Seminar- Dr. Lizeth Magaña (APL) Secrets in the Shadows: A Cross-Instrument Investigation of Lunar Polar Volatiles with LRO

Lunar volatiles provide a record of the delivery, migration, and retention of volatile species within the Earth–Moon system and represent potentially accessible resources for future exploration. Yet, determining the abundance, distribution, and physical state of lunar volatiles remains challenging, particularly within the permanently shadowed regions (PSRs) at the lunar poles. The Lunar Reconnaissance Orbiter (LRO) has provided over 15 years of lunar observations, revealing evidence, with various degrees of confidence, consistent with cold trapped volatiles at the poles. Complementary measurements acquired by LRO’s suite of instruments provide a powerful means of constraining the distribution and physical properties of these volatile deposits. We present UV observations from the Lyman-Alpha Mapping Project (LAMP), radar scattering from the Miniature Radio-Frequency instrument (Mini-RF), and roughness observations from the Lunar Orbiter Laser Altimeter (LOLA) to constrain the lateral and vertical extent and abundance of volatiles within south polar cold traps. We find far-UV band ratios within south polar cold traps are consistent with a small amount of surficial H₂O ice (up to ~5wt%) intimately mixed with regolith as well as increased surface porosity. In contrast, CO₂ and NH₃ ices are not confidently delineated. Further, correlations with surface roughness and volatile hosting potential indicate that surface observations of the topmost ~100 nm may be linked to volatile populations extending into the near subsurface. Indeed, a case study of Amundsen crater finds reduced roughness (50 m and 30-120 m baselines) and increased radar reflectivity at regions where UV observations are consistent with surficial ice. Together, these observations demonstrate the value of a cross-instrument approach for characterizing lunar polar volatiles and provide constraints on their distribution and physical environment within lunar cold traps.