Cosmogenic Radionuclide Records of Hayabusa Aggregate and Particle Samples
Kunihiko Nishiizumi1, Marc W. Caffee2, Keisuke Nagao3, Kees C. Welten1, Jozef Masarik4
Space Sciences Laboratory, Univ. of California, Berkeley, CA 94720-7450, USA., 2Dept. of Physics & Astronomy, Purdue
Univ., West Lafayette, IN 47907-2036, USA., 3Div. of Polar Earth-System Sci., KOPRI, Incheon 21990, Korea, 4Faculty ofMath. & Physics, Comenius Univ., SK-842 15, Bratislava, Slovakia

1

Hayabusa2 arrived at the C-type asteroid 162173 Ryugu in June 2018, and successfully collected surface samples from two
sampling sites, returning ~5.4 g of material to Earth on December 6, 2020. The surface samples stored in Chamber A werecollected by the 1st touchdown (TD) on Ryugu’s surface on February 21, 2019. A crater (diameter of ~14 m) on Ryugu’s
surface was made using a collision device - denoted “Small Carry-on Impactor (SCI)” - on April 5, 2019 [1]. The samples in
Chamber C were collected proximal to the north side of this artificial crater by the 2nd TD on July 11, 2019 and possibly containejecta from the crater [2]. Distance between TD1 and TD2 is ~820 m.
Our studies are based on the measurement of those nuclides produced in asteroidal surface materials by cosmic rays - bothsolar (SCR) and galactic cosmic rays (GCR). Cosmic-ray-produced (cosmogenic) nuclides are used to determine the durationand nature of the exposure of materials to energetic particles. Our goals are to understand both the fundamental processes on
the asteroidal surface and the evolutionary history of its surface materials. For Hayabusa2 samples, there are several specificquestions we aim to address: (1) are the Chamber C samples, collected during the 2nd TD ejecta deposits from the artificial crater,(2) if so, what is the original depth of each recovered sample in the Ryugu regolith, and (3) what is the surface exposure time,
mixing rate, and erosion/escape rate of Ryugu’s surface? To answer these questions, we were allocated and received particles
from Chamber A and Chamber C for measurements of cosmogenic radionuclides and noble gases as a part of initial analysis of
Ryugu. We have measured cosmogenic 10Be (t1/2 = 1.36 x 106 yr), 26Al (7.05 x 105 yr), 36Cl (3.01 x 105 yr), and stable noble
gases in those samples [3-5]. Based on noble gas analysis of ~2 dozen Ryugu samples, we found that cosmic ray exposure(CRE) ages of Chamber A (surface) samples, A0105, range from 2.9 to 7.5 Myr and Chamber C (sub-surface) samples, C0106,
range from 1.6 to 5.8 Myr based on 21Ne concentrations [3, 6]. We also found that four C0106 particles were exposed at depthof ~50, 110, 130, and 145 g/cm2 respectively and had different CRE ages based on cosmogenic nuclide measurements [3, 5].
To further study of the exposure condition of Ryugu surface materials, we obtained one grain, A0130, from Chamber A and3 grains, C0012, 0162, and 0182 from Chamber C. In addition, we obtained two aggregate samples, A0221 and C0212, inorder to determine average exposure ages and depths for both Chamber A and C samples. As shown above, each grain had
different exposure histories (age and depth). This is similar to what we found for exposure histories of individual grains oflunar core samples. While cosmogenic radionuclides of lunar bulk soils show smooth depth profiles, the measured radionuclide
concentrations of individual rock fragments at the same depth show deviations from the smooth depth profiles [7].
Each sample was gently crushed by a mortar and pestle made from sapphire and then divided into two fractions, one fraction
for cosmogenic radionuclides (this work) and one for noble gases measurements [8]. The samples were individually transferred
to a small Al weighing boat and the masses were determined using an ultra-micro balance. For cosmogenic radionuclide
analysis, the sample was transferred to a Teflon bomb and dissolved with HF and HNO3 mixture in the presence of Be and Cl
carriers. After Cl was separated as AgCl for 36Cl measurements, a small analysis aliquot was taken for chemical analysis by
ICP-OES. Beryllium, Al, and Mn were separated by ion chromatography, using anion and cation ion exchange columns, andBe and Al were purified for AMS measurements. To serve as a baseline comparison, a few grains of the Orgueil CI chondrite
were analyzed using the same protocols. Beryllium-10 and 26Al AMS analyses were performed at PRIME Lab, Purdue
University [9]. Measured isotopic ratios were normalized by AMS standards [10, 11] and converted to radionuclide
concentrations (dpm/kg).
Chemical compositions in Ryugu samples measured by ICP-OES are shown in Table 1. Since sample sizes are slightly
larger than previous Ryugu initial analysis, data show less scatter. Bulk chemical compositions of samples from TD1 and TD2
determined using ICP-MS [12] are also shown in the table. Our analysis of A0221 and C0212 are in good agreement withanalysis of TD1 and TD2 samples determined by [12]. Noticeably, both our two samples and published analysis of TD1 andTD2 samples [12] were obtained from aggregate samples and not individual grains. Although [12] concluded that are no
systematic differences in chemical composition between the samples from TD1 and TD2 sites, our limited measurements indicatethat Ca is slightly higher and Fe is lower in TD1 samples than that of TD2.

Table 1. Chemical compositions in Ryugu samples and Orgueil CI chondrite.
Sample

Mg
(%)
9.32
10.84
10.54
10.74
10.81
9.36
10.77
10.69
10.42
7.37
9.63

A0130
A0221
C0012
C0012
C0162
C0182
C0212
Ryugu (TD1)*
Ryugu (TD2)*
Orgueil CI
Orgueil CI#

Al
(%)
0.94
0.90
0.91
0.91
0.90
0.84
0.98
0.86
0.90
0.64
0.60

K
(ppm)
720
520
600
580
570
400
550
520
600
440
530

Ca
(%)
1.45
1.69
1.09
1.18
1.08
0.95
1.18
1.63
1.37
0.60
0.76

Ti
(ppm)
520
530
460
490
570
510
510
480
470
340
-

Mn
(ppm)
1990
3040
2020
2340
2120
1510
2370
3000
2490
1380
1680

Fe
(%)
18.39
19.76
21.15
20.11
20.75
18.63
20.53
19.49
20.22
14.23
17.76

Co
(ppm)
540
560
600
560
560
520
590
550
590
400
540

Ni
(%)
1.13
1.20
1.31
1.21
1.26
1.13
1.26
1.18
1.22
1.18
1.04

*[12], #Previous measurement (unpublishd 2003)

Cosmogenic nuclide 10Be and 26Al concentrations in Ryugu samples are shown in Table 2 along with that of Orgueil CI
chondrite. Using the MCNP Code System [13], we calculated the GCR production rates of 10Be and 26Al by spallation reactions
for a body having a 2π geometry with Ryugu’s chemical composition [12]. Based on the comparison of the observed
radionuclide concentrations with model calculated 10Be and 26Al production rate depth profiles, assuming the radionuclide
concentrations in Ryugu are saturated, we obtained the first order estimation of exposure depth of each sample and shown in
Table 2. Based on those depths we calculated 21Ne production rates and calculated 21Ne CRE ages in each sample [8]. The
calculated exposure depths and CRE ages of each grain obtained by TD2 scatter, in similar fashion as previous works [3, 5].
The preliminary estimation of average exposure depth of aggregate sample A0221 is somewhat deeper than those of each grain
obtained from TD1. The depth range of aggregate sample C0212 collected by TD2 is estimated to be 110 - 140 g/cm2 basedon 10Be concentration. The 26Al concentration of C0212 indicates much shallow depth of 10 – 90 g/cm2. One possible
explanation is that C0212 contains a small amount of surface material that contains high SCR produced 26Al. The measurementof thermal neutron-capture produced 41Ca (t1/2 = 1.0 x 105 yr) – in progress - is critical to further constrain the exposure depth ofeach sample.
Table 2. Cosmogenic nuclide 10Be and 26Al concentrations in Ryugu samples and Orgueil CI chondrite.
1026
Sample
Mass
Be
Al
Depth
(mg)
(dpm/kg)(dpm/kg)(g/cm2)A0130
0.676
9.94 ± 0.29
29.2 ± 1.3
10 - 70
A0221
10.718
11.23 ± 0.10
27.4 ± 0.6
70 - 100
C0012
4.200
7.50 ± 0.10
24.3 ± 0.8
90 - 140
C0012
7.274
7.43 ± 0.15
23.3 ± 0.8
110 - 150
C0162
1.531
7.58 ± 0.21
24.6 ± 1.0
95 - 145
C0182
0.983
6.28 ± 0.15
25.3 ± 1.3
85 - 135
C0212
8.406
9.06 ± 0.09
29.3 ± 0.6
110 -140
Orgueil CI
6.000
14.91 ± 0.31
35.9 ± 1.2
Orgueil CI#
52.60
21.19 ± 0.36
40.4 ± 0.8#

Previous measurement (unpublished 2003)

Acknowledgments: We thank Hayabusa2 project team and Hayabusa2 curation members. Orgueil was obtained from
MNHN-Paris. This work was supported by NASA’s LARS program.
References:[1] Arakawa M. et al. (2020) Science. 368, 67-71. [2] Tsuda Y. et al. (2020) Acta Astronautica. 171, 42-54. [3] Nagao K. et al.
(2022) Meteor. Planet. Sci. 57, A337 #6320. [4] Nishiizumi K. et al. (2022) Lunar Planet. Sci. LIII, #1777. [5] Nishiizumi K. etal. (2022) Hayabusa Symposium 2022. S21-08. [6] Okazaki R. et al. (2022) Science. 379, eabo0431. [7] Nishiizumi K. et al.
(1985) Lunar Planet. Sci. XVI, 620-621. [8] Nagao K. et al. (2023) Hayabusa Symposium 2023 (this meeting). [9] Sharma P. etal. (2000) Nucl. Instrum. Methods Phys. Res. B 172, 112-123. [10] Nishiizumi K. (2004) Nucl. Instrum. Methods Phys. Res.
B223-224, 388-392. [11] Nishiizumi K. et al. (2007) Nucl. Instrum. Methods Phys. Res. B258, 403-413. [12] Yokoyama T. etal. (2022) Science. 379, eabn7850. [13] Masarik J. and Reedy R. C. (1994) Geochim. Cosmochim. Acta. 58, 5307-5317.

Noble Gases of the 1st and 2nd AO Ryugu Samples Collected by the Hayabusa2 Spacecraft
Keisuke Nagao1*, Kunihiko Nishiizumi2, Marc W. Caffee3, Hwayoung Kim1, Changkun Park1, Jong Ik Lee1, Jozef Masarik4
KOPRI, Incheon 21990, Korea, 2Space Sciences Laboratory, Univ. of California, Berkeley, CA 94720-7450, USA.,3Dept. ofPhysics & Astronomy, Purdue Univ., West Lafayette, IN 47907-2036, USA, 4Comenius Univ., Bratislava, Slovakia, *present
address: Seki 2082, Maniwa-shi, Okayama 719-3156, Japan. knagao520@gmail.com
1

Hayabusa2 arrived at the C-type asteroid 162173 Ryugu in June 2018, and successfully collected surface samples fromtwo sampling sites, returning ~5.4 g of samples to Earth on December 6, 2020. Surface samples stored in Chamber A werecollected during the 1st touchdown (TD) on Ryugu’s surface on February 21, 2019. A crater (diameter of ~14 m) on Ryugu’s
surface was made using a collision device - denoted “Small Carry-on Impactor (SCI)” on April 5, 2019 [1]. Samples in Chamber
C were collected proximal to this artificial crater and are possibly ejecta from the north side of the crater by the 2nd TD on July11, 2019 [2].
Our studies on the Hayabusa2 samples are based on the measurement of those nuclides produced in asteroidal surface
materials by both solar (SCR) and galactic cosmic rays (GCR). Cosmic-ray-produced (cosmogenic) nuclides are used todetermine the duration and nature of the exposure of materials to energetic particles [3]. Our goals are to understand both thefundamental processes on the asteroidal surface and the evolutionary history of its surface materials. These processes occur overtimescales spanning the present to 109 yrs into the past, and are important not only for understanding the history of Ryugu’s
surface but also for studies of asteroid-meteoroid evolutionary dynamics. For Hayabusa2 samples, there are several specificquestions we aim to address: (1) are the Chamber C samples, collected during the 2nd TD, ejecta deposits from the artificial
crater, (2) if so, what is the original depth of each recovered sample grain in the Ryugu regolith, and (3) what is the averagesurface exposure time, mixing rate of regolith materials, and erosion/escape rate of Ryugu’s surface? We investigate and utilize
cosmogenic radionuclides (10Be, 26Al, 36Cl, and 41Ca) and noble gases, especially cosmogenic 21Ne in Ryugu samples. Expected
maximum cosmogenic nuclide concentrations in millimeter-sized (~1 mg in mass) Ryugu sample are a few times 105 - 107 atoms
or lower. These values are higher than the present detection limits of accelerator mass spectrometry (AMS) and noble gas mass
spectrometry, but 2 orders of magnitude smaller than normal studies of cosmogenic nuclide measurements in meteoritic materials.
We present here the noble gas isotopic compositions of 6 samples (Table 1) allocated as the 1st and 2nd AO. Noble gases
were measured with the system of modified-VG5400 mass spectrometer at Korea Polar Research Institute (KOPRI). The noble
gas system had been used to measure the Itokawa samples at the University of Tokyo [4], and then moved to KOPRI afterward
in 2015. Noble gases were extracted from each sample using a miniature furnace specially designed for small samples, using a
Ta-tube with a Mo-crucible. A sample dropped into the crucible is heated from outside of the Ta-tube by a W-heater. Electric
current applied to the W-heater is controlled by a computer program monitoring the heating temperature with a W-Re
thermocouple. Samples were installed in a glass-made sample holder, which was set on the furnace and preheated for a day at
about 120°C to remove atmospheric noble gas contamination adsorbed on the samples. Stepwise heating was applied to extract
noble gases, i.e., 200, 900, and 1700°C for small samples (A0130, C0162, and C0182), and 200, 600, 900, 1200, and 1700°C forlarger samples (A0221, C0012, and C0212). The extracted noble gases from each sample were purified and separated into 5
fractions, i.e., He, Ne, Ar, Kr, and Xe, then measured isotope abundances and isotopic ratios for each fraction.
Total values of concentrations of 4He, 20Ne, 36Ar, 84Kr, and 132Xe, and isotope ratios of He, Ne, and Ar obtained by the
stepwise heating method are presented in Table 1. Data of Orgueil CI chondrite measured in this work are also presented forcomparison. Solar He and Ne with very high concentrations of 4He (14.9 and 9.3×10-4 cm3STP/g) and 20Ne (2.0 and 1.5×10-3
cm3STP/g) were observed for the aggregate samples A0221 and C0212, respectively. These samples showed 20Ne/22Ne ratios of
12.8–13.7 in the temperature range of 200–900°C. The ratios are close to the value of 13.78 for solar wind (SW) [5]. Releasepeaks of 4He for these samples were at the heating temperature of 600°C, for which 3He/4He was 3.9×10-4, slightly lower thanthe SW value of 4.64×10-4 [5]. Smaller amounts of SW He and Ne are also indicated in A0130. Neon isotopic compositions forother samples are a mixture of several primitive components, e.g., P1 (Ne-Q), P3 (presolar diamond), and Ne-E(H) (SiC) [6].
Xe isotopic ratios, e.g., 130Xe/132Xe, 129Xe/132Xe, and 136Xe/132Xe, indicate that trapped Xe is mostly Q-Xe component, with asmall or negligible contribution of cosmogenic and HL or fissiogenic Xe.
Concentrations of cosmogenic 3He were difficult to calculate, because only a small excess of cosmogenic 3He wasobserved at the low heating temperatures at 200–900℃ for some samples (3He/4He = 5.2, 7.3, 4.9, and 4.8×10 -4 for A0221,
C0012, C0162, and C0212, respectively), and most 3He/4He ratios were between 1.23×10-4 for trapped Q-He [6] and 4.64×10-4
for SW [5]. Neon isotopic compositions are a mixture of several primitive components, e.g., SW [5], P1 (Ne-Q), P3 (presolar
diamond), and Ne-E(H) (SiC) [6], to which a small contribution of cosmogenic 21Ne was detected. Calculated concentrations ofcosmogenic 21Ne in excess of the assumed trapped 21Ne/22Ne = 0.029 are presented in Table 1. The concentrations of cosmogenic
21
Ne are (4.06–11.9)×10-9 cm3STP/g. The concentrations of 11.9 and 9.83×10-9 cm3STP/g for aggregate samples A0221 andC0212, respectively, are higher than those observed for the initial analysis samples, (1.6–7.8)×10-9 cm3STP/g [7, 8]. Exposure
depths were estimated from preliminary measurements of 10Be and/or 26Al in same samples. Then, each production rate P21 was
obtained by new calculation using the MCNP Code System. Calculated cosmic ray exposure (CRE) ages are shown in Table 1.
CRE ages calculated for the samples from Chamber-A are roughly 4 and 11 Myr for A0130 and A0221, respectively. CRE agesfor 3 samples from Camber-C, C0012, C0162, and C0182, are in the range of 3–5 Myr, while C0212 has longer CRE age of 89 Myr. The CRE ages of 3–5 Myr for the samples from Chamber-A and -C are similar to the reported ages for initial analysis
samples, 3–5 Myr [7] and 5 Myr [8]. Contrary to these grain samples, two aggregate samples A0221 and C0212 with longer
CRE ages are enriched in SW-Ne. Samples measured in the present work must have been irradiated heterogeneously by both
GCR and SW on the Ryugu’s surface before sampling by the Hayabusa2.
Table 1. Concentrations and isotopic ratios of noble gases 1) in 6 Ryugu samples and Orgueil CI chondrite.
4
20
36
84
3
21
Stepwise
Sample
Mass
He
Ne
Ar
Kr 132Xe
He/4He 20Ne/22Ne 21Ne/22Ne 38Ar/36Ar 40Ar/36Ar
NecosmP 213)
mg
heating2)
10-9cm3STP/g
10-4
10-9 cm3 STP/g 10-9 cm3 STP/g/Myr
A0130
0.2086
3 steps
219000
1230
1600
15.9
19.3
3.84
10.54
0.06540.1858
1.79
4.41
1.10-1.20
A0221
1.66105 steps 1490000
20400
3430
16.9
18.5
3.54
12.85
0.03620.1842
0.485
11.9
1.20
C0012
2.21795 steps
97700
472
1530
15.9
19.6
3.59
8.27
0.09780.1861
0.419
4.06
1.12–1.20
C0162
0.1886
3 steps
118000
706
1430
15.3
17.7
4.46
8.68
0.09840.1867
1.34
5.83
1.13–1.17
C0182
0.27683 steps
93800
432
1370
20.5
17.0
3.80
8.09
0.12800.1876
1.18
5.45
1.15–1.20
C0212
0.82325 steps
932000
15200
2720
16.1
18.7
3.89
12.95
0.03710.18490.427
9.83
1.12–1.17
Orgueil(CI) 1.7205
3 steps672000
1130
1260
13.0
15.7
3.51
10.08
0.10990.18562.37
9.37
2.224)
1)
Isotopic ratios of Kr and Xe are not presented.
2)
Heating temperatures are 200, 900, and 1700°C for 3 steps, and 200, 600, 900, 1200, and 1700°C for 5 steps.
3)
Each depth was estimated based on prelininary measurements of cosmogenic radionuclides. The production rates and CRE ages were not included ±5 % uncertainty of our new
calculations and experimental errors.
4)

