Analysis of the Apollo Surface Magnetic Field Data and Lunar Magnetic Field Interactions with Solar Wind

Abstract:

The Apollo 12, 15 and 16 missions included the Lunar Surface Magnetometer (LSM) experiment, and the LSM data collected during 1969 – 1975 will continue to be the major source of lunar surface magnetic field observations before long-duration geophysical stations can be established on the Moon again. In this study, we examine the restored Apollo magnetic field records at the three Apollo sites and compare them with solar wind measurements by Explorer 35 and other concurrent spacecraft. The three Apollo sites have very different levels of crustal magnetization, allowing us to investigate the solar wind interaction with the crustal field with different strengths. We find that the solar wind dynamic pressure is the external parameter that has the strongest control of the measured surface magnetic field, an expected result considering the solar wind compression of the crustal field. At the Apollo 15 site where crustal magnetization is the weakest, the relative direction of the external magnetic field can also be a factor. We also present the estimated crustal magnetic fields at the three Apollo sites when the solar wind effects are removed statistically.