Year: 2025
Type: article
Abstract: On September 5, 2024, at 00:39 China Standard Time (CST), an asteroid named 2024 RW1, approximately 1.2 meters in diameter, entered Earth’s atmosphere and exploded at an altitude of 25 kilometers northeast of the Philippines. The asteroid was detected by the Catalina Sky Survey (CSS) on September 4, 2024, at 5:43 UTC, making it the 9th asteroid successfully predicted to impact Earth in advance. Furthermore, it was the first such asteroid with a predicted impact in Asia. The asteroid’s discovery and rapid follow-up observations led to an estimation of its impact probability exceeding 30%, based on data aggregated by the International Astronomical Union’s Minor Planet Center (MPC). This study employed China’s self-developed System for Hazardous Asteroids Risk Prediction (SHARP) to conduct a comprehensive analysis of the 2024 RW1 event. SHARP incorporates the Imminent Impactor Scenario module (SHARP-IIS), designed specifically for short-term impact prediction. By utilizing real-time observational data from the MPC, SHARP-IIS performs processes such as observational data processing, orbit determination, orbit propagation, and impact prediction. The system’s performance was validated using observational data from the National Aeronautics and Space Administration (NASA), achieving a minimal airburst timing error of just 0.5 seconds and a minimal positional error of less than 20 kilometers, demonstrating its precision and reliability. The initial orbit of 2024 RW1 was calculated using 17 observational data, covering an observation arc of approximately two hours. Due to the short arc, we used the distances of the asteroid relative to the observatory at the initial and final observation times as optimization variables and employed a genetic algorithm to perform initial orbit determination. After that, based on the initial orbit, the least squares algorithm was used for precise orbit determination, generating the orbital elements of the asteroid. Subsequently, considering the gravitational influence of the Earth, Sun, and Moon, as well as the Earth’s non-spherical gravitational effects, orbit propagation was performed using 17, 30, and 42 sets of observational data. The predicted times for the asteroid reaching the atmospheric boundary were 16:30, 16:33, and 16:39, respectively. For impact prediction, the physical properties of the asteroid, such as absolute magnitude, diameter, and density, were inferred or assumed based on observational data. The pancake model was employed to simulate the asteroid’s disintegration process during atmospheric entry. The results show that the disintegration strength has a strong influence on the airburst time and location. When the disintegration strength was assumed to be 15 MPa, the predictions were closest to the monitoring data released by NASA’s Center for Near-Earth Object Studies (CNEOS), with an airburst time error of 0.5 seconds and location error of 18.5 kilometers. The successful prediction of 2024 RW1’s trajectory and impact, completed two hours before the event, highlights the accuracy and precision of SHARP-IIS. The analysis demonstrates the capability of SHARP-IIS in real-time prediction, which is crucial for short-term prediction and threat warning. As the first successful demonstration of its application, this study demonstrates the potential for China’s autonomous systems in planetary defense and emphasizes the necessity of continued improvements to enhance future prediction reliability and adaptability to different scenarios.
DOI: 10.1360/tb-2025-0041
Authors: Jiening Zhao, Shujuan Geng, Kaiduo Wang, Mingtao Li
Language: English
Topic: Astro and Planetary Science
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W4408042314