The low visible to near-infrared reflectance of the surface of mercury has been attributed in part to the presence of carbon. Most visible and infrared spectrograph (virs) spectra of mercury are…

This is a $207,619.40 grant awarded by the National Aeronautics and Space Administration (NASA) to the University of Hawaii at Manoa to conduct research related to the chemical composition of the surface of Mercury. The research aims to determine the specific forms of carbon present on the planet's surface, including graphite and amorphous carbon, and how these materials change over time due to space weathering. The research will analyze data from the Messenger mission and conduct laboratory experiments to simulate the effects of space weathering. This grant is relevant to NASA's Discovery and Data Analysis Program (DDAP) and the results will help improve understanding of the geology and formation of Mercury. No set-aside designation was mentioned in the award details.

The low visible to near-infrared reflectance of the surface of mercury has been attributed in part to the presence of carbon. Most visible and infrared spectrograph (virs) spectra of mercury are best modeled by including a nanophase carbon component in addition to nanophase iron added to bright, relatively spectral neutral host matrix. In this model of the virs spectra, the average global submicroscopic carbon on the surface of mercury is estimated to be ~1.3 WT%. An analysis of the northern hemisphere of mercury with messenger gamma-RAY spectrometer (GRS) estimates a carbon abundance of ~1.4 WT%. Several studies suggest that a spectral unit called the low-reflectance material (LRM), contains a large abundance of carbon compared to average, presumably in the form of graphite. In several cases, the LRM occurs as ejecta around craters, which indicates a layer of LRM exists underneath the surface. A recent analysis using the neutron spectrometer on messenger found that the LRM has a 1 3 WT% greater abundance of carbon relative to the surrounding area. With time, there is accumulating evidence that the LRM contains of carbon, but the properties of the carbon are unknown. The goals of this proposed study are to determine the potential phases of carbon that are present within the LRM as well as understand how fresh carbon material physically changes with increasing exposure to space weathering. Objectives: the proposed work has 3 main objectives: 1) we will obtain and simulate space weathering on carbon material, such as graphite, in the laboratory to understand the changes in visible to near-infrared spectra of carbon material with increasing exposure to space weathering and to study the space weathering products. 2) we will determine the consistency of the virs spectra of the LRM deposits with various forms of carbon, including both amorphous carbon and graphite, and at both macroscopic and nanophase grain sizes, and contrast these with the properties of background mercury that requires both nanophase iron and carbon to properly fit the visible to near-infrared spectra. The principal aim is to determine if LRM spectra are consistent with exposure of coarse-grained carbon that may in turn have been space weathered. 3) we will determine the variation of LRM units (e.g., composition and grain size). Relevance: this proposed study is relevant to ddap because the proposed work will determine the form of carbon that is present within the LRM and we will use and analyze already publically available virs data from messenger, which was a discovery mission. Determining the form that the carbon exists will be important to understanding the petrology of mercury and also help guide petrologic experiments, as each phase of carbon would provide hints to the environment IT formed in (e.g., temperature and pressure).