain the observed and calculated off-nadir surface
echo powers. Based on them, we could estimate the effective permittivity of the lunar surface materials. The estimated effective
permittivity is 2 - 3 in the highland, 3 - 4 in the maria. In addition, it was found that there areas whose effective permittivity
reaching ˜5 in the eastern part of Oceanus Procellarum and the western part of Mare Imbrium.
Discussion: By using the estimated effective permittivity of the lunar surface, we can derive the bulk density of the lunar
surface materials. The derived bulk density is 1.2 - 1.8 g/cm3 in the highlands, 1.8 - 2.3 g/cm3 in the maria, and approximately
2.6 g/cm3 in the high-permittivity areas in Oceanus Procellarum and Mare Imbrium. The differences of estimated bulk density
among the previous studies [Wiezorek et al., 2013; Carrier et al., 1991] and this study could be explained by the depth dependenceof the bulk density of the lunar surface soils and rocks. The areas of high permittivity in the eastern part of Oceanus Procellarum
and western part of Mare Imbrium coincide with young lava flow units in PKT region. We can consider two possible reasons:(i) The regolith layer is thinner than other mare regions due to short exposure to the meteorite impacts. (ii) The bulk density ishigher than other mare regions due to high abundance of the ilmenite.

Keywords: SELENE(Kaguya), Lunar Radar Sounder (LRS), permittivity, Oceanus Procelluram, Mare Imbrium, Digital terrain
model (DTM)

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PPS23-02

Room:A02

Time:May 25 14:30-14:45

Relationship between topography and latest mare volcanism at 2.0 Ga of the moon
KATO, Shinsuke1∗ ; MOROTA, Tomokatsu1 ; WATANABE, Sei-ichiro1 ; YAMAGUCHI, Yasushi1 ;OTAKE, Hisashi2 ; OHTAKE, Makiko2
1

Division of Earth and Planetary Sciences, Graduate School of Science, Nagoya University, 2 Japan Aerospace Exploration
AgencyLunar mare basalts, the most common volcanic feature on the Moon, provide insights into compositions and thermal history of
lunar mantle. According to the radiometric ages of the lunar basalt samples and the model ages of mare basalt units determinedby crater counting with remote sensing data, the great extent of mare basalts was formed at 3.2 to 3.8 Ga. Temporal variationof the mare basalt eruptions also indicates that magma activity has a second peak at the end of mare volcanism (∼2 Ga), andthe latest eruptions were limited in the Procellarum KREEP Terrane (PKT), which is characterized by high abundances of heatproducing elements. In order to understand the magma source of the latest volcanism and mechanism for causing the second
peak, we examined the correlation between the titanium contents and eruption ages of mare basalt units using compositionaland chronological data updated by SELENE/Kaguya. Although the systematic relationship is not observed globally, a rapid
increase in mean titanium (Ti) content occurred at 2.3 Ga in the PKT, suggesting that the magma source of mare basalts changed
at that time. The high-Ti basaltic eruptions can be correlated with the second peak of volcanic activity at ∼2 Ga. The latest
volcanic activity can be induced by a high-Ti super hot plume originated from the core-mantle boundary. If the super hot plume
was occurred, the topographic features formed by the super hot plume may be remained. Then, we calculated the difference
between topography and selenoid and found the circular feature like a plateau in the center of the PKT, which scale is ∼1000 km
horizontal and ∼500 m vertical. Moreover, mare ridges in this region seem to connect with the plateau. Using detailed modelsof the flexural response of the lunar elastic lithosphere, we estimated the elastic thickness at the time of occurrence of the super
hot plume. From our results, the effective elastic thickness at the period of latest volcanism is estimated 20 ‒ 30 km, which isthinner than that of the period before ∼2 Ga. These results suggest that the up lift of lithosphere caused by the super hot plume.
Keywords: titanium content, super hot plume, selenoid, effective rlastic thickness, lunar mantle, the Procellarum KREEP Terrane

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PPS23-03

Room:A02

Time:May 25 14:45-15:00

Impact history in the last 3 billion years based on the lunar rayed craters
KATO, Mami1∗ ; MOROTA, Tomokatu1
1

Nagoya University Graduate School of Environmental Studies

The Moon preserves the impact history in the last 4.0 Ga as the cratering record, which provide important information tounderstand collisional and orbital evolutions of small bodies in the solar system. Standard lunar cratering chronologies have been
based on combining radiometric ages of Apollo and Luna samples and crater densities of landing sites. However, the impact
history cannot be resolved in the past 3.0 Ga because of the absence of samples with radiometric age ranging from 3.0 to 1.0 b.y.
On the other hand, from crater density of lunar rayed craters and statistics of terrestrial craters it has been suggested hypotheses
that the cratering rate has increased or decreased in recent.
In this study, we determined relative ages of rayed craters using SELENE/TC image data to place constraints on the cratering
rate in the last ∼1 Ga. Formation age of the surface of the planet can be estimated by crater counting, based on the idea that old
area have more craters than young area. We performed crater counting on the ejecta blanket of 67 rayed craters larger than 20
km in diameter. The results indicate that 27 rayed craters are younger than the crater Copernicus, whose the formation age isestimated as 0.81 Ga from the Apollo 12 samples.
Based on the crater density of rayed craters younger than Copernicus, the average cratering rate for craters larger than 10 km
in diameter in the past 0.81 Ga is estimated to be 5.56×10-4 km−2 y−1 , which is 0.66 times lower than that in the past 3.2 Ga.
The main source of impactors in the Earth-Moon system is the main asteroid belt located between the orbits of the Mars andJupiter. The decreasing cratering rate revealed in this study indicates that the total number of asteroids in the main belt has been
decreasing for last 3.0 Ga.

