The identification and characterization of the most pristine physical state of ejecta deposits is a critical first step towards understanding the processes of ejecta emplacement and identifying the…

This is a grant awarded by the National Aeronautics and Space Administration (NASA) to the Connecticut State University System, specifically Central Connecticut State University, to conduct research on characterizing the physical properties and modification of crater ejecta deposits on Mars. The research aims to identify the most pristine ejecta deposits and understand the processes contributing to their erosion and deposition. The grant has a ceiling value of $292,341.34 and a period of performance ending on August 31, 2020. The award is not associated with a set-aside program.

The identification and characterization of the most pristine physical state of ejecta deposits is a critical first step towards understanding the processes of ejecta emplacement and identifying the effects of later modification on these deposits. The majority of martian craters that appear to be morphologically fresh or well-preserved, however, are observed to be modified by deposition and/or erosion processes in meter-scale high-resolution images. We propose to characterize the relationship between meter-scale morphologic and physical properties of both pristine and modified crater ejecta on mars by closely comparing visible morphology and thermophysical (e.g., albedo and thermal inertia) properties. In order to select the most pristine ejecta deposits for characterization, we will first need to identify well-preserved fresh crater deposits. Initially we will examine craters with identifiable RAY systems, as crater rays are often considered to be a hallmark of fresh impacts. Crater rays are thought to form from high velocity primary ejecta, which in turn creates a deposit that is a combination of primary ejecta, dense secondary craters and their overlapping secondary ejecta. The characteristics of these craters will then be compared to other impacts thought to be relatively well-preserved, with the goal of identifying the thermophysical properties and visible morphologies associated with the most well-preserved ejecta deposits. Finally, we would examine the changes in both thermophysical and visible properties of ejecta as they are subjected to later modification. Thermophysical properties of ejecta would be examined using thermal infrared data acquired by the thermal emission imaging system (themis) aboard the mars odyssey spacecraft. These images will be used to better understand the preservation state of ejecta deposits, and thereby potentially constrain 1) which ejecta blankets may represent the least modified and best-representative examples of primary ejecta characteristics, and 2) the types of processes contributing to erosion and/or deposition of crater ejecta. The thermophysical results will be compared with visible morphologies observed at meter to decameter scale in high-resolution images, including those from the high resolution imaging science experiment (hirise) and context imager (CTX), both onboard the mars reconnaissance orbiter spacecraft, as well as narrow angle images from the mars orbiter camera (MOC-NA, mars global surveyor mission) and the high resolution stereo camera (hrsc, mars express spacecraft). These comparisons will allow for a detailed examination of the surface and near-surface physical properties of ejecta deposits, which are the result of both primary impact and secondary modification processes.