Water on the Moon may have terrestrial origins – at least in part. As researchers have discovered, the formation of ice on the surface of our satellite is driven by electrons also coming from the Earth’s magnetosphere. Understanding these processes may prove crucial for future manned missions to the Moon.
The Earth is surrounded by a magnetosphere – an area of magnetic field – that shields it from the solar wind. It deflects the plasma streams heading towards us so that they safely flow around the Earth, creating a long, magnetic “tail” on the night side. This tail consists of ions coming not only from the Sun, but also from our planet.
Many bodies in the solar system do not have a magnetosphere, which leaves them exposed to the solar wind. The Moon is regularly bombarded with ion beams, which causes “cosmic weathering” of its surface. Solar wind has so far been considered the main cause of water formation on the Moon, but a study published a few days ago in the journal Nature Astronomy suggests that water is also formed in a completely different place.
An international team of scientists analyzed remote sensing data collected by the Moon Mineralogy Mapper measurement instrument of the Indian mission Chandrayaan-1. First of all, they were interested in the moments when the satellite was hiding inside the Earth’s magnetic “tail” – this is the only moment when its surface is not bombarded by the solar wind.
As Shuai Li from the University of Hawaii at Manoa explained, researchers initially expected that without exposure to solar plasma, water molecules would not form on the Moon. However, the results showed something completely different – they occurred at the same rate as during solar wind impacts.
– This indicates that there may be processes in the magnetic tail that drive water formation or sources that are not directly related to solar wind particles. In particular, radiation from high-energy electrons shows similar effects to protons coming from the Sun, he said.-
Water and iron
A previous study in which Li was involved showed that oxygen in the Earth’s magnetic tail causes iron on the Moon to rust. “This shows that mother Earth is strongly connected to her Moon, although we still don’t know how strongly,” he admitted.
Scientists stressed that understanding the processes responsible for water formation on the Moon is crucial to understanding its evolution, as well as to ensuring water resources for future human research. The new discovery may also help explain where the ice in the permanently shadowed regions of the moon comes from.
Main photo source: NASA