Radar astrometry of near-Earth asteroids from the Arecibo Observatory

• Autores: Venditti, F. C. F.; Marshall, S.; Zambrano-Marin, L. F.; Ferrais, M.
• Año de publicación: 2025
• Idioma: inglés
• Tipo de recurso: documento de conferencia
• Materia: Ciencias Astronómicas; Planetary radar; Near-Earth asteroids; Radar astrometry
• Institución: Universidad Nacional de La Plata

The Arecibo Observatory had the world’s most powerful planetary radar system until December 2020, which provided ground-based observations whose quality could only be exceeded with a spacecraft flyby. Radar allows one to characterize near-Earth asteroids (NBAs) in terms of size, shape, spin, and surface properties, and to discover natural satellites that form binary and triple asteroid systems. In addition, radar astrometry is a valuable tool for orbit refinement, providing precise measurements that can significantly improve the accuracy of orbit determination, Every year about 40-60 recently discovered NBAs were observed at Arecibo. Radar offers the great advantage of controlling the properties of the transmitted signal. The changes in the received echo compared to the transmitted signal provides clues about the characteristics of the object. The time de­ lay gives information about the distance to a target with precision as fine as meters, and the Doppler-shifted frequency of the echo provides the radial velocity with precision as fine as mm/s, making it possible to detect even small changes in the orbit due to perturbations, such as the nongravitational acceleration generated by the Yarkovsky effect. Radar astrometry can also quickly eliminate impact false alarms with the improvement of estimates of an asteroid’s orbital elements. Therefore, radar astrometry is crucial for planetary defense. We will present an overview of radar astrometric observations of NBAs obtained using the Arecibo planetary radar system during nearly 60 years of operations and how their orbits were secured after radar observations. Especially for newly discovered objects, that usually have large orbit uncertainties, Doppler and/or range measurements can prevent the object from being lost and requiring re-discovery in the future.
Facultad de Ciencias Astronómicas y Geofísicas