LAMP Sheds Light on Lunar Water Molecules

Scientists used the LAMP instrument of the Lunar Reconnaissance Orbiter (LRO) of NASA to observe the movement of water molecules on the Moon.

Moon was considered an extremely arid object, up until the last decade or so, with hardly any signs of water on its surface. Technological advancements allowed the researchers to trace sparse populations of water molecules that were bound to the lunar soil. In order to enhance their understanding of these water molecules, they used the measurements from the Lyman Alpha Mapping Project (LAMP). It was observed that the concentration of water molecules increases as we move towards higher altitudes. Similarly, the amount and locations of these molecules vary considerably on the basis of the time of day. Dr. Kurt Retherford, the Principal Investigator of the LAMP instrument, referred to the significance of this finding by saying,

“This is an important new result about lunar water, a hot topic as our nation’s space program returns to a focus on lunar exploration. We recently converted the LAMP’s light collection mode to measure reflected signals on the lunar dayside with more precision, allowing us to track more accurately where the water is and how much is present.”

Tightly-bound Water Molecules

The report published in the journal ‘Geophysical Research Letters’ suggested that the water remains tightly bound to the regolith until the surface starts to heat up. This is when the molecules tend to hop around as they bounce to a new, colder location to populate the exosphere of the Moon. They continue to stay there until the temperature on the surface drops down. This thermal desorption of water molecules generally takes place around lunar noon when the temperatures are at their peak.

Dr. Michael Poston, a Research Scientist on the LAMP team who had previously studied lunar samples collected by the Apollo Missions, mentioned that this new research is extremely useful to understand the bonding of water with the surface materials because it reveals the amount of energy that is required to remove the molecules from the surface. He said,

“Lunar hydration is tricky to measure from orbit, due to the complex way that light reflects off of the lunar surface. Previous research reported quantities of hopping water molecules that were too large to explain with known physical processes. I’m excited about these latest results because the amount of water interpreted here is consistent with what lab measurements indicate is possible.”

Role of Solar Wind

According to a popular theory proposed by scientists, hydrogen ions in the solar wind are responsible for most of the water molecules on Earth. If this idea is true, the ‘water spigot’ should essentially turn off, when the Moon is shielded from solar wind as it passes behind the Earth. However, the data extracted from the LAMP showed that the quantity of water doesn’t decrease when the lunar satellite of our planet is shielded by the Earth. This clearly refers to the fact that water molecules build up over time and doesn’t rain down directly from the solar wind. Amanda Hendrix, the Lead Author of the paper who works as a Senior Scientist at the Planetary Science Institute, talked about this result in the following words:

“These results aid in understanding the lunar water cycle and will ultimately help us learn about the accessibility of water that can be used by humans in future missions to the Moon. Lunar water can potentially be used by humans to make fuel or to use for radiation shielding or thermal management; if these materials do not need to be launched from Earth that makes these future missions more affordable.”

You can have a look at this amazing discovery in the video below.