Prodction rate in 4π-geometry for CI chondrites [9].

Acknowledgment: We thank Hayabusa2 project team, especially the curation members. We also thank HMNH-Paris forproviding Orgueil sample.
References[1] Arakawa M. et al. 2020. Science 368, 67–71[2] Tsuda Y. et al. 2020. Acta Astronautica 171, 42–54[3] Reedy R. C. et al. 1983. Annu. Rev. Nucl. Part. Sci. 33, 505–537.
[4] Nagao K. et al. 2011. Science 26, 1128–1131.
[5] Heber V. S. et al. 2009 Geochim. Cosmochim. Acta 73, 7414–7432.
[6] Ott U. (2002) Noble gases in Geochem. and Cosmochem., Rev. in Mineral. Geochem. 47, 71–100.
[7] Nagao K. et al. 2022. Meteoritical Soc. Meeting, Abstract #6134.
[8] Okazaki R. et al. 2023. Science 379, 788.
[9] Eugster O. 1988. Earth Planet Sci. Lett. 52, 1649–1662.

T21 3)
Myr
3.7–4.0
9.9
3.4-3.6
5.0–5.2
4.5–4.7
8.4–8.8
4.22

Insights into Early Solar System Isotopic Reservoirs Inferred from Ryugu
Quinn R. Shollenberger1, Jan Render1, and Gregory A. Brennecka1
1
Lawrence Livermore National Laboratory
Introduction: Returned primitive Solar System material presents a unique opportunity to address multiple important
planetary science questions. Recent work has demonstrated that material returned from the Japan Aerospace Exploration
Agency’s (JAXA) Hayabusa2 mission from Cb-type asteroid (162173) Ryugu is most closely related to Ivuna-type (CI)
carbonaceous chondrites [e.g., 1-2], which have a chemical composition similar to that of the Sun’s photosphere. The pristinenature and CI-like chemical composition of Ryugu samples allows researchers to use bulk-rock nucleosynthetic isotope
anomalies to establish genetic relationships to planetary bodies and to refine our knowledge of the isotopic evolution of the
Solar System, as well as the accretion history of the terrestrial planets [e.g., 1-6].
The initial isotopic study of four Ryugu particles found it has an indistinguishable Fe isotope composition from CI
chondrites—which is itself different from all other carbonaceous chondrites [2]. This led to the conclusion that a third isotopic
reservoir may have existed in the early Solar System for CI and CI-like bodies to form separate from the carbonaceous andnon-carbonaceous reservoirs. However, the existence of a third isotopic reservoir has recently been challenged through two
different models [7-8], and those studies have shown that the isotopic dichotomy between carbonaceous and non-carbonaceous
meteorites extends to Fe isotopes. These authors suggest that the appearance of an apparent third isotopic reservoir in themeteorite record reflects a lack of Fe isotope data from carbonaceous achondrites [8]. Here we report Fe and Ti isotopic
analyses with the addition of Ni isotope compositions on a bulk sample from Ryugu to shed new light on the isotopic
reservoirs present in the early Solar System.
Methods: Ryugu particle A0208, provided by JAXA, was analyzed in this study. This particle was part of a surface sample
that was collected in Chamber A during the first touchdown of the Hayabusa2 spacecraft. Approximately 8 mg of Ryugu
particle A0208 was weighed and dissolved in a pre-cleaned PFA vial using a combination of concentrated HF:HNO3, followedby aqua regia. Two procedural blanks as well as the geostandards BCR-2 and BHVO-2 were processed alongside our Ryugu
sample for all procedures. Following dissolution, we obtained major and trace element concentrations using a Thermo
Scientific Element XR ICP-MS at Lawrence Livermore National Laboratory (LLNL) following previously published methods[9].
All samples were processed through multiple chemical separations to purify the elements of interest using previously
established procedures. The first separation was to isolate Fe from the sample matrix [10] followed by purification of Ti [e.g.,
11] and Ni [e.g., 12]. Yields of our procedures were >80% and the blanks were negligible considering the total amount ofmaterial processed for Fe, Ti, and Ni. Iron and Ni isotopic analyses were performed on a Thermo Scientific Neptune Plus MCICPMS at LLNL while Ti isotopes were measured on a Thermo Scientific Neoma MC-ICPMS at LLNL [e.g., 2, 11-12].
Results and Discussion: Whereas the previously analyzed Ryugu particles were all around 25 mg or less [1-2], our particle
A0208 weighed only 8 mg. Despite this difference and the limited masses in general, we observe that our Ryugu particle
exhibits elemental concentrations comparable to what has been reported in previous work (Fig. 1). Shown in figure 1 are major
and trace element concentrations obtained for particle A0208 against the average concentration data from the initial Ryugu
study [1], demonstrating overall excellent agreement. A few
small differences exist between the two works (the mostnotable being Be), which are readily explained byheterogeneities at these small sample scales (< 25 mg).
Figure 1. Major and trace element abundances of Ryugu A0208
particle of this work plotted against the average concentrations
determined for Ryugu particles A0106, A0107, and C0108 from[1]. With a few exceptions, most elements are in good agreement
between the two studies. Uncertainties for ICP-MS data from thisstudy are estimated to be ±5%, whereas error bars shown for datafrom [1] are two standard deviations of the two ICP-MS
measurements reported in that work.

Shown in Figure 2 are select Ti, Fe, and Ni isotope data commonly used for genetic comparison of meteoritic materials.
Our measured Fe and Ti isotopic compositions are indistinguishable from other Ryugu particles as well as from CI chondrites[1-2]. The overlapping Fe and Ti isotopic compositions of our Ryugu particle with previous measurements indicate that sample
heterogeneity is not a big concern for major elements analyzed here. Although specific values and uncertainties were notprovided in [13], our Ni isotope data from Ryugu particle A0208 appear to be consistent with these previous Ni isotope
measurements as well as CI chondrites (Fig. 2). This result offers further support to the interpretation that Ryugu is mostclosely related to CI chondrites [1-2, 13].
The new Ti, Fe, and Ni isotopic data obtained in this study demonstrate that Ryugu and CI chondrites may plot on acontinuation of a trend defined by the carbonaceous chondrites. Previous studies have suggested that CI chondrites and Ryugu
may have formed at greater heliocentric distances compared to other carbonaceous chondrites [e.g., 2, 13-14] and our data aresupportive of this interpretation given that Ryugu and CI chondrites are an endmember in the carbonaceous reservoir. While
our data do not clearly provide evidence for the existence of a third isotopic reservoir in the early Solar System as previously
suggested [2], this is not ruled out, either. Additional isotopic measurements are underway at LLNL for Cr and any finalized
data and further interpretations will be reported at the meeting.

Figure 2. Plots of µ54Fe vs. µ50Ti, µ62Ni vs. µ50Ti, and µ54Fe vs. µ62Ni, where µ designates parts per million deviation from a terrestrial
standard. Ryugu particle A0208 from this study is the large light blue diamond, previous Ryugu measurements are shown as a light blue
triangle, average CI chondrite as a light blue circle, carbonaceous chondrites (CC) as dark blue circles, non-carbonaceous meteorites (NC) in
red circles, and Earth as a green square. Iron and Ti isotopic data from [2]. Ni isotopic data compiled from [15-19].

Acknowledgements: The authors thank JAXA for providing Ryugu particle A0208 that was used in this study. This work
was performed under the auspices of the U.S. DOE by LLNL with contract DE-AC52-07NA27344 with release number
LLNL-ABS-848622. This work was funded by the Laboratory Directed Research and Development program of Lawrence
Livermore National Laboratory (23-LW-015).
References[1] Yokoyama T. et al. (2022) Science 10.1126/science.abn7850. [2] Hopp T. et al. (2022) Science Advances 8, eadd8141. [3]Fischer-Gödde M. & Kleine T. (2017) Nature 541, 525-527. [4] Burkhardt C. (2021) Science advances 7, eabj7601. [5]Schiller M. et al. (2020) Science Advances 6, eaay7604. [6] Burkhardt C. et al. (2019) Geochimica et Cosmochimica Acta 261,
145-170. [7] Marrocchi Y. et al. (2023) The Astrophysical Journal Letters 954, L27. [8] Yap T. & Tissot F.L.H. (2023) Icarus
405, 115680. [9] Wimpenny J. et al. (2022) Earth & Planetary Science Letters 578, 117318. [10] Rolison J. M. et al. (2019)
Applied Geochemistry 103, 97-105. [11] Shollenberger Q. R. et al. (2022) Geochimica et Cosmochimica Acta 324, 44-65. [12]Render J. et al. (2018) The Astrophysical Journal 862, 26. [13] Spitzer F. et al. (2023) LPSC #2488. [14] Desch S.J. (2018)
The Astrophysical Journal 238, 11. [15] Steele R.C.J. et al. (2012) The Astrophysical Journal 758,59. [16] Tang H. & Dauphas
N. (2012) Earth & Planetary Science Letters 359-360, 248-263. [17] Tang H. & Dauphas N. (2014) Earth & Planetary Science
Letters 390, 264-274. [18] Regelous M. et al. (2008) Earth & Planetary Science Letters 272, 330-338. [19] Burkhardt C. et al.
(2017) Meteoritics & Planetary Science 52, 807-826.

Nickel isotopic composition of Ryugu and the link between CI and other carbonaceous chondrites
T. Kleine F. Spitzer1, C. Burkhardt1, the Hayabusa2-initial-analysis chemistry team, and the Hayabusa2-initial-analysis core1
Max Planck Institute for Solar System Research, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
The initial analyses of samples returned from Cb-type asteroid 162173 Ryugu by JAXA’s Hayabusa2 mission provided
isotopic, mineralogical, and chemical evidence for a close link of Ryugu to CI chondrites [1,2]. A subsequent study has shownthat Ryugu and CI chondrites share the same nucleosynthetic Fe isotope signatures, which are distinct from those of othercarbonaceous chondrites [6]. This not only demonstrates that Ryugu and CI chondrites are genetically linked, but also that they
derive from another reservoir than all other carbonaceous chondrites [3]. However, the origin of these distinct Fe isotopic
compositions of CI chondrites/Ruygu compared to other carbonaceous chondrites is not well understood. Nickel isotopes holdconsiderable promise to further investigate the genetic link between Ryugu and CI chondrites. When normalized to 61Ni/58Ni,
CI chondrites do not only display the largest µ62Ni and µ64Ni anomalies among carbonaceous chondrites (where µiNi is theparts-per-million deviation from terrestrial standard values), but they also have a distinct µ60Ni composition compared to allother known carbonaceous chondrite-like materials. We obtained four Ryugu samples (A0106–A0107, A0106, C0108, C0107)
along with six carbonaceous chondrites including the CI chondrites Orgueil and Alais, which have been chemically processedalongside the Ryugu samples [2]. In addition, we also measured several grouped and ungrouped carbonaceous chondrites.
Chemical purification of Ni involved a 3-step ion-exchange chromatographic procedure that achieves sufficiently low 58Fe/58Ni
and 64Zn/64Ni ratios in the final purified Ni cuts to allows for accurate and precise correction of isobaric interferences. All
isotope measurements were performed on the Thermo Scientific NeptunePlus MC-ICP-MS at the Institut für Planetologie,
University of Münster. Instrumental mass bias is corrected by internal normalization to either 61Ni/58Ni or 62Ni/61Ni using the
exponential law. All data are reported in the µ-notation as the parts per 106 deviation relative to the standard.
The new Ni isotopic data for CM, CO, CV, and CR chondrites agree
well with those reported in previous studies and reveal that thesechondrites are characterized by negative µ60Ni and positive µ62Ni andµ64Ni values (Fig. 1). The two ungrouped carbonaceous chondrites
Tagish Lake (TL) and Tarda, for which no Ni isotopic data have beenreported previously, have Ni isotope anomalies similar to thosecarbonaceous chondrites. By contrast, CI chondrites display distinct
Ni isotopic compositions and particular distinctly larger µ64Ni andµ60Ni compared to other carbonaceous chondrites (Fig. 1).
Importantly, the Ni isotopic compositions of all four Ryugu samples
overlaps with those of the CI chondrites, indicating distinct Ni
isotopic compositions of CI chondrites/ Ryugu compared to all othercarbonaceous chondrites (Fig. 1). This is consistent with theFig. 1: µ60Ni versus µ64Ni for non-carbonaceous (NC) andnucleosynthetic Fe isotope variations among carbonaceous chondrites, carbonaceous (CC) meteorites. CI chondrites and Ryugu
which also reveal a uniquely distinct composition for CI chondrites have distinct Ni isotopic compositions compared to NC andCC meteorites.
and Ryugu [3].
Isotopic variations among carbonaceous chondrites are thought to reflect variable proportions of three main components
having distinct isotopic compositions: refractory inclusions (e.g., CAI), chondrules/chondrule precursors, and CI chondrite-like
matrix [4, 5]. The incorporation of CI chondrite-like matrix in other groups of carbonaceous chondrites is consistent withsystematic variations of (i) volatile element contents, (ii) mass-dependent isotope fractionations of moderately volatileelements, and (iii) nucleosynthetic 54Cr anomalies with the fraction of matrix in each chondrite. However, in Ni isotope space,
CI chondrites (and Ryugu) are offset from the composition of other carbonaceous chondrites, indicating that CI chondrites are
not fully representative of the matrix in other groups of carbonaceous chondrites. Instead, this matrix appears to have formed
from different precursor material than CI chondrites, either because it formed in a different area of the disk or because it was
modified by processes in the disk prior to its incorporation in carbonaceous chondrites.
References[1] Yada T. et al. 2022. Nature Astronomy 6:214–220. [2] Yokoyama T. et al. 2022. Science abn7850. [3] Hopp T. et al. 2022.
Science Advances 8:8141. [4] Alexander 2019. Geochimica et Cosmochimica Acta 254:277-309. [5] Hellmann et al. 2023.
Astrophysical Journal Letters 946: L34.

