Exospheric water and hydroxyl from ladee data and models this proposal will combine datasets from two lunar atmosphere and dust environment explorer (ladee) instruments the neutral mass spectrometer…

This federal contract award to the University of Maryland Baltimore County (UMBC) was granted by the National Aeronautics and Space Administration (NASA) to conduct research on the lunar exosphere. The $261,041.86 grant will combine data from two instruments on the Lunar Atmosphere and Dust Environment Explorer (LADEE) spacecraft to improve understanding of water and hydroxyl signatures on and above the lunar surface. The proposed work will use models of the lunar exosphere and surface to analyze the LADEE data and quantify the amounts of water and hydroxyl. This research is relevant to NASA's Lunar Data Analysis Program, as it addresses priorities around characterizing the lunar exosphere and the distribution of volatiles on the Moon. UMBC has a history of supporting NASA programs through prime contract and grant awards for research, measurement, and analytical services. The University System of Maryland is the parent organization for UMBC.

Exospheric water and hydroxyl from ladee data and models this proposal will combine datasets from two lunar atmosphere and dust environment explorer (ladee) instruments the neutral mass spectrometer (NMS) and the ultraviolet spectrometer (UVS) with models of the exosphere and the thin surficial reservoir that replenishes IT in order to improve our understanding of the water and hydroxyl signatures on and above the moon. Preliminary analyses of ladee data have revealed the presence of water group neutrals in the lunar exosphere. OH and atomic oxygen emission were measured by the ladee UVS, whereas water and OH above instrument background levels were measured by NMS. The proposed data analysis tasks, led by UVS PI colaprete and NMS COI benna, will extend the initial analyses and derive key additional information from ladee data, such as the ratio of H2O/OH in the exosphere, the local time dependence for each species, and whether this atmosphere is spurious or continuously present. The exospheric detections have implications for the amounts of water and hydroxyl on the lunar surface which will be quantified via a multispecies simulator of the lunar exosphere and extreme surface. The simulator adopts microphysical parameters about the interaction of water and hydroxyl with the lunar surface that were derived lately by laboratory experiments on lunar samples led by collaborator t. Orlando. For example, the model considers the different ways with which water interacts with hydrophobic mare soils versus mature highlands soils. The proposed ladee data analyses will provide critical constrains to the exosphere model such as source rates. By comparing numerical experiments from this comprehensive model with ladee data we will understand the mechanisms supporting the water/OH exosphere, the sinks to the solar wind or to the surface, and constrain the abundance range of the hydroxyl and water surficial reservoirs. This investigation is relevant to the ldap program as IT addresses several high priority areas of lunar research outlined in the call, such as 1) characterization of the global variability and structure of the lunar exosphere, and 2) distribution, transport, and characterization of [water] volatiles on the moon. Data analysis and theoretical modeling tasks are approximately equally emphasized. The proposed modeling tasks are absolutely necessary for ladee data interpretation.