Keywords: Moon, crater, cratering chronology

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PPS23-04

Room:A02

Time:May 25 15:00-15:15

Lunar surface areas with featureless reflectance spectra revealed by hyperspectral remotesensing
YAMAMOTO, Satoru1∗ ; NAKAMURA, Ryosuke2 ; MATSUNAGA, Tsuneo1 ; OGAWA, Yoshiko3 ; ISHIHARA, Yoshiaki4 ;MOROTA, Tomokatsu5 ; HIRATA, Naru3 ; OHTAKE, Makiko4 ; HIROI, Takahiro6 ; YOKOTA, Yasuhiro1 ;HARUYAMA, Junichi4
1

NIES, 2 AIST, 3 Univ. of Aizu, 4 JAXA, 5 Nagoya Univ., 6 Brown Unv.

Spectral Profiler (SP) onboard SELENE/Kaguya has obtained continuous spectral reflectance data (hyperspectral data) for
about 70 million points (0.5 by 0.5 km footprint) on the Moon in the visible and near-infrared wavelength ranges. Using adata ming approach with all the SP data (SP data mining), we have revealed the global distributions of several-kilometer-widesites with exposed end members of various minerals on the lunar surface: olivine-rich sites, purest anorthosite (PAN) sites,
orthopyroxene-rich sites, clinopyroxene-rich sites, and spinel-rich sites. These results are based on the analysis for the diagnostic
absorption bands of λ = 1µm and 2µm in the continuous reflectance data for the lunar major minerals. On the other hand, it has
also been reported that there are several sites on the Moon exhibiting no absorption band for 1µm and 2µm (hereafter, featurelessspectra or FL-spectra). However, it still remains unclear what is the origin for the FL spectra on the Moon. For the interpretationsof the origin of the FL spectra, we need to understand the global occurrence trends of FL sites on the Moon. In this study, we
conducted the global survey to reveal the global distribution of the FL sites using the SP data ming. From the global distribution
data, we will discuss the possible mechanisms and its implications for the lunar primordial crust.
Keywords: remote sensing, hyperspectral, Moon, Kaguya/SELENE

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PPS23-05

Room:A02

Time:May 25 15:15-15:30

Mineralogy of the lunar highland crust based on the Kaguya reflectance spectra
OHTAKE, Makiko1∗ ; YAMAMOTO, Satoru2 ; MATSUNAGA, Tsuneo2 ; OGAWA, Yoshiko3
1

Japan Aero space Exploration Agency, 2 National Institute for Environmental Studies, 3 The University of Aizu

Introduction: The composition of the lunar highland crust is among the most important information for understanding theformation mechanism of the lunar highland crust and the composition of the lunar magma ocean. Previously, the composition of
the lunar highland crust was estimated mainly based on measurements of the lunar returned samples. Measurements of returned
lunar samples and meteorites indicate that the lunar highland crust typically consists of plagioclase and low-Ca pyroxene withminor amounts of other mineral phases. However, it is not clear if the low-Ca pyroxene really is a major mafic silicate componentof the highland crust because the returned samples may not be a representative material of the entire highland crust. Therefore,
this study investigated the mafic silicate phase and estimated its composition within the highland crust by using remote sensing
reflectance spectra of the lunar surface.
Method: We used reflectance spectra acquired by the Kaguya Spectral Profiler (SP), which has a spectral coverage of 500 to
2600 nm in 300 bands and a spatial resolution of 500 x 500 m. Among the global SP data, all of the 570 purest anorthosite(PAN) [1] spectra identified and reported by [2] were analyzed by using the modified Gaussian model (MGM) [3]. Several MGM
parameters, a number of fitted peak and peak parameters (center wavelength, width, and strength) of each peak at the starting
point were tried, and the results were cross evaluated. The compositions of silicate mafic minerals were estimated by comparing
the peak fit results and the known correlation between absorption center wavelength and mineral composition.
Results: Most (93%) of peak, which corresponds to the mafic silicate phase, has a center wavelength shorter than 980 nm,
suggesting that these mafic silicates in the PAN rocks are low-Ca pyroxene (65% are shorter than 950 nm). Note that the low-Ca
pyrox-ene in this study implies pyroxene having less than a 0.2 molar ratio of Ca/(Ca+Mg+Fe) smaller than 0.2. Data points
having a center wavelength shorter than 980 nm had a strong absorption band and were not a product of weak ambiguousabsorption spectra. Six percent of the data have center wavelengths between 980 nm and 1040 nm, which correspond to the highCa pyroxene composition. The remaining 1% of the data with longer center wavelengths around 1050 nm possibly corresponds
to olivine or glass. No apparent phase difference (low-Ca and high-Ca pyroxene difference) is observed between the nearsideand the farside.
Discussion: Our results indicate that the majority of the PAN layer in the lunar highland crust globally consists of anorthite andsmall amounts of low-Ca pyroxene, the major mafic silicate component, rather than high-Ca pyroxene or olivine. This result is
consistent with the previous work based on measurements of the lunar material from the lunar surface mixing layer with limited
global coverage and confirms the homogeneous modal abundance within the lunar highland crust. The short center wavelengthsof the PAN rocks at Jackson crater, which located at the farside highland suggest relatively higher Mg# (Mg/(Mg + Fe) in moleper cent) (around 70) in this region than the near side. This evidence is in good agreement with previous work [4], which suggests
the presence of magnesian anorthosite in the farside highland.
References: [1] Ohtake, M. et al. (2009) Nature, 461, 236-240. [2] Yamamoto, S. et al. (2012) Geophys. Res. Let., 39,
L13201. [3] Sunshine, J. et al. (1990) J. Geophys. Res. 95, 6955-6966. [4] Ohtake, M. et al. (2012) Nature GeoSci. 5, 384-388.

