Bennu surface model - v1.4
Unless otherwise stated, the spacecraft altitude above Bennu is calculated as the distance between the s/c and the sub-spacecraft point.
The sub-spacecraft point is defined as the point where a straight line drawn from the s/c to the center of Bennu intersects the surface of Bennu.
The surface of Bennu is represented by topographic data contained in the "bennu_g_03170mm_spc_obj_0000n00000_v020.bds" DSK file created by the OSIRIS-REx Altimetry Working Group on 2019-01-22 with global coverage at 31.7 meter resolution.
The rotational and ellipsoidal shape constants for asteroid Bennu are obtained from bennu_v14.tpc NAIF's data file.
Unless otherwise stated, this model is used for the calculations up to and including the TAG phase.
Here's an image of the Bennu shape model used to calculate the s/c altitude.
The heatmap shows the distance between a point on the surface of Bennu and the center of Bennu.
The popup label shows the longitude ("x"), the latitude ("y") and the distance ("z") in meters.
Here's the elevation of the Bennu surface above the reference triaxial ellipsoid (see next heatmap).
Here's the reference triaxial ellipsoid with radii: 282.365, 268.05, 249.245 m.