The lunar environment while in the Earth's magnetosphere represents a unique plasma regime, in which we can directly detect the Moon's effects on the ambient plasma environment. To a much greater degree than in the solar wind, the presence of the Moon and its exosphere perturb the ambient plasma environment. We identified and analyzed a variety of different effects of this interaction. We mapped four different interaction signatures and analyzed the solar and solar wind parameters during their occurrence. Confirming previous work, we found that the lunar events investigated in this paper tend to occur above the lunar dayside surface. In addition, we found that magnetospheric activity indices are higher during the categorized lunar events. This suggests that when the terrestrial magnetosphere is more active, as a result of solar wind activity, the terrestrial magnetospheric plasma and electromagnetic fields interact with lunar plasma to create the observed perturbations. (C) 2021 COSPAR. Published by Elsevier B.V. All rights reserved.

In order to study the plasma convection in the deep magnetotail lobes near lunar orbit, we investigated ions originating from the tenuous exosphere and surface of the Moon, which are measured by the Acceleration, Reconnection, Turbulence, and Electrodynamics of Moon's Interaction with the Sun (ARTEMIS) spacecraft. Directly measuring the plasma convection in the tail lobes is difficult, due to the typically large positive spacecraft potential. In this work we show that in the terrestrial magnetotail near the Moon, the convection velocity can be estimated by measuring the velocity of lunar ions. Determining what factors control the lobe convection is important in understanding the linkage between the upstream conditions and the dynamics of the tail lobes. Based on systematic analysis of multiple ARTEMIS observations and OMNI data, we find that the interplanetary magnetic field (IMF) and magnetospheric activity plays an important role in controlling plasma convection in the near-Moon lobes.

In order to study the acceleration of ions originating from the tenuous exosphere and surface of the Moon, we analyzed data from the ElectroStatic Analyzer (ESA) and Flux Gate Magnetometer (FGM) carried by the Acceleration, Reconnection, Turbulence, and Electrodynamics of Moon's Interaction with the Sun (ARTEMIS) spacecraft. Previous investigations have modeled the acceleration of lunar ions by the motional electric field of the surrounding plasma. However, in the terrestrial magnetotail, where the lunar ion density can equal or even exceed the ambient plasma density, other forces may play an important role in the tenuous plasma environment. Determining what forces govern lunar ion motion is important in understanding their interaction with the ambient plasma in the unique environment of the magnetotail. Based on a detailed analysis of two individual ARTEMIS observations, we find that magnetic pressure and magnetic tension forces may play an important role in accelerating the lunar ions.

The Acceleration, Reconnection, Turbulence, and Electrodynamics of the Moon's Interaction with the Sun (ARTEMIS) spacecraft observes outflowing molecular ionospheric ions at lunar distances in the terrestrial magnetotail. The heavy ion fluxes are observed during geomagnetically disturbed times and consist of mainly molecular species ( N2+, NO+, and O2+, approximately masses 28-32amu) on the order of 10(5)-10(6)cm(-2)s(-1) at nearly identical velocities as concurrently present protons. By performing backward particle tracing in time-dependent electromagnetic fields from the magnetohydrodynamic Open Global Geospace Circulation Model of the terrestrial magnetosphere, we show that the ions escape the inner magnetosphere through magnetopause shadowing near noon and are subsequently accelerated to common velocities down the low-latitude boundary layer to lunar distances. At the Moon, the observed molecular ion outflow can sputter significant fluxes of neutral species into the lunar exosphere while also delivering nitrogen and oxygen to the lunar volatile inventory.

Observations of heavy ions of lunar origin give important information regarding lunar exospheric processes, especially with respect to exospheric particle abundance and composition. Electrostatic analyzers without a time-of-flight provide highly sensitive, absolute density detection but without mass discrimination. Here we place constraints on lunar ion species through inference of the average ion mass using such instruments. The technique is based on the plasma quasi-neutrality requirement, an independent electron density measurement, and the fact that electrostatic analyzers underestimate the ion density by the square root of the ion mass. Applied to a case of such observations by ARTEMIS in the terrestrial lobe reported by Poppe et al. (2012), our technique suggests an average mass of 28 amu for lunar pickup ions. This result, consistent with the lower limit of 24 amu derived in the Poppe et al. model, suggests that the observed ions were most likely Al+ and Si+. The technique is also refined and applied to a more complicated event with a series of heavy ion surges in the plasma sheet, to show the spatial and/or temporal dependence of the observed lunar ion species. The technique is particularly timely given the planned conjunctions and coordinated lunar studies by NASA's Acceleration, Reconnection, Turbulence and Electrodynamics of the Moon's Interaction with the Sun (ARTEMIS) and Lunar Atmosphere and Dust Environment Explorer missions.

We use Acceleration, Reconnection, Turbulence and Electrodynamics of the Moon's Interaction with the Sun (ARTEMIS) measurements of lunar exospheric pickup ions in the terrestrial magnetotail lobes combined with a particle-tracing model to constrain the source species and distributions of the lunar neutral exosphere. These pickup ions, generated by photoionization of neutral species while the Moon is in the magnetotail lobes, undergo acceleration from both the magnetotail convection electric field and the lunar surface photoelectric field, giving rise to distinct pickup ion flux, pitch angle, and energy distributions. By simulating the behavior of lunar pickup ions in the magnetotail lobes and the response of the twin ARTEMIS probes under various ambient conditions, we can constrain several physical quantities associated with these observations, including the source ion production rate and the magnetotail convection velocity (and hence, electric field). Using the model-derived source ion production rate and established photoionization rates, we present upper limits on the density of several species potentially in the lunar exosphere. In certain cases, these limits are lower than those previously reported. We also present evidence that the lunar exosphere is displaced toward the lunar dawnside while in the terrestrial magnetotail based on fits to the observed pickup ion distributions.