Kecheng Du^a,b et al. (>5)

Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2025.116821]
^aCollege of Surveying and Geo-Informatics, Tongji University, Shanghai, China
^bShanghai Key Laboratory for Planetary Mapping and Remote Sensing for Deep Space Exploration, Tongji University, Shanghai, China
Copyright Elsevier

In January 2019, China’s Chang’e-4 (CE-4) spacecraft successfully landed in Von Kármán crater on the farside of the Moon. During nearly six years of operation until November 2024, the Visible and Near-infrared Image Spectrometer (VNIS) onboard the Yutu-2 rover acquired in-situ spectral data along an approximately 1600 m traverse path, offering critical opportunities to investigate subtle mineralogical variations within the patrol region. In this study, we analyzed these spectral data using a sparse spectral decomposition method with TiO2 constraints to quantitatively estimate the abundances of six lunar minerals, including high‑calcium pyroxene, low-calcium pyroxene, olivine, plagioclase, ilmenite and agglutinate/glass. We further examined the mineralogical properties of regolith and rocks in Yutu-2’s patrol area to identify trends and correlations in compositional variations. By comparing results with Kaguya Multiband Imager data products, we identified a gradual decreasing spatial distribution in plagioclase abundance along the traverse path, likely attributable to ejecta from the Zhinyu crater. Furthermore, analysis of Moon Mineral Mapper (M3) data revealed samples with similar spectral characteristics near Zhinyu crater, supporting this hypothesis. Additionally, the impact of secondary impact craters on local regions was qualitatively and quantitatively assessed using VNIS spectral features and agglutinate/glass abundance. These findings enhance understanding of the complex origin and evolution of materials at the CE-4 landing site region.

Fred Jourdan^a,b,c, Nicholas E. Timms^c, Tomoki Nakamura^d, William D.A. Rickard^b, Celia Mayers^b

Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2025.09.020]
^aWestern Australian Argon Isotope Facility, Curtin University, Australia
^bJohn de Laeter Centre, Curtin University, Australia
^cSpace Science and Technology Centre & School of Earth and Planetary Sciences, Curtin University, Australia
^dLaboratory for Early Solar System Evolution, Department of Earth Science Graduate School of Science, Tohoku University Aoba, Sendai, Miyagi Japan
Copyright Elsevier

Asteroid Itokawa is made of reassembled fragments from a monolithic parent asteroid which got shattered during a collision with a large object. Data are scarce regarding the metamorphic processes that occurred on the monolithic parent body and the age and nature of the catastrophic disruption event. Here, we investigate the timing of the metamorphism inside the parent body of Asteroid Itokawa and the age and nature of the catastrophic breakup event recorded in particles returned from Itokawa. We studied three regolith dust particles recovered by the Hayabusa space craft from the rubble pile asteroid 25,143 Itokawa using electron backscatter diffraction, time-of-flight secondary ion mass spectrometry, and ⁴⁰Ar/³⁹Ar dating techniques. Our results show that none of the particles show noticeable sign of shock metamorphism. Two of the particles yielded ⁴⁰Ar/³⁹Ar age of 4559 ± 61 and 4130 ± 33 million years (Ma), while a third particle returned a maximum error age of 703 ± 53 Ma. When combined with existing data, and diffusion models, these results show that ∼4.5 billion years (Ga) ago, Itokawa’s parent monolithic body cooled down from a peak metamorphism temperature ∼800 °C to ∼300 °C in less than 64 million years at a depth of >20 km. Then at ∼4.22 Ga, Itokawa’s parent body was shattered in a collisional process involving a heterogeneous temperature distribution during the impact, with some regions escaping shock metamorphism and experiencing less than a few hundred degrees Celsius. The fragments re-agglomerated in a larger rubble pile body where they subsequently cooled down over tens of millions of years. For the next 4 billion years, Asteroid Itokawa was regularly impacted and progressively shrunk by mass wasting.