The Interaction Between The Moon And The Earth's Magnetosphere

The Moon is the only Earth's natural satellite,the study of the interaction of the Moon and the Earth's magnetosphere can be used as a baseline to understand other bodies lacking both magnetic field and atmosphere.During most of lunar period,it immerses in the solar wind where is inundated with plasma from the Sun.During the rest of 3-5 days every lunation,the Moon is in the Earth's magnetosphere,in which most of the solar wind particles are shielded.However,the Earth's magnetosphere is not empty,instead occupied by the Earth wind whose ion constituents and energies are different from the solar wind.The particle species in the Earth wind consist of both solar wind and terrestrial species(i.e.,H+,He+,O+,N2+,NO+,O2+),and the range of the particle energy become larger and particle fluxes will be typically several times lower than in which the solar wind.Hence,the Earth's magnetosphere and the Moon interact with each other when the Moon enters into the magnetosphere.In this paper,we will study the interaction between the terrestrial magnetosphere and the Moon,including the influence of the particles from Earth's magnetosphere on the formation of the lunar surface water,the possible association between the lunar phase and the geomagnetic activity.In the first chapter,the comprehensive background information of interaction between the Moon and plasma were introduced,including the plasma interactions with solar system bodies,solid surfaces in space environment,lunar plasma environment according to the study on the interaction between the Moon and solar wind,the interaction between the Moon and the Earth 's magnetosphere,and compare the similarities and differences between the solar wind and the magnetosphere.In the second chapter,our study about the influence of magnetosphere on the lunar surficial water is described.Using the data from the Electrostatic Analyzer(ESA)onboard ARTEMIS satellites,we calculate the average ion energy spectrum and-1 KeV median/inter-quartile values of ion energy flux incident on the Moon for five years to determine the prominent plasma environment boundaries between the solar wind and the Earth's magnetosphere.Furthermore,we use the Moon Mineralogy Mapper(M3)data from January 26,2009 to February 14,2009 to calculate the OH/H2O abundance on the lunar surface.The duration in the Earth's magnetosphere is determined according to the magnetic field and particle data from the MAP-PACE instrument onboard the Kaguya satellite.Then we find that the ion energy flux at 1 KeV(the typical energy of solar wind)reduces about two orders of magnitude when the Moon passes through the Earth's magnetosphere.However,it is found unexpectedly that the surficial OH/H2O abundance at polar regions when in the magnetosphere remains the same level as that in solar wind.Moreover,we calculate the hydrogen loss due to diffusion using analytic approach when the Moon passes through the Earth's magnetosphere and the results show that the hydrogen loss will reach more than 50%.Hence,in addition to the hydrogen atoms implanted by the solar wind and retained in minerals,we suggest that proton flux from the Earth's magnetosphere can also contribute to lunar hydration.In the third chapter,we study the possible association between the lunar phase and the geomagnetic activity.Using ARTEMIS satellite magnetic field intensity and plasma data(density,temperature,etc.),the duration of the Moon in the Earth's magnetosphere can be found,and then determine the relative region of the Earth's magnetosphere using plasma Beta(the ratio between thermal pressure and magnetic pressure)value.We counted and analyzed temporal variation of the index of three intervals near the Moon's orbit respectively,i.e,lobe,plasma sheet and boundary layer.Our results show that there is a certain relationship between geomagnetic activity and lunar phase:geomagnetic activity declines before the full moon and enhances after the full moon,and the occurrence rate of the Moon in the Earth's magnetosphere plasma sheet shows a reverse trend.It indicates the interaction between the Moon and magnetosphere.