Xiongyao Li | Searcharxiv

arXiv2026

Tianwen-2 target asteroid (469219) Kamo'oalewa probably develops an Itokawa-compositional but ultra-highly space-weathered surface

China's Tianwen-2 mission plans to return samples from a small, rapidly spinning Earth quasi-satellite (469219) Kamo'oalewa. Previous studies linked Kamo'oalewa to lunar composition and origin. Here, we propose another scenario. We reanalyzed the reflectance spectrum of Kamo'oalewa and obtained an absorption band center at 1.001+-0.028 um (error is 1sigma), consistent with LL chondrites. We then conducted space weathering (SW) experiments on meteorites and found that highly space-weathered LL chondrite powder (but not slab) successfully reproduced the reflectance spectrum of Kamo'oalewa. We further traced the dynamical origin of Kamo'oalewa and found that it probably originated from the v6 secular resonance, and more specifically, the Flora family. Kamo'oalewa exhibits a similar composition to Itokawa and 7 objects in the Flora family, but with a higher degree of space weathering. We, therefore, proposed that Kamo'oalewa probably originated from the Flora family and developed an Itokawa-compositional, highly space-weathered, fine-regolith-dominated surface.

astro-ph.EP↗

arXiv2022

Experiments on the Electrostatic Transport of Charged Anorthite Particles under Electron Beam Irradiation

To reveal the effect of secondary electron emission on the charging properties of a surface covered by micron-sized insulating dust particles and the migration characteristics of these particles, for the first time, we used a laser Doppler method to measure the diameters and velocities of micron-sized anorthite particles under electron beam irradiation with an incident energy of 350 eV. Here, anorthite particles are being treated as a proxy for lunar regolith. We experimentally confirm that the vertical transport of anorthite particles is always dominant, although the horizontal transport occurs. In our experiments, some anorthite particles were observed to have large vertical velocities up to 9.74 m~s$^{-1}$ at the measurement point. The upper boundary of the vertical velocities $V_{\rm{z}}$ of these high-speed anorthite particles are well constrained by its diameter $D$, that is, $V_{\rm{z}}^2$ linearly depends on $D^{-2}$. These velocity-diameter data provide strong constraints on the dust charging and transportation mechanisms. The shared charge model could not explain the observed velocity-diameter data. Both the isolated charge model and patched charge model appear to require a large dust charging potential of $-$350 to $-$78 V to reproduce the observed data. The micro-structures of the dusty surface may play an important role in producing this charging potential and in understanding the pulse migration phenomenon observed in our experiment. The presented results and analysis in this paper are helpful for understanding the dust charging and electrostatic transport mechanisms in airless celestial bodies such as the Moon and asteroids in various plasma conditions.

astro-ph.EP↗