[1] Impact craters have been used as a standard metric for a plethora of planetary applications for many decades, including age-dating, geologic mapping and stratigraphic relationships, as tracers for surface processes, and as locations for sampling lower crust and upper mantle material. Utilizing craters for these and other investigations is significantly aided by a uniform catalog of craters across the surface of interest. Consequently, catalogs of craters have been developed for decades for the Moon and other planets. We present a new global catalog of Martian craters statistically complete to diameters D ≥ 1 km. It contains 384,343 craters, and for each crater it lists detailed positional, interior morphologic, ejecta morphologic and morphometric data, and modification state information if it could be determined. In this paper, we detail how the database was created, the different fields assigned, and statistical uncertainties and checks. In our companion paper (Robbins and Hynek, 2012), we discuss the first broad science applications and results of this work.

The Pluto system was recently explored by NASA's New Horizons spacecraft, making closest approach on 14 July 2015. Pluto's surface displays diverse landforms, terrain ages, albedos, colors, and composition gradients. Evidence is found for a water-ice crust, geologically young surface units, surface ice convection, wind streaks, volatile transport, and glacial flow. Pluto's atmosphere is highly extended, with trace hydrocarbons, a global haze layer, and a surface pressure near 10 microbars. Pluto's diverse surface geology and long-term activity raise fundamental questions about how small planets remain active many billions of years after formation. Pluto's large moon Charon displays tectonics and evidence for a heterogeneous crustal composition; its north pole displays puzzling dark terrain. Small satellites Hydra and Nix have higher albedos than expected.

NASA's New Horizons spacecraft has revealed the complex geology of Pluto and Charon. Pluto's encounter hemisphere shows ongoing surface geological activity centered on a vast basin containing a thick layer of volatile ices that appears to be involved in convection and advection, with a crater retention age no greater than ~10 million years. Surrounding terrains show active glacial flow, apparent transport and rotation of large buoyant water-ice crustal blocks, and pitting, the latter likely caused by sublimation erosion and/or collapse. More enigmatic features include tall mounds with central depressions that are conceivably cryovolcanic and ridges with complex bladed textures. Pluto also has ancient cratered terrains up to ~4 billion years old that are extensionally faulted and extensively mantled and perhaps eroded by glacial or other processes. Charon does not appear to be currently active, but experienced major extensional tectonism and resurfacing (probably cryovolcanic) nearly 4 billion years ago. Impact crater populations on Pluto and Charon are not consistent with the steepest impactor size-frequency distributions proposed for the Kuiper belt.

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[1] We have generated a new, 384,343-entry global crater database of Mars, statistically complete for craters with diameters D ≥ 1 km. In this release, the database contains detailed morphologic and morphometric data for craters D ≥ 3 km (future releases will extend these to smaller diameters). With detailed topographic data for the largest crater database to-date, we analyzed crater depth-to-diameter ratios for simple and complex morphologies across various terrains and for the planet as a whole and investigated the simple-to-complex morphology transition. Our results are similar to those in the published literature, but we found a substantial terrain dependence of the simple-to-complex transition that occurs at $11-km-diameter craters at high latitudes. This suggests a model that requires melting of volatiles during high-latitude crater formation that fill the crater during the modification phase but will still support the simple morphology to larger diameters. We also use this database to reexamine previously observed distributions and patterns to show its fidelity and to further explore other global relationships of fresh craters, those with central peaks, pits, and summit pits. We present the global distribution of craters with different types of ejecta and morphometric properties. Overall, this database is shown to be comparable to previous databases where there is overlap and to be useful in extending prior work into new regimes.Citation: Robbins, S. J., and B. M. Hynek (2012), A new global database of Mars impact craters ≥1 km: 2. Global crater properties and regional variations of the simple-to-complex transition diameter,