The magnesium isotope composition of samples returned from asteroid Ryugu

1

Martin Bizzarro1,2*, Martin Schiller1, Tetsuya Yokoyama3 and the Hayabusa2 Initial Analysis Team
Centre for Star and Planet Formation, Globe Institute, University of Copenhagen, Copenhagen, K 1350, Denmark.*email:bizzarro@sund.ku.dk
2
Université Paris Cité, Institut de Physique du Globe de Paris, CNRS, 75005 Paris, France
3
Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Tokyo 152-8551, Japan.

The nucleosynthetic isotope composition of planetary materials provides a record of the heterogeneous distribution of stardust
within the early Solar System. Thus, nucleosynthetic signatures can be used to infer genetic relationships between early formed
bodies and, ultimately, provide constraints on their accretion regions. In December 2020, the Japan Aerospace Exploration
Agency Hayabusa2 spacecraft returned to Earth the first samples of a primitive asteroids, namely the Cb-type asteroid Ryugu.
This provides a unique opportunity to explore the kindship between primitive asteroids and carbonaceous chondrites. Based on
chemistry, mineralogy, petrology and isotope systematics of various elements, it has been proposed that Ryugu samples areclosely related to Ivuna-type (CI) carbonaceous chondrites. Indeed, the bulk nucleosynthetic isotope compositing for tracers
like 54Cr and 50Ti as well as the chemical abundances of most elements are within the range of CI chondrites. Moreover, like
CIs, Ryugu samples experienced extensive aqueous alteration in the presence of water and mainly consist of hydrous silicates(serpentine and saponite) and other secondary minerals (i.e., carbonate, magnetite, and sulfide) interpreted to have formed
during asteroidal fluid circulation.
High-precision Mg isotope measurements can provide a novel perspective on the kinship between Ryugu with CI chondrites
and, by extension, the accretion region of Cb-type asteroids. Magnesium isotope variability in Solar System materials canoriginate from the decay of the short-lived 26Al nuclide as well as primary nucleosynthetic processes. Moreover, Mg isotopes
can also be fractionated according to their masses by high-temperature events in the protoplanetary disk or, alternatively, by
low-temperature parent body secondary. Thus, the combination of high-precision mass-independent and mass-dependent Mg
isotope compositions is useful to understand genetic relationships and accretion history of planetary materials.
Here, we report high-precision µ26Mg* and µ25Mg values of Ryugu samples together with those of CI, CM, CV and ungroupedcarbonaceous chondrites. The stable Mg isotope composition of Ryugu aliquots define µ25Mg values ranging from –160±20
ppm to –272±30 ppm, which extends to lighter compositions relative to Ivuna-type (CI) and other carbonaceous chondrite
groups. We interpret the µ25Mg variability as reflecting heterogenous sampling of a carbonate phase hosting isotopically light
Mg (µ25Mg ~–1400 ppm) formed by low temperature equilibrium processes. After correction for this effect, Ryugu samples
return homogenous µ26Mg* values corresponding to a weighted mean of 7.1±0.8 ppm. Thus, Ryugu defines a µ26Mg* excess
relative to the CI and CR chondrite reservoirs corresponding to 3.8±1.1 and 11.9±0.8 ppm, respectively. These variations
cannot be accounted for by in situ decay of 26Al given their respective 27Al/24Mg ratios. Instead, it requires that Ryugu and the
CI and CR parent bodies formed from material with a different initial 26Al/27Al ratio or that they are sourced from material
with distinct Mg isotope compositions. Thus, our new Mg isotope data challenge the notion that Ryugu and CI chondrites
share a common nucleosynthetic heritage.

Oxygen isotope systematics of crystalline silicates in comet Wild 2: Comparison to anhydrous
minerals in Ryugu and CI chondrites
Noriko T. Kita1, Mingming Zhang1, Donald E. Brownlee2 and David J. Joswiak2
1
WiscSIMS, Department of Geoscience, University of Wisconsin-Madison2
Department of Astronomy, University of Washington
Initial analyses of Ryugu returned samples indicated that they are similar to CI (Ivuna-type) carbonaceous chondrites,
which mainly consist of minerals that formed by parent body aqueous alteration [e.g., 1-5]. Discovery of CO2 bearing fluidinclusions in Ryugu pyrrhotite suggests that the Ryugu parent body accreted in the outer solar system beyond the CO2 and H2Osnowlines (>3-4 au [2]). Kawasaki et al. [6] conducted oxygen isotope analyses of anhydrous minerals, such as olivine andpyroxene that are extremely rare in Ryugu and CI chondrite Ivuna. They examined the distribution of mass-independent
fractionation factors of oxygen 3-isotopes, expressed by ∆17O (= δ17O – 0.52 × δ18O), in olivine grains from Ryugu and CI
chondrites, and found them to be similar to those of comet Wild 2 from the NASA Stardust mission [7-12]. They suggested thatthe formation region of the Ryugu asteroid could have been farther into the outer solar system than most carbonaceous chondrites
and closer to the accretion region of comets.
Here, we summarize oxygen isotope data of olivine and pyroxene from comet Wild 2. To date, ~90 relatively coarsegrained particles (>2 µm to upto 60 µm) have been analyzed for oxygen isotopes, including ~20 from the literature [7, 9-13] and~70 from recent studies [14-16]. These latter studies include more than 50 particles extracted from the longest type B Stardust
track (~17 mm) T227, which contains numerous relatively coarse (>2 µm up to 20 µm) particles in the bulb region in addition
to at least four terminal particles (TP). The largest TP measures 60 µm in diameter and has a porphyritic chondrule-like texture[16]. The majority of Wild 2 particle analyses were conducted at the WiscSIMS IMS 1280 using a 2 µm-sized primary beam [7,9, 12-16]. Oxygen isotope data of individual olivine and pyroxene particles are shown in the plot of ∆17O versus Mg# (molar[Mg]/[Mg+Fe] in Figure 1. This diagram has been used for the studies of meteoritic chondrules to understand the isotope
signatures of precursors and redox states during their formation [e.g., 17]. We also summarize published oxygen isotope analysesof olivine and pyroxene from Ryugu [6, 18] and other CI chondrites [6, 19-20] for comparison (Figure 2).
Wild 2 olivine and pyroxene show a wide range of Mg# ranging from 100 to 50 and are evenly distributed (Figure 1).
The ∆17O values are bimodal where most particles are 16O-poor with ∆17O values ranging from –7‰ to +7‰ and others with
∆17O of ~ –22‰, values similar to CAIs in carbonaceous chondrites. The latter 16O-rich particles are either LIME (low iron and
Mn-enriched) olivine, nearly pure forsterite, or enstatite, all which are with highest Mg#≥98. They are likely early solar nebula
condensates similar to those in AOAs [9,12]. In addition, rare occurrences of 16O-rich relict olivine have been identified, suchas in the chondrule-like object Gozen-sama, studied by [7]. The 16O-poor particles show a general tendency of a slight increasein ∆17O values with decreasing Mg# (Figure. 1). The majority of Wild 2 particles (60-70%) are FeO-rich (Mg#<90) and manyof them show zero to slightly positive ∆17O values. Similar results have been obtained from Giant Cluster IDP U2-20GCA [21],which is considered to be of cometary origin [22]. They overlap with data from CR chondrite chondrules [16, 23-25], suggestinga genetic relationship between CR chondrites and cometary particles [e.g., 9], though FeO-rich chondrules are uncommon in CR
chondrites and do not show ∆17O values higher than 1‰ [12, 16, 21].
Olivine and pyroxene data from Ryugu and CI chondrites are summarized in Figure 2. Most grains have high Mg#(≥98) with bimodal ∆17O values of ~–5‰ and –22‰ and minor FeO-rich grains show ∆17O values of ≤0‰. Similar to Wild 2
particles, 16O-rich olivine grains are often Mn-rich [6, 18, 20] and may be related to AOAs (e.g., [26]). However, the majorityof 16O-poor olivine and pyroxene in Ryugu and CI chondrites cluster at the ∆17O values of –5‰, which are uncommon among
Wild 2 particles. Ryugu and CI data are more similar to chondrule data in major carbonaceous chondrites, such as CMs and CVs(e.g., [27-28]). Rare chondrule-like objects were identified in Ryugu [29], though they are substantially smaller than typicalchondrules in carbonaceous chondrites.
Several Wild 2 particles are chondrule-like objects containing plagioclase and glass [7, 9-11, 16, 30]. Two of them werestudied for 26Al-26Mg chronology, but do not show any resolvable excess 26Mg [9, 31], suggesting that they formed later than 34 Ma after CAI formation (by assuming homogeneity of 26Al in the solar system). In contrast, the Ryugu and CI chondrite parent
bodies might have accreted much earlier ~2 Ma after CAIs and experienced aqueous alteration by the heat generated from 26Al
decay [2]. Thus, a major difference between anhydrous minerals in comets and CI chondrites could be related to the timing ofaccretion in the outer solar system. Comet Wild 2 contains late-forming (>3 Ma) chondrule-like materials, which may haveformed in the outer solar system [16]. They were not present in the Ryugu and CI chondrite-forming regions at the time of the
CI chondrite parent body accretion.

Figure 1. Mg# vs. Δ17O relationship among olivine and pyroxene particles in comet Wild 2 (after Zhang et al. [16]). Data sources: Literature[7, 9-13], T227 [16] and others [14-15]. Data from CR chondrules [17, 23-25] are plotted for comparison (error bars are ignored). Chondrulelike objects are shown as circles [7, 9, 11, 16] including 16O-rich relict olivine data [7, 16].

Figure 2. Mg# vs. Δ17O relationship among olivine and pyroxene grains in Ryugu (K23 [6]; L22 [18]) and CI chondrites Orgueil (P20 [19]),
Ivuna (K23, M22 [20]), and Alais (M22). The Wild 2 comet data (Figure 1) and CM and CV chondrite chondrule data [27-28] are shown forcomparison (error bars are ignored). Majority of 16O-poor Ryugu and CI chondrite data show systematically lower ∆17O and higher Mg# thanthose of Wild 2.

References [1] Yokoyama T. et al. 2023. Science 379:eabn7850. [2] Nakamura T. et al. 2023. Science 379:eabn8671. [3] Ito M.
et al. 2022. Nat. Astron. 6:1163–1171. [4] Nakamura E. et al. 2022. Proc. Jpn. Acad., Ser. B 98:227–282. [5] Yamaguchi A. et
al. 2022. Nat. Astron. 7:398–405. [6] Kawasaki N. et al. 2022. Sci. Adv. 8:eade2067. [7] Nakamura T. et al. 2008. Science
321:1664–1667. [8] Nakamura-Messenger K. et al. 2011. MaPS 46:1033–1051. [9] Nakashima D. et al. 2012. EPSL 357–
358:355–365. [10] Ogliore R. C. et al. 2012. ApJ. L745:L19. [11] Ogliore R. C. et al. 2015. GCA 166:74–91. [12] Defouilloy
C. et al. 2017. EPSL 465:145–154. [13] Joswiak D. J. et al. 2014. GCA 144:277-298. [14] Chaumard N. et al. 2018. Abstract#2163. 49th LPSC. [15] Zhang M. et al. 2022. Abstract #1057. 53rd LPSC. [16] Zhang M. et al. 2023. Abstract #. 1711. 54th
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2020. GCA 269: 451-465. [20] Morin G. L. F. et a. 2022. GCA 332: 203-219. [21] Zhang M. et al. 2021. EPSL 564:116928.
[22] Joswiak D. J. et al. 2017. MaPS 52:1612-1648. [23] Connolly H. C. and Huss G. R. 2010. GCA 74:2473–2483. [24] Schrader
D. L. 2013. GCA 101:302-327. [25] Schrader D. L. 2014. GCA 132:50-74. [26] Mikouchi T. et al. 2022. Abstract #. 1935. 53rd
LPSC. [27] Chaumard M. et al. 2018.GCA 228: 220-242. [28] Hertwig A. T. et al. 2018. GCA 224:116-131. [29] Nakashima D.
et al. 2023. Nat. Commun. 14:532. [30] Joswiak D. J. et al. 2012. MaPS 47:471-524. [31] Nakashima D. et al. 2015. EPSL
410:54-61.