Keywords: Kaguya, Moon, crust, reflectance spectra

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PPS23-06

Room:A02

Time:May 25 15:30-15:45

Unsupervised Classification of the Moon’s Surface Reflectance Spectra and GeologicalSignificance (1)ISHIHARA, Yoshiaki1∗ ; HAREYAMA, Makoto2 ; OHTAKE, Makiko1
1

JAXA, 2 St. Marianna Univ. of Med.

Great successes of recent lunar missions provide vast amount of varieties of remote sensing data. Analysis of those newdata provide some new key evidences, such as pure-plagioclase rocks (e.g., Ohtake et al., 2009) and olivine rich rocks (e.g.,
Yamamoto et al., 2010), for studying solidification process of the Lunar Magma Ocean (LMO) and following lunar evolutions.
Those key evidences require us to reconsider the LMO solidification process. One approach to study this problem is requiring
following step, reconstruction of compositions and structures for primitive crust by removing influences of volcanisms, impact
cratering, and other geological effects. For reconstructing primitive crust, we have to generate a global geological map covers
recent findings, so we started a project to build a new lunar geological map to reconstruct structures and composition of the lunar
primitive crust. Because of huge volume of recent data set, fully manual classify by expert researchers is not realistic, and then,we have been trying to use some data mining methods for basic unit candidate estimation.
In this study, we show some classification results of SELENE Multiband Imager (MI) data and Spectral Profiler (SP) dataapplied data mining methods, and compare them with a fully manual classification result for a limited area. Our classification
procedure consists of two steps; Independent Component Analysis (ICA) and Iterative Self-Organizing Data Analysis (ISODATA). Detail strategy of our procedure is presented by Hareyama et al. in this meeting.
Our procedure generally works well. The classification results in mare region indicate that could detect some types of marebasalt flows. Especially high-Ti basalt in Oceanus Procellarum and the Mare Tranquillitatis are clearly identified. Ejecta deposits
of fresh ray craters are also clearly identified. In addition, we compare classification results our procedure around the Aristarchus
region with that of fully manual classification result by a researcher (M.O.). These two agrees each other generally. Then, we
consider our procedure capture the lunar geological context and useful for the first step of building lunar geological map.

Keywords: Moon, Geological Map, Unsupervised Classification

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PPS23-07

Room:A02

Time:May 25 15:45-16:00

Study of carbon-bearing materials formed by impact process on the Moon
MIURA, Yasunori1∗
1

Visiting Univ.(In & Out)

Introduction:
In the solar system (terrestrial planets), it is required to study overall processes of volatile carbon between planets (with andwithout global air and water) and the Moon without global air. Recently author has studied such complicated and unsolved
problems [1-4]. In the present paper, the collision formation of carbon-containing materials is mainly to discuss it on celestialbodies without global air (the moon, asteroids and Mercury) that do not have the atmosphere, especially on the moon [3].
Volatiles in the Moon :The Moon has original reservoirs of carbon-bearing volatiles from successive growth of fine dust particles to become celestial
body size. However, the Moon is close to planet Mars size, but the volatiles- reservoirs are difficult to keep during characteristic
abrupt collision process to be escaped away[1-3].
Problem of carbon dioxides atmosphere :Water vapor changes liquid phase by quenching process. However, carbon dioxides-rich atmosphere keeps in a gaseous state
by relative cooling, so that it should be taken into something to hot air estimated from the experimental results. In this sense, Marsand Venus with carbon dioxides-rich atmosphere are difficult to form global water system if a global water should be present
before global gas-rich system[3]. The Moon is therefore celestial body to discuss the interior carbon-bearing volatiles [3].
Formation of carbon-containing materials of the Moon:
Because the Moon has no atmosphere globally, two-stages growth of separated carbon-rich macro-grains with high-pressure
form cannot be expected because of no collision with global air on the airless Moon [3]. It is only possible to growth macroscopically in the shallow interiors (from dust-growth or fragments of air planet separated) by successive meteoritic collisions on
the surface[4]. Carbon-bearing materials on the Moon are localized and minor contents of carbon-bearing materials in the glass,carbon, carbide and carbonates related with shock-wave processes[1-3].
Problem of global water on the Moon:
It might discuss possible formation of global air and water on the Moon and celestial bodies from experimental results. Fromlaboratory experiments, carbon-bearing air which might be possible to generate a global water on air- planets of Mars and Venus
is generally difficult, but it is not impossible by the proposed two methods ideally. On the other hand, formation of global wateron air-less Moon (also Mercury and asteroids) is relatively very difficult, but it might be not impossible if the Moon becomes
global air-bearing celestial body prepared by any proposed process[3].
Summary:
1) Formation of the atmosphere and seawater to any celestial body such as the Moon, can be discussed from experimental
results of carbon-containing materials formed.
2) Carbon dioxides atmosphere can be reduced or cooled from state-condition of hot gas by any proposed experiments.
3) Lunar carbon-bearing grains of glass, carbon, carbide and carbonate can be grown microscopically and locally in the interior
by successive process of impacts.
Reference:[1] Miura Y. (2011): LPSC 42(2011), #2817.
[2] Miura Y. et. al. (1996) Antarctic Meteorites XX1(Tokyo), 107-110.
[3] Miura Y. (2015): LPSC2016 (LPI), #1811, #1666.
[4] Miura Y. (2009): Patent application.

