Assessing the Probability of Extinction-Level Near-Earth Object Impacts Over a Millennium: A Dual-Methodological Approach

The threat of a catastrophic Near-Earth Object (NEO) impact constitutes a well-documented and quantifiable existential risk to terrestrial life. This comprehensive evaluation assesses the probability of an extinction-level or civilization-ending asteroid strike occurring within the next 1,000 years. By synthesizing two distinct and highly complementary analytical paradigms—the probabilistic statistical analysis of geological impact records and the deterministic orbital mechanics derived from modern optical and radar sky surveys—this paper provides an exhaustive and nuanced risk assessment. The deep-time historical record yields a low but demonstrably non-zero baseline probability using Poisson distribution models, highlighting the inevitability of cosmic impacts on a geological timescale. Conversely, current high-precision observational data, compiled and analyzed by institutions such as the Center for Near-Earth Object Studies (CNEOS), reduces the near-term deterministic risk of a known large-scale asteroid impact to effectively zero. However, critical vulnerabilities remain in the architecture of planetary defense, specifically regarding uncatalogued sub-kilometer bodies, long-period comets, and interstellar objects. This report delineates the physical thresholds of impactors, dissects the mathematical frameworks governing both probabilistic and kinematic risk, and evaluates the current and future technological landscape of planetary defense.