Scientists have observed «direct and definitive» evidence of water ice on the moon’s surface. The discovery, a decade in the making, shows that water ice exists in both the southern and northern poles of Earth’s only natural satellite.
The findings, published in the Proceedings of the National Academy of Sciences, show that the ice near the moon’s south pole is mostly contained in lunar craters like Haworth, Shoemaker, Sverdrup, and Shackleton. In the north, the ice has been distributed more widely across the surface.
The initial discovery of water ice on the moon was made by a joint mission between NASA and the Indian Space Research Office (ISRO). The ISRO spacecraft Chandrayaan-1 entered orbit around the moon in 2008, and the craft released an impactor probe that slammed into the lunar surface in November of that year. The impact revealed water ice beneath the surface of the moon, and additional observations suggested water ice could be on the surface near the poles as well. In 2010, scientists reported that data from Chandrayaan-1 indicated 40 permanently darkened craters on the moon’s surface, leading to estimates of 600 million metric tons of water ice.
Further study of data from NASA’s Moon Mineralogy Mapper (M3) instrument on the spacecraft has led to direct and definitive evidence of that ice. An imaging spectrometer, the M3 created the first mineralogical map of the lunar surface.
Light reflecting off the moon tends to be near the red part of the spectrum due to iron produced as the surface is hit by space weather. However, when analyzing the moon’s craters, the M3 picked up strong blue wavelengths, representing direct evidence of water ice on the moon’s surface.
The new discovery means that future missions to the moon could possibly access surface ice, supporting astronauts during extended stays. According to a report from NASA JPL, «water would possibly be accessible as a resource for future expeditions to explore and even stay on the moon, and potentially easier to access than the water detected beneath the moon’s surface.»
With new research suggesting that the moon may have at one point even hosted life, it’s clear that there that there’s a lot left to learn about Earth’s nearest neighbor.