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NASA NTRSDate not supplied

Mineralogy and Space Weathering of Fine Fraction Recovered from Asteroid (162173) Ryugu

JAXA Hayabusa2 spacecraft brought back 5.4 g of samples from the near-Earth C-type asteroid (162173) Ryugu to Earth on December6th, 2020 [1]. The returned samples give us a unique opportunity to investigate material from the surface of a C-type asteroid that is expected to record space weathering. Here, we report the mineralogy of fine fraction of the Ryugu grains and a variation of their surface features related to space weathering.

T. Noguchi↗
NASA NTRSDate not supplied

Analysis of Samples from Asteroid Ryugu Returned by Hayabusa2

After returning to Earth in the winter of 2020, the samples from Cb-type asteroid Ryugu were stored under atmosphere-free conditions at the Extraterrestrial Materials Curation Center of ISAS/JAXA, and investigated for basic descriptions (sample imaging, weighing, etc.). They were distributed to six initial analysis teams in Japan in June 2021. The "Stone" team, in charge of analysis of coarse particles (>1 mm in size), conducted a series of analyses using a variety of techniques including reflectance spectra measurement, synchrotron-radiation three-dimensional elemental and mineralogical analysis, bulk elemental analysis using muon beam, Fe valence state measurement by XANES and Mössbauer spectroscopy, detailed mineralogical and petrological characterization by scanning and transmission electron microscopes. Physical and thermal properties of Ryiugu samples were measured to understand the response to shock and heating. In this talk, I would like to introduce summary of analysis results and what comes to be known about the formation and evolution of asteroid Ryugu.

Tomoki Nakamura↗
NASA NTRSDate not supplied

Characteristics of Mineralogy and Space Weathering Observed on the Grains in the Fine Fraction Samples Returned From the C-type Asteroid Ryugu.

Samples returned from near-Earth C-type asteroid Ryugu by the JAXA Hayabusa2 spacecraft have been investigated from June, 2021. Our Min-Pet Fine ("sand") sub-team have investigated mineralogy and petrology and space weathering of grains in the fine fraction of the samples. Space weathering is alteration induced mainly by solar wind irradiation and micrometeoroid impact. Here, we report mineralogy and microstructural and chemical features related to space weathering of Ryugu grains.

Takaaki Noguchi↗
NASA NTRSDate not supplied

Mineralogy and space weathering found in the fine-grained samples returned from the C-type asteroid Ryugu

The JAXA Hayabusa2 spacecraft returned samples from near-Earth C-type asteroid Ryugu. Our Hayabusa2-initial-analysisMin-Pet Fine (“Sand”) team has investigated mineralogy and petrology and space weathering of grains in the fine-grained fraction of the samples. Space weathering is alteration induced mainly by solar wind irradiation and micrometeoroid impact. Here, we report the mineralogy, microstructural, and chemical features related to space weathering of the Ryugu grains.

Takaaki Noguchi↗
NASA NTRSDate not supplied

Analysis of "Stone" Samples from C-Type Asteroid Ryugu

As a part of activities of initial analysis, we analyzed eighteen Ryugu “stone” samples of 1 ~ 8mm in size: seven stones from the 1st touch down site and eleven from the 2nd touch down site. Ryugu stones were analyzed first using X-rays, UV, visible, near-infrared, mid-infrared, and muon probes for surface reflectance spectra, internal 3D structure and element distribution, crystal structures, and bulk composition of light elements such as C, N, and O. Measurements for magnetic, thermal, and physical properties using some stones were also performed. TOF-SIMS analysis of fluid inclusions as being continued. Small particles separated from some stones were analyzed by IR-CT. Based on 3D-CT images of individual stones, objects of interests were identified, separated by pFIB cutting, and exposed by polishing on the surface of epoxy disks. FE-EPMA/FE-SEM analysis was made on ~40 polished epoxy disks for chemical composition and textural observation. FIB sections and small (~15 μm in size) fragments were separated from polished surface and analyzed by TEM, STXM,XRF, and nano-CT.

T. Nakamura↗
NASA NTRSDate not supplied

Presolar C- and O-rich Grains in the Matrix and a Clast in Asteroid Ryugu

Presolar grains formed in the outflows of dying stars and some have been preserved in primitive meteorites, interplanetary dust particles, and comet Wild 2 samples. Presolar silicates are one of the most abundant presolar phases, but are prone to destruction by parent body hydrothermal alteration. Refractory presolar phases, such as oxides and carbides, are more resistant to such alteration. Samples from asteroid Ryugu returned by JAXA’s Haya-busa2 mission show evidence for extensive aqueous alteration. To constrain the abundance of presolar grains in Ryugu, we conducted NanoSIMS isotopic mapping of fragments of a C0002 grain from Chamber C, perhaps from the asteroid sub-surface.

