Lunar secrets: Earth's electrons spark formation of water on the moon

New research reveals earth's electrons as surprising source of moon's water

INDIA-SPACE/ Image of the moon taken by Chandrayaan-3 | ISRO

Researchers have unveiled a fascinating cosmic connection – earth's electrons could be playing a pivotal role in shaping the lunar landscape and, astonishingly, aiding in the creation of water on the Moon's surface. 

Understanding the presence and distribution of water on the Moon is essential in unraveling the mysteries of its birth and evolution. It also holds the promise of providing valuable water resources for future lunar explorations. Furthermore, this discovery could shed light on the origins of the previously detected water ice in the Moon's permanently shadowed regions.

Earth, with its protective magnetic shield known as the magnetosphere, wards off the harsh effects of space weather and the Sun's harmful radiation. As the solar wind sweeps past, it molds and extends this magnetic cocoon, forming a lengthy tail on the night side of our planet. Within this magnetotail resides a region called the plasma sheet, which contains high-energy electrons and ions sourced from both Earth and the solar wind.

Previously, scientists primarily focused on the role of high-energy ions in the lunar space weathering process. The solar wind, comprised of energetic particles like protons, constantly bombards the Moon's surface and was thought to be the primary driver behind water formation on our celestial neighbor.

This exciting discovery, led by a planetary scientist from the University of Hawai'i at Mānoa, has been published in the prestigious journal Nature Astronomy.

Building on his previous research that unveiled how oxygen from Earth's magnetotail was causing iron on the Moon's polar regions to rust, Shuai Li, an assistant researcher at UH Mānoa's School of Ocean and Earth Science and Technology (SOEST), turned his attention to understanding the changes in lunar surface weathering as the Moon passed through Earth's magnetotail – an area that effectively shields the Moon from solar wind but not the Sun's light.

Li explains, "This provides a natural laboratory for studying the formation processes of lunar surface water. When the Moon is outside of the magnetotail, the lunar surface is bombarded with solar wind. Inside the magnetotail, there are almost no solar wind protons, and water formation was expected to drop to nearly zero."

Li and his colleagues meticulously analyzed remote sensing data collected by India's Chandrayaan-1 mission between 2008 and 2009. They specifically examined how water formation changed as the Moon journeyed through Earth's magnetotail, which includes the plasma sheet.

To their astonishment, the remote sensing data revealed that water formation in Earth's magnetotail was nearly identical to the conditions outside the magnetotail. This suggests the presence of additional water formation processes or novel water sources unrelated to solar wind protons. Surprisingly, the radiation from high-energy electrons appears to have similar effects as solar wind protons.

Li concludes, "This discovery, along with my previous findings of rusty lunar poles, underscores the profound connection between Mother Earth and her lunar companion in many uncharted aspects."

In future research, Li plans to collaborate on a lunar mission within NASA's Artemis program, aiming to monitor the plasma environment and water content on the lunar polar surface during different phases of the Moon's traversal through Earth's magnetotail. This promises to uncover even more secrets about the intricate relationship between our planet and its enigmatic satellite.