Keywords: The Moon, Carbon-bearing materials, Impacts, Volatiles, Experiment, Global air and water

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PPS23-08

Room:A02

Time:May 25 16:15-16:30

Solar wind-regolith interaction in space: Observations at Moon and Phobos
FUTAANA, Yoshifumi1∗
1

Swedish Institute of Space Physics

In this presentation, we discuss whether the backscattering of plasma particles is a common physical process of plasma-surface
interaction in space. The backscattered protons were first discovered by a plasma package, MAP/PACE, on board the Japanese
lunar orbiter, Kaguya. Later, the backscattered protons and neutral hydrogen atoms have been frequently reported near the Moon,for example, by the SARA sensor on Chandrayaan-1. We first review the characteristics of the backscattered protons observed in
the lunar environment.
Then, we report the survey of the dataset from the ion sensor (IMA) on board Mars Express recorded during its close encounters
to Phobos. During one of the closest encounters (˜60 km) we could clearly identify proton signal apart from the solar wind.
Careful assessment has lead us to conclude that the signal is the Phobos origin. The characteristics of the Phobos protons arequite similar to those of the reflected lunar protons. The observation provides the first evidence proving that the backscattering is
a common process for regolith-plasma interaction in space.
Keywords: solar wind, proton reflection, regolith, Moon, Phobos, backscattering

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PPS23-09

Room:A02

Time:May 25 16:30-16:45

Exploration of the lunar internal structure using a small-sized penetrator and its perspective
YAMADA, Ryuhei1∗ ; ISHIHARA, Yoshiaki2 ; KOBAYASHI, Naoki2 ; MURAKAMI, Hideki3 ; GOTO, Ken2 ;SHIRAISHI, Hiroaki2 ; TANAKA, Satoshi2 ; HAYAKAWA, Masahiko2
1

National Astronomical Observatory of Japan / RISE Project, 2 Japan Aerospace Exploration Agency, 3 Kochi University

Information about the lunar interior has been obtained by the seismic exploration through the Apollo mission, the gravimetric
explorations of the Kaguya and GRAIL missions, and other geodetic observations such as the Lunar Laser Ranging (LLR). However, we have not sufficiently constrained the lunar deep mantle and the core from available geophysical data, and the material
and temperature in the lunar deep region are still uncertain. In addition, we have some uncertainties even about lunar crustal
thickness and structure. Clear detections of lunar seismic phases which pass through the lunar deep and crustal regions will be
required to reveal the structures. The penetrator, a hard-landing probe with a high sensitive seismometer developed in the former
LUNAR-A project, is a powerful tool to carry out new lunar seismic observation.
To demonstrate utility of the penetrator system for scientific observations, we proposed a mission plan, named APPROACH,
in which one penetrator is loaded onto a small satellite launched by the 3rd Epsilon Launch Vehicle. In this proposal, we hadsome plans to perform scientific observations; those are determination of the lunar crustal thickness using travel time data frommeteoroid impact events located by the ground observation of the impact flashes, current lunar seismic activities compared withthat during the Apollo-era and the first heat flow measurement on the lunar highland. However, the proposal could not be accepted because the success rate of the observation with only one penetrator was insufficient for acceptance.
In this situation, we currently make a modification to the mission plan so as to load two small-sized penetrators onto the small
satellite. We aim to reduce the size of the penetrator to two-thirds size keeping the already established high shock durability. In
this presentation, we firstly report some plans to reduce size of the penetrator and the effect of the downsizing on scientific observations. Then, we describe scientific expectation from the seismic and heat-flow observation using the small-sized penetrator.
Finally, we will discuss future plans to study the lunar origin and evolution by the lunar seismic observations using the penetrator
system after the achievement of first observation by the system.

Keywords: Penetrator, Lunar intarnal exploration, Moonquake observation, Heat flow observation, Small-sized exploration
satelite

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PPS23-10

Room:A02

Time:May 25 16:45-17:00

Present status of the active X-ray spectrometer development for future lunar landing mission
NAGAOKA, Hiroshi1∗ ; HASEBE, Nobuyuki1 ; KUSANO, Hiroki1 ; NAITO, Masayuki1 ; SHIBAMURA, Eido1 ;AMANO, Yoshiharu1 ; OHTA, Tohru1 ; FAGAN, Timothy1
1

Waseda University

The Active X-ray Spectrometer (AXS) consisting of an active X-ray generator and a silicon drift detector (SDD) has beendeveloped for future lunar landing missions. The AXS can determine the elemental composition of rock samples by X-Ray Fluorescence spectroscopy which provides the geochemical data of rock samples. The AXS has each outstanding features as excellent
energy resolution, compact and light weight, low power consumption, and no high voltage power supply and no radioisotopes.
The X-ray generator is made of some pyroelectric crystals, peltier device and thin metal target. The instrument of the AXS andthe present status of its development are presented and discussed.
Keywords: X-ray fluorescence spectroscopy, active X-ray spectrometer, lunar landing mission, elemental analysis

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PPS23-11

Room:A02

Time:May 25 17:00-17:15

Study on X-ray Fluorescence for Future Lunar Landing Mission - Surface Roughness andRatios of Characteristic X-ray NAITO, Masayuki1∗ ; HASEBE, Nobuyuki1 ; NAGAOKA, Hiroshi1 ; KUSANO, Hiroki1 ; KUWAKO, Masaki1 ;OYAMA, Yuki1 ; SHIBAMURA, Eido1 ; AMANO, Yoshiharu1 ; OHTA, Toru1 ; MATIAS LOPES, Jose A.2
1

