In the inner asteroid belt, the mean sizes of the high-inclination, non-family asteroids increase with increasing orbital inclination (Dermott et al. 2018). We have shown (Dermott et al. 2020). that this observation is accounted for by Yarkovsky-driven orbital evolution that results in the loss of small asteroids from the inner belt through the escape hatches at the secular resonance and the 3:1 Jovian mean motion resonance. From the observed asteroid size and orbital inclination correlation, we calculate that, on average, over the age of the solar system, the semimajor axes of the asteroids change on a timescale 13.4 Gyr. This Yarkovsky timescale is an upper limit because (a) asteroids experience collisional evolution and thus their current sizes are mostly less than their formation sizes and (b) it is possible that the spin directions of the asteroids have experienced reversals with the result that the sense of orbital evolution, either towards or away from the Sun, has not been constant over the age of the solar system. Here, we analyze the distributions of the sizes and orbital elements of the asteroids trapped in the Martian 1to 2 mean motion resonance. Analysis of these distributions will allow us to separate the rate of orbital evolution due to Yarkovsky forces averaged over the age of the solar system from the current rate of evolution averaged over the past 107 years.
Dermott, S. F., Christou, A. A. & Li, Dan. The common origin of family and non-family asteroids. Nature Astronomy 2, 549-554 (2018).
Dermott, S. F., Li, Dan & Christou, A. A. A new observational constraint on the Yarkovsky-driven mobility of main belt asteroids. ArXiv: 2006.15170 (June 30, 2020).