Yarkovsky effect on small near-earth asteroids: Mathematical formulation and examples

The Yarkovsky effect is a subtle nongravitational phenomenon related to the anisotropic thermal emission of Solar System objects. Its importance has been recently demonstrated in relation to the transport of material from the main asteroid belt (both to explain the origin of near-Earth asteroids and some properties of meteorites) and also in relation to the aging processes of the asteroid families. However, unlike the case of the artificial satellites, the Yarkovsky effect has never been measured or detected in the motion of natural bodies in the Solar System. In this paper, we investigate the possibility of detecting the Yarkovsky effect via precise orbit determination of near-Earth asteroids. Such a detection is feasible only with the existence of precise radar astrometry at multiple apparitions. Since the observability of the Yarkovsky perturbation accumulates quadratically with time the time span between radar observations is a critical factor. Though the current data do not clearly indicate the Yarkovsky effect in the motion of these bodies, we predict that the next apparition of several asteroids tin particular, 6489 Golevka, 1620 Geographos, and possibly 1566 Icarus) might reveal its existence. Moreover, we show that the Yarkovsky effect may play a very important role in the orbit determination of small, but still observable, bodies like 1998 KY26. If carefully followed, this body may serve as a superb probe of the Yarkovsky effect in its next close approach to the Earth in June 2024. (C) 2000 Academic Press.