Hemispherical differences in the shape and topography of asteroid (101955) Bennu

Area of Science:

• Planetary Science
• Asteroid Geophysics
• Surface Morphology

Background:

• Near-Earth asteroids (NEAs) provide insights into solar system formation.
• Understanding asteroid shapes and surface features is crucial for mission planning and hazard assessment.

Purpose of the Study:

• To construct a high-resolution digital terrain model of asteroid (101955) Bennu.
• To analyze and compare the morphological characteristics of Bennu's northern and southern hemispheres.

Main Methods:

• Utilized laser altimeter data to create a global digital terrain model (DTM) with 20 cm resolution.
• Separately modeled the northern and southern hemispheres to identify distinct geological features and processes.

Main Results:

• Longitudinal ridges in the northern hemisphere extend into the south but are obscured by surface material.
• The southern hemisphere exhibits more large boulders, retaining surface material and suggesting greater subsurface strength.
• The northern hemisphere has fewer large boulders, showing evidence of boulder dynamics and surface flow, resulting in higher slopes and a less regular shape.

Conclusions:

• Bennu's hemispheres display significant morphological differences attributed to boulder distribution and surface processes.
• An initial asymmetric boulder distribution followed by partial disruption likely shaped Bennu's current form, including wedge formation.