Thermal History and Fragmentation of Ureilitic Asteroids: Insights from the Almahata Sitta Fall

Prior to recovery the Almahata Sitta fall was observed as the asteroid 2008 TC3 on an Earth-bound trajectory, providing a unique link between spectral data and ureilite composition. The event has also provided insight into the nature of ureilitic objects in space. In particular, the large size (4 m3) and low density (2.2 g/cm3) of the object combined with near-complete disintegration upon entry suggest a porous and loosely-consolidated body [1]. Accordingly, recovered fragments are small in size (1.5-283g) and represent several different ureilite lithologies. Some recovered fragments appear brecciated while others do not. We use chemical and mineralogic data to dissect the thermal history of this new ureilite, then use this information to compare the inferred size of fragments within the asteroid to those initially dislodged from a common ureilite parent body (UPB).