The circumlunar environment is a dusty plasma consisting of small particles of lunar regolith, photoelectrons, electrons, and solar wind ions. When moving around the Earth, part of the trajectory of the Moon passes through the Earth's magnetosphere. In addition, the magnetic field is characteristic for some areas on the Moon, the so-called lunar magnetic anomalies. The magnetic field values above these areas can exceed the magnetic field values of the Earth's magnetosphere in the region of the Moon's trajectory by one or two orders of magnitude. The magnetic field and photoelectron density gradients can lead to the development of drift turbulence. The relevant conditions are discussed in this work.

The possible effect is studied of the magnetic field of Earth's magnetotail and the magnetic field in the regions of magnetic anomalies of the Moon on the processes of formation of dusty plasma above the Moon. It is shown that due to the action of the magnetic field in Earth's magnetotail, transfer of charged dust is possible over long distances above Moon's surface. Accordingly, the dusty plasma above the surface of the Moon illuminated by the solar radiation can exist in the entire range of lunar latitudes. The transfer of dust grains over long distances due to the uncompensated magnetic component of Lorenz force is a new qualitative effect that is absent in the absence of magnetic field. The magnetic component of Lorenz force acting on the dust grain from the fields of magnetic anomalies is either lower or comparable to the similar force calculated for the magnetic fields of Earth's magnetotail. However, due to the substantial localization of magnetic anomalies, their effect on the dynamics of charged dust grains above the Moon's surface does not lead to new qualitative effects.

Despite their small scales, lunar crustal magnetic fields are routinely associated with observations of reflected and/or backstreaming populations of solar wind protons. Solar wind proton reflection locally reduces the rate of space weathering of the lunar regolith, depresses local sputtering rates of neutrals into the lunar exosphere, and can trigger electromagnetic waves and small-scale collisionless shocks in the near-lunar space plasma environment. Thus, knowledge of both the magnitude and scattering function of solar wind protons from magnetic anomalies is crucial in understanding a wide variety of planetary phenomena at the Moon. We have compiled 5.5years of ARTEMIS (Acceleration, Reconnection, Turbulence and Electrodynamics of the Moon's Interaction with the Sun) observations of reflected protons at the Moon and used a Liouville tracing method to ascertain each proton's reflection location and scattering angles. We find that solar wind proton reflection is largely correlated with crustal magnetic field strength, with anomalies such as South Pole/Aitken Basin (SPA), Mare Marginis, and Gerasimovich reflecting on average 5-12% of the solar wind flux while the unmagnetized surface reflects between 0.1 and 1% in charged form. We present the scattering function of solar wind protons off of the SPA anomaly, showing that the scattering transitions from isotropic at low solar zenith angles to strongly forward scattering at solar zenith angles near 90 degrees. Such scattering is consistent with simulations that have suggested electrostatic fields as the primary mechanism for solar wind proton reflection from crustal magnetic anomalies.

This paper reports on the Sub-keV Atom Reflecting Analyzer (SARA) experiment that will be flown on the first Indian lunar mission Chandrayaan-1. The SARA is a low energy neutral atom (LENA) imaging mass spectrometer, which will perform remote sensing of the lunar surface via detection of neutral atoms in the. energy range from 10 eV to 3 keV from a 100 kin polar orbit. In this report we present the basic design of the SARA experiment and discuss various scientific issues that will be addressed. The SARA. instrument consists of three major subsystems: a LENA sensor (CENA), a solar wind monitor (SWIM), and a digital processing unit (DPU). SARA will be used to image the solar wind-surface interaction to study primarily the surface composition and surface magnetic anomalies and associated mini-magnetospheres. Studies of lunar exosphere sources and space weathering on the Moon will also be attempted. SARA is the first LENA imaging mass spectrometer of its kind to be flown on a space mission. A replica of SARA is planned to fly to Mercury onboard the BepiColombo mission.