Oxygen isotopic composition of dolomite in Ryugu: New insights into the thermal history of the
Ryugu parent body.
Wataru Fujiya1, Takayuki Ushikubo2, Shingo Sugawara1, Akira Yamaguchi3, Kohei Fukuda4, Martin R. Lee5, Kentaro Terada4,
Phillip A. Bland6 and Bryan J. Travis7
1
Faculty of Science, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki 310-8512, JAPAN (wataru.fujiya.sci@vc.ibaraki.ac.jp),2
Kochi Institute for Core Sample Research, JAMSTEC, 3National Institute for Polar Research, 4Osaka University, 5Glasgow
University, 6Space Science and Technology Centre, Curtin University, 7Planetary Science Institute
Introduction: Ryugu samples underwent extensive aqueous alteration, and a variety of secondary minerals such as
phyllosilicate, oxide, sulfide, and carbonate formed during water-rock interaction [1-5]. Among the secondary minerals,
carbonates are of particular interest because their O and C isotopic compositions reflect the conditions of aqueous alteration,and because they can be dated using the 53Mn-53Cr systematics. Previous studies of the O and C isotopic compositions of
dolomite (CaMg(CO3)2) in Ryugu have suggested that it formed at temperatures lower than 80 °C [1,2,6,8] when the system
was approaching equilibrium [7,8]. The 53Mn-53Cr dating of Ryugu carbonate suggests that their formation may have spanned
as much as 5 Myr [1,6]. Therefore, Ryugu carbonate potentially helps us decipher the thermal history of the Ryugu parent
body. However, it is unclear whether Ryugu carbonate formed during prograde alteration when temperature was increasing or
during retrograde cooling, which makes it difficult to establish a realistic thermal history model. In this work, we investigatedthe O isotopic compositions of dolomite in Ryugu samples A0203 and C0192 to further constrain its formation conditions.
Also, we will measure the O isotopic compositions of magnetite in these samples to estimate the O isotopic equilibrium
temperatures between dolomite and magnetite.
Experimental: Prior to isotope work, the microstructures of dolomite grains in samples A0203 and C0192 were characterizedby Transmission Electron Microscopy (TEM) using a FEI T20 operated at 200 kV. The in-situ O-isotope analyses on two andsix dolomite grains from A0203 and C0192, respectively, were performed using CAMECA IMS 1280-HR [9]. Negative ionsof 16O−, 17O−, and 18O−, produced by a focused Cs+ primary ion beam (~30 pA, 3-4 µm in diameter), were simultaneously
detected with a Faraday cup (FC) for 16O− signals and two electron multipliers (EMs) for 17O− and 18O−. Instrumental massfractionation was corrected using a series of dolomite–ankerite standards [10]. The uncertainties on δ17O, δ18O, and Δ17O
values were typically ±1.12, ±0.86, and ±1.35‰ (2σ), respectively.
Results and discussion: TEM showed that dolomite grains in A0203 and C0192 differ in their crystal size and habit, withthose in A0203 typically being 1-2 m size euhedral crystals whereas C0192 dolomite is coarser and anhedral. The analyzed
dolomite grains have only a small variation in δ18O values as observed by previous studies [1,6-8]. The δ18O values of A0203
and C0192 dolomite are at the higher and lower end of those reported previously and clustered at 32.91 ± 0.47‰ (N = 6; 2SE)
and 26.54 ± 0.58‰ (N = 2; 2SE), respectively. Notably, the Δ17O values of A0203 and C0192 dolomite are also systematicallydifferent (−1.13 ± 0.82‰ and 0.46 ± 0.36; 2SE). A similar anti-correlation between δ18O and Δ17O values can also berecognized for the previous data, implying that Ryugu dolomite with higher δ18O values tends to have lower Δ17O values [6-8].
The Δ17O, and possibly, δ18O values of aqueous fluids are expected to have decreased during progressive aqueous alteration
because of the O-isotope exchange between water and anhydrous rock which initially had higher and lower Δ17O (and δ18O)
values [11,12]. Thus, the A0203 dolomite with lower Δ17O values likely precipitated from more evolved fluids that underwent
O-isotope exchange to a greater extent than the C0192 dolomite. On the other hand, the equilibrium O isotopic fractionation
between water and dolomite is larger at lower temperatures with the δ18O values of dolomite being higher than those of water[13]. Therefore, the A0203 dolomite with higher δ18O values likely precipitated at lower temperatures than the C0192 dolomite.
These observations may suggest that Ryugu dolomite formed during retrograde cooling. This argument is in line with the small
variation in δ13C values observed for Ryugu dolomite, which suggests its formation in higher O fugacity at the later stage of
aqueous alteration [7]. For further information regarding the formation conditions of dolomite, we plan to measure the 53Mn53
Cr ages of dolomite in A0203 and C0192.
References:[1] Yokoyama T. et al. 2022. Science 379: eabn7850. [2] Nakamura E. et al. 2022. Proc. Jpn. Acad., Ser. B 98: 227-282. [3] Ito
M. et al. 2022. Nat. Astron. 6: 1163-1171. [4] Nakamura T. et al. 2022. Science 379: eabn8671. [5] Yamaguchi A. et al. 2023.
Nat. Astron. 7: 398-405. [6] McCain K. A. et al. 2023. Nat. Astron. 7: 309-317. [7] Fujiya W. et al. 2023. Nat. Geosci. 16:
675-682. [8] Kita N. T. et al., submitted. [9] Fujiya W. et al. 2020. Geochim. Cosmochim. Acta 274: 246-260. [10] Śliwiński,M. G. et al. 2016. Geostand. Geoanal. Res. 40: 157-172. [11] Clayton & Mayeda 1984. Earth Planet. Sci. Lett. 67: 151-161.
[12] Marrocchi et al. 2018. Earth Planet. Sci. Lett. 482: 23-32. [13] Zheng Y.-F.et al. 1999. Geochem. J. 33: 109-126.

Numerical Simulation of Ryugu’s Thermophysical Properties using the Discrete
Element Method
B. Agrawal1 , M. Grott1 , J. Knollenberg1 , J. Biele2 , B. Gundlach3 , J. Blum4
1

German Aerospace Center, Berlin, Germany, 2 German Aerospace Center, Köln, Germany, 3 Westfälische
Wilhelms-Universität Münster, Germany, 4 Technische Universität Braunschweig, Germany

Between June 2018 and November 2019, the Hayabusa2 mission [1] investigated the near-Earth asteroid (162173)
Ryugu. The main objective of the mission was to study this pristine C-type asteroid to better understand the origin
and evolution of materials in the early solar system. Hayabusa2 deployed the MASCOT lander in October 2018 andfollowing a detailed remote sensing and in-situ investigation, Hayabusa2 returned samples to Earth in December 2020.
A summary of main findings of the mission was recently reviewed by [2], who also compared results obtained during
the remote sensing, in-situ, and sample analysis phases.
The detailed study of Ryugu over scales ranging from the micro (sample) scale to global remote sensing data revealed
that while several properties derived from remote sensing and in-situ analysis agree very well with results obtained fromthe sample analysis, some discrepancies exist [2]. These scale dependent effects include properties like reflectance andthermophysical properties. Here, we focus on the derived thermal properties, which were determined using MASCOT’s
MARA radiometer [3], the Hayabusa2 orbiter’s TIR thermal infrared imager [4], as well as the returned samples [5].
−2 −1 −1/2
While in-situ and remote sensing data roughly agree, yielding thermal inertias of 282+93
K s[6, 7] and−25 Jm−2 −1 −1/2
−2 −1 −1/2
225 ± 45 Jm K s[4, 8], respectively, sample analysis indicates values of 890 ± 45 Jm K s[5], which arethus about three times as large.
The reason for the observed scale dependence of the thermophysical properties remains unknown, but it has been
proposed that the difference could be caused by a thermal shielding effect on intermediate scales [5]. Cracks may,for example, be generated by thermal fatigue and a conceptual model of how these cracks may be distributed
insidepboulders is shown in the left panel of Fig. 1. Thermal fatigue would extend to a few skin depths dϵ = κP/π, whereκ = k/ρcp is thermal diffusivity, ρ is density, cp is specific heat, and P is the period of the forcing (a day-night cycle).
Remote sensing instruments like MARA and TIR are sensitive to material over a similar depth range, while samples
could contain considerably less cracks.

Figure 1: Left: Conceptual model of scale dependence of thermophysical properties. The range of materials sampled
by the in-situ and remote sensing instruments MARA and TIR is indicated in blue, while the returned samples areindicated in green. On large scales, the material may exhibit abundant cracks due to insolation induced fatigue, whilesamples may contain only few cracks. Middle: Modeling approach including cracks induced by thermal fatigue using
discrete elements. Fatigue induced cracks separating particles are indicated in blue. Right: First results of simulatingheat flow through a bed of monodisperse particles without cracks. Colour represents particle temperatures going fromred (hot) to blue (cold).
Our project focuses on exploring this discrepancy and formulating a thermophysical model of the boulders including cracks and sintering. To understand the thermophysical properties of asteroids, we base our model on the
LIGGGHTS(R)-PUBLIC package [9]. It is an open source discrete element method particle simulation software built
for simulating general granular motion and atomic/molecular dynamics. The program integrates Newton’s equationsof motion for a large collection of spherical particles which interact via short or long range forces. The inter-particle
forces are determined based on a user selected contact model which can encompass interactions such as elastic (contact) forces, rolling friction, cohesion and surface geometry of particles. In addition to mechanical interactions, thepackage can also be used to study the thermal energy transport between particles in contact. This is governed by1the thermal conductivities of the particles and their contact areas. Here we specify contact areas as the cross sectionof the geometrical overlap of two spherical particles. Upon introducing cracks in a random packing of monodisperse
particles (middle panel in Fig. 1), we intend to study the thermal properties of the bulk material.
As a benchmark test for the numerical code we calculate the steady-state heat flow through a particle-bed toreproduce the relation between thermal conductivity, contact areas, and particle radii. Once in thermal equilibrium,
thermal conductivity of the bed can be calculated given the specified temperature boundary conditions and resulting
heat flux through the bed. This can then be compared to analytical and experimental results for monodisperse
particles [10]. First results of the simulation are shown in the right hand panel of Fig. 1 where heat is flowing
vertically downwards through a bed of cohesion-less particles with adiabatic boundary conditions elsewhere.
Once the numerical method has been benchmarked using monodisperse cohesion-less particles, we will include
polydisperse particles and a parameterized description of enhanced heat transport through inter-particle bonds. Using
the contact area as a tuning parameter we fit the numerical results to the thermal properties, as derived from sample
analysis [5]. Then, cracks will be introduced as outlined in the middle panel of Fig. 1 and the associated reduction inthermal conductivity will be investigated. In this way, we will systematically study the amount of material disruption
necessary to match the remote sensing observations [7, 6, 4].

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Christoph Kloss et al. In: Progress in Computational Fluid Dynamics 12.2-3 (2012), pp. 140–152.

[10]

N. Sakatani et al. In: AIP Advances 7.1 (Jan. 2017), p. 015310.

2

Defect and exsolution microstructures in four pyroxene-rich grains from Itokawa
Falko Langenhorst1,2, Agnese Fazio1, and Dennis Harries3
1Analytical Mineralogy of Nano- and Microstructures, Institute of Geoscience, Friedrich Schiller University Jena, Germany
2Hawai’i Institute of Geophys. and Planetology, School of Ocean and Earth Science and Technology, University of Hawai’i at Manoa, USA
3European Space Resources Innovation Centre, Luxembourg Institute of Science and Technology, 41 rue du Brill, L-4422Belvaux,

Luxembourg

Introduction: In 2010, the Hayabusa spacecraft returned precious regolith grains from the rubble pile asteroid 25143 Itokawa.
Subsequent investigations confirmed the link between LL4-6 ordinary chondrites and the S-type asteroid Itokawa and revealed
its eventful past [1, 2]. The processes reported in regolith grains comprise thermal annealing in the original parent body and thefull range of space weathering effects from surface amorphization by ion bombardment to collisional fragmentation [2-6].
Pyroxenes, the second most abundant phase in ordinary chondrites, are an important source of information on these processes,
as they develop various process-indicative defects. Thus, we pursued here a systematic study of the microstructures in orthoand clinopyroxene grains from Itokawa and discuss the results in terms of thermal metamorphism and space weathering.
Samples and methods: In the context of the 4th International Announcement of Opportunity for Hayabusa sample
investigation, we have obtained four pyroxene-containing Itokawa particles: RB-QD04-0092, RA-QD02-0205, RB-CV-0192,
and RB-CV-0144 [7]. These grains were cut by focused ion beam (FIB) preparation on a scanning electron microscope (SEM)
and then studied by analytical transmission electron microscopy (TEM), following the procedure described by [6].
Results: RB-QD04-0092 is a flat grain (29 x 26 x 12 μm) consisting of orthopyroxene (En78Fs21Wo1) and olivine (Fo71-78).
Both olivine and orthopyroxene show defects that are compatible with local shock metamorphism, i.e. olivine contains [001]dislocations, while orthopyroxene is pervaded by multiple (100) clinoenstatite lamellae. The regolith grain shows a 40-70 nm
wide continuous damaged rim due to solar wind irradiation.
RA-QD02-0205 is a prismatic grain (55 x 43 x 15 µm) that only consists of a single crystal orthopyroxene (En74Fs24Wo2). The
dominant defects are also pervasive (100) clinoenstatite lamellae, which are decorated by partial dislocations. The grain issurrounded by a 50 nm thin polynanocrystalline rim.
RB-CV-0192 is also prismatic in shape (19 x 10 x 8 µm), and contains both orthopyroxene (En76Fs23Wo1) and clinopyroxene(En50Fs7Wo43). Adjacent olivine, plagioclase, and whitlockite were detected, too. Besides (100) clinoenstatite lamellae inorthopyroxene there are no other defects. The solar wind damaged polynanocrystalline rim is up to 50 nm thick.
RB-CV-0144 is 17 x 12 x 5 µm in size and contains both orthopyroxene (En79Fs20Wo1) and clinopyroxene (En50Fs6Wo44). The
pyroxenes possess subgrain boundaries and are traversed by thin (up to 10 nm) (100) exsolution lamellae. One side of theentire regolith grain displays a polynanocrystalline and layered rim of up to 60 nm thickness.
Discussion: The presence of amorphous to nanocrystalline rims documents the solar wind damage of Itokawa grains.
Moreover, the occurrence of shock defects in localized areas of olivine and pyroxenes (clinoenstatite lamellae anddislocations) as well as the absence of microcraters on their surfaces indicate that cascades of collisions took place in theregolith. As consequence of active space gardening the effective exposure time of regolith grains must have been reduced. Of
particular interest is the observation of thin exsolution lamellae in pyroxene, whose width of up to 10 nm points to slow
cooling rates of < 1 °C per 1000 years at peak temperatures of 800°C [2, 8].
Acknowledgements: We thank JAXA for providing access to the Itokawa particles. FIB-TEM facilities at FSU Jena were
funded by the Gottfried-Wilhelm-Leibniz award to FL (LA 830/14-1). AF is grateful to the Alexander von Humboldt
Foundation for a postdoctoral grant.
References[1] Noguchi T., et al. 2011 Science 333:1121. [2] Nakamura T. et al. 2011 Science 333:1113. [3] Keller L.P. and Berger E.L.
2014 Earth Planets and Space 66:71. [4] Noguchi T., et al. 2014 Meteoritics & Planetary Science 49:188. [5] Harries D. andLangenhorst F. 2014 Earth Planets and Space 66:163. [6] Langenhorst F., et al. 2014 Earth Planets and Space 66:118. [7] Fazio
et al. 2020 Vol.14, EPSC2020-645. [8] Weinbruch S. and Müller W.F. 1995 Geochimica et Cosmochimica Acta 59: 3221.