A N Nguyen↗
NASA NTRS2023

Early Fluid Activity on Ryugu Inferred By Oxygen, Carbon, and 53Mn-53Cr Isotopic Analyses of Carbonates and Magnetite

Samples from asteroid Ryugu returned by the Hayabusa2 mission contain evidence of extensive alteration by aqueous fluids and appear related to the CI chondrites. To understand the sources of the fluid and the timing of chemical reactions occurring during the alteration processes, we investigated the oxygen, carbon, and 53Mn-53Cr systematics of carbonate and magnetite in two Ryugu particles. We find that the fluid was initially between 0−20 °C and enriched in 13C, and 17O and 18O, and subsequently evolved towards lighter carbon and oxygen isotopic compositions as alteration proceeded. Carbonate ages show that this fluid-rock interaction took place within the first ~1.8 million years of solar system history, requiring early accretion either in a planetesimal less than ~20 km in diameter or within a larger body which was disrupted and reassembled.

Astromaterials↗
NASA NTRSDate not supplied

Cr-Rich and Al-Rich Oxide Grains With 16O-Rich Compositions in Ryugu Samples

Samples returned from asteroid Ryugu by JAXA’s Hayabusa2 mission are CI-like, with abundant hydrated and secondary phases [1]. Rare anhydrous minerals occur in the matrix of the major lithology and in chemically distinct clasts. Oxygen isotopic analysis of coarse (> 10 µm) anhydrous Mg-rich silicates revealed a bimodal distribution, with some grains having compositions similar to amoeboid olivine aggregates (AOAs) and others having compositions similar to chondrule phenocrysts [2, 3]. We previously analyzed < 2 µm-sized Mg-rich silicates within a clast that also showed a range of O isotopic compositions (δ18O from -38 to +5 ‰) [4]. In this study, we conducted coordinated isotopic and mineralogical analysis of anhydrous oxide grains found in the matrix of Ryugu samples

A. N. Nguyen↗
NASA NTRS2023

Ryugu Asteroid Sample Return Provides A Natural Laboratory for Primordial Chemical Evolution

The samples returned from near-Earth asteroid (162173) Ryugu provide a pristine record of the 4.6 billion years since the birth of the Solar System. The Hayabusa2 initial analysis team has integrated a range of analytical techniques to investigate Ryugu’s organic chemistry. Here, we highlight their latest findings, the potential questions which may be answered, and provide an overview of new prospects in the decade to come.

Asteroids↗
NASA NTRS2023

Soluble Organic Matter Molecular Atlas of Ryugu Reveals Cold Hydrothermalism on C-Type Asteroid Parent Body

The sample from the near-Earth carbonaceous asteroid (162173) Ryugu is analyzed in the context of carbonaceous meteorites soluble organic matter. The analysis of soluble molecules of samples collected by the Hayabusa2 spacecraft shines light on an extremely high molecular diversity on the C-type asteroid. Sequential solvent extracts of increasing polarity of Ryugu samples are analyzed using mass spectrometry with complementary ionization methods and structural information confirmed by nuclear magnetic resonance spectroscopy. Here we show a continuum in the molecular size and polarity, and no organomagnesium molecules are detected, reflecting a low temperature and water-rich environment on the parent body approving earlier mineralogical and chemical data. High abundance of sulfidic and nitrogen rich compounds as well as high abundance of ammonium ions confirm the water processing. Polycyclic aromatic hydrocarbons are also detected in a structural continuum of carbon saturations and oxidations, implying multiple origins of the observed organic complexity, thus involving generic processes such as earlier carbonization and serpentinization with successive low temperature aqueous alteration.

Asteroids, comets and Kuiper belt↗
NASA NTRS2023

Investigating the Effects of Space Weathering in Ryugu Samples Using Coordinated Microanalyses

Airless planetary surfaces are characterized by a distinct lack of an atmosphere or magnetic field, leading to direct 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 airless surfaces. 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 and reflectance 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 remote sensing spectroscopy [1,4]. Studies of space weathering have primarily focused on anhydrous silicate minerals, reflecting the main components of the available returned samples from the Moon and S-type asteroid Itokawa [3,5,6]. However, our understanding 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 mineralogical similarities 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.

