The Shape of Bennu.

The Origins, Spectral Interpretation, Resource Identification, and Security Regolith Explorer (OSIRIS-REx) spacecraft will begin its resolved imaging of Bennu in late October 2018. We will report on the initial global digital terrain model constructed using these approach images (pixel scales ≥ 0.3 m). We will present the global shape, volume, and surface area of the asteroid. Focus will be on the geometric and topographic nature of the object, including insights from overlain images. Preliminary measurements presented will include the topography of a possible equatorial ridge, the sizes and positions of the largest surface mega-clasts and boulders and craters (>1.5 m), and surface roughness at ≥1.0m scale. These observations will provide the geomorphological evidence needed to establish whether or not Bennu is a rubble pile, and provide broad constraints on processes that contributed to the formation and evolution of Bennu. The shape and topographic characteristics of Bennu will be discussed in a wider context through comparisons to Eros, Itokawa, and Ryugu.