Asteroid Itokawa … but when did form exactly?
F. Jourdan1, N.E. Timms1, T. Nakamura2, W.D.A. Rickard1, C. Mayers1
1
Curtin University, Perth, GPO Box U1987, WA, Australia
2
Tohoku University, Aoba, Sendai, Miyagi 980-8578, Japan
Rubble piles asteroids consist of reassembled fragments from shattered monolithic asteroids and are much moreabundant than previously thought in the solar system. In earlier studies (1, 2), we analysed five regolith dust
particles recovered by the Hayabusa space probe from the rubble pile asteroid 25143 Itokawa, using a workflow
of microstructural analysis by electron backscatter diffraction (EBSD), element mapping by time-of-flightsecondary ion mass spectrometry (ToF-SIMS ± atom probe) and 40Ar/39Ar geochronology. We showed that
Itokawa must have formed before or at ca. ≥ 4. 2 Ga and concluded that rubble pile asteroids can survive
ambient solar system bombardment processes for extremely long periods. Here, we continue our quest tounderstand the bombardment history of Itokawa with the so far seemingly elusive goal of precisely pinpointing
the age and nature of the catastrophic breakup of Itokawa’s parent body. Only through a larger number of40
Ar/39Ar ages on single particles and U/Pb ages on phosphate grains (3) coupled with careful particle
characterizations, will we be able to achieve this goal. With that in mind, we analysed three new particles.
RA-QD02-0300 (dia. = 190 µm) is composed of olivine, plagioclase, with minor troilite. EBSD and ToF-SIMS
analyses show that the plagioclase in this particle is distributed in vein-like structures and has a finepolycrystalline texture of <10 µm grains with abundant inclusions and K-rich exsolutions. This suggests it
represents recrystallised melt domains. Olivine crystals show no sign of shock deformation. We obtained aplateau age of 4130 ± 33 Ma (P = 0.55). Noticeably, this age is very similar to previous results from otherparticles at 4219 ± 35 and 4149 ± 41 Ma (1), indicating an age concentration around that time. Could it be thatthe parent body of Itokawa broke up at ca. 4.2 Ga while some of the impact heated material slowly cooled down
inside the newly formed insulating rubble pile asteroid over ca. 100 million years? This scenario is tantalizing as
it would be similar to the scenario proposed by (4) for the breakup of an initially hot chondritic parent body at
4.5 Ga and with subsequent debris cooling at rates of ca. 1 to 10 °C/Ma inside the rubble pile asteroids.
RA-QD02-0306 (160 µm) is composed of olivine and plagioclase with minor troilite and chromite. This particle
is the only 40Ar/39Ar-dated particle which contains measurable solar wind, with a 38Ar/36Ar ratio of 0.188 ±0.049 (2σ) that is indistinguishable from modern solar wind value. Along with the presence of abundant microcraters, melt drop and blisters observed on the surface of the particle observed by (5), this indicates that thisparticle spent some time directly at the surface of the asteroid. This particle shows a structured 40Ar/39Ar age
spectrum, with two different portions attributed to the gas released by the plagioclase and olivine phases.
Plagioclase yielded a mini-plateau (59 % 39Ar released) age of 4557 ± 61 Ma (P = 0.71) similar to the U-Pb
phosphate age of 4640 ± 360 Ma obtained by (3) on another particle, suggesting that it recorded the initialcooling deep inside Itokawa’s parent asteroid and was not affected by heat during the breakup process. This
demonstrates that, during the breakup of Itokawa’s parent body, part of the asteroid experienced minimum tonegligible shock pressure and temperature increase. This is similar to the conclusions reached via impact
modelling calculated for the rubble pile asteroid Ryugu (6). This is also in excellent agreement with breakup
models of structurally weakened monolith asteroids that do not require a particularly large impactor to shatter(7).
RA-QD02-0311 (108 µm) is composed of olivine, Ca-rich pyroxene, plagioclase and troilite. Elemental maps
show that this particle contains very little plagioclase compared to the other particles and most of the K is
contained in a rim-like structure exposed at the edge of the particle. Olivine crystals show no sign of shock
deformation, yet 40Ar/39Ar dating reveals a complex age spectrum with maximum weighted-mean age of 705 ±53 Ma (P=0.39) including 47% of 39Ar released and indicating an impact ≤ 0.7 Ga. This maximum age, coupledwith an available impact age of 2291 ± 139 Ma (2) and maximum age estimates (1, 8), suggests that impact
events happened many times during the history of Itokawa and that the high porosity of the rubble pile material
was able to convert low-shock events into high temperature spikes, sufficient to reset and/or partially reset the40
Ar/39Ar chronometer (2) in some material.
In summary, we propose that Itokawa’s parent body was disrupted ca. 4.2 billion years ago in a process
involving heterogenous temperature distribution during the impact. Some of the heated material, mixed withcold material, cooled down inside a larger version of Itokawa, possibly over a period of ca. 100 Ma. Itokawa
kept being bombarded and eroded by small impactors since its formation with some of these events recorded by
the 40Ar/39Ar system.
References[1] Jourdan et al. 2023. Proceedings of the National Academy of Sciences 120, e2214353120. [2] Jourdan et al.,2017. Geology 45, 819-822. [3] Terada et al., 2018. Scientific Reports 8, 11806. [4] Lucas et al., 2020. Geochim
Cosmochim Ac 290, 366-390. [5] Matsumoto et al., 2018. Icarus 303, 22-33. [6] Nakamura et al., 2022. Science
379, eabn8671. [7] Michel et al. 2004. Icarus 168, 420-432. [8] Park et al., 2015. Meteoritics and Planetary
Science 50, 2087-2098.

Characterization of a mass movement site in Bennu’s Bralgah Crater and implications for other asteroids
Yuhui Tang1, D.S. Lauretta1, R.-L. Ballouz2, D.N. DellaGiustina1, C.A. Bennett1, D.R. Golish1
1
Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA.
2
The Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA.
Near-Earth asteroids such as Bennu and Ryugu have boulder-covered surfaces and latitude-dependent slope
distributions, signifying that mass movements of boulders perform significant roles in the surface evolution of these small
bodies. The OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, and Security–Regolith Explorer) mission[1] documented numerous locations on Bennu exhibiting evidence of mass movements of surface material, mostly towards thelower elevation equatorial region [2]. One such location, contained within Bralgah Crater, was considered (but not used) by the
mission as a candidate site for sample collection; thus, high-resolution images collected during reconnaissance of this area
allow a more detailed survey than would be possible elsewhere [3] [Fig. 1]. An apparent flow “wake” downhill from a 4.8-mdiameter central boulder in the area, where medium-sized boulders are much less prevalent than in the surrounding terrain,provides an opportunity to investigate the characteristics of mass flow on the asteroid. Through boulder mapping andtopographic analysis, we found evidence of a pileup behind the central boulder, as well as a strong orientational preference ofthe boulders in this area [Fig. 2]. This preferential long-axis orientation exhibits the same westward deflection from theexpected downslope direction that we observed at another mass movement site in Bennu’s northern hemisphere [4], implyingthat a global mechanism with effects mirrored between the northern and southern hemispheres is affecting the mass flows.
We performed dynamical simulations of seismic shaking using the discrete-element N-body code PKDGRAV [5–8]to better constrain the conditions that may have formed the landscape. In these simulations, we used boulder sizes similar to
those surveyed at the Bralgah Crater site and an environment with a similar 4.8-m-diameter central boulder. We were able toreplicate the pileup of material uphill from the central boulder and the wake downhill from it, producing similar elevation
profiles created by a lack of downflowing material in the wake area [Fig. 3].
Simulations also showed a preferential orientation emerging, with a strong possibility for preferential orientation
parallel to direction of motion. Combined with the orientational preference observed in this and other studies of Bennu’s
landscape, this indicates that the Coriolis effect could be a major factor in the mass movement of boulders and would help to
explain the westward deflection of the boulders’ long-axis orientation. Numerical simulations show that the Coriolis effect isstrong enough to induce an east-west displacement of the boulders, which can amount to 10% of the downslope displacement,
which could lead to the observed orientational preferences. This effect would be expected to occur on other fast-spinning
asteroids, such as Ryugu, where this hypothesis predicts a similar orientational preference, with eastward deviation from thepoleward migration of the boulders.

Figure 1. A map of the survey area (magenta outline) within Bralgah Crater, projected in ArcGIS, with the central boulder (long axis, 4.8 m)
highlighted by the light blue best-fit ellipse. The downhill direction is north in this area.

Figure 2. Orientations of the surveyed boulders as a rose diagram (A) and histogram (B), with the data best fitted by a bimodal von Mises
distribution (green) with peaks at 94.1° and 164.2° (p-value = 0.839). (C) The empirical distribution function (black line) and cumulative
distribution function (green line) of the orientations, used for the K-S tests to derive the p-values.

Figure 3. (A) Elevation map of the study site, overlayed with arrows indicating the direction of greatest slope, with the locations of theelevation profiles along longitudes 321°E and 323°E marked in cyan and orange, respectively. (B) The elevation profiles indicated in (A),with the 321°E line profile (cyan) crossing the middle of the central boulder. The blue dashed line represents the best-fit slope of the pileup
area uphill from the central boulder, extrapolated across the entire mass movement length. The extrapolated profile ranges from 0.8 to 1.6 m
above the actual elevation profile downhill from the central boulder, with greater differences further north (downhill). (C) Elevation profile
of simulations after one shaking. The cyan solid line shows elevation along the center of the wake, and the orange dashed-dot line shows theelevation along a parallel transect away from the wake.

References[1] Lauretta, D. S., et al. (2017). OSIRIS-REx: Sample Return from Asteroid (101955) Bennu. Space Science Reviews, 212(1–2), 925–984. https://doi.org/10.1007/s11214-017-0405-1[2] Jawin, E. R., et al. (2020). Global Patterns of Recent Mass Movement on Asteroid (101955) Bennu. Journal of GeophysicalResearch: Planets, 125(9). https://doi.org/10.1029/2020JE006475[3] Lauretta, D. S., et al. (2021). OSIRIS-REx at Bennu: Overcoming challenges to collect a sample of the early Solar System.
In Sample Return Missions (pp. 163–194). Elsevier. https://doi.org/10.1016/B978-0-12-818330-4.00008-2[4] Tang, Y., et al. (2023). Simulating impact-induced shaking as a triggering mechanism for mass movements on Bennu.
Icarus, 395, 115463. https://doi.org/10.1016/j.icarus.2023.115463[5] Ballouz, R.-L. (2017). Numerical Simulations of Granular Physics in the Solar System [Ph.D., University of Maryland,College Park].
[6] Richardson, D. C., Quinn, T., Stadel, J., & Lake, G. (2000). Direct Large-Scale N-Body Simulations of Planetesimal
Dynamics. Icarus, 143(1), 45–59. https://doi.org/10.1006/icar.1999.6243[7] Schwartz, S. R., Richardson, D. C., & Michel, P. (2012). An implementation of the soft-sphere discrete element method ina high-performance parallel gravity tree-code. Granular Matter, 14(3), 363–380. https://doi.org/10.1007/s10035-012-0346-z[8] Zhang, Y., et al. (2017). Creep stability of the proposed AIDA mission target 65803 Didymos: I. Discrete cohesionlessgranular physics model. Icarus, 294, 98–123. https://doi.org/10.1016/j.icarus.2017.04.027

Photometry of Ryugu and SCI crater as inferred by ONC images
A. Longobardo1, M. Angrisani1, E. Palomba1, F. Dirri1, Y. Yokota2, T. Kouyama3, R. Honda4 and the Hayabusa2/ONC
Team
1

INAF-IAPS, via Fosso del Cavaliere 100, 00133 Rome, Italy
JAXA-ISAS, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara City, Kanagawa Prefecture, 252-5210, Japan
3
National Institute of Advanced Industrial Science and Technology, Umezono 1-1-1, Tsukuba, 305-8568, Japan;
4
Kochi, University, Kochi, Japan
2

The JAXA/Hayabusa2 rendezvoused with the Ryugu asteroid from June 2018 to November 2019, performing an
artificial impact experiment on 5th April 2019.
The goal of this work is to study the photometric properties’ variation of the target area (latitude 4.5-10°N; longitude299-305°E) after the artificial impact experiment. This is done by applying an empirical method based on the statisticalanalysis of the ONC camera’s dataset (in particular, the v band, centred at 0.55 m), similar to that applied to several
asteroids (e.g., Longobardo et al., 2014; 2018) and to the NIRS3 dataset of Ryugu (Longobardo et al., 2022).
The method has been firstly applied on the entire dataset acquired between March and April 2019, covering most of the
Ryugu surface. The first step was the retrieval of the equigonal albedo, by applying the Akimov disk function. The
obtained equigonal albedo is independent of incidence and emission angle when phase angle is lower than 60°, while aslight dependence is still present for larger phase angles.
Then, the average phase function of Ryugu was obtained. This is very similar to that obtained on the NIRS3 dataset(i.e., in a different spectral range), according to our expectations.
Then, we calculated two photometric parameters R20 (i.e., the radiance factor at 20° phase) and PCS1540 (i.e., the phasefunction steepness between 15° and 40° phase angles) and compared them to photometric parameters calculated onphase functions of other asteroids visited by space missions and on both disk-integrated and disk-resolved phasefunctions of Ryugu obtained by Tatsumi et al. (2019). The disk-resolved phase functions by Tatsumi et al. (2019) andobtained in this work are in good agreement.
Nevertheless, the Ryugu’s disk-resolved phase function is much flatter than other dark asteroids. Otherwise, the diskintegrated phase function of Ryugu is in good agreement with other dark asteroids. This is the ascribed to the fact thatdark bodies’ phase function flattens with improving spatial resolution due to the reducing role of shadowing. A similar
behaviour was observed on other dark asteroids, i.e., Ceres (Longobardo et al., 2019) and Bennu (Golish et al., 2021).
Finally, we focused the analysis on the artificial impact area by comparing phase curves before and after the impact.
Currently, the only variations observed are within uncertainties, but we need to enlarge the dataset before to give any
definitive conclusion.
Acknowledgements. We thank the ONC development/operations Team.
References
Golish et al. (2021), Icarus 357, 113724
Longobardo et al. (2014), Icarus 240, 20-35
Longobardo et al. (2019), Icarus 320, 97-109
Longobardo et al. (2022), A&A 666, A185
Tatsumi et al. (2019), A&A 639, A83

The shape distributions of sub-mm-sized impact experiment fragments from Allende meteorite
Tatsuhiro Michikami1, Akira Tsuchiyama2,3,4, Axel Hagermann5, and Sunao Hasegawa61

Faculty of Engineering, Kindai University, Hiroshima Campus, 1 Takaya Umenobe, Higashi-Hiroshima, Hiroshima 739-2116,
Japan, (michikami@hiro.kindai.ac.jp), 2Research Organization of Science and Technology, Ritsumeikan University, 1-1-1
Nojihigashi, Kusatsu, Shiga, 525-8577, Japan, 3CAS Key Laboratory of Mineralogy and Metallogeny/Guangdong Provincial
Key Laboratory of Mineral Physics and Materials, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences (CAS),
511 Kehua Street, Wushan, Tianhe District, Guangzhou, 510640, China, 4CAS Center for Excellence in Deep Earth Science,
Guangzhou 510640, China, 5Luleå University of Technology, Space Campus, 981 28 Kiruna, Sweden, 6Institute of Space andAstronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa 252-8510, Japan.
Several spacecraft have shown that kilometer-sized or smaller asteroids, such as Itokawa, Ryugu and Bennu, are covered withregolith particles. The shapes of regolith particles are considered clues to understanding their formation and evolution on asteroid
surface. Ryugu particles are likely fragments resulting from impacts on the asteroid's surface. However, there has been a lack oflaboratory impact experiments specifically examining the shapes of fragments in carbonaceous chondrites, which originate fromcarbonaceous asteroids like Ryugu and Bennu. In this study, we take the first step towards a better understanding of the shapesof impact fragments in carbonaceous chondrites. We conducted an impact experiment on the carbonaceous meteorite Allendeand investigated the shape distributions of sub-mm-sized impact fragments using X-ray microtomography. As a result, weobserved many fragments cross-sections along the chondrule boundary. In addition, these fragments tended to be rounder thanpreviously observed impact fragment shapes. However, because the total number of these fragments is relatively small, theoverall shape distribution of the fragments was found to be the same as that of previous impact fragment shapes. This finding
will be useful for understanding the formation process of regolith layers on the asteroid surface, Itokawa particles, Ryugu
particles, and Bennu particles scheduled to return to Earth.

