arXiv subjects

Yifei Jiao

Publications and source records attributed to Yifei Jiao.

6 recordsLinked to original sources

arXiv2026

The Material Point Method (MPM) for simulating hypervelocity impact on asteroids

Shock-physics numerical codes are essential tools for describing the short but extreme fragmentation stage of the hypervelocity impact process on asteroids. However, accurately representing complex interior structures, surfaces, and contact mechanics in these events remains a significant challenge for traditional hydrocodes. This study introduces and validates an innovative yet underutilized technique, i.e., the Material Point Method (MPM), to simulate hyper-velocity impacts on asteroids. This approach offers new perspectives and solutions for capturing complex interfaces and handling the contact and boundary conditions in asteroid impact simulations. Our MPM implementation incorporates critical improvements to material models, including a pressure-dependent C^1 continuous yield criterion with quantifiable plastic strain, and a resolution-independent Grady-Kipp fragmentation model, to capture the complex physics of geological materials under extreme conditions. The framework is rigorously validated against laboratory impact experiments and benchmarked with smoothed particle hydrodynamics (SPH) simulations, confirming its robustness and precision. Crucially, when applied to asteroid-scale collisions, our model successfully reproduces the formation of large, coherent fragments analogous to (433) Eros. This work establishes MPM as a validated and powerful extension to the planetary scientist's toolkit, enabling the expansion of the parameter space and the treatment of complex contact and boundary conditions, which will enable more realistic simulations of asteroid evolution, family formation, and planetary defense scenarios.

astro-ph.EP↗

arXiv2026

Investigating tidal stripping of a pre-existing moon as the origin of Saturn's young icy rings

The origin of Saturn's rings has been debated for decades. Measurements from Voyager and Cassini have suggested that the rings could be as young as ~100 Myr and composed of nearly pure water ice. Several scenarios have been proposed to explain these properties. One hypothesis (Wisdom et al 2022) is that the rings formed through the recent tidal disruption of a pre-existing moon, Chrysalis, which experienced a close encounter with Saturn following its highly eccentric orbit. However, the mechanism by which this hypothesis would have formed the rings remains largely unexplored, in particular, whether Chrysalis could supply ring material of the desired mass and composition. To address these questions, we perform smoothed particle hydrodynamics simulations to investigate the tidal response of Chrysalis during close encounters with Saturn. Our results demonstrate that preferential tidal stripping of the ice mantle from a differentiated Chrysalis can produce rings with both mass and composition resembling the present rings -- provided that the closest encounter occurs between the parabolic Roche limits for ice ~1.53Rs and rock ~1.07Rs -- consistent with Wisdom et al 2022. Moreover, multiple close encounters can extend the effective disruption limit by spinning up the body, enhancing the tidal stripping efficiency. Following close encounters, the rocky remnant of Chrysalis would have been removed in less than few kyr, either by collision with Saturn or ejection onto a hyperbolic orbit. These findings support the hypothesis that Saturn's rings could originate from a recent lost moon, and imply a highly dynamical evolution of the Saturnian system over the past few hundred million years.

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arXiv2026

Observation Timelines for the Potential Lunar Impact of Asteroid 2024 YR4

The near-Earth asteroid 2024 YR4 -- a $\sim$60 m rocky object that was once considered a potential Earth impactor -- has since been ruled out for Earth but retained a $\sim$4.3% probability of striking the Moon in 2032. Such an impact, with equivalent kinetic energy of $\sim$6.5 Mt TNT, is expected to produce a $\sim$1 km crater on the Moon, and will be the most energetic lunar impact event ever recorded in human history. Despite the associated risk, this scenario offers a rare and valuable scientific opportunity. Using a hybrid framework combining Monte Carlo orbital propagation, smoothed particle hydrodynamics (SPH) impact modeling, and N-body ejecta dynamics, we evaluate the physical outcomes and propose the observation timelines of this rare event. Our results suggest an optical flash of visual magnitude from -2.5 to -3 lasting several minutes directly after the impact, followed by hours of infrared afterglow from $\sim$2000 K molten rock cooling to a few hundred K. The associated seismic energy release would lead to a global-scale lunar reverberation (magnitude $\sim$5.0) that can be detectable by modern seismometers. Furthermore, the impact would eject $\sim$10$^8$ kg of debris that escapes the lunar gravity, with a small fraction reaching Earth to produce a lunar meteor outburst within 100 years. Finally, we integrate these results into a coordinated observation timeline, identifying the best detection windows for ground-based telescopes, lunar orbiters, and surface stations.

