Assessment of the 2880 impact threat from asteroid (29075) 1950 DA

Abstract: In this paper we perform an assessment of the 2880 Earth impact risk for asteroid (29075) 1950 DA. To obtain reliable predictions we analyze the contribution of the observational dataset and the astrometric treatment, the numerical error in the long-term integration, and the different accelerations acting on the asteroid. The main source of uncertainty is the Yarkovsky effect, which we statistically model starting from 1950 DA's available physical characterization, astrometry, and dynamical properties. Before the release of 2012 radar data, this modeling suggests that 1950 DA has 99% likelihood of being a retrograde rotator. By using a 7-dimensional Monte Carlo sampling we map 1950 DA's uncertainty region to the 2880 close approach b-plane and find a 5 x 10^-4 impact probability. With the recently released 2012 radar observations, the direct rotation is definitely ruled out and the impact probability decreases to 2.5 x 10^-4.