Waseda University, 2 University of Coimbra

Landing and roving observation for planetary bodies provides more detailed local information of geochemistry, mineralogy andpetrology with remote sensing observation[1]. An X-Ray Fluorescence spectroscopy (XRF) is a powerful method on/around thelanding point in-situ measurement of chemical abundance. Lunar surface is so heavily weathered by meteorites, micrometeorites,
the solar wind, and the cosmic rays that surface grindings of lunar samples should be performed by a rock abrasion tool to remove
the weathered surface before the XRF measurements. The relations between surface roughness of sample and ratios of observed
characteristic X-ray intensity are studied on the basis of both experiments and simulations[2, 3]. In this presentation, the resultsof experiments and simulations of grinding level needed for the XRF measurements on planetary surface are compared anddiscussed.
[1] T. Hashimoto et al., 2011, Acta Astronautica 68, 1386-1391. [2] H. Kusano et al., 2013, Proc. SPIE 8852, 88520B. [3] M.
Naito et al., Nucl. Instrum. Methods Phys. A, to be published.
Keywords: Lunar sample, X-ray fluorescence, Active X-ray Spectrometer, Surface roughness

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PPS23-12

Room:A02

Time:May 25 17:15-17:30

Visual Tracking using SIFT to Solve Time-Delay Problem in Remote Operation
NISHIYAMA, Hiroyuki1∗ ; SHIMIZU, Sota2 ; NAGAOKA, Hiroshi1 ; HASEBE, Nobuyuki2
1

Dept. of Applied Physics, Waseda University, 2 ARISE, Waseda University

This paper proposes and describes a method to solve a time-delay problem when a direction of a camera in the wide angle
fovea vision system (WAFVS) equipped on a lunar exploring rover is contorlled remotely from the ground control station on theearch. That is, we need to control the camera view direction acculately in order to obtain visible ray band images of a target indetail using WAFVS, but the time-delay often causes WAFVS to fail to capture the target in the central field of view of the input
image when the rover is moving around. The authors acheive correct camera view direction control by applying SIFT operator
to track a target candidate from past images to future images storaged temporarily in the computer on the rover. Experimental
results show this implementation is successfully done and indicate how to apply WAFVS for this task.
Keywords: Exploring Rover, Remote Operation, Visual Tracking, SIFT, Wide Angle Fovea Sensor, Time Delay

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PPS23-13

Room:A02

Time:May 26 09:00-09:15

Toward a 3D spherical modeling of lunar mantle convection
OGAWA, Masaki1∗ ; YANAGISAWA, Takatoshi2 ; KAMEYAMA, Masanori3
1

Graduate School of Arts and Sciences, Univ. of Tokyo, 2 Japan Agency for Marine-Earth Science and Technology, 3 Geodynamic
Research Center, Univ. of Ehime
Earlier two-dimensional models of coupled magmatism-mantle convection system raise two issues concerning the evolution of
the lunar mantle. One is to understand why lunar magmatism continuously occurs with a characteristic time of several hundred
million years. When the Rayleigh number of the lunar mantle Ra exceeds the critical value for the onset of thermal convection
Rc, earlier two-dimensional models suggest that a positive feedback, called the magmatism-mantle upwelling (MMU) feedback,
operates to make magmatism episodic and vigorous; magmatism occurs continuously and mildly as observed on the Moon only
when Ra <Rc. Another issue is to understand why mare magmatism continued until as recent as about a billion years ago.
Magmatism extracts heat producing elements (HPEs) and earlier two-dimensional models predicts that lunar magmatism shouldhave waned much earlier because of this HPEs extraction. A possible solution to this issue is that the lunar mantle contains areservoir that is enriched in HPEs and compositionally dense at depth. The nature of thermal convection in a basally heatedmantle with a small core, however, has not been investigated enough to resolve these issues. To estimate Rc and to understandthe nature of thermal convection in the lunar mantle, we are carrying out a linear perturbation analyses and numerical simulationof thermal convection in a spherical shell with a small core.
Keywords: the Moon, mantle evolution, 3D spherical shell, mantle convection, numerical simulation

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PPS23-14

Room:A02

Time:May 26 09:15-09:30

Flow patterns in spherical mantles with small size of core; the effect of temperature dependent viscosity
YANAGISAWA, Takatoshi1∗ ; OGAWA, Masaki2 ; KAMEYAMA, Masanori3
1

Japan Agency for Marine-Earth Science and Technology, 2 Graduate School of Arts and Sciences, Univ. of Tokyo, 3 Geodynamic
Research Center, Univ. of Ehime

Clarifying the effects of three-dimensional spherical geometry on mantle convection is a major issue of mantle dynamics interrestrial planets. We study in detail the nature of thermal convection of a variable viscosity fluid in the basally heated sphericalmantle of small planets with a small core, keeping in mind the application of our numerical models to the Moon. Sphericalgeometry affects mantle convection mildly when the ratio of the core-radius to the planetary radius r CM B takes an Earth-likevalue of 0.55, while it is thought to affect strongly when r CM B is small like Moon around 0.2. Here, we investigate the flow
pattern systematically for r CM B from 0.1 to 0.6 with small to large viscosity dependence on temperature. We first estimate thecritical Rayleigh number Rc for the onset of convective motion at various r CM B and the magnitude of temperature-dependenceof viscosity by a linear perturbation analysis. Then, we study the convective flow pattern of thermal convection above Rc by
numerical simulation. The result of our simulation is in good agreement with the linear analysis. The nature of convective flow
pattern considerably changes as r CM B smaller than about 0.4. The flow pattern has smaller number of up- and down-wellings.
We established regime diagrams of convection pattern in relation to the Rayleigh number and the temperature dependence ofviscosity, for various value of r CM B . Stronger temperature dependence of viscosity is necessary for realizing the stagnant-lid
regime of convection for smaller r CM B . It is due to the relatively smaller volume of high temperature region near the CMB. The
horizontally averaged temperature at mid mantle remains low despite the strong temperature variation of viscosity when r CM B
is small.
Keywords: Moon, 3D spherical shell, mantle convection, size of the core, flow pattern

