Earth-Originated Electrons Potentially Contributing to Lunar Hydration

Surface Water Distribution on the Moon, as Credited to Li and Team, 2023

Researchers from the University of Hawai‘i have ascertained that electrons from Earth’s plasma sheet impact the Moon’s surface changes and might play a role in water formation. This revelation enhances our grasp of the Earth-Moon interconnection and suggests new avenues for exploration.

Headed by a planetary scientist from the University of Hawai‘i at Mānoa, a research group has found that high-energy electrons present in Earth’s plasma sheet influence erosional processes on the Moon. Crucially, these electrons could be facilitating the genesis of water on the lunar surface. This study was disclosed in the Nature Astronomy journal on September 14.

Comprehending the quantities and dispersion of lunar water is vital for insights into the Moon’s formation and development, as well as for securing water supplies for future human endeavors on the Moon. The recent discovery may also shed light on the origins of water ice that has been previously detected in perpetually shadowed areas on the Moon.

Earth’s Protective Magnetosphere and Its Consequences

Earth’s magnetic field creates a protective shell around the planet, commonly referred to as the magnetosphere, which serves to shield Earth from cosmic weathering and harmful solar radiation. Solar winds exert pressure on this magnetosphere, elongating it into a tail on the night side of the Earth. The plasma sheet within this magnetotail is an area rich in high-energy electrons and ions originating from both Earth and solar winds.

Historically, scientific investigations have largely concentrated on the impact of high-energy ions, such as those found in solar winds, on the Moon’s weathering and other celestial bodies lacking atmospheres. Solar winds, comprised of high-energy particles like protons, have long been considered a primary mechanism for water formation on the Moon.

Earth’s Magnetotail’s Influence on Lunar Conditions

Expanding upon his earlier research, which demonstrated that Earth’s magnetotail oxygen is oxidizing iron in the Moon’s polar regions, Shuai Li, an assistant researcher at the University of Hawai‘i at Mānoa’s School of Ocean and Earth Science and Technology (SOEST), sought to explore alterations in lunar surface weathering as the Moon transits through Earth’s magnetotail. This region nearly completely insulates the Moon from solar winds, albeit not from solar light photons.

Li stated that this sets up an excellent test environment for studying the processes contributing to lunar surface hydration. “When situated outside of the magnetotail, the lunar surface is subjected to solar winds. Within the magnetotail, it was assumed that water formation would be significantly reduced.”

By examining remote sensing data collected between 2008 and 2009 by India’s Chandrayaan 1 Moon Mineralogy Mapper instrument, Li and his colleagues evaluated changes in water formation as the Moon moved through Earth’s magnetotail, inclusive of the plasma sheet. Li expressed astonishment that water formation levels within Earth’s magnetotail nearly mirrored those recorded when the Moon was not in Earth’s magnetotail. This suggests alternate mechanisms or new water sources in the magnetotail not directly correlated to solar wind proton implantation.

Li summed up, stating that this discovery, along with his prior work on lunar poles oxidization, emphasizes the intricate and often unacknowledged relationship between Earth and its Moon.

Future Directions for Research

Li plans to further this line of research by participating in NASA’s Artemis programs aimed at monitoring plasma conditions and water content on the polar lunar surface during different phases of the Moon’s transit through Earth’s magnetotail.

Reference: “Formation of lunar surface water associated with high-energy electrons in Earth’s magnetotail” by S. Li, A. R. Poppe, T. M. Orlando, B. M. Jones, O. J. Tucker, W. M. Farrell, and A. R. Hendrix, published on September 14, 2023, in Nature Astronomy.
DOI: 10.1038/s41550-023-02081-y

Frequently Asked Questions (FAQs) about lunar water formation

More about lunar water formation

• University of Hawai‘i Research Publication
• Nature Astronomy Journal
• Moon Mineralogy Mapper Instrument
• NASA’s Artemis Programs
• Chandrayaan 1 Mission Overview
• Earth’s Magnetosphere Explained
• Previous Work on Lunar Poles Oxidization