Meteor showers not only produce spectacular shows in the night sky; they might also be responsible for freeing sodium and potassium from Moon rocks. The results are published this week in Science.
NASA’s Lunar Atmosphere and Dust Environment Explorer (LADEE) spacecraft has observed an increase in gas released when the Moon is hit by meteorites. The spacecraft measured the abundance of the two elements every 12 hours for more than five months. A significant increase was seen in the abundance of sodium and potassium during a meteor stream bombardment, with the former returning to the pre-strike level within days, and the latter taking several months.
The Moon is covered in a thin tenuous gas layer that is technically known as an exosphere. It’s a mixture of noble gasses, products of radioactive decay and solar wind bombardment. It has a density of less than a trillionth of Earth’s atmosphere and it needs constant replenishment due to how quickly it is lost to space.
“To understand the Moon’s exosphere requires insight into the processes controlling it, including the interaction of meteoroid showers as well as solar wind bombardment and ultraviolet radiation of the surface,” said Anthony Colaprete, lead author of the study, in a statement.
“Understanding how these processes modify the exosphere allows researchers to infer its original state. Since these processes are ubiquitous across the Solar System, knowledge gained by examining the Moon’s exosphere can be applied to a range of other bodies, granting us greater insight into their evolution through time,” Colaprete added.
The same phenomenon was seen happening on Mercury as well. Mercury and the Moon are two of the many objects in the Solar System that possess an exosphere, but the Moon is a perfect nearby laboratory to understand how exospheres are formed.
“These observations enable us to constrain the physical processes that contribute to the lunar exosphere,” said Menelaos Sarantos, co-author of the paper. “We’re using these findings to build new exosphere models of how the space environment interacts with the surfaces of airless bodies, which we can use to better predict the processes and behaviors around similar bodies.”