Spectral characterization of (98943) 2001 CC21, fly-by target of Hayabusa2#
Perna D.1, Barucci M.A.2, Belskaya I.2,3, Birlan M.4,5, Bourdelle de Micas J.1, Dotto E.1, Fornasier S.2, Hasegawa S.6, Ieva S.1,
Inasaridze R.7, Ishiguro M.8, Kitazato K.9, Krugly Yu.3, Kuroda D.10, Mazzotta Epifani E.1, Palomba E.11 and Yoshikawa M.4
INAF – Rome Observatory, Italy. 2LESIA – Observatoire de Paris, France. 3Kharkiv National University, Ukraine. 4IMCCE –Observatoire de Paris, France. 5Astronomical Institute of the Romanian Academy, Romania. 6ISAS-JAXA, Japan. 7E.
Kharadze Georgian National Astrophysical Observatory, Abastumani, Georgia. 8Seoul National University, South Korea.
9
Aizu University, Japan. 10Japan Spaceguard Association, Japan. 11INAF-IAPS, Italy

1

To help solving uncertainties about the surface composition and possible heterogeneity of asteroid (98943) 2001 CC21, next
fly-by target of Hayabusa2#, we acquired new visible and NIR photometric and spectroscopic data.
Visible (BVRI) spectrophotometry was obtained on November 2022 in the framework of the European NEOROCKS project,using the 1.2-m telescope located at the Haute-Provence observatory in France. Details of the observations and data reduction
are given in [1]. The measured colors are within the range of values typical for S-complex. Figure 1 shows a comparison of thespectral behaviors of 2001 CC21 and templates of Sq, Sr, L and K-types according to the Bus-DeMeo classification scheme [2].
Our observations are well consistent with Sq or Sr types and do not support a L-type classification. This result is in agreementwith recently published data on polarimetry and near-infrared spectrometry of this asteroid [3].
On January-February 2023, we also used the 2.6-m NOT telescope (La Palma, Canary Islands, Spain) to acquire visible spectra
and NIR photometry of 2001 CC21 at different rotational phases. These data, currently under reduction, will allow us to further
constrain its surface composition and possible heterogeneity.
On January 22, 2023 we observed 2001 CC21 in R band and covered the whole rotational period (Fig.2). The CCD
observations were carried out using the 0.7-m telescope at the Abastumani Astrophysical Observatory, Georgia. The lightcurve
amplitude is 0.75 mag and Prot ⁓ 5.03 hours.
Preliminary results confirm the S-complex taxonomy, and suggest a subtle spectral variation with the rotational phase. An
overview of our results will be presented and discussed at the Symposium.

Figure 1.

Comparison of 2001 CC21 obtained data with

Figure 2.

Lightcurve obtained on Jan 22, 2023.

different asteroid taxonomic templates [4].

References[1] Hromakina et al. 2021. MNRAS 520:3143. [2] DeMeo F. et al. 2009. Icarus 202:160. [3] Geem J. et al. 2023. MNRAS
525:L17. [4] Barucci at al. 2023. Abstract #2015, ACM 2023.

Asteroid (142) Polana at 3 µm and its Connection to Primitive Near-Earth Asteroids
Driss Takir1
Jacobs, NASA JSC
Introduction: Impacts between asteroid-sized objects have dominated the solar system's history and played a significant rolein forming asteroid families. The New Polana family is a low-inclination and the most prominent low-albedo family within the
inner Main Belt between the v6 secular resonance at ~2.0 AU and the 3:1 mean-motion resonance with Jupiter at ~2.5 AU [1].
This family formed over 2000 Myr ago and is parented by the B-type asteroid (142) Polana [1]. [2] and [3] found that primitivenear-Earth asteroids (NEAs), including Hayabusa2’s asteroid target (162173) Ryugu and OSIRIS-REx’s asteroid target(101955) Bennu, are likely disrupted fragments that originated during the formation of the New Polana family. Other possible
sources of primitive NEAs in the inner Main Belt include the Clarissa, Erigone, Polana, and Sulamitis, families and thecollisionally evolved background asteroids outside these families [2, 4].
The age of the solar system is longer than the collisional lifetime of asteroid Bennu [5], a rubble pile asteroid with amean diameter of 490.06 ± 0.16 m [6] and a spinning top-like shape [7]. Asteroid 142 Polana, the largest remnant of the New
Polana family [1], has been spectrally (~0.5-2.5 µm) and dynamically linked to asteroid Bennu [e.g., 2]. Bennu’s spectra were
measured over the wavelength range from 0.4 to 4.3 µm with OSIRIS-REx Visible and InfraRed Spectrometer (OVIRS) [8].
Here, we investigate the compositional linkage of asteroids Polana and Bennu using 3-µm Polana spectra measured at theInfrared Telescope Facility (IRTF).
1

Results: Polana's prism (0.7- 2.5 µm) spectra
exhibit a broad concave feature centered~1.21 µm with a band depth of ~11%. The
spectrum has a slight positive slope toward
wavelengths greater than 1.2 µm. We
acquired two Prism sets of Polana, the first at
12:32 UTC and the second at 12:48 UTC on
July 2nd, 2023. Spectra of the two prism sets
are similar, showing no compositional
heterogeneity in the observed surface of
Polana. On the other hand, Polana's LXD(1.9– 4.2-µm) spectra do not reveal any
pronounced spectral features in the ~2.0-4.0µm spectral range, suggesting that thisasteroid is not hydrated (Figure 1).
Figure 1. Spectra of asteroids Bennu and Polana. The ~1.2-µm band in Polana is
more pronounced than in Bennu. Bennu’s spectrum is an average
spectrum measured at the 10:00 a.m. station. Unlike Bennu, Polana does not show
a pronounced feature at ~3-µm. Slope-removed spectra are normalized at 2.2 µm.

Discussion: Prism’s spectrum of Polana shows a broad feature centered around 1.2 µm (Figure 1), possibly due to amorphousiron-rich silicates abundant in least-processed CO carbonaceous chondrites that experienced minimal aqueous alteration andthermal metamorphism [10, 11]. Magnetite was also suggested to cause the 1.2-µm feature in B-type asteroids [12]. The 1.2µm feature in the Polana spectrum is much deeper and more pronounced than Bennu's, suggesting that Polana has moreabundant amorphous silicates or magnetite on its surface than Bennu. Polana was previously observed by [13], and its spectra
SNR did not allow the authors to confirm the presence of a feature at ~3-µm. In this work, the LXD spectrum of Polana wasfound to be featureless (does not exhibit a 3-µm feature within two sigma), suggesting that Polana’s surface is much lesshydrated than Bennu’s. Bennu’s spectra were measured by OSIRIS-REx’s OVIRS spectrometer, revealing that this primitive
asteroid is hydrated (the 3-µm band has a depth of ~20%) consistent with CM-, CI-, or CR-type carbonaceous chondrites [9].
In addition, Polana’s LXD spectra do not indicate the presence of organics and/or carbonates, unlike Bennu, whose spectra
were found to be consistent with carbonates dominated by calcite and aromatic and aliphatic organics with CH bonds [14, 15].
The lack of pronounced water (OH/H2O), organic materials, and carbonates features on asteroid Polana could be
related to the degree of heating produced by shock metamorphism during the New Polana family-forming event and the ejecta
reaccretion that contributed to additional heating. To lose most of its surface hydrated minerals, including serpentines, Polana
had to be exposed to impact temperatures higher than ~800 K [16]. Heating generated by disruptive collisions (families
forming events) is substantial, where the temperature of almost all the parent bodies increases from 300 K (initial temperature)
to 700 K [17]. [18] concluded that the hydration state of the members of a collisional family is heterogeneous and mainly
depends on the impact energy level within the family.
Several factors can affect the degree of heating and shock metamorphism during family-forming events, including theimpactor velocity and size, porosity within the asteroid's parent body, and material ejection efficiency. [19] found that in
rubble-pile asteroids, the impactor velocity and size are the main factors responsible for high-grade shock metamorphism in
impacts occurring in the Main Belt. According to these authors, changing the porosity, responsible for the overall energy

absorption within the parent body, from 10% to 30% in their simulations only slightly decreases the shock pressure andtemperature.
Another possibility for explaining the discrepancy between Polana and Bennu in the 3-µm band could be that the New
Polana family-forming event exposed the parent body's deep interior. The dislodged Bennu fragment from the parent bodycontains phyllosilicates, organics, and carbonate, unlike the exposed interior of the parent body that does not include thesematerials.
Laboratory experiments on carbonaceous chondrites have shown that space weathering can also affect the spectral
characteristics of these chondrites [20, 21]. For example, irradiating these carbonaceous chondrites can cause their nearinfrared spectra to become bluer and brighter or redder and darker depending on several factors, including their initial albedo.
Space weathering can also cause the band depth of mineral absorptions at 0.7 and 3.0 µm to decrease receptively by 12 % to50% [22]. Space weathering could cause the band depth at 3.0 µm to degrade significantly over time. The New Polana is oneof the older families in the Main Belt (~2000 Myr, [1]). Near-Earth asteroids’ lifetimes are ~10 Myr [3]; therefore, Bennu
would have been less exposed to space weathering than Polana was.
Exogenic materials and breccias are common in NEAs (e.g., [23]). Exogenous basaltic materials were discovered on
the rubble pile asteroid Bennu, linked to inter-asteroid mixing that occurred at macroscopic scales after the end of theplanetesimal formation [24]. It is possible that exogenic hydrated (in addition to basaltic) materials landed on Bennu,
contributing to its hydration level.
Remote sensing observations of the primitive NEAs Ryugu and Bennu suggested that these two asteroids experienceddifferent aqueous alteration histories, as revealed by the characterization of their surface composition using the 3-µm band.
The NIRS3 instrument on board hayabusa2 detected a weak and narrow absorption feature centered around 2.27 µm across theobserved Ruguy’s surface, attributed to hydroxyl-bearing minerals [25]. Returned samples from Ryugu confirmed that thisasteroid has a similar composition to CI-type carbonaceous chondrites [26]. OSIRIS-REx’s OVIRS detected a broader anddeeper 3-µm band in Bennu compared to NIRS3 observations of Ryugy. Based on their 3-µm hydration features, it is more
likely that Ryugu and Bennu came from different parent bodies with distinct aqueous alteration and thermal histories. With thecurrent ground-based observations of Polana and due to strong Earth atmospheric absorptions that affect the ~2.7-µm region, it
is not feasible to fully assess if this asteroid has a 3-µm band like the narrow and subtle band found in Ryugu. An approved
JWST program to observe Polana (with the NIRSpec and MIRI instruments) will allow us to further investigate Polana's
connection to Bennu and Ryugu.
References: [1] Walsh, K.J et al. 2013. Icarus 225, 283–297. [2] Campins, H. et al. 2010, ApJ, 721, L53. [3] Bottke, W. F etal. 2015, Icarus, 247, 191. [4] Arredondo, A. et al. 2021. Volume 368, 1. Icarus. [5] Bottke, W. F. 2015et al. Icarus 247, 191271. [6] Barnouin, O. S. et al. 2019. Nat.Geosci. 12, 247–252. [7] Lauretta, D. S. et al. 2019 Nature 568, 55–69. [8] Reuter, D.
C. et al. 2018. Space Sci. Rev., pp. 214, 54. [9] Hamilton, V. E et al. 2019, Nat. Astron., 3, 332. [10] Cloutis, E.A. et al.
2012. Icarus 220, 466–486. [11] McAdam, M. and Gustafsson, A. 2021. Icarus 369 (2021) 114592. [12] Yang, B., Jewitt,
D.2010. The Astronomical Journal, 140:692–698. [13] Rivkin, A. S. et al.2022 Planet. Sci. J. 3, 15. [14] Kaplan, H. H. et al.
2020, Science, 370, eabc3557. [15] Kaplan, H.H. et al. 2021. A&A 653, L1. [16] Nakamura, T. Yamato 2016. Earth Planet.
Sci. Lett. 242, 26–38. [17] Davison, T.M et al. 2010. Icarus 208 468–481. [18] Michel, P. 2020. et al. Nature Communications
volume 11, Article number: 2655. [19] Güldemeister et al. 2022. The Planetary Science Journal, 3:198 (12pp). [20] Lantz et al.
2018. Space weathering trends on carbonaceous asteroids: possible explanation for Bennu’s blue slope? Icarus 302, 10–17.
[21] Thompson, M. S. et al. Icarus 319, 499-511. [22] Matsuoka, M.et al. ApJL 890 L23. [23] Bischoff, A. et al. 2010.
Meteorit. Planet. Sci. 45, 1638–1656. [24] DellaGiustina et al. Nature Astronomy, 5, January 2021 | 31–38. [25] Kitazato et al.
2019. Vol 364, Issue 6437 pp. 272-275. [26] Yada et al. 2021. Nature Astronomy volume 6, pages214–220.

Unveiling dark objects in Solar System: grain size effects on the infrared spectrum of mineral
mixtures in presence of opaque components
G. Poggiali1,2, L. Fossi2, A. Wargnier1, J. Beccarelli3, J.B. Brucato2, M.A. Barucci1, P. Beck4, M. Matsuoka5, T. Nakamura6, M.
Pajola3, S. Fornasier1,7, F. Merlin1, A. Doressoundiram1, T. Gautier8 and G. David1
1
LESIA-Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université de Paris Cité, 92195 Meudon
Principal Cedex, France (giovanni.poggiali@obspm.fr)
2
INAF-Astrophysical Observatory of Arcetri, Firenze, Italy3
INAF-Astronomical Observatory of Padova, Padova, Italy
4
Institut de Planétologie et d’Astrophysique de Grenoble, OSUG/CNRS, Grenoble, France
5
The Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan
6
Department of Geophysics, Tohoku University, Sendai Miyagi, Japan
7
Institut Universitaire de France (IUF), 1 rue Descartes, F-75231 Paris Cedex 05, France,
8
LATMOS, CNRS, Sorbonne Université, Université Versailles St-Quentin, Guyancourt, France
Dark surfaces characterize several bodies in the Solar System: from primitive carbonaceous asteroids to the enigmatic surfaceof Phobos and Deimos, our knowledge on the spectroscopic behaviour of low albedo surfaces is still incomplete. A dark
surface can be related to multiple factors, for example presence of opaque material [1] or strong surface alteration [2]. In order
to interpret remote sensing data, laboratory studies remain a pivotal tool to unveil the surface physical state and composition.
Several processes can be simulated in the laboratory, but the preparation and analysis of complex mixing of analog material isone of the most fundamental tool and, at the same time, one of the most complex study when multiple components are used. In
this work, we aim to study how dark material
mixed with basaltic material at different grain sizes
can affect the spectroscopic features from near- to
mid-infrared (1.25-25 µm).
Our sample set includes four series of basaltic mix(feldspar and pyroxene), at different grain sizes
from < 50 µm to 1000 µm, mixed with amorphous
carbon at increasing weight percentages from 1%
to 50%. We analysed several features on the
spectrum of each mineral mixture: (i) near infraredslope; (ii) 2.7 µm OH-stretching band; (iii)
Christiansen features; (iv) Reststrahlen band andTransparency feature. Measurements presented inthis work [3], for the first time take into account alarge wavelength range and point towards a criticaleffect of dark material with a different outcome foreach grain size. Some of the most interesting
results involved the slope and the different
behaviour of the Reststrahlen band. This dataset
will be a good support in the interpretation of
Figure 1. Infrared spectra of basaltic mixtures [BAS] at different grain sizes,
upcoming data from Phobos Martian Moon
<50, 50-200, 200-500 and 500-1000 μm, with addition in different
eXploration mission, as well as in understanding of
proportions,from 1 to 50%, with synthetic amorphous carbon [SAC].
previous data from dark surfaces in the Solar
System like Ryugu and Bennu.
References[1] Cloutis et al 1990, Icarus, 84 (2), 315-333 [2] Hasegawa et al 2022, The Astrophysical Journal Lettes, 939, L9 [3] Poggiali
et al 2023, Astronomy & Astrophysics (submitted)

Investigating the effects of space weathering in Ryugu samples using coordinated microanalyses.

1

L. E. Melendez1, M. S. Thompson1, L. P. Keller2, S. A. Eckley3, and C. J. Snead2
Department of Earth, Atmospheric, and Planetary Sciences, Purdue University, West Lafayette, IN (melendl@purdue.edu)
2
ARES, NASA Johnson Space Center, Houston, TX
3Jacobs, NASA Johnson Space Center, Houston, TX.

