Trajectory and physical properties of near-Earth asteroid 2009 BD

Abstract

Abstract. We analyze the trajectory of near-Earth asteroid 2009 BD, which is a candidate target of the NASA Asteroid Redirect Mission. The small size of 2009 BD and its Earth-like orbit pose challenges to understanding the dynamical properties of 2009 BD. In particular, nongravitational perturbations, such as solar radiation pressure and the Yarkovsky effect, are essential to match observational data and provide reliable predictions. By using Spitzer Space Telescope IRAC observations and our model for the thermophysical properties and the nongravitational forces acting on 2009 BD we obtain probabilistic derivations of the physical properties of this object. We find two physically possible solutions. The first solution shows 2009 BD as a 2.9 ± 0.3 m diameter rocky body with an extremely high albedo that is covered with regolith-like material, causing it to exhibit a low thermal inertia. The second solution suggests 2009 BD to be a 4 ± 1 m diameter asteroid with albedo 0.45 ± 0.35 that consists of a collection of individual bare rock slabs. We are unable to rule out either solution based on physical reasoning. 2009 BD is the smallest asteroid for which physical properties have been constrained, providing unique information on the physical properties of objects in the size range smaller than 10 m.

Low thermal conductivity of the superfast rotator (499998) 2011 PT

“…Similarly, using thermal infrared observations, we can estimate the thermal inertia of an asteroid using a suitable thermophysical model (see Delbó et al 2015, and references therein). Combining these measurements with the Yarkovsky drift estimation, we can break the degeneracy between thermal inertia and density, and can directly derive the bulk density of the object (Chesley et al 2014;Farnocchia et al 2014;Mommert et al 2014a,b;Rozitis et al 2014;Reddy et al 2016).…”