The night's light bulb, the moon, has always been thought to be extremely dry. But over the years, scientists have been discovering that this may not be the case. Recently, a group of researchers from NASA discovered that the moon's side that faces the sun contains water.
Moon with a chunk taken out revealing water molecules. Below is the SOFIA airplane. Background is a sunset sky. (Image courtesy of NASA)
Many studies done in the past have found water particles by analyzing rocks and soil that were brought back during the Apollo missions from years ago. This research group took a different approach by using a telescope-airplane hybrid called SOFIA (Stratospheric Observatory for Infrared Astronomy).
SOFIA is a modified Boeing 747-SP airplane that holds a 2.7m telescope. SOFIA can reach up to 45,000 feet in the air. This height is much higher than Mount Everest, the tallest mountain globally, which is only 29,029 feet high!
The SOFIA, NASA’s flying telescope. (Image courtesy of NASA)
The researchers also used an instrument called FORCAST that uses infrared light to detect signals from very far distances, including the moon. Using the FORCAST and SOFIA, the researchers sent out signals towards two locations on the moon: the Clavius crater (found in the moon’s southern hemisphere) and the Mare Serenitatis (a dark plain created by lava from asteroid impacts).
The emission signals that were reflected from the Clavius crater were measured to be 6 micrometres. This is the same wavelength emitted by molecular water; thus, they concluded that what they found was water.
This begs the question: where did the water come from? There are several ways water can end up on the moon. One phenomenon comes from the idea that tiny meteorites crashing into the moon cause glass formation (made from the high temperature melting surrounding rocks) that contains water. Another theory suggests that existing hydroxyl (-OH) molecules in the moon’s soil react to create water due to the high temperatures the moon faces during midday.
Meteorite crashing into moon. (Image courtesy of NASA)
The signal from SOFIA wasn’t able to tell the researchers if the signal came from within a glass particle or the soil. Still, it is known that a large amount of the moon’s soil is anhydrous (lacking water), so they concluded that the signal they observed came from water trapped within glass created during a meteorite impact.
Impact glass found on the moon. These shards came from the Apollo missions. (Image courtesy of N. E. B. Zellner, 2019)
Another question you might be wondering: How much water did they find? Assuming the water was trapped in glass, they calculated that the abundance of water was between 100 to 400 micrograms/gram, about one 12-ounce bottle of water. This isn’t much (even the Sahara desert has more water!), but this is 4x more water than what was found in soil samples collected from lower latitudes in Apollo missions, suggesting that the composition of the moon’s surface may be different than what we thought.
Finding 12 ounces of water on the mood may seem insignificant, but even the smallest amount of water on a planetary surface can signify past life. Additionally, water on the moon will definitely be a useful tool for astronauts travelling to the moon in 2024. NASA has been brainstorming methods to build a lunar base on the moon, which would contain resources for astronauts like water, food, oxygen, and any tools they would need while in space. The potential for a lunar base on the moon would increase the efficiency of research conducted in space because it would eliminate the need for round trips from the moon to Earth to restock. Tapping into the natural resources of the moon would allow for cheaper rocket fuel and less expensive space travel.
Future research is directed towards seeing how this molecular water changes over time and looking at larger areas to see if the geography affects water formation.
References:
Honniball, C. I., Lucey, P. G., Li, S., Shenoy, S., Orlando, T. M., Hibbitts, C. A., . . . Farrell, W. M.
(2020, October 26). Molecular water detected on the sunlit Moon by SOFIA. Retrieved
from https://www.nature.com/articles/s41550-020-01222-x#_blank
Potter, S. (2020, October 26). NASA's SOFIA Discovers Water on Sunlit Surface of Moon.
sunlit-surface-of-moon/
Proudfit, L. (2015, April 21). SOFIA Overview. Retrieved from
https://www.nasa.gov/mission_pages/SOFIA/overview/index.html
Sharp ZD;Shearer CK;McKeegan KD;Barnes JD;Wang YQ;. (n.d.). The chlorine isotope
composition of the moon and implications for an anhydrous mantle. Retrieved from
https://pubmed.ncbi.nlm.nih.gov/20688980/
Zellner, N. E. (2019, November 15). Lunar Impact Glasses: Probing the Moon's Surface and
Constraining its Impact History. Retrieved from
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019JE006050
Featured image courtesy of Wix
Article Author: Vanessa Wong
Article Editors: Maria Giroux, Victoria Huang