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PPS23-15

Room:A02

Time:May 26 09:30-09:45

Formation of anorthosite on the Moon through magma ocean fractional crystallization
ARAI, Tatsuyuki1∗ ; TSUCHIYA, Taku2 ; MARUYAMA, Shigenori3
1
3

Department of Earth and Planetary Sciences, Tokyo Institute of Technology, 2 Geodynamics Research Center, Ehime University,
Earth-Life Science Institute, Tokyo Institute of Technology

Geological records of the moon have a potential to reveal early evolution of the earth. 4.4Ga anorthosite on the Moon formed
as by fractional crystallization of the lunar magma ocean (LMO). It has been generally accepted that the lunar bulk composition isenriched in FeO compared with the bulk silicate earth, which is critical to make large plagioclase/melt density difference enoughto form the anorthosite. However, the bulk moon composition likely has the same composition of the earth, which is supported byisotopic similarities for the two bodies and recent giant impact modeling. In this study, critical condition of fractional crystallization of plagioclase is assessed for the BSE composition by taking into account crystal/melt density difference, viscosity of melt,
crystal size, and Rayleigh number of the magma ocean. This study modeled solidification process of the LMO and calculatedchange of melt composition by use of MELTS/pMELTS. Density and viscosity of melt were calculated by use of first-principles
simulations.
Results of thermodynamic calculations indicate that melt is basaltic (Mg# = 0.59) when plagioclase starts to crystalize. Viscosity of the basaltic melt ranges 20 - 10 Pa s whereas density ranges 2.60 - 2.71 g/cc for 0 - 1 GPa where plagioclase crystallizes.
Comparison between critical crystal diameter calculated from the viscosity and density and crystal diameter of plagioclase (5 18mm) of anorthosite suggests that crystal fraction of magma, ϕ = 0.55 is required to make convection of magma ocean moderateenough that plagioclase could separate from the melt. Results of critical crystal diameter for olivine/pyroxene indicate that the
crystallized mafic minerals would also be entrained in the viscous basaltic melt until ϕ = 0.55 is attained. In that case, large
amount of mafic minerals are entrained in the magma along with plagioclase, which is enough to account for the ϕ = 0.55 in themagma. For the melt composition when crystal fraction ϕ = 0.55 is attained, the basaltic melt is enriched in FeO enough thatplagioclase could float to the surface of the moon. Application of the discussion to the terrestrial magma ocean has insight into
the surface evolution of the Hadean Earth, which would be related to the evolution of life.
Keywords: Moon, Anorthosite, Magma ocean, Density and viscosity of melt, Hadean Earth

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PPS23-16

Room:A02

Time:May 26 09:45-10:00

High pressure phase relationships of the Fe-Ni-C system and its implications to the lunar
core structure
KISHIMOTO, Shumpachi1∗ ; URAKAWA, Satoru1
1

Graduate schol of natural science and technology, Okayama University

We investigate the phase relationships of the Fe-Ni-C systems at 5 GPa equivalent to the lunar core condition using multi anvilhigh pressure apparatus. We determined the precise melting relationships of the Fe-Ni-C system at 5 GPa. We also elucidate thestability field of (Fe,Ni)3 C and (Fe,Ni)7 C3 carbide phase. In the meeting we will discuss the composition and the structure of thelunar core using the present data based on the seismic model of Weber et al. (2011).
Keywords: high pressure, lunar core, Fe-Ni-C system, phase relationships

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PPS23-17

Room:A02

Time:May 26 10:00-10:15

Particle simulations on plasma and dust environment near lunar vertical holes
MIYAKE, Yohei1∗ ; NISHINO, Masaki n2
1

Graduate School of System Informatics, Kobe University, 2 The Solar-Terrestrial Environment Laboratory, Nagoya University

Japanese lunar explorer ”Kaguya” has discovered vertical holes on the Moon surface. The diameter and depth of the holes
are both in a range of 50 through 100 m, which produces a higher depth-to-diameter ratio than typical impact craters. The holes
are thus expected to create characteristic plasma and dust environment around it. It is of practical importance to assess such a
distinctive environment, reminding that a future landing mission plans to explore the lunar holes and caverns associating to theholes.
In the present study, we apply our original particle-in-cell simulator EMSES, which have been used to study spacecraftplasma interactions, to assessment of day-side plasma environment around lunar vertical holes. We have a three-dimensional
computational domain including a simplified lunar hole structure and introduce a solar wind plasma inflow to the lunar surface.
We also simulate the photoelectron emission from the lunar surface by taking into account the presence or absence of sunlightillumination, and its incident angle. We will show simulation results on the properties of lunar surface charging near the hole andits dependence on changing solar wind plasma conditions. We also report the progress of further investigations into dust grain
environment around the hole, based on the electrostatic environment self-consistently computed by our simulator.

