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It was shown that nanodiamonds were easily formed from carbon film containing Si. The growth of diamond and beta-SiC is controllable by adjusting the heating temperature and the proportion of Si. Present result will develop a wide range of new opportunities for research and applications in the field of nanotechnology.

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TiC crystallites less than 3 nm in size showed an absorption feature at 14.3 um. This 14.3 um absorption was hardly seen in specimens ranging from bulk material to grains 50 nm in size. The absorption feature at 14.3 um was weakened due to the growth of TiC crystallites by heat treatment. If the carbide grains were covered with a carbon layer, the absorption peaks were remarkably weakened, i.e., the absorption intensity depended on the grain surface.

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The origin of the strong interstellar 217.5 nm absorption feature appearing in the interstellar extinction curve is a long-standing problem in astrophysics. In the present study, by a simple method, soot with sharp absorption features around 220 nm was produced from methane gas. We found that the absorption peak positions of the present soot can be controlled by the production temperature. Analyzed results of soot by high-resolution electron microscope clarified that the origin of the absorption peak at 217.5 nm was a graphitic structure with a diameter of 5 nm order.

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[in Japanese]

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Surface Mg isotopic compositions of forsterite, evaporated in vacuum at 1504-1786^oC, were measured by ion microprobe in order to investigate anisotropy in isotopic fractionation during evaporation. The degree of Mg isotopic fractionation of evaporated forsterite is the largest for the (001) surface and the smallest for the (010) surface at the range of experimental temperatures, showing anisotropy of isotopic fractionation. The isotopic fractionation factors between ²⁶Mg and ²⁴Mg at 1692^oC, which were obtained using a diffusion-controlled isotopic fractionation model during evaporation, are 1.028, 1.023 and 1.017 for the (001), (100) and (010) surfaces, respectively.

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[in Japanese]

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Conditions of shock waves in the solar nebula that heat and crystallize amorphous silicate dust particles have been clarified in detail. Some shock waves are found to be able to crystallize amorphous dust particles. Moreover, in the case of the minimum mass solar nebula model, amorphous dust particles in a closer region whose distance from the sun is less 20 AU may be crystallized, while dust particles in a further region beyond 20 AU cannot be. This result suggests that short period comets formed in a distant region should not contain any crystalline, whereas long-period comets formed in a close region can have; this is consistent with observations.

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We obtained ²⁶Al ages of Type I chondrules in a least equilibrated carbonaceous chondrite (CC) Y-81020 (CO3.0). Bulk chemical compositions of Type I chondrules in the MgO-(CaO+Al₂O₃)-SiO₂ ternary diagram vary from near CI compositions to relatively Ca-Al-Si-rich compositions toward Al-rich chondrules. The chondrules with near CI composition tend to be older (1-2Myr after CAIs) than more Ca-Al-Si-rich ones (2-3Myr after CAIs). Considering the texture and chemical zoning profiles of individual chondrules, Type I chondrules in CC initially had near solar compositions and added Ca-Al-rich component with time, and Si evaporated and recondensed during heating, which resulted in compositional zoning in individual chondrules.

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It is widely accepted that terrestrial planets are formed in2 stages. First step is the coagulation of km-sized planetesimals,which results in the formation of Mars-sized protoplanets.These protoplanets are orbitally stabilized by eccentricity dampingdue to tidal interaction with a gas disk until significant fraction of disk gas is depleted.In the next stage, planets are formed through the accretion of protoplanets. When the planets are just formed, their eccentricities are still large. Kominami \& Ida (2002) shows that the eccentricities can be diminished by including the effect of gravitational gas drag by a remnant gas disk, and succeeded to form Earth-like planets.This gravitational drag force becomes effective when the mass of the bodyis larger than that of the Moon.However, simulations including this gravitational drag effect on the stage from planetesimal to protoplanets have not done yet.Since the protoplanet's mass is larger than the mass of the Moon,this effect may change the outcome distribution of the protoplanets.We would like to do the N-body simulations on formation of protoplanetsincluding the effect of gravitational gas drag from the disk, and seehow the drag effects the formation of protoplanets.

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[in Japanese]

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It is generally thought that the terrestrial planets experience the Mars-sized giant impacts. Such giant impacts modify the atmosphere obtained before the giant impact stage. Genda and Abe (2003) clarified that the significant atmosphere (35-90%) survived the giant impact blown-off event in the case of no ocean. In this study, we consider the case that an ocean exists at the planetary surface, which is likely in the Earth's orbit. The existence of an ocean greatly enhances the atmospheric loss due to evaporation of water. There is the possibility that the above escape mechanism explains the differences between the present Earth's and Venus' atmospheres.

