Journal article
Investigating the Moon's Interaction With the Terrestrial Magnetotail Lobe Plasma
Geophysical research letters, Vol.48(9), e2021GL093566
05/16/2021
DOI: 10.1029/2021GL093566
Abstract
We present observations of the Moon's plasma interaction in Earth's magnetotail lobes by the ARTEMIS mission, and compare these to hybrid model results to constrain the global properties of the lunar electromagnetic environment. We identify, for the first time in the magnetotail lobes, a low-energy wake extending multiple lunar radii downstream of the Moon along the ambient flow direction. This wake is tilted out of the lunar optical shadow, allowing for detection of the otherwise unobservable cold ambient magnetospheric plasma. Similar eclipse encounters may provide additional opportunities to measure this low-energy plasma potentially originating from the terrestrial ionosphere. We find lunar ionospheric outflow extending multiple Moon radii downstream that generates asymmetries in the Moon's plasma environment and shares characteristics with the plasma interactions of Rhea, Tethys, and Dione. The extensive ARTEMIS data set may therefore provide additional insights into the plasma environments near moons of the outer solar system.
Plain Language Summary Earth's Moon is exposed to a wide range of particle and magnetic field environments during its 29.5-day orbit. When outside of Earth's magnetosphere, the Moon experiences the rapidly flowing, dense solar wind plasma. However, for a few days each month, the terrestrial magnetosphere shields the Moon from the solar wind; instead, it is exposed to the low-density plasma within Earth's magnetotail lobes. For these conditions, we report observations from the Acceleration, Reconnection, Turbulence, and Electrodynamics of the Moon's Interaction with the Sun (ARTEMIS) spacecraft orbiting the Moon. By modeling the Moon's plasma interaction in the lobes, we find that dense, lunar ionospheric particles drastically perturb the local plasma environment, similar to moons in the outer solar system. On the nightside, we provide the first observation of an extended, cold plasma wake tilted out of the Moon's optical shadow. This geometry allowed ARTEMIS to measure an otherwise invisible, ambient magnetospheric ion population that is responsible for shaping the lunar plasma interaction. Hence, the Moon acts as a natural filter for plasma observations in the Earth's magnetotail, an effect that may therefore be used to understand loss processes of Earth's ionospheric plasma.
Key Points
We provide the first observational and modeling evidence of a cold ion wake downstream of the Moon when located in Earth's magnetotail lobes
Using the Moon as a natural solar shield, we reveal an otherwise hidden, cold ion population that may originate from Earth's ionosphere
The lunar plasma environment in the terrestrial magnetotail lobes provides a link to the plasma interactions at outer solar system moons
Details
- Title: Subtitle
- Investigating the Moon's Interaction With the Terrestrial Magnetotail Lobe Plasma
- Creators
- Lucas Liuzzo - University of California, BerkeleyAndrew R. Poppe - University of California, BerkeleyJasper S. Halekas - University of IowaSven Simon - Georgia Institute of TechnologyXin Cao - University of Iowa
- Resource Type
- Journal article
- Publication Details
- Geophysical research letters, Vol.48(9), e2021GL093566
- Publisher
- Amer Geophysical Union
- DOI
- 10.1029/2021GL093566
- ISSN
- 0094-8276
- eISSN
- 1944-8007
- Number of pages
- 11
- Grant note
- 80NSSC20K0311 / NASA/LDAP Grant NAS5-02099 / NASA; National Aeronautics & Space Administration (NASA) German Ministry for Economy and Technology 50-OC-0302 / German Center for Aviation and Space
- Language
- English
- Date published
- 05/16/2021
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984429013802771
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