BENGALURU: A team led by researchers from the University of Hawaii (UoH) at Manoa in the US, while using India’s Chandrayaan-1 mission’s remote sensing data, found that high-energy electrons from Earth could be playing a crucial role in water formation on the Moon.
They have found that these electrons are from the Earth’s plasma sheet, reaching the Moon when the latter is in the magnetotail of the Earth with the Sun on one side and the Moon on the other side of the Earth. The magnetotail is the broad elongated extension of the earth’s magnetosphere away from the sun, and the Moon comes inside this during its revolutions around the Earth.
Solar wind is known to bombard the Moon’s surface with high-energy particles, and protons, and that is thought to be one of the main ways for water formation on the Moon. However, that happens only when the Moon is outside of the Earth’s magnetotail, which protects the Moon from the solar wind.
Shuai Li, assistant researcher at the UH Manoa School of Ocean, explained: “Inside the magnetotail, there are almost no solar wind protons and water formation was expected to drop to nearly zero.” The researchers assessed the changes in water formation as the Moon traversed through Earth’s magnetotail, which includes the plasma sheet.
“To my surprise, the remote sensing observations showed that the water formation in Earth’s magnetotail is almost identical to the time when the Moon was outside of the Earth’s magnetotail,” Li said. “This indicates that, in the magnetotail, there may be additional formation processes or new sources of water not directly associated with the implantation of solar wind protons. In particular, radiation by high energy electrons exhibits similar effects as the solar wind protons.”
M3 found water molecules in lunar dust plume
The research, published in the journal Nature Astronomy, concluded that Earth could be contributing to water formation on the lunar surface with its electrons striking the lunar surface when the Moon comes in its magnetotail.
The UoH researchers analysed the data gathered by an imaging spectrometer, the Moon Mineralogy Mapper (M3), which was a payload on board Chandrayaan-1. The mission was launched on October 22, 2008, and on November 14 that year, it released a surface impacter called Moon Impact Probe, which struck the lunar surface near the Shackleton Crater, raising a huge plume of dust.
The M3 had detected water molecules in this lunar dust plume, which was a breakthrough discovery of the presence of water and water hydroxyl on the Moon’s surface. Chandrayaan-1 mission ended on August 28, 2009, when earth stations lost contact with the orbiting spacecraft. The researchers used the data disseminated by ISRO’s Indian Space Science Data Center.