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Nylon spheres of 7mm in diameter were shot on gypsum targets at the impact velocity of 4.3km/sec. Two or three dimensional velocity vector, time of the ejection and mass were measured and/or estimated for each fragment by use of high-speed video cameras. Fragments are classified into two groups as earlier fragment group and later fragments group. The earlier group has almost the same mass-velocity distribution as one in Nakamura and Fujiwara (1991) obtained for disruptive event. The later fragments group, which only be seen in cratering event, consists of numbers of slow and small fragments, ejected normal to the target surface.

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We measured the crater dimensions, ejecta size and ejecta velocity, and made comparison between our results and a model of Melosh (1983).

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Impact experiments were conducted for ice-silicate mixture to measure ejection velocities of disrupted fragments. The mixture was composed of water ice and serpentine power with the mass ratio of one to one. As a result of the impact disruption with the velocity of 3~4 km/s, the antipodal velocity (V_a) of each sample with the size (L_t) of 15 to 30 mm was measured to show that Va = a Lt^-2.5. This V_a is 2 to 3 times lower than that obtained for water ice at the same impact velocity.

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In the study of the formation of chondrule, it is important to explain the observed distribution of its size. Especially, it is difficult to quantitatively estimate the maximal size of chondrule, since the complicate effects of deformation and disruption are included. Therefore we performed two-dimensional simulation of deformation and disruption of a droplet with SPH for incompressible fluid. In this simulation, we adopted the effect of the surface tension. Using this simulation, it was confirmed that whether a drop was deformed or disrupted was dependent on the Weber number. Our results will be used to quantitatively investigate the distribution of maximal size of chondrule in shock wave heating model.

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[in Japanese]

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The short-period comet 67P/Churyumov-Gerasimenko (hereafter 67P/C-G) is the target of the ESA ROSETTA mission. The spacecraft will be launched on 2004 February 24 (UT).We observed 67P/C-G in optical wavelengths at Kiso Observatory 105cm Schmidt telescope and at University of Hawaii 2.2m telescope between 2002 September 9 and 2003 June 4 (UT). The comet 67P/C-G had passed its perihelion on 2002 August 18. We used the R-band and B-band filters.
To better understand the observed dust trail images, we created a series of dynamical simulation for the dust particles ejected from the comet nucleus. The size of dust particles near the nucleus appear to be relatively large. Based on the comparison between the obtained images and our model calculation, we discuss the size distribution of the dust particles ejected from the 67P/C-G nucleus.

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[in Japanese]

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Stability of amino acids and related compounds in lunar environments was investigated. Samples added to simulated lunar regolith were more stable than those without regolith upon gamma-irradiation. Bound amino acids (proteins and "simulated interstellar amino acid precursors") were more stable than free amino acids. When amino acids were irradiated after water was removed by freeze-drying, their decomposition was not observed up to dose of 15 kGy. The present results suggest that lunar organic compounds supplied by comets were good targets for future lunar missions.

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[in Japanese]

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The lunar heat flow experiments were made at Apollo 15 and 17 landing sites, both of which are located near the margin of the circular basins. In such locations, the megaregolith thickness is expected to have a large lateral variation. Warren and Rasmussen (1987) pointed out that the Apollo heat flow measurements are significantly affected by lateral variation of megaregolith thickness, because a very low thermal conductivity of megaregolith tends to focus the heat flux to thin regolith area from thick regolith area.
But the lunar surface heat flow is affected not only by regolith thickness variation but also topographic variation and distribution of heat-generating elements. The present study aims to study these effects on the measured heat flow values at Apollo 15 and 17 sites, using a numerical simulation of the thermal state of the Moon. The models used here are much more quantitative and much finer in spatial resolution than the previous studies.
In the present models, we assume the abundance distribution of the heat-generating elements, such as U, and Th, in the lunar crust is represented by the following equation:
C(h) = Co exp (-h/D)
where h is depth, Co is the surface abundance, and D is the skin depth which indicates the degree of upper-crust concentration of the heat-generating elements.
The results indicate that the effects of topography and regolith thickness variation on the surface heat flow amount to about 10 to 50% of the observed values and suggest that a significant correction must be made in order to obtain a regionally representative value from Apollo heat flow experiments. Comparison of the corrected heat-flow values at Apollo 15 and 17 sites suggests that the skin depths, D's at Apollo 15 and 17 sites are 20 to 40 km, which is much larger than terrestrial skin depth, D=10 km (Lachenbruch, 1970). This large D value suggests that the incompatible elements is more homogeneously distributed in the Moon than in the Earth and that the lunar crust was generated in large quantities in a short time.