Keywords: Moon, vertical hole, space plasma, lunar surface charging, dust grain, PIC simulation

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PPS23-18

Room:A02

Time:May 26 10:15-10:30

Full Particle-In-Cell 3D simulation on the solar wind response to a lunar magnetic anomaly
USUI, Hideyuki1∗ ; UMEZAWA, Misako1 ; MIYAKE, Yohei1 ; NISHINO, Masaki n2 ; ASHIDA, Yasumasa3
1

Graduate school of system informatics, 2 STELAB Nagoya University, 3 RISH Kyoto University

The objectives of the current research is to reveal the plasma environment disturbed by the magnetic anomaly found on themoon surface by considering the plasma kinetics. In this study, by performing three-dimensional full Particle-In-Cell simulations, we will discuss the plasma response to Reiner Gamma which is one of the typical and famous magnetic anomalies on
the moon. The size of a magnetic anomaly is characterized by distance L from its center at which the equilibrium is satisfied
between the pressure of the magnetic field of the dipole and that of the solar wind. In the Earth’s magnetosphere, L implies themagnetopause location. We particularly focused on meso-scale magnetic dipoles in which L is smaller than the gyroradius ofions in the solar wind but larger than the electron Larmor radius. Contrary to the Earth’s magnetosphere, difference of dynamics
between ions and electrons with respect to the local magnetic field play an important role in the magnetosphere formation. In
other words, electron-ion coupling through a dipole field becomes important. The simulation results show that a meso-scale
magnetosphere is clearly created even if the ion gyroradius is larger than L. We found that electron dynamics are important in
the process of meso-scale magnetosphere formation. Around the distance of L from the dipole center, charge separation occurs
because of the difference of dynamics between electrons and ions. Then intense electrostatic field is locally induced and ions,which are assumed unmagnetized in the meso-scale magnetic dipole, are eventually influenced by this electric field. We also
examined the plasma dynamics at dayside magnetosphere. Ions which encounter the magnetic anomaly start to gyrate around the
local magnetic field. However, electrons which are basically magnetized make drift motion with ExB velocity. This difference ofthe plasma dynamics causes intense boundary current in the dayside region. In the case of Reiner Gamma, the magnetic field isalmost perpendicular to the solar wind. In such a situation, increase of plasma and magnetic field densities is found in the dayside
region in the simulation results. We are also interested in the plasma response when the direction of IMF changes because themagnetic field reconnection occurring in the dayside region will affect the formation of the meso-scale magnetosphere. One of
the interesting findings is that the solar wind ions do not reach the moon surface in Reiner Gamma. We will discuss this point byconsidering the plasma dynamics as well as the electrostatic field observed over the Reiner Gamma region.
Keywords: Magnetic anomaly, Reiner Gamma, Meso-scale magnetic dipole, Solar wind response, Plasma particle simulation

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PPS23-19

Room:A02

Time:May 26 10:30-10:45

Ion cyclotron waves observed by Kaguya/LMAG around the moon in the Earth’s magnetosphere
NAKAGAWA, Tomoko1∗ ; TSUNAKAWA, Hideo2
1

Information and Communication Engineering, Tohoku Institute of Technology, 2 Deparment of Earth and Planetary Sciences,
Tokyo Institute of Technology
Narrowband ion cyclotron waves as found by Apollo 15 and 14 Lunar Surface Magnetometers were detected in the magnetic
field data obtained by MAP/LMAG magnetometer on board Kaguya at an altitude of 100 km above the moon in the tail lobe of
the Earth’s magnetosphere. The frequency of the waves was near the local proton cyclotron frequency. They had a significant
compressional component. They were detected on the dayside, on the nightside, or above the terminator of the moon. Analysisof the waves detected by Kaguya would contribute the understanding of the moon-plasma interaction.
Keywords: ion cyclotron wave, Kaguya, LMAG, moon, cyclotron frequency, lobe

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PPS23-20

Room:A02

Time:May 26 11:00-11:15

Observation of the solar wind protons and alpha particles over lunar magnetic anomalies
KATO, Daiba1∗ ; SAITO, Yoshifumi2 ; NISHINO, Masaki n3 ; YOKOTA, Shoichiro2 ; TSUNAKAWA, Hideo4
1

Department of Earth and Planetary Science, The University of Tokyo, 2 Institite of Space and Astronautical Science, Japan
Aerospace Exploration Agency, 3 Solar-Terrestrial Environment Laboratory, Nagoya University, 4 Department of Earth and Planetary Sciences, Tokyo Institute of Technology
Lunar surface is directly affected by solar wind because the Moon has neither thick atmosphere nor global magnetic field.
However, there exist locally magnetized regions called lunar magnetic anomalies on the lunar surface. Strong lunar magnetic
anomalies can prevent solar wind from impacting the lunar surface. Research on the interaction between solar wind and lunar magnetic anomalies has been carried out by in-situ observations, numerical simulations and laboratory experiments, since
the discovery of the lunar magnetic anomalies in 1960s. Since lunar magnetic anomalies greatly affect the incident solar windplasma and plasma around the Moon, investigation on the interaction between solar wind and lunar magnetic anomalies is quite
important.
The solar wind consists of protons as a major component and several percent of alpha particles as a second major component.
The flux of the magnetically reflected solar wind ions is about several tens percent of the incident solar wind ion flux. So
far, nobody has ever investigated the reflected solar wind ions over lunar magnetic anomalies in terms of the ion species. Since
more than 90% of the solar wind ions are protons, the current knowledge of the interaction between solar wind ions and lunar
magnetic anomalies is highly dependent on the behavior of protons. Note that the incident solar wind alpha particles can bedetected clearly, but the reflected alpha particles are not easily observed. Thus analysis of both proton and alpha particles will
led us to more detailed understanding of the plasma structure over lunar magnetic anomalies.
In this study, we have analyzed mass identified low energy ion data observed by a low energy ion mass spectrometer MAPPACE-IMA on Kaguya. We have newly found that reflected protons and reflected alpha particles show significantly different
behaviors over lunar magnetic anomalies. In most cases, the bulk velocity of the reflected ions is slightly reduced from theincident solar wind bulk velocity, and the temperature of the reflected ions is higher than the incident solar wind ions. We havefound that the bulk velocity of the reflected alpha particles is much lower than the bulk velocity of the reflected protons. We havealso found that the ratio of the reflected alpha particle flux to the incident solar wind alpha particle flux is much less than the ratioof the reflected proton flux to the incident solar wind proton flux. There seems to be multiple reasons why the existence of thereflected alpha particles were not clear; 1) there exists large difference in E/q (E: kinetic energy, q: charge) between incident solar
wind alpha particles and the reflected alpha particles and 2) the reflected alpha particle flux is quite low. It clearly shows that thereflection of the solar wind ions is not an ideal magnetic mirror reflection but the reflection includes non-adiabatic processes.
Keywords: Moon, plasma, solar wind, magnetic anomaly

