The US Naval Research Laboratory (NRL) has discovered solar-wind hydrogen in Apollo lunar samples, provided by a NASA-funded research mission for investigation and testing.
Researchers said that water on the surface of the Moon is a ‘potentially vital’ resource for future moon bases and space exploration, but effective use of the resource depends on developing an understanding of where and how within lunar dust and soil (regolith) the water is formed and retained.
Solar wind hydrogen, which can form molecular hydrogen, water and/or hydroxyl on the lunar surface, reacts and is retained differently depending on regolith mineral content, thermal history, and other variables.
NRL used transmission electron microscopy to analyse Apollo lunar soil 79221, which uses a particle beam of electrons to view thin specimens and create a highly magnified image.
Hydrogen signatures were detected in samples in vesicles, small holes left behind after lava cools, which suggests that solar wind is being trapped in detectable quantities, proving a potential reservoir and source of hydrogen that could aid future bases and space explorations.
The imaging found solar-wind hydrogen concentrated in vesicles as molecular hydrogen, in the calcium-phosphates apatite and merrillite.
In a statement, Dr. Katherine D. Burgess, geologist in NRL’s Material Science and Technology Division and study lead, said: “This is the first-time scientists have demonstrated detection of hydrogen-bearing species within vesicles in lunar samples.
“Previously, the same team at NRL used… techniques such as scanning transmission electron microscopy and electron energy loss spectroscopy to detect helium in lunar samples, and other researchers have found water in other planetary samples, but this is the first publication to show hydrogen in-situ in lunar samples.”
The NRL said that space-based resource identification is a key factor in planning for government and civilian-led space exploration.
Dr. Burgess said: “Hydrogen has the potential to be a resource that can be used directly on the lunar surface when there are more regular or permanent installations there.
“Locating resources and understanding how to collect them prior to getting to the Moon is going to be incredibly valuable for space exploration.”
The research article was published in Communications Earth & Environment, and can be read in full here.
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