Hydrogen-rich regolith samples suggest the presence of water on Moon
The Chinese Academy of Sciences recently studied 17 lunar regolith (loose fragments of rock and glass) samples brought back to Earth by the Chang'e-5 lander. The tests revealed that the samples were more hydrogen-rich than those returned by Apollo missions. Researchers believe that solar winds- a continuous stream of charged particles emitted by the Sun- might have embedded hydrogen molecules in lunar soil.
Why does this story matter?
What surprised scientists were that the Chang'e-5 regolith specimens, which came back in December 2020, were far richer in hydrogen than the Apollo missions samples. These hydrogen atoms can react with oxygen atoms, and form water. This opens up an interesting possibility- astronauts landing on the Moon in the future might have direct access to water.
Where did Chang'e-5 lander dock?
All six Apollo missions landed and collected samples from what can be considered the Moon's equator, where the temperature is roughly 107 degrees Celsius. There, the hydrogen, hydroxide, and water, trapped in the regolith, easily escape or "outgas" due to the heat. Chang'e-5, on the other hand, docked 43 degrees north of the equator, where the temperature is approximately 77 degrees Celsius.
Cooler temperatures might have helped regolith retain more hydrogen
Scientists believe that the cooler temperatures recorded at higher altitudes on the Moon might be the reason why the Chang'e-5 regolith samples retained more hydrogen. Researchers heated some of Chang'e-5's samples to temperatures well above the noontime temperatures here for about 28 hours. They discovered that only about 20% of the trapped hydrogen escaped, which proved the stability of hydrogen-rich regolith samples.
The polar regolith at the Moon contains 560ppm of water
After a series of modeling-based investigations, researchers concluded that the regolith near the lunar poles contains an average of about 560 parts per million (ppm) of water. This figure is almost similar to the estimates by the Moon Mineralogy Mapper, a NASA-supported guest instrument that flew aboard Chandrayaan-1. It estimated that the polar regolith contained approximately 400-700ppm of water (not counting the ice).
The lander picked up 2m-deep lunar rock samples
Among the suite of samples on the Chang'e-5 lander were specimens collected from the top few centimeters of regolith, and rock samples drilled from about two meters deep. Scientists were able to study the crust's younger section apart from learning about higher lunar latitudes.
Why is this study important?
NASA's Artemis 3 mission, which will be the first Artemis mission to land astronauts on the Moon, will dock somewhere close to the lunar South Pole. This will be close to the region where the Chinese lander picked up regolith samples. The supplies of hydrogen and water there could make the satellite, the "spacefaring equivalent of a gas station."
