44th Lunar and Planetary Science Conference (2013) 2015.pdf SOLAR WIND FLUENCE TO THE LUNAR SURFACE. D. M. Hurley1,3, W. M. Farrell2,3, 1JHU Applied Phys- ics Laboratory (
[email protected]), 2NASA Goddard Space Flight Center, 3NASA Lunar Science Institute. Monolayers delivered in one lunation Introduction: The unperturbed solar wind bom- 90 bards the dayside of the Moon with electrons, protons, 60 and heavier ions throughout most of a lunation. Ex- cept when the Moon is in the Earth’s magnetotail for a 30 few days each lunation, the solar wind (shocked solar 0 N. Latitude wind in the magnetosheath, and unshocked solar wind -30 beyond Earth’s bow shock) has access to the dayside -60 surface of the Moon. Investigations of how the solar -90 wind could contribute to the composition and optical 0 90 180 270 360 properties of the lunar surface have a long history (e.g. E. Longitude [1-7]. Yet, it is instructive to revisit this issue and ex- Figure 2. The solar wind proton fluence as a function of amine the solar wind interaction piece by piece. selenographic position is shown in terms of fractions of Delivered Flux: The upper limit on the solar wind an equivalent monolayer of OH. The solid lines neglect thermal effects while the dashed lines include thermal as a potential source of OH can be established by as- effects. suming all of the incident solar wind protons are re- tained in the lunar regolith. The quiescent solar wind is implanted 3He as a resource guide. Fig. 2 shows the variable, but has density, n, of ~5 p+cm-3 and velocity, calculated fluence for one lunation assuming a spheri- v, of ~350 km s-1.