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SELENE (SELenological and ENgineering Explorer) loaded with MI (multi-bandimager) and SP (Spectral Profiler), will be launched in 2005. This study is envisioned fordeveloping the automated technique for detailed geological mapping of lunar surfaceusing the geographical and spectral features processed by the wide width data acquiredby MI, and the linear data acquired by SP. This paper shows the result of extraction and classification craters using the Clementine UVVIS images.

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In many icy satellites, extensional tectonic features can be seen. These surface features considered to be formed due to surface tensional stress, and a source of the stress is generally considered to be global volume change of the satellite. In the evolution of the icy satellites, solidification of the liquid water has significantly contributed to formation of the extensional features. To estimate the stress state in the icy shell, first, we performed a numerical simulation for an internal thermal history and a moving phase boundary problem. Furthermore, we calculate the stress in the viscoelastic shell due to solidification of liquid water. We will report the results of these calculations and its dependence of satellites' size and shell viscosity.

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[in Japanese]

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For the terrestrial planets, the evolution of the plate is controlled by the thermal state of the interior. And vice versa, the thermal evolution is influenced by the plate thickness. We predict that the plate thickness is selected for the heat to be transported most efficiently from the interior of the planets to the surface. We will show the effects of the self-control of the plate evolution on the thermal state in the planets.

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It is important to estimate a lunar crustal thickness because it directly indicates the depth of "Magma Ocean (Warren, 1985)". Recent analyses of Apollo seismic data show that the existence of a crust seems to be significantly sharower than that of Apollo-era conclusions (Khan and Mosegaad 20002; Lognonne et al., 2003); approximately 60 km thick at the Apollo 12 site (Toksoz et al., 1974). In this study assuming that the Bouguer gravity is the consequence of variations in the thickness of a crust, we present a global structure of the lunar crust by using gravity, topography data, and such new seismic constraints.In the previous lunar crustal thickness model (Zuber et al., 1994; Neumann et al., 1996; Wieczorek and Phillips, 1998), horizontal crustal density distributions are not considered although the heterogeneity of a crustal composition inferred from the VIS and NIR multispectral properties on the lunar surface (e.g. Lucey et al., 1998) is obvious.There are correlations between the iron abundances of lunar samples and those inferred normative densities. Therefore we model a horizontally heterogeneous density model of lunar crust by using both iron abundances on the lunar surface as measured by the Lunar Prospector gamma-ray spectrometer (Lawrence et al., 2001) and iron abundance-normative density relations of lunar samples. We also model the vertical distribution of the density of crust by using the pressure dependence of elastic velocities of lunar rocks in laboratory measurements (e.g. Mizutani et al., 1974), which is resulted from pore closures of rocks due to hydrostatic pressure.

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Contribution of Tidal Heating to Thermal History of the Moon

Y. Morisawa (University of Tokyo, ISAS), H. Mizutani (ISAS)

1. Introduction
The Moon was much closer to the Earth in the past than at present. The distance of the Moon from the Earth is about 60Re (Re = Earth radius) at present, and was about 3Re in the past. Therefore, the early lunar thermal state is thought to be strongly affected by the tidal dissipation.

2. Purpose
The possible contributions of tidal heating to lunar thermal history are investigated by Peale and Cassen (1978). But Peale and Cassen calculated the tidal heating taking into account the orbital evolution and concluded that tidal contributions to lunar thermal history were probably not important, so lunar thermal history was essentially controlled by radiogenic sources and initial accretional heating. The purpose of the present study is to reexamine the Peale and Cassen's conclusion from a view point that the tidal dissipation is significantly affected by the orbital evolution and internal structure of the Moon.

3. Calculation
We calculate the lunar thermal history, taking into account the orbital evolution and the possible internal structures of the early Moon. The procedure of calculation is on the basis of Peale and Cassen et al. (1978) and Kawakami and Mizutani et al. (1986).

4. Conclusion
The calculation results indicates that the tidal dissipation may be an important source of the heat energy and that the thermal history and orbital evolution must be coupled in order to better understand the early thermal history. But there exist several uncertain parameters for example dissipation factor Q and eccentricity, so we discussed the dependence of lunar thermal evolution on the uncertain parameters.