Introduction: Airless planetary surfaces are characterized by a distinct lack of an atmosphere or magnetic field, leading todirect exposure to the effects of hypervelocity micrometeoroid impacts and solar wind ion irradiation [1]. These processes,
cumulatively known as space weathering, gradually alter the microstructural and chemical properties of the grains on airlesssurfaces. Signatures of space weathering include vesiculated textures, amorphous grain rims (upper ~100 nm), solar flare
tracks, and Fe-bearing nanoparticles (npFe) [2,3]. The accumulation of these microstructural space weathering characteristics,
particularly the presence of npFe, alters the spectral properties of airless regoliths resulting in changes in spectral slope andreflectance of the surfaces, and the attenuation of characteristic absorption bands in the visible to near-infrared (Vis-NIR)
wavelengths. These spectral changes complicate our ability to accurately interpret the mineralogy of airless bodies via remotesensing spectroscopy [1,4]. Studies of space weathering have primarily focused on anhydrous silicate minerals, reflecting themain components of the available returned samples from the Moon and S-type asteroid Itokawa [3,5,6]. However, ourunderstanding of space weathering of primitive, organic-rich carbonaceous materials is still a work in progress. The Japan
Aerospace Exploration Agency (JAXA)’s Hayabusa2 mission offered the first opportunity to directly investigate carbonaceous
asteroids by returning samples from C-type asteroid (162173) Ryugu. Initial studies of Ryugu samples show mineralogicalsimilarities to CI chondrites along with surface modifications consistent with space weathering. These surface modifications
are primarily in the form of µm-thick silicate melts, amorphized phyllosilicates, glassy spherules, and burst vesicles [3,7]. Here,
we report results from coordinated microanalytical techniques to further our understanding of the mineralogy and space
weathering of carbonaceous materials.
Samples and Methods: We have been allocated two Ryugu particles returned by Hayabusa2; one particle collected at each of
the two touchdown sites (A0152 and C0178). To understand the internal microstructure, mineralogy, and surface morphologyof the two particles, we used X-ray computed tomography (XCT) to scan the samples using the Nikon XTH 320 micro-XCT at
NASA Johnson Space Center (JSC) (Fig. 1). We also completed a higher-resolution sub-volume scan on the Zeiss Xradia 620
Versa at the University of Texas at Austin High Resolution X-ray CT Facility (UTCT) (Fig. 1). We segmented the dataset to
identify different phases (e.g., sulfide minerals) and their spatial distribution using Dragonfly software. Due to the friable
nature of the sample, small fragments were shed from the main mass during sample transport. We transferred <500 µm
fragments of each particle to SEM mounts covered with carbon tape and coated the fragments with evaporated carbon. The
stubs were characterized using the Quanta 3D FEG focused ion beam scanning electron microscope (FIB-SEM) at NASA JSC
using both backscatter (BSE) and secondary electron (SE) imaging detectors along with a 70 mm2 SDD energy dispersive Xray spectroscopy (EDS) detector (Fig. 2).
a

c

1 mm
b

1 mm
d

1 mm

1 mm

Figure 1. XCT scan of grain A0152 (a) and C0178 (b) with a resolution of 2.15 µm per voxel.
Volume renderings with bright (higher relative Z number) phases (i.e., pyrrhotite and magnetite) inyellow for A0152 (c) and C0178 (d).

a

25 µm

b

c

5 µm

5 µm

1 µm

d

e

g

5 µm

30 µm

1 µm

f

Figure 2. (a) Backscattered electron image (BEI) of one of the subparticles from A0152 with Fe1-xS (e.g., pyrrhotite (b)) and characteristic
signatures of space weathering, including (c) melt droplets and (d) vesicular textures. This melt deposit was targeted for further analysis in
the TEM, with electron transparent thin sections prepared using FIB-SEM (e). The BF STEM image from the resulting FIB section (f)shows a region with a sub-µm impact spherule on the surface on top of a darker melt layer. The composite RGB image (g) shows Mg (red),Fe (green), and S (blue), revealing a Mg-rich melt layer and a spherule with nanophase Fe and FeS inclusions.

Particles from chamber A that displayed vesicles or melt textures on their surface (indicators of micrometeoroid bombardment)
were targeted for the preparation of three focused ion beam (FIB) sections for further analysis in the scanning transmission
electron microscope (STEM). Particles from chamber C reflected the expected mineralogy of Ryugu but evidence of space
weathering has not been identified on these grains. Two FIB sections were extracted from the phyllosilicate matrix andmagnetite grains for comparison to the space-weathered regions of A0152. Bright field (BF) and dark field (DF) STEM images
and chemical maps of the FIB sections were acquired using the JEOL 2500SE STEM equipped with a 60 mm2 ultra-thinwindow silicon drift energy-dispersive EDS detector at JSC.
Discussion and Conclusions: XCT results indicate that the grain is a micro-breccia, and that hexagonal sulfide grains (likely
pyrrhotite) are ~10 to ~200 µm wide are distributed throughout the fine-grained phyllosilicate and carbonate-rich matrix.
Magnetite (Fe3O4) particles were also observed in both samples, exhibiting both framboidal and plaquette morphologies. 3D
shape (SPO) and crystallographic (CPO) preferred orientations of sulfides (Fig. 1b) are being analyzed using Blob3D and
3DGrainMapper software, respectively. Currently, surface mesh renderings of A0152 and C0178 are being explored forevidence of impact cratering events, following [8]. SEM analysis of fragments from A0152 revealed vesiculated melt layers
and frothy melt textures with melt spherules with embedded nanoparticles, resembling the deposits observed in simulated
micrometeoroid bombardment [9]. STEM imaging confirmed the presence of Mg-rich phyllosilicates (serpentine and saponite),magnetite with variable morphologies, sulfides, and dolomite, consistent with previous studies of Ryugu samples indicating a
low temperature aqueous alteration history [10, 11]. EDS analyses of these FIB sections of these regions revealed impact
Sulfidespherules and melt layers (up to 200 nm thick) containing abundant nanophase Fe-S and Fe-Ni-sulfides. Many of the
Beads
nanoparticles are polyphasic, as opposed to the monomineralic nanoparticles observed in experimental samples. The melt
layers have varying compositions depending on the underlying grain matrix: phyllosilicate grains have Ni-rich and Fe-poor
melt layers while carbonate grains have Fe-, Mg- and O-rich melt layers. None of the particles analyzed thus far from C0178
exhibit textures characteristic of space weathering, which may be due to the comparatively ‘fresh’ nature of the subsurface
sampling site, but we plan on proposing for additional grains for further analysis. We will continue to analyze these samples tobetter understand the effects of space weathering on carbonaceous
1 regolith in preparation for the analysis of returned samples
from asteroid Bennu by OSIRIS-REx this year.
References[1] Pieters C. M. and Noble S. K. (2016) Journal of Geophysical Research 121(10): 1865–1884. [2] Keller L. P. and McKay D.
S. (1997) Geochimica et Cosmochimica Acta 61:2331–2341. [3] Noguchi T. et al. (2014) Meteoritics & Planetary Science
49:188–214. [4] Chapman C. R. (2004) Annual Review of Earth and Planetary Sciences 32:539–567. [5] Taylor L. A. et al.
(2001) Journal of Geophysical Research: Planets 106:27985–27999. [6] Nakamura, T. et al. (2011) Science 333: 1113–1116.
[7] Matsumoto, T. et al. (2021) Hayabusa Symposium 2021. NIPR.[8] Hamann, C. et al. (2023) 86th Annual Meeting of the
Meteoritical Society Conference Abstract 2692. [9] Thompson M.S. et al. (2019) Icarus 319: 499–511. [10] Matsumoto T. et al.
(2021) Nature Communications 11:1–8. [11] Nakamura T. et al. (2022) Science 379: 6634–6785. [12] Tomioka et al. (2023)
Nature Astronomy 7: 669–677.

Impact-induced melting and fragmentation of C-type asteroid regolith
inferred from impact craters on a large Ryugu sample
C. Hamann1, E. Bonato2, A. Maturilli2, K. Mahlow1, M. Patzschke3, R. Luther1, K. Kurosawa4, G. Alemanno2,
S. Schwinger2, A. Van den Neucker2, M. Baqué2, L. Hecht1,5, A. Greshake1, and J. Helbert2
1
Museum für Naturkunde Berlin, 10115 Berlin, Germany. 2German Aerospace Centre, 12489 Berlin, Germany. 3Bruker Nano
Analytics, 12489 Berlin, Germany. 4Planetary Exploration Research Center, Chiba Institute of Technology, Narashino 2750016, Japan. 5Institute of Geological Sciences, Freie Universität Berlin, 12249 Berlin, Germany.
The surfaces of airless planetary bodies are continually exposed to hypervelocity impacts of micrometeoroids and the influx ofsolar-wind ions as well as electromagnetic radiation emitted from the sun or other galactic sources [1,2]. Over time, theseprocesses gradually alter the morphologies, microstructures, and chemical compositions of regolith grains exposed to space [3–7], which is collectively known as space weathering. Because space weathering alters the optical properties of space-exposed
regolith (e.g., [2]), understanding space weathering of various types of planetary surfaces is critical for interpretation of remotesensing data obtained from such surfaces and for matching various meteorite types to potential parent bodies. However, while
the effects of space weathering on anhydrous regolith materials is well understood on the basis of samples returned from theMoon (e.g., [3,4]) and S-type asteroid Itokawa (e.g., [5–7]), space weathering of hydrous, carbonaceous-chondrite (C-type) likeasteroidal surfaces is poorly understood so far. Samples returned by JAXA’s Hayabusa2 mission from C-type near-Earth asteroid
Ryugu (e.g., [8,9]) allow us to directly study the processes and products of space weathering of C-type asteroid regolith. Previous
studies demonstrated that the uppermost surfaces of regolith grains returned from Ryugu’s surface are amorphous and dehydrated
due to influx of solar-wind ions [10,11]. In addition, small microcraters typically less than 10 µm across and splashes of quenchedmelt—presumably impact melts—have been reported from several Ryugu samples [10,12]. To better understand the role ofmicrometeoroid impacts in space weathering of C-type asteroids, we studied the impact-crater population on Ryugu sample
A0112, which is a large (3.0 × 1.8 mm) regolith grain collected at the first touchdown site from the asteroid’s immediate surface.
Scanning electron microscopy (SEM) at Museum fürNaturkunde Berlin, Germany and Bruker Nano Analytics,
Berlin, Germany as well as X-ray micro-computed
tomography (μCT) at Museum für Naturkunde Berlin
revealed the presence of three large, crater-like
depressions of 150–270 μm diameter as well as of several
smaller, circular pits of between 5 and 20 μm diameter on
one of the surfaces of A0112 (Fig. 1). High-magnification
SEM imaging furthermore revealed the presence of frothy,
highly vesicular materials that are interpreted as quenched
impact melts (cf. [10]) lining the bottoms and walls of thelarge and many of the small crater-like depressions (Fig.
2). Reflectance spectra obtained at German Aerospace
Centre, Berlin, Germany from the frothy material lining
Figure 1. SEM-BSE images of the crater-covered side of A0112 (A) andthe largest crater-like depression are almost featurelessthe largest impact crater surrounded by a spall zone and surface-related,
between 2 and 4 µm (Fig. 3) and resemble those obtained
impact-produced fractures (B).
from the CI chondrite Ivuna heated to 700 °C [13]. Control
spectra obtained from the non-crater-bearing sides of A0112 are consistent with infrared spectra of other Ryugu samples (e.g.,[14]) and showed pronounced spectral features at 2.71 µm and 3.32 and 3.46 µm that correspond to OH-bearing phyllosilicatesand carbonates, respectively. Elemental analysis by energy dispersive X-ray spectroscopy (EDS) and EDS element distribution
maps showed that the frothy materials are quenched silicate–sulfide emulsions, which suggests that the crater-like depressions
and pits are impact craters. Quenched melt splashes up to 300 μm across exist not only on the crater-bearing side of A0112, butalso on an additional side of the sample. These are similar in chemical composition to the frothy layers described recently fromother Ryugu samples [10] and invariably comprise silicate–sulfide emulsions. High-resolution EDS element distribution maps
furthermore suggest that the quenched melts contain immiscible FeNi metal droplets (cf. [11]). In terms of major-element

chemistry,themeltsplashes on A0112 matchfusion crusts around the CI
chondrites Orgueil andAlais [15] and resemble aquenched melt particle oflikely impact-melt origin
Figure 2. SEM-SE image (A) and element distribution map (B) of quenched impact melts lining the bottoms
recently reported fromof the large impact craters on A0112. (C) SEM-BSE image of quenched melt splashes on the surface ofOrgueil [16]. Furthermore,
A0112. A high-magnification element distribution map of the quenched melt splashes is shown in the inset.
μCT scans revealed that thesubsurfaces adjacent to and below the large craters are intensely fractured; in particular, we observed fracture patterns resemblingradial, concentric, and spallation fractures known from impact experiments in the strength regime (e.g., [17] and references
therein). Consistent with lunar microcraters [17], large craters >150 µm are surrounded by irregular spallation zones whereas
small craters <40 µm are almost perfectly bowl-shaped.
While investigations on the impact craters and quenched melts on A0112 are ongoing,
our preliminary results provide information on the nature and magnitude of impactinduced processing of C-type asteroid surfaces in relation to solar wind-induced space
weathering. Sample A0112 appears to be the most intensely shocked Ryugu sample
investigated so far—the majority of smaller Ryugu samples were so far reported to beeither essentially unshocked [18] or only marginally affected by micrometeoroid impacts,with solar wind-derived modifications dominating over impact-induced modifications[10–12]. Our findings of relatively large craters and abundant quenched impact melts on
A0112 suggests that micrometeoroid impacts play an equally important role in space
weathering of C-type asteroid regoliths as solar-wind induced modifications do. Impactinduced fracturing and spallation associated with the large craters on A0112 also informs
on the efficiency of impact-induced fragmentation of grains in C-type asteroid regoliths[19]: Our observations suggest that spallation zones of micrometeoroid impact craters arelikely sources of hydrated carbonaceous micrometeoroids arriving on Earth,contradictory to recent proposals based on unshocked to mildly shocked Ryugu grains[18]. This hypothesis is based on the fact that spall fragments ejected from spall zones
surrounding hypervelocity impact craters are typically unshocked (e.g., [20]), but detailed
numerical models using the iSALE shock physics code are currently being computed toprobe peak pressures and temperatures in the spall zones surrounding the craters on
A0112. If A0112’s microcrater population is representative of Ryugu’s surface, ourresults have relevance for evaluation of the relative roles of thermal [21,22] vs. impacttriggered [17] comminution of, and dust production from, C-type asteroid regolith.
Acknowledgments: We thank JAXA for allocation of Ryugu sample A0112.

Figure 3. Reflectance spectra obtained
from the largest impact crater on A0112(red) compared against a spot far awayfrom the craters (blue). Also shown are
spectra of bulk A particles (green; [14]),
carbonate- and CH-rich spots on
Chamber A particles (light blue; [14]),and heated Ivuna CI chondrite (yellow
and pink; [13]) for comparison.

References[1] Hapke B. 2001. Journal of Geophysical Research Planets 106: 10039–10073. [2] Pieters C. M. and Noble S. K. 2016. Journalof Geophysical Research Planets 121: 1865–1884. [3] Keller L. P. and McKay D. S. 1997. Geochimica et Cosmochimica Acta
64: 2331–2341. [4] Pieters C. M. et al. 2000. Meteoritics & Planetary Science 35: 1101–1107. [5] Noguchi T. et al. 2011. Science
333: 1121–1125. [6] Noguchi T. et al. 2014. Meteoritics & Planetary Science 49: 188–218. [7] Thompson M. S. et al. 2014.
Earth, Planets and Space 66: 89. [8] Yokoyama T. et al. 2023. Science 379: eabn7850. [9] Nakamura T. et al. 2023. Science 379:
eabn8671. [10] Noguchi T. et al. 2023. Nature Astronomy 7: 170–181. [11] Melendez L. E. et al. 2023. Abstract #6286. 86th
Meteoritical Society Meeting. [12] Nakato A. et al. 2023. Earth, Planets and Space 75: 45. [13] Hiroi T. and Pieters C. M. 1996.
Abstract #551. 27th LPSC. [14] Pilorget C. et al. 2022. Nature Astronomy 6: 221–225. [15] Genge M. H. and Grady, M. M. 1999.
Meteoritics & Planetary Science 34: 341–356. [16] Zolensky M. et al. 2022. Meteoritics & Planetary Science 57: 1902–1919.
[17] Hörz F. et al. 2020 Planetary and Space Science 194: 105105. [18] Tomioka N. et al. 2023. Nature Astronomy 7: 669–677.
[19] Flynn, G. J. 2009. Planetary and Space Science 57: 119–126. [20] Melosh H. J. 1984. Icarus 59: 234–260. [21] Delbo M.
et al. 2014. Nature 508: 233–236. [22] Delbo M. et al. 2022 Nature Geoscience 15: 453–457.

