The YORP effect for meter-sized asteroids

The spin states of meter-sized asteroids should evolve rapidly due to the Yarkovsky–O’Keefe–Radzievskii–Paddack (YORP) effect. While these asteroids are very challenging to observe, artificial geosynchronous (GEO) satellites are convenient analogues given that they are driven primarily by solar torques, evolve rapidly, and are easy to observe. These artificial objects could provide insight about the evolution of their natural counterparts. Recent studies of YORP for defunct GEO satellites with full and tumbling-averaged models have uncovered rich dynamical structure with tumbling cycles, angular momentum sun-tracking, and tumbling resonances. Applying the tumbling-averaged YORP models to meter-sized pseudo asteroids, we find that the solar torque structure yields sun-tracking precession in many cases, particularly for asteroids with at least some elongation. Precession about the sun line results in the long-term obliquity averaging to roughly 90°. As a result, the sun-tracking behavior could potentially shut off Yarkovsky drift for these asteroids and thereby limit their mobility out of the main asteroid belt. For some asteroid shapes, tumbling cycles with alternating spin up and spin down are also observed. These tumbling cycles offer a possible avenue to prevent spin-driven disruption of meteoroids.