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PPS23-21

Room:A02

Time:May 26 11:15-11:30

Early global expansion of the Moon: constraints from topographic characteristics on linear gravity anomalies
SAWADA, Natsuki1∗ ; MOROTA, Tomokatsu1 ; KATO, Shinsuke1 ; ISHIHARA, Yoshiaki2 ;HIRAMATSU, Yoshihiro3
1

Nagoya University Graduate School of Environmental studies, 2 Japan Aerospace Exploration Agency, 3 Kanazawa University
Graduate School of Natural Science and Technology

According to numerical models of the lunar thermal evolution, the lunar radius temporary increased at the lunar early stage
because of a thermal expansion resulted from mantle remelting after the magma ocean solidification. However, no clear evidenceof lunar early global expansion was observed because many impacts have transformed the lunar surface. Recently, the Gravity
Recovery and Interior Laboratory (GRAIL), which was launched in 2011 by NASA, measured the lunar gravity field with highaccuracy. Andrew-Hanna et al. [2013] identified large linear gravity anomalies (LGAs) from the analysis of the GRAIL gravity
data, and suggested that the LGAs resulted from ancient intrusions or dykes formed by magmatism with the global expansion.
To test the hypothesis, we investigated topographical profiles across the LGAs. In addition, we determined formation ages of
LGAs to constrain the timing of the global expansion.
We used 1/1024-degree gridded lunar topographic data from LOLA Data Archive [http://imbrium.mit.edu/LOLA.html LOLA GDR(LROL-LOLA-4-GDR-V1.0)]. The topographic profiles across the LGAs were calculated in a range of 300 km from the LGAs. We
found graben-like topography along the LGAs, suggesting that the LGAs were formed in the tensile stress field accompaniedwith the global expansion.
We performed crater counting in areas of 50 km distance from the LGAs to constrain the timing of the global expansion. The
estimated formation ages of LGAs are distributed in a range from 4.3 to 3.9 Ga with a peak at 4.1 Ga, corresponding to the oldest
ages of the Apollo basaltic samples and lunar basalt meteorites [e.g., Terada et al., 2007]. The results suggest that the lunar global
expansion begun at 4.3 Ga.
We estimated the lunar radius change as a function of time based on the estimated ages. We assumed that the topography of
the LGAs simply were a dale consisting of two normal faults. The increase of lunar radius is estimated to be ˜2.2 km at most,consistent with the estimation from a lunar thermal model [e.g., Zhang et al., 2014].
Keywords: linear gravity anomaly, early global expansion, tensile stress, topography, crater chronology

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PPS23-22

Room:A02

Time:May 26 11:30-11:45

Magnetic anomalies, dynamo and true polar wander of the Moon
TAKAHASHI, Futoshi1∗ ; TSUNAKAWA, Hideo2 ; SHIMIZU, Hisayoshi3 ; SHIBUYA, Hidetoshi4 ;MATSUSHIMA, Masaki2
1

Department of Earth and Planetary Sciences, Kyushu University, 2 Department of Earth and Planetary Sciences, Tokyo Instituteof Technology, 3 Earthquake Research Institute, University of Tokyo, 4 Department of Earth and Environmental Sciences, Kumamoto University
Applying the latest advanced paleomagnetic technique to the Apollo samples, it is now well established that the Moon once
had an ancient core dynamo operated from 4.2 to 3.56 billion years ago, or even younger age. Because these results are basedon paleointensity retrieved from unoriented samples, any directional information cannot be obtained. Instead, we focus on themagnetic anomalies on the Moon. Since the magnetization of the lunar crust in the magnetic anomalies could be records of anearly core dynamo of the Moon, the magnetic anomalies may yield directional information of the lunar paleomagnetic field. Here
we present results of our global survey of magnetic anomalies on the lunar surface using magnetometer data acquired by the Lunar Prospector and Kaguya spacecraft. Using an iterative inversion method, we extract magnetization vectors from well-isolated
magnetic anomalies and derive the positions of paleomagnetic poles. We find two distinct clusters of the resultant paleomagnetic
poles: one near the present rotation axis and the other at mid-latitude (Takahashi et al., 2014). The result is consistent with adipole-dominated lunar magnetic field generated by a core dynamo that was reversing the polarity. It is also implied that theMoon experienced a polar wander event. Additional inversion results for well-isolated central magnetic anomalies based on thesurface vector mapping method (Tsunakawa et al., 2014) suggest existence of the third cluster of the lunar magnetic pole.
References
Takahashi, F., H. Tsunakawa, H. Shimizu, H. Shibuya, and M. Matsushima (2014), Reorientation of the early lunar pole, Nature Geosci. ,7, 409-412, doi:10.1038/ngeo2150.
Tsunakawa, H., H. Shibuya, F. Takahashi, H. Shimizu, and M. Matsushima (2014), Regional mapping of the lunar magnetic anomalies at the surface: Method and its application to strong and weak magnetic anomaly regions, Icarus , 228, 35-53,
doi:10.1016/j.icarus.2013.09.026.
Keywords: magnetic anomaly, dynamo, core, polar wander

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