Presentation Information
[PPS04-P23]A Consensus Global Crater Database for Ceres as a Foundation for Chronologic and Geomorphic Investigations
*Rachael Hoover1, Michelle Kirchoff1, Simone Marchi1 (1.Southwest Research Institute Boulder)
Keywords:
Ceres,Impact Craters,Database
Ceres preserves a complex record of impact cratering modified by volatile activity and crustal rheology, yet the timing and mechanisms of these coupled processes remain unresolved. Key questions include the apparent deficit of large craters (Marchi et al., 2016), the extent of viscous relaxation and resurfacing, and the relationships between impacts and localized features such as fractures, pitted terrains, flow-like ejecta, and organic-rich deposits. New constraints on these issues require detailed, internally consistent global and higher resolution regional crater databases capable of supporting both chronology and process-based investigations.
We are creating a consensus global crater database for Ceres using Dawn Low-Altitude Mapping Orbit Framing Camera imagery. The database integrates previously published crater identifications (e.g., Marchi et al., 2016; Hiesinger et al., 2016; Gou et al., 2018; Zielnhofer and Barlow, 2021) with new mapping and standardized measurement protocols. We have completed a global catalog of craters with diameters >=5 km, and ongoing work is extending the catalog toward global completeness for craters >=1 km in diameter. Standardized crater measurements include locations, diameters, morphological classifications, degradation states, and identification confidence. Secondary crater designations are assigned where obvious (i.e., where spatial clustering or chaining is observed). Morphological attributes include crater shape, ejecta characteristics, albedo variations, and interior, rim, and ejecta morphologies, including polygonal crater classifications indicative of near-surface stress fields and crustal structural controls. We are also calculating depth-to-diameter ratios for craters in our database to assess variations in degradation and surface properties across Ceres.
We will present spatial density distributions of craters >=5 km across Ceres to assist in evaluating global resurfacing patterns and regional variations in crater retention. We also compare our comprehensive dataset to previously published datasets and present methods and preliminary results for crater depth measurements using Dawn-derived global topography. In addition, we summarize newly published analysis of higher resolution (diameter >=200 m) regional crater populations around Ernutet to constrain the origin of organic-rich material on Ceres (Kirchoff et al., in press). Crater size-frequency analyses indicate a formation age of ~400-900 Ma, substantially older than estimated survivability timescales for exogenically delivered organics. Volume estimates of the observed organics also exceed plausible delivery by the impactor, supporting an endogenous origin. These results demonstrate the value of integrating crater chronology with morphologic and compositional analyses to evaluate links between impact processes and volatile-rich crustal reservoirs on Ceres.
We are creating a consensus global crater database for Ceres using Dawn Low-Altitude Mapping Orbit Framing Camera imagery. The database integrates previously published crater identifications (e.g., Marchi et al., 2016; Hiesinger et al., 2016; Gou et al., 2018; Zielnhofer and Barlow, 2021) with new mapping and standardized measurement protocols. We have completed a global catalog of craters with diameters >=5 km, and ongoing work is extending the catalog toward global completeness for craters >=1 km in diameter. Standardized crater measurements include locations, diameters, morphological classifications, degradation states, and identification confidence. Secondary crater designations are assigned where obvious (i.e., where spatial clustering or chaining is observed). Morphological attributes include crater shape, ejecta characteristics, albedo variations, and interior, rim, and ejecta morphologies, including polygonal crater classifications indicative of near-surface stress fields and crustal structural controls. We are also calculating depth-to-diameter ratios for craters in our database to assess variations in degradation and surface properties across Ceres.
We will present spatial density distributions of craters >=5 km across Ceres to assist in evaluating global resurfacing patterns and regional variations in crater retention. We also compare our comprehensive dataset to previously published datasets and present methods and preliminary results for crater depth measurements using Dawn-derived global topography. In addition, we summarize newly published analysis of higher resolution (diameter >=200 m) regional crater populations around Ernutet to constrain the origin of organic-rich material on Ceres (Kirchoff et al., in press). Crater size-frequency analyses indicate a formation age of ~400-900 Ma, substantially older than estimated survivability timescales for exogenically delivered organics. Volume estimates of the observed organics also exceed plausible delivery by the impactor, supporting an endogenous origin. These results demonstrate the value of integrating crater chronology with morphologic and compositional analyses to evaluate links between impact processes and volatile-rich crustal reservoirs on Ceres.