Fine-Grained Regolith on the Young Asteroids (1270) Datura and (5026) Martes

Regolith is found on most, if not all, solid planetary surfaces but its formation timescales are uncertain, especially on asteroids. To place constraints on these timescales, we characterised the surface properties of two "young asteroids" with estimated ages of <600 kyr. The two asteroids were observed in the thermal-infrared with the ESO VLT VISIR instrument, and thermal modelling of the data surprisingly found the presence of fine-grained regoliths on both asteroids.