The investigation of lunar farside and nearside space environments

The lunar space environment in the magnetosphere is quite different from that in the solar wind. By using the ARTEMIS and Wind observations, we studied the difference of the lunar space environment in different magnetosphere regions during SEP and non-SEP events. During this time, the Earth's magnetosphere should act as a protective shield for solar wind particles. However, that's not the case. The rover of ChangE-4 from Jan. 2019 to Nov. 2019 has an opportunity to investigate the lunar farside surface environment, when the moon was in the solar wind. First, we have divided the ARTEMIS data into three parts, when the moon was located in plasma sheet (PS), plasma sheet boundary layer (PSBL), and lobe regions from Sep. 2011 to Aug. 2019. The yearly-averaged data shows that the ion fluxes of energies >0.1 MeV at different regions have no evident difference during the non-SEP events. Compared with the PS and PSBL regions, ions with energies >0.1 MeV can be shielded efficiently in the lobe regions during the SEP events. The ion fluxes of energies >0.1 MeV observed during the SEP events are two or three orders of magnitude larger than that observed during the non-SEP events. At the full moon time, the case study shows that the large-scale deflection of the magnetopause was observed and reproduced by ARTMIES probes and MHD simulations on 8 March 2012, exposing the moon to hazardous solar wind particles. The magnetopause deflection is due to the influence of the solar wind Vy, which consistent with the windsock effect. Last, the LND data of ChangE-4 shows that the proton differential flux has no correlation with the solar zenith angle. The proton with higher energy has the higher flux from 9 MeV to 35 MeV, which may be caused by galactic cosmic rays.