Speakers
- Prof. Valerio Carruba Ph.D. — Universidade Estadual Paulista (Unesp)
- Dr Xin Liu — Nanjing University & Macau University of Science and Technology
Abstract
Two distinct studies are presented. The first investigated the influence of the von Zeipel–Lidov–Kozai (ZLK) mechanism on co-orbital asteroids of terrestrial planets. A survey of known Venus, Earth, and Mars co-orbitals, using orbital integrations and a clone-based statistical approach, identified ZLK states. No pure ZLK states were found for Venus co-orbitals, though 2020 TV10, a Venus co-orbital, poses a potential Earth impact risk. For Earth, 17 new ZLK librators were identified, including 2012 FC71 and 2021 VU12 librating around 0°, and 2008 WM64, 2019 NC1, 2020 DX1, and 2022 UO10 around 180°. Asteroid 2016 CA138 may librate around 270°. These ZLK states provide dynamical protection from close Earth encounters. For Mars, 2017 XG62, a quasi-satellite, is the only known co-orbital librating around 90°, a high-inclination ZLK state that insulates it from encounters with other terrestrial planets. The second study developed an improved method for analyzing collision probability for asteroids detected on too-short observational arcs (TSAs). This approach combines the admissible region method with differential algebra (DA) and automatic domain splitting (ADS) for managing orbital uncertainties. The admissible state region is systematically partitioned, with orbital parameters and close-encounter distances represented by Taylor expansions for continuous, high-precision uncertainty propagation. The method effectively identifies regions of high collision probability and handles abrupt jumps in encounter time. Tests on past impactors like 2019 MO and 2008 TC3 demonstrated accurate impact probability calculations, which converge to nearly 100% with longer observation arcs. This framework offers a systematic and transparent assessment of impact risk for TSAs, proving valuable for imminent impactors with computational times typically ranging from 10 to 60 minutes.
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