Temporal variability of thermal-cycling induced fracturing in chondrites
N. Latsia1, J. Borg1, E. Kaufmann1, M. Granvik1,2 and A. Hagermann11Luleå University of Technology
2
University of Helsinki
Regolith on asteroid surfaces was thought to be a result of micrometeoroid impacts [1], but some recent studies [2,3] claim that
thermal fatigue is the dominant regolith production process on airless bodies. Thermal fatigue is produced by diurnal and/or
annual variations on the surface temperature of asteroids and its efficiency depends on the heliocentric distance, the rotation
period, and the thermal inertia of the asteroid’s surface. A fundamental assumption of previous studies is that thermal fatigue
remains effective over thousands, or even millions, of thermal cycles. However, the Kaiser effect, extensively studied in thefield of fracture mechanics on terrestrial rocks, states that fracturing on materials ceases when previously exerted load levels
are not exceeded [9]. Previous research has demonstrated that the thermal properties of CM2 chondrites depend on theirmineralogy [11]. Thus, the thermal expansion coefficient of each mineral at specific temperature changes can be translated into
different mechanical loads resulting from thermal fatigue.
We aim to observe the time-resolved crack propagation induced by thermal stresses over subsequent thermal load cycles inmeteorites – acting as asteroid analogues – in order to understand the role of thermal fatigue in eroding asteroid surfaces.
According to several studies, Ryugu is similar to CI [5,6,7,8] and CM [8] carbonaceous chondrites, and hence provides groundtruth observations for these samples. We investigate CI, CM, and, for comparison, LL chondrites to examine the behaviour ofthermal fatigue on different petrographic types of meteorites. The samples are subjected to a minimum of 100 cycles at
ΔT=210K as the temperature variation of C-type NEAs is 200K [2]. To identify the spatial occurrence of pre-existing andpropagating cracks, the samples are scanned using X-ray tomography.
We aim to use non-destructive testing (NDT) methods to detect the time and frequency of crack initiation and propagation.
NDT methods are used in many industries to identify and characterize the integrity of a material’s surface and interior without
interfering with its destruction [10]. The Kaiser effect predicts a decrease in the number of produced stresses as the number ofthermal cycles increases, considering that the previous maximum and minimum temperatures of each cycle remain constant at
170Co and -40Co respectively. If the Kaiser effect is applicable, we expect to see the effects of thermal fatigue wane after a few
thermal cycles, suggesting that other mechanisms, such as chemical alteration, are contributing to the breakdown process ofasteroids.
References[1] Housen K.R. et al. 1979. Icarus 39(3) 317-351. [2] Delbo M. et al. 2014. Nature 508(7495) 233-236. [3] Molaro J.L. et al.
2015. JGR Planets 120(2) 255-277. [4] Sakatani N. et al. 2021. Nature Astron 5(8) 766-774. [5] Yokoyama T. et al. 2022.
Science 379(6634) abn7850. [6] Yada et al. 2022. Nature Astron 5(3) 214-220. [7] Kitazato K. et al. 2021. Nature Astron 5(3)246-250. [8] Grott M. et al. 2020. JGR 125(12) e2020JE006519. [9] Kaiser J. 1950. A study of acoustic phenomena in tensile
heat (PhD Thesis). [10] Dwivedi K. S. et al. 2017. Materials Today 5(2) 3690-3698. [11] Opeil C.P. et al. 2020. MAPS 55(8).

CALICO – an ESA M7 proposal to Explore Dwarf Planet Ceres
Axel Hagermann1, Stefan Schröder1 and the CALICO Consortium1Luleå University of Technology
Dwarf planet Ceres was the first member of the asteroid belt to be discovered. It is much richer in water than the other objects
in the asteroid main belt, which suggests an origin elsewhere. Ceres’ surface also shows clear signs of recent, possibly ongoing,
geological activity and is regarded is the closest ocean world to Earth. The ocean worlds of the outer Solar System are of
extreme interest for their potential to support biological activity over geological timescales. Unsurprisingly, the explorationof these enigmatic bodies is one of the priorities of ESA’s Voyage 2050 strategy.
One region on Ceres of particular interest is Occator crater with its bright evaporite deposits, the so-called faculae. Formed by
the extrusion of subsurface liquids, these deposits offer a window into Ceres’ interior. In response to ESA’s call for an M7
mission the international CALICO consortium, led by Luleå University of Technology, proposed CALICO (Ceres
Autonomous Lander Into Crater Occator), a mission that will land in Occator crater and analyse the salt- and organics-rich
deposits of Vinalia Faculae.
CALICO’s science questions cover three themes:
1.
Ceres as an active ocean world2.
Ceres’ potential for habitability
3.
Ceres’ origin and evolution
CALICO will investigate carbon and organic material in the subsurface brine to assess the potential for complex organic
chemistry, it will determine the physicochemical conditions to assess habitability. It will look for the chemical elements
required for the building blocks of life and the elements required for biological energy production.
In order to unravel Ceres’ origin and evolution, CALICO will pay special attention to the role of ammonia in its interior andthe origin of Ceres’ water as well as its magnetic history. CALICO will investigate the links between Ceres, asteroids, comets
and carbonaceous chondrites.
In this talk, the mission concept and science payload of the CALICO mission will be presented, with a brief overview of theevolution and status of the proposal.

Next Generation small body Sample Return mission: a concept study for a future Japanese mission
to a comet
Hiroyuki Kurokawa1, Yuri Shimaki2, Naoya Sakatani2, Ryota Fukai2, Tatsuaki Okada2, Yoko Kebukawa3, Jun Aoki4, Atsushi
Kumamoto5, Taichi Kawamura6, Satoshi Tanaka2, Eri Tatsumi2, Seitaro Urakawa7, Yuichi Tsuda2, Osamu Mori2, Takanao
Saiki2, The Next Generation Small Body Sample Return WG
1
University of Tokyo, 2Japan Aerospace Exploration Agency, 3Tokyo Institute of Technology, 4Osaka University, 5Tohoku
University, 6Université Paris Cité/Institut de Physique du Globe de Paris, CNRS, 7Japan Spaceguard Association

The Next Generation small body Sample Return (NGSR) mission is a future solar-system exploration mission for sample
return from a solar system small body under consideration. In February 2023, we newly launched the Science Working Group(WG) for the NGSR mission. The Science WG studies science goals and mission payloads of the NGSR. In collaboration with
the Engineering WG, the Science WG aims to propose the NGSR as a strategic large-class mission which will be launched in
2030s by ISAS, JAXA. The strategic large-class mission will be selected in late 2024.
The NGSR targets a comet to bring back its subsurface materials and to explore its surface and internal structure. The Science
WG defined the NGSR as a mission to unveil the origin of the solar system, namely, I) the origin of the solar-system“materials” in galactic evolution and II) the origin of the solar-system “bodies” to form planetesimals. For those science goals,
we categorize science objectives as follows: Science objective I-1) unveiling the types of parent stars of the solar-system
materials and their fractions, I-2) elucidating the origins of cometary organic matters, II-1) clarifying whether comets arerubble-pile or a pebble-pile bodies, and II-2) elucidating the formation environment of comets.
Science Goal I can be mainly achieved by sampling and analysis of subsurface materials of the target comet. In contrast to
surficial materials that experienced alteration caused by space weathering and cometary activities, subsurface materials arethought to be pristine record of the original solar-system building blocks and, consequently, of the evolution of materials in ourgalaxy. Excavating and sampling subsurface materials are needed. Moreover, we are planning to install a mass spectrometerfor in situ analysis of volatile materials that will potentially be altered and/or lost before the sample recovery.
Science Goal II can be mainly achieved by physical explorations of the interior structure with a radar and/or seismometer.
Pebble-pile bodies (pristine first-generation of planetesimals) and rubble-pile bodies (disrupted and re-accreted planetesimals)
should have different interior structures; only the latter are thought to possess meter-scale internal voids. The meter-scale
heterogeneity can induce different propagation and reflection patterns for both radio and seismic waves.

Intermediate bodies of Asteroids and the Moon from an Earth 3GMS model
Yasunori MIURA
Department of Earth System Sciences, Faculty of Science, Yamaguchi University

Introduction: Previous formation model of active water planet Earth has been static description of three material states (3MD)from various planetary and Earth sciences, which have been studies in details for more description as public definition fromscientific researched fields to public library and museum for educated words. On the others hands, there are two unsolved itemsof 1) formation of active Earth planet, and 2) formation of inactive Asteroids and the Moon-Mars comparatively in the Earthtype planetary bodies. The main purpose of the paper is to new active Earth formation model called here as Active Three Material
States (A3MS) to be continued to be young products on global and local sites of the planet now [1,2] (Table 1).
Problem and characteristics of the previous 3MD model: The previous 3MD model shows typical merits for the definition ofeach terminology word on educational sites of school, library, book and museum sites, though it shows some demerits for static
description (without previous and future changes in details). This is mainly because planet Earth is not static but so active globallyand locally as complicated phenomena to be changed one direction in wide Universe totally. In fact, we meet difficult spots(totally inactive with old history of primordial ages) to explain the details and comparison of extraterrestrial bodies of many
Asteroids and the Moon and Mars even in neighbor celestial bodied in the Earth-type planetary bodies of the Solar System. We
have to make more detailed figure of active planet Earth from various academic fields of geology, rocky minerals, mixed rocks,
physics-chemistry-biology contently with news sciences of environmental and computer information. It is herewith keeping
unsolved problem for many academic researched fields separated into individual academic fields [3,4].
New model of present S3MS model: It might be difficult to young scientists who study one of many academic fields preciously
for present wide points of academic fields to be explained. However, new wider scientists (even older scientists) fromfundamental Earth sciences (mineral-rock chemistry, micro-observation analyses and wide geological sciences) are possibly
solved totally, where they should be studied also wide planetary fields of planet, physics-chemistry and active shock wave fieldsof quake-volcano-impacts (QVI) processes comparatively [5,6].
Main points of new A3MS model: The present A3MD model shows possible explanation for active process of rocky solid
system of Earth which are activated energy naturally to change rocks from older to newer ages among three material states ofsolid, fluid liquid-to vapor air (SLV), which we can see younger trends of Earth totally. Compared short human life age, the solidof Earth are surely changed with longer times (due to life with light elements from carbon organic molecules with fluid system,compared with rocky system of Earth with longer ages of change comparatively with continued change processes).
Meaning of existences of Atmosphere and Ocean systems on rocks (VLS) to Earth: On primordial period of Earth, naturalactivation energy (QVI) has been started from no ocean system by gravitational quake (tidal) and rocky system to be found threeplanets and the Moon and Asteroids on the Earth-type planetary zone. However present earth site has change to produce, keepin side fluid and solid rock inside as mixture of fluids and vapors for some geological periods to be more active on driedprimordial Earth with huge collisions (i.e. planetary-planetary, and/or multiple asteroids collision, where might be the most big
chance of formation of global ocean mixed fluid system, where characteristic aspects of fluid liquid phases are showing boundaryas image boundaries with irregular round shapes and light molecules with many elements involving between solid (rock) andvapor (air) phases formed as global ocean system on water planet Earth during decreased temperatures and continuous lower
temperature among three material states (VLS) with new formed active phenomena of plate quake and volcano locally to keep
moderate temperature kept in Earth system as moderate complex processes on active Earth now [2-4].
Comparative differences of Earth and other celestial bodies: The present A3MS model can be explained younger planet Earthby natural active phenomena QVI events, which can be shown by major differences between young Earth and other bodies
beyond Earth. The Mineral crystals defined from mall to large sizes with colorful units of Earth can be formed by ocean plate
activities of quake and volcano with interior magmatic melting with irregular but continuous movements under room-temperature
condition of water-Earth, though inactive celestial bodies of Asteroids and the Moon show tiny assemblages of rocks withprimordial ages. Continuous magma melting and metamorphic events are used to be formed final pure and large mineral crystalof quartz SiO2 and CaCO3 calcite carbonates (gem mineral) only water planet Earth. Ocean fluids are water mixed with many
tiny elements from light to heavy metals brought by many asteroid impacts on ocean for longer geological periods, where as insimilar process of mixed rocks to pure mineral crystal the mixed fluid of ocean water can be produces to pure water of rain andunderground water or glacier ice globally as small percentage as pure products on active Earth. Life shows the similar A3MS
assemblages on the rocks of water planet earth corporately as shown in different paper. This suggest comparatively organic life
works can be seen in the complicated and continuous A3MS process discussed in this paper shortly, which it suggests that life
system of organic compounds can be existed and continued the A3MS system on active Earth as we can observed clearly.
Intermediate steps of various Asteroids 1M to the Moon 1M , and Mars 2MS from active planet Earth A3MS: From whole
differences between inactive 1MS (one material state) of Asteroids compared with 2MS (two material states) , the Asteroids
show initial collision aggregates with various grains and rocks of Si-system (mountain rocks), Ca system (ocean rocks) and Fegroup system(heavy iron) with some contents of non-mineral elements of CO(HN)-systems synthesized in organic compounds
on active planet Earth. From active A3MS model, products of non-mineral CHO-system are obtained in continuous and active
planet Earth easily. For inactive Asteroids and the Moon, light element CHO-system groups are easily formed from products
contained carbon elements (cf. steel parts) with impacted sample collections and/or analytical procedures by collision less-shock
wave reactions by electron, ion and laser beam bombardments in analytical cambers are extremely carefully to be interpreted on
the paper [5]. In short, many joined aggregates can be observed in many parts of the Asteroids before forming the Moon or Mars
planet as intermediate solid-aggregated rocks before forming the water planet Earth with other active group of life-A3MS systemgroups [2].

Table.1 Comparison of material states MS of Earth, Asteroid and other extraterrestrial bodies.
Celestial bodies

Mineral or Rocks

Organic Life System

Earth (water planet)

Active three material states (A3MS) system

Non-mineral light elements (CHON) system

Asteroids, the Moon (Mars)

A material state (1MS) Intermediate mixture

Store in solid interior (mixture), Contamination?

Summary: The present work has been summarized as follows.
(1) Active planet model A3MS can be explained on Earth, but others inactive bodies are 3MS on the Solar System.
(2) This model can explain younger rock of Earth and older rocks of other bodies of Asteroids.
(3) New large crystals and life system on Earth and mixed rocks on Asteroids might be explained in the model.
(4) Aggregates observed in the Asteroids before forming the Moon or Mars planet as intermediate solid-aggregated rocks before
forming the water planet Earth with other active groups of life system groups.

References: [1] Miura Y. (2018) IMA-22,1189. [2] Miura Y. (2023) JAMS. E5-15. [3] Wilson J.T. (1965) Nature, 207 (4995),
343-347.

[4] Miura Y. (1996) Shock-Wave Handbook (SV, Tokyo),1073-1209. [5] Miura Y. and Kato T. (1993) AIP, 283, 488-

492. [6] Miura Y. (1992) Celestial Mechanic. & Dynamical Astro. (KA), 54, 249-253.