Speaker
Description
The interiors of asteroids, that is, their bulk composition and structure, are largely unknown today except for a few special cases. Apart from drilling and radar sounding, both of which are techniques yet to be applied to asteroids, let alone applied to a large number of asteroids, our knowledge of asteroid interiors is based on indirect observations such as rotation rates as well as the compositions of members of asteroid families. In recent years, two destruction mechanisms have been shown to have non-negligible effect on the population of near-Earth asteroids (NEAs). First, asteroids are not falling all the way into the Sun (Farinella et al. 1994) but instead they are destroyed on orbits that bring them relatively close to the Sun (Granvik et al. 2016). The primary mechanism causing the destruction is still to be firmly determined, but one of the leading hypotheses at the moment is that solar irradiation is the main contributing factor, and an asteroid's composition affects the distance at which it is destroyed. Second, tidal disruptions during close and slow encounters with terrestrial planets have been proposed to affect NEAs, but the importance of tidal disruptions on the population level was discovered only recently (Granvik & Walsh 2024). Whereas the susceptibility to a destruction close to the Sun is likely to be primarily determined by an asteroid's bulk composition, the susceptability for tidal disruption is likely to be primarily determined by interior structure of the asteroid. The major benefit compared to all other destruction mechanisms affecting NEAs, apart from collisions with planets, is that the rate of close encounters with both the Sun and the planets can be readily estimated through dynamical simulations. We can thus carry out simulations to predict the rate of asteroid destruction close to the Sun and planets as a function of bulk composition and structure. The resulting effects on the NEA population, in practice changes in orbit, size, and compositional distributions, can then be compared with observations by telescopic surveys. The approach allows for testing different models of asteroid interiors by comparing to observational data obtained by telescopic surveys. I will summarize current and future efforts to understand the details of the destruction mechanisms and to utilize them for constraining the interior characteristics of asteroids including telescopic surveys, population models, laboratory experiments, and space missions.