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arXiv2025

The Detectability of Lunar-Origin Asteroids in the LSST Era

While most near-Earth asteroids (NEAs) are thought to originate from the main belt, recent discoveries have suggested the existence of a lunar-derived NEA population, such as the asteroids Kamo'oalewa and 2024 PT5. These objects may hold key clues to the dynamical evolution of NEAs and the recent impact history of the Earth-Moon system. However, the population, distribution, and dynamical characteristics of these Lunar-Origin Asteroids (LOAs) remain poorly constrained. By combining the lunar ejecta production with N-body orbital simulations of the ejecta, we investigate their orbital evolution in the past millions of years and the current LOA population, revealing their significant potential for detection by future surveys. Specifically for the Vera C. Rubin Observatory's upcoming Legacy Survey of Space and Time (LSST), we predict an average detection rate of about 6 LOAs (with D > 5 m) per year. Additionally, we find that the LOAs tend to approach from sunward and anti-sunward directions, with encounter velocities significantly lower than those of typical NEAs. These findings offer valuable insights in guiding targeted ground-based surveys and planetary defense efforts for LOAs in the future.

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arXiv2025

Probing the Moon from Future Asteroid Impacts: A Review

The Earth--Moon system has been experiencing impacts from asteroids and comets for billions of years. The Moon, as an airless body, has preserved a distinct record of these events in form of impact craters and ejecta deposits, offering valuable insights into the impact history and surface evolution of the Moon. However, the ancient impact relics can only provide limited information to the lunar interior structure, with an absence of the Moon's immediately dynamic response to the impact events. With human lunar exploration entering an era of sustained presence, e.g., lunar research station and human return, we propose a new concept to probe the lunar subsurface and interior by investigating the future asteroid impacts in real time. This can be achieved by integrating 1) ground- and space-based telescopes, 2) lunar-based seismometers and rovers, and 3) in-situ investigations around the impact sites. A promising opportunity arises with the possible lunar impact of the 60-m-sized asteroid 2024~YR4 in 2032 (impact probability $\sim$4.3\%), an event of once-in-ten-thousand-years rarity. Comprehensive observations of such events would greatly enhance our understanding of the Moon's structure and evolution, and have significant implications for the future lunar resource utilization and planetary defense missions.

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arXiv2024

Asteroid Kamo`oalewa's journey from the lunar Giordano Bruno crater to Earth 1:1 resonance

Among the nearly 30,000 known near-Earth asteroids (NEAs), only tens of them possess Earth co-orbital characteristics with semi-major axes $\sim$1 au. In particular, 469219 Kamo`oalewa (2016 HO3), upcoming target of China's Tianwen-2 asteroid sampling mission, exhibits a meta-stable 1:1 mean-motion resonance with Earth. Intriguingly, recent ground-based observations show that Kamo`oalewa has spectroscopic characteristics similar to space-weathered lunar silicates, hinting at a lunar origin instead of an asteroidal one like the vast majority of NEAs. Here we use numerical simulations to demonstrate that Kamo`oalewa's physical and orbital properties are compatible with a fragment from a crater larger than 10--20 km formed on the Moon in the last few million years. The impact could have ejected sufficiently large fragments into heliocentric orbits, some of which could be transferred to Earth 1:1 resonance and persist today. This leads us to suggest the young lunar crater Giordano Bruno (22 km diameter, 1--10 Ma age) as the most likely source, linking a specific asteroid in space to its source crater on the Moon. The hypothesis will be tested by the Tianwen-2 mission when it returns a sample of Kamo`oalewa. And the upcoming NEO Surveyor mission will possibly help us to identify such a lunar-derived NEA population.

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