The Lunar Neon Exosphere Seen in LACE Data

Killen, Rosemary M ; Williams, David R ; Park, Jaekyun ; Tucker, Orenthal J ; Kim, Sang-Joon

关键词: AMBIGUITY;    APOLLO LUNAR SURFACE EXPERIMENTS PACKAGE;    ATMOSPHERIC COMPOSITION;    CALIBRATING;    EXOSPHERE;    LUNAR ATMOSPHERE;    LUNAR COMPOSITION;    LUNAR SURFACE;    MASS SPECTROMETERS;    MONTE CARLO METHOD;    PHOTOIONIZATION;    SOLAR WIND;    SURFACE TEMPERATURE;   

RP-ID  :  GSFC-E-DAA-TN68702

学科分类：天文学(综合)

美国|英语

来源: NASA Technical Reports Server

【 摘 要 】

Using the LACE data from Apollo 17 we have found measured neon densities consistent with the 20Ne surface number densities reported by Cook et al. (2013) for normal conditions, terminator surface densities of 3 (±1.5) × 10(exp 3) per cu.cm. These values are almost an order of magnitude less than those reported by Benna et al. (2015) for CME conditions. Using a Monte Carlo model and assuming the normal solar wind and a photoionization lifetime for Ne of 300 days, our result was more consistent with the Benna (2015) result than our measured result. Two lunations showed an increase in Ne during the night, consistent with the simulation, but two of the lunations showed a decrease in surface number density through the night. We have shown that explaining the Ne distribution is not as simple as assuming dynamic equilibrium with the solar wind and an exosphere accommodated to the local surface temperature.