¹Xiaoying Liu et al. (>10)
Journal of Geophysical Research: Planets (in Press) Link to Article [https://doi.org/10.1029/2026JE009653]
¹Key Laboratory of Planetary Science and Frontier Technology, Chinese Academy of Sciences, Beijing, China
Published by arrangement with John Wiley & Sons

Asteroid impact, playing a key role in shaping the Moon, is a consequence of the orbital dynamical evolution of the Solar System. While the impact flux can be deduced from lunar craters, the impactor populations and their temporal variations remain poorly understood. We analyzed Fe-Ni metals in 40 impact clasts from the Chang’e-6 lunar soils and demonstrated that most of them are asteroidal remnants. The majority of these clasts (27 out of 40) originated from local basalt, where the asteroidal materials were accumulated after basaltic eruption at 2.8 billion years ago (Ga). The remaining 13 clasts are exotic feldspathic materials, delivered from the ancient lunar highlands, preserving asteroid remnants from ∼4.3 Ga to the present. By classifying the asteroid impactors based on the Ni, Co, P, Ir, and Au contents of the metals, we identified distinct impactor populations for the two clast types. All carbonaceous chondrite metals are exclusively found in seven of the basaltic impact clasts, providing robust evidence for a late-stage bombardment by carbonaceous asteroids. The significant increase in carbonaceous impactors can be attributed to orbital dynamical events between 4.3 and 2.8 Ga, including giant planet migration, the Yarkovsky effect, or breakup of large carbonaceous asteroids. These findings, together with the exponentially declining impact flux, imply that only a small proportion of carbonaceous asteroids were delivered to the early Earth-Moon system, and provide further constraints on the dynamical evolution of the Solar System.

¹P. J. Gasda et al. (>10)
Journal of Geophysical Resrach: Planets (in Press) Open Access Link to Article [https://doi.org/10.1029/2025JE009153]
¹Los Alamos National Laboratory, Los Alamos, NM, USA
Published by arrangement with John Wiley & Sons

NASA’s Curiosity rover is exploring a 5 km tall sedimentary mound that is hypothesized to record the transition from a warm and wet (phyllosilicate-rich) to a cold and drier (sulfate-rich) Mars. Evidence of magnesium sulfate-bearing rock has shown that Curiosity has crossed through this phyllosilicate-sulfate transition. Recently, Curiosity arrived at the Amapari Marker Band, a darker, indurated unit that can be traced laterally for tens of kilometers in orbiter images. Here, Curiosity found evidence for a very broad lake, and bedforms interpreted as wave-ripple laminated sedimentary rock that likely was deposited in shallow water in the explored location, before becoming a deeper lake. These rocks are enriched in Fe, Mn, and Zn which has major implications for groundwater paleohydrology in Gale crater. Three formation hypotheses are considered: concretion formation during early diagenetic alteration of shallow lake sediments, laterization or leaching of the sediments, and addition of Fe, Mn, and Zn by a mildly acidic and reducing groundwater interacting with a redox and/or pH front in a stratified lake. The preferred interpretation of the metal enrichments within the Amapari Marker band sedimentary rocks is that they formed in a shallow water environment at a redox and/or pH front within the ripple unit, which drove precipitation and concentration of metals. If the enrichments are due to groundwater alteration, these processes could link subsurface and surface environments. Water and the presence of high amounts of redox sensitive elements and other metals are favorable indicators for habitability.