Far-Ultraviolet Observations of Condensed Volatiles at the Lunar South Pole and the Pre-Perihelion Coma of Comet C/2013 A1 (Siding Spring) by Lro-Lamp

Date
2021
Authors
Magana, Lizeth Ofelia
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Abstract

Ultraviolet spectroscopy is a powerful tool in characterizing planetary bodies throughout the Solar System. The Lyman Alpha Mapping Project (LAMP) ultraviolet spectrograph onboard the Lunar Reconnaissance Orbiter (LRO) is uniquely equipped to observe Permanently Shaded Regions (PSRs) on the lunar surface. The dissertation focuses on an analysis of LAMP's nighttime measurements of surface-reflected UV light. We investigate the presence of cold-trapped volatiles within lunar PSRs, focusing on six regions: Faustini, Shoemaker, Haworth, Cabeus, Amundsen, and an unnamed cold trap region, adjacent to Haworth and Shoemaker. We expand upon previous similar LAMP PSR studies by more than doubling the data used in previous analyses and incorporating improved data quality and spectral filtering. We find areas of high Off-band (175 nm - 190 nm) to On-band (148 nm - 162 nm) albedo ratio within cold traps, consistent with the presence of water ice, and observe lower albedos within the cold trap regions than in the surrounding non-cold trap regions across all wavelengths, consistent with previous findings of increased regolith porosity within cold traps. We find further evidence of cold trapped volatiles by examining Off-band/On-band ratios with annual maximum temperature. The next part of the dissertation focuses on LAMP's observations of comet C/2013 A1 (Siding Spring), a long-period comet. The comet coma was imaged from lunar orbit and coma emissions of atomic oxygen were resolved and used to estimate H2O and OH production rates. Upper limits to atomic hydrogen, carbon, and CO abundances were additionally determined. We further place 3-σ limits on the production of CO.

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Keywords
Comet, Lunar, Moon, Oort cloud, Production rate, Volatiles, Lunar reconnaissance orbiter
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Department
Physics and Astronomy