[Reference]
[1]Peale, S., and P. Cassen. Contribution of Tidal Dissipation to Lunar Thermal History. Icarus 36, 245-269 (1978).
[2] Kawakami,S., and H. Mizutani. Thermal history of IO. Icarus 70, 78-98 (1986).

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Many features became clear about deep moonquakes which are detected by seismological observation in the Apollo missions during 1969 - 1977. However, the details about behavior of tidal stresses in the focus region of deep moonquakes are not becoming clear, and it is only conjecture in the present which passed through a little more than 30 years from the Apollo missions.
In this study, in order to construct the first step of a new theory about the relationship between lunar tidal stress and deep moonquakes, we noted a behavior of tidal stress itself.
Calculation of tidal stresses has adopted a semi-analytical lunar ephemeris (ELP 2000/82) which is proud of the high precision given by Chapront and Chapront (1982) about the relative position of the Earth-Moon system, using the y function method given by Takeuchi (1950). A used lunar internal structure model is based on Nakamura et al. (1982) obtained by the analysis of the Apollo seismic data and a density structure uses Tanaka et al. (1990).
The size and amplitude of tidal six components which were calculated change with the depth or positions, even when the internal structure of the moon is considered as fixation. We picked up the largest tidal stress component at a depth of 900km at every 5deg. grid points from longitude 0 to 90deg. and latitude 0 to 80deg. for a model with a core of 400km in radius and plotted in the selenographical map, a tidal stress distribution will be qualitatively classified into six zones: (1) Low longitude and Low latitude zone, (2) Middle longitude and Low-to-middle latitude zone, (3) High longitude zone, (4) Low-to-middle longitude and Middle-to-high latitude zone, (5) Middle longitude and High latitude zone, and (6) Low longitude and High latitude zone. These zones are dominated by SIGMA_rr, SIGMA_rphi, SIGMA_phiphi, SIGMA_rtheta, SIGMA_thetaphi, and SIGMA_thetatheta, respectively. If this is checked with the hypocenter distribution of deep moonquakes, the hypocenter will be concentrated on the SIGMA_rr- and the SIGMA_rphi-dominated zones, especially the SIGMA_rphi-dominated zone, and it will be thought that these components are working as a dominant trigger to an occurrence of deep moonquakes. Itagaki et al. (2003) concluded the possibility of the existence of a toroidal motion of the lunar interior, such as the east and/or west-ward flow in the lunar deep mantle. If the deep moonquake is controlled by the tidal shear stress, the observed depth distribution can be explained by a core model having the core radius of 400 to 600 km.
Consequently, although the focus which can be grasped clearly also exists that the SIGMA_rr component is a trigger in the SIGMA_rr zone which is next concentrating focus, the moonquake of the half which belongs to this zone has generated at the very deep point of a depth of 1100km or more, where the SIGMA_thetatheta and the SIGMA_phiphi components dominate. The result indicates the deep moonquakes which occur at points deeper than 1100km may be generated by different mechanism from the deep moonquakes which occur in the average depth of around 900km.

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We performed impact experiments in order to investigate formation of transient craters in gravity regime. Based on the results, we will discuss the scaling laws for transient craters.

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ALIS (Akita Lunar Imaging Spectrometer) is a telescopic imaging spectrometer which we developed for Space Station Lunar Observatory project. A purpose of this project is to establish the photometric model of the moon as a spectral radiance standard of space-borne imaging instruments by repeated observation of the moon with a VIS/NIR (Visible and Near Infra-red light) from the International Space Station. We developed a calibration method to gain absolute radiance and relative reflectance of the moon from ALIS data and present geologic variations of reflectance spectra. This project is carried out as a part of 'Ground-based Research Announcement for Space Utilization' promoted by Japan Space Forum.

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Precise lunar phase functions are necessary for a compositional analysis of Clementine UV-VIS images. Phase functions are considered to have both wavelength dependence and geological-type dependence. The lunar reflectance spectrum has been successfully clustered in to 9 spectral groups by applying Self-Organizing Map (SOM) method in three wavelengths, 415nm, 750nm, 950nm (Yokota 2002). The validity of the clusters were shown by comparing the results with the spectral unit map of USGS and the compositional distribution obtained by Lunar Prospector. Yokota (2002) developed a method of determining the phase functions precisely by selecting pairs of observation data that observe the same surface but has a different phase angle, And obtainded the phase functions for each spectral group.
We have made several lunar regolith samples that correspond to each spectral group. Then, we measured the reflectance spectra and obtained the phase functions for each sample. We will compare the results with the previous works and examine what factors control the phase functions.

