Double Asteroid Redirection Test (DART)
DART Shape (Digital Terrain) Model Bundle

data_derived_dimorphos_model_v004 Collection - Contains version 4.0 of Dimorphos shape model produced using SPC
data_derived_dimorphos_model_v003 Collection - Contains version 3.0 of Dimorphos shape model produced using SPC.
data_derived_didymos_model_v003 Collection - Contains version 3.0 of Didymos shape model produced using SPC
Document Shape Model collection - contains documentation pertaining to the Shape Model data collections

This bundle was created by the DART SOC. This bundle is archived at the Small Bodies Node of the
Planetary Data System. Questions about this bundle may be directed to Dany Waller or
Olivier Barnouin:
Dany.Waller@jhuapl.edu
Olivier.Barnouin@jhuapl.edu

Data Abstract
=============
We provide digital terrain model models and ancillary derived data products of Didymos 
and Dimorphos. These data were produced with imaging collected during the DART impact
with Dimorphos. This collection consists of digital terrain models, surface information 
(elevation relative to a geiod, slope, surface geopotential, surface gravity) and tilt 
maps. These products are accompanied with a definition of these asteroid's coordinate 
system, volume, and dart impact location.

Data Set Overview
=================
The shape of Didymos and Dimorphos is obtained using stereophotoclinometry (SPC; Gaskell 
et al. 2008) SPC combines stereo techniques with photoclinometry to derive the tilt of 
an asteroid’s  surface. This shape modeling technique estimates surface tilts at each 
pixel of a given image by initially using stereo parallax, and a photometric function, 
to constrain a relationship between a surface’s tilt and observed albedo. With this 
relationship in hand, the tilts of a piece of asteroid surface imagined at multiple 
emission and incidence angles can be obtained via least-squares that best duplicates 
the input images. Once the surface tilts are obtained, the geometric height across 
each map can be determined by integrating over the tilts in a logical manner. These
individual terrain maps (called “maplets”) of the surface can then be joined together 
to produce global and local digital terrain models. SPC processing includes the use of 
asteroid limb and terminator data to initially constrain the shape of an asteroid. 

From this model, and estimates of the mass of Didymos and Dimorphos, surface information 
critical to interpret the surface geology and tilt characteristics can be obtained 
(see Barnouin, O.S. et al. 2020). We provide both global and local products. The local 
product is centered on the DART impact site. The coordinate and other attributes for 
Didydmos and Dimorphos are captured in the "DART Coordinate System for Didymos and 
Dimorphos" documents. Users are encouraged to read the DART Shape Model SIS 
for additional information.

References
==========
Gaskell et al. 2008, Characterizing and navigating small bodies with imaging data. 
Meteoritics and Planetary Science 43, 1049–1061. https://doi.org/10.1111/j.1945-5100.2008.tb00692.x
Barnouin, O.S. et al. 2020 Digital terrain mapping by the OSIRIS-REx mission. Planetary and 
Space Science 180, 104764. https://doi.org/10.1016/j.pss.2019.104764
Barnouin, O.S. et al. 2023, DART Coordinate System for Didymos, PDS document. https://doi.org/10.26007/30x0-fv64
Barnouin, O.S. et al. 2023, DART Coordinate System for Dimorphos, PDS Document. https://doi.org/10.26007/7312-sc96
Barnouin, O.S. et al. 2023, DART Shape Model Collection SIS, PDS document. (within https://doi.org/10.26007/rvvf-pn04)