Terrestrial Molecular Ion Outflow Observed at the Moon

The Acceleration, Reconnection, Turbulence, and Electrodynamics of the Moon's Interaction with the Sun (ARTEMIS) spacecraft observes multiple instances of 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 28-32 amu) on the order of 105 to 106 cm-2 s-1 at nearly identical velocities as concurrently present protons. By performing backwards particle tracing in time-dependent electromagnetic fields from the magnetohydrodynamic Open Global Geospace Circulation Model (OpenGGCM) of the terrestrial magnetosphere, we show that the ions escape the inner magnetosphere through magnetopause shadowing near noon and are subsequently accelerated down-tail to lunar distances. This type of circulation, energization, and transport within Earth's magnetosphere appears fundamentally different from that seen at planets with much smaller, induced magnetospheres (i.e., Venus and Mars). Here, we expand upon previous observations by investigating the spatial distribution of the molecular ion observations in the magnetotail and by correlating times of molecular ion observations with geomagnetic activity and solar wind drivers. While the outflow mechanism is unknown, these observations reveal a direct pathway for plasma from the ionosphere to the deep magnetotail. While the heavy molecular densities are low (about 0.01 cm-3, two to three orders of magnitude lower than the ambient proton density) their presence may impact the magnetotail plasma dynamics such as the reconnection rate and wave propagation properties.