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Development status and preparation of preliminary science papers of Lunar Imager / SpectroMeter (LISM)

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The Lunar Imager/ SpectroMeter (LISM) is an instrument being developed for the SELENE project that will be launched in 2005. Multiband Imager (MI) is one of the three LISM sensors. MI is a high-resolution multiband imaging instrument consisting of two visible and near infrared sensors and will obtain the lunar global mapping of mineral distribution in nine bands to understand the origin and evolution of the Moon. One of the main research targets of MI is crater central peaks; therefore we selected crater central peaks as an example to evaluate MI's flight model performance and predicted scientific returns. Results of this evaluation confirmed MI's superior performance and advantages compared to the Clementine multiband spectral datasets.

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Rock surface observations are important method for the landing planetary survey, such as SELENE-B mission. We developed the imaging spectral microscope, and estimated the most appropriate roughness of rock surface. To be observed minerals structures, these rock surfaces should be polished, but element of specular reflection is strong at polished surfaces. And at spectral observation, element of diffused reflection is important for analysis of these data. We have to determine the most appropriate roughness of rock surface for the observation of our landing survey.

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We have been studying the instrumentation onboard the lander and rover for a lunar geological exploration with the SELENE-B that demonstrates the next generation technologies of a pin-point and soft landing on planetary surfaces of scientific interest and an autonomous controlled scientific rover. In this mission, imaging spectroscopy and multi-band imagery will characterize the target site around a crater central peak and gamma-ray spectrometry will measure radioactivity along the rover's track. Lunar rocks and soils at the target crops or around the lander are selected to brush up and grind for detailed analyses by microscopy and x-ray fluorescence/diffraction method. The systematic configuration of instruments is also introduced.

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Hafnium and tungsten are both highly refractory elements, and hafnium is a lithophile element whereas tungsten is a moderately siderophile element that should strongly partitioned into metal phases during metal/silicate segregation. The Moon may have formed from debris created by a giant impactor that hit the Earth with a glancing blow, after terrestrial core formation. The decay of now extinct 182Hf (half-life, 9Myr) to 182W is an ideal chronometer for tracing this process, because Hf is retained in the silicate mantle while W is largely partitioned into the core during core segregation (Halliday et al. 1996; Lee et al. 1997).It has been argued that the age of terrestrial core formation was limited by accretion time, that it started very early, and that it was largely completed within the first 10-20 Myr or less of Earth history (Jacobsen & Harper 1996; Lee & Halliday 1995, 1996). And recently, according to the new results of measurements of W isotope compositions and Hf/W ratios of several meteorites, it shows that the main growth stage for the Earth is largely completed in 10 Myr, and the Moon-forming giant impact is dated at 29 Myr (Kleine et al. 2002; Yin et al. 2002). However, they applied only magma ocean model and two-stage model. Magma ocean model considers exponentially decreasing rates of accretion and the rate of core formation limited by the accretion rate, and two-stage model has strict time significance only in the case where there is complete equilibration between the core and the silicate mantle at a single point in time, with no subsequent additions of material to the Earth (Harper & Jacobsen 1996; Jacobsen 1998). They assumed that a single giant impact could give rise to this perfect resetting on Hf-W chronometer.In this study, we consider the effect of partial resetting on Hf-W system by multiple giant impacts. We show limit of the age estimation by Hf-W chronometry, and on the other hand, possibility to constrain the required resetting ratio by giant impacts or other equilibrating events.Recent works on planetary formation show that several tens of Mars-sized protoplanets are formed through a successive accretion of planetesimals in the terrestrial planet region (Kokubo & Ida 1998; Wetherill & Stewart 1989). Then we consider two different stages: (1) protoplanets formation stage and (2) giant impacts stage. Primarily, in the stage of planetary accretion, metal of impactor and silicate of target are equilibrated each other, then Hf-W chronometer of this equilibrated region is reset. This resetting continues during the metal sink in the silicate to reach the core of target body. We assume metal of impactor split into lots of metal sphere grains sinking in a silicate melt at a velocity following from Stokes sedimentation equation and reset its chronometer. Achieved resetting ratio is estimated through the volume of target add the volume of impactor divided by the volume reset its chronometer.As the result of these considerations, we show this chronometer cannot determine the age of melt-silicate separation precisely and achieving large resetting ratio is not so easy by giant impact or other. To determine the age of core formation of Earth by Hf-W chronometry, we should determine the number and the resetting ratio of each giant impacts, and to achieve the high resetting ratio of Mars (= 0.6), we should reexamine the theory of planetary formation or introduce certain drastic events for Mars.

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