L E Melendez↗
NASA NTRS2026

Hermal Evolution of Volatile-Rich Planetesimals: Implications for Lithological Diversity in Ryugu and CI Chondrites

Ryugu samples and CI chondrites record aqueous alteration processes in primitive, volatile-rich planetesimals and exhibit a wide range of lithologies defined by mineral assemblages and alteration degrees as proposed to be types I–VI in [4]. The similarity in lithological diversity and proportions between Ryugu and CIs suggests that they originated from parent bodies with comparable internal structures and thermal histories. However, the mechanism responsible for generating such lithological diversity within a single parent body remains unclear.

S Yamazaki↗
NASA NTRS2017

NASA Curation Preparation for Ryugu Sample Returned by JAXA's Hayabusa2 Mission

The NASA OSIRIS-REx and JAXA Hayabusa2 missions to near-Earth asteroids Bennu and Ryugu share similar mission goals of understanding the origins of primitive, organic-rich asteroids. Under an agreement between JAXA and NASA, there is an on-going and productive collaboration between science teams of Hayabusa2 and OSIRIS-REx missions. Under this agreement, a portion of each of the returned sample masses will be exchanged between the agencies and the scientific results of their study will be shared. NASA’s portion of the returned Hayabusa2 sample, consisting of 10% of the returned mass, will be jointly separated by NASA and JAXA. The sample will be legally and physically transferred to NASA’s dedicated Hayabusa2 curation facility at Johnson Space Center (JSC) no later than one year after the return of the Hayabusa2 sample to Earth (December 2020). The JSC Hayabusa2 curation cleanroom facility design has now been completed. In the same manner, JAXA will receive 0.5% of the total returned OSIRIS-REx sample (minimum required sample to return 60 g, maximum sample return capacity of 2 kg) from the rest of the specimen. No later than one year after the return of the OSIRIS-REx sample to Earth (September 2023), legal, physical, and permanent custody of this sample subset will be transferred to JAXA, and the sample subset will be brought to JAXA’s Extraterrestrial Sample Curation Center (ESCuC) at Institute of Space and Astronautical Science, Sagamihara City Japan.

Nakamura-Messenger, Keiko↗
NASA NTRS2019

Overview of Carbonaceous Chondrites in the US Antarctic Meteorite Collection: Implications for Understanding Bennu and Ryugu

Spectral studies of the target asteroids of the OSIRIS-REx and Hayabusa2 missions - Bennu and Ryugu - have included comparisons to several samples from the US Antarctic meteorite collection including MET 00639 (CM2), MET 01072 (CM2), ALH 83100 (CM1/2), and LAP 02277 (CM1). The fact that these four samples provide insight into understanding these asteroids leads one to wonder what carbonaceous chondrites (CCs) are represented in the US collection and are there others that might also be helpful for comparison? Here is an overview of the CCs in the collection (n=930) and a demonstration of the great diversity of samples available as a resource to these missions.

Righter, K.↗
NASA NTRSDate not supplied

Direct Measurement of the Composition of Aqueous Fluids from the Parent Body of Asteroid 162173 Ryugu

Imaging using X-ray absorption contrast by synchrotron nano-computed tomography (47.4 nm/voxel, 7keV) of a Ryugu pyrrhotite crystal (C0002-FC012-from the second touch-down site) revealed probable fluid inclusions (Fig. 1A,B) [1]. The inclusions were completely encapsuled in pyrrhotite, suggesting the fluids were trapped in the early stages of crystal growth, and filled with low-Z material. We performed Time-of Flight-Secondary Ion Mass Spectrometry (TOF-SIMS) depth profiling and high-resolution map-ping at -120°C to exposure and measure the composition of the trapped fluids in a frozen state.

M Zolensky↗
NASA NTRSDate not supplied

Regolith Processes Revealed by Carbonaceous Chondrites with Implications for Asteroids Ryugu and Bennu, and the Martian Moon Phobos

C-complex asteroids frequently exhibit reflectance spectra consistent with thermally metamorphosed or shocked carbonaceous chondrites and brecciation. Petrographic evidence of impact shock melting and brecciation has been presented for CM and CI chondrites, which we review here as a reminder of what we expect in the returned Ryugu, Bennu and Phobos samples.

Michael Zolensky↗