China’s Chang’e 5 lunar probe has discovered the first ever evidence of water on the Moon’s surface. The probe captured photos of the Moon rock and the surrounding lunar soil where the water was found.
The Chinese scientists published the discovery in a peer-reviewed article entitled “In situ detection water on the Moon using the Chang’e 5 Lander” on January 7th in the peer reviewed journal Science Advances.
How water on the moon was discovered up-close
Scientists from the Institute of Geology and Geophysics of China Academy of Sciences (IGGCAS), led by a joint research team, analyzed photos and reflectance spectral information captured by Chang’e 5 lander. The Chang’e 5 lander’s onboard lunar mineralogical spectrometer was used to analyze the data at the landing site. This instrument analyzes the mineralogical composition in a small area of the Moon’s surface using visible and infrared lights.
Based on how water molecules absorb light, you can estimate the water content. However, infrared light is not able to detect water. The heat from the moon’s surface can alter the readings. Researchers in the study were able compensate by using a thermal correction model.
The data showed that both soil and lightweight and porous Vesicular Rock had water content. However, it was very low: the lunar soil contained less than 120ppm and the rock had about 180ppm. This is equivalent to 120 grams (4.06 fluid-ounces) of water per ton of soil, and 180 grams (6.09 fluid-ounces/ton) of water per ton of rock.
Scientists think the soil may have been water-infused from solar wind. However, the rock’s higher water content may be due to an unknown source beneath the Moon’s surface. The rock could have been ejected from the moon’s interior during a previous volcanic eruption.
After analysing the soil and rock samples, Chang’e 5 landed on the Chang’e 5 lander to collect them (which weighed 1.73kg/3.82lbs) and return them to Earth scientists.
Lin Honglei, an IGGCAS researcher tells Xinhua that the returned samples contain a mix of granules on the surface as well as beneath. This explains the importance of on-site detections. An in-situ probe is able to measure the outermost layer on the lunar surface.
Another First: Water on the Moon Detected
Although there have been previous evidences of water on the Moon’s surface, these were based on lunar samples that were returned from Earth or data from instruments far away.
A 2008 study of samples of lunar rock collected during Apollo missions in 1960s and 1970s found evidence of water molecules trapped within volcanic pebbles.
2018: Scientists used data from NASA’s Moon Mineralogy Mapper to prove that water ice exists on the Moon’s surface.
NASA announced that scientists have found evidence of water ice on Moon’s surface in the darkest and most remote parts of the polar regions. These ice deposits could be ancient and are scattered around the globe. The majority of the ice at the southern pole is concentrated in lunar craters. However, the northern pole’s ice spreads more widely but is less scattered.
NASA’s Stratospheric Observatory for Infrared Astronomy, (SOFIA), flew a modified Boeing 747 with a powerful telescope in 2020. It confirmed for the first-time that water is present on the moonlit surface.
NASA stated that “this discovery suggests that water may be distributed across lunar surface, and is not limited to cold, shaded places.” SOFIA detected water molecules (H2O), in Clavius Crater. Clavius Crater is one of the largest craters visible on Earth. It’s located in the Moon’s southern hemisphere. This location has data that shows water concentrations between 100 and 412 parts per millions. That’s roughly the equivalent of a 12-ounce water bottle. The soil is spread over the lunar surface in a cubic meter.
Paul Hertz, Director of NASA Astrophysics Division, stated that there were indications H2O – the familiar water that we know – could be present on the moonlit side. It is now known.
The latest confirmation that water is on the Moon’s surface by the Chang’e 5 Lander was not done from Earth orbit or lunar orbit, but on-site. This is a historic first.
In a press release, the Chinese Academy of Sciences stated that “many orbital observations and samples measurements made over the past decade have shown evidence for the existence of water (as H2O and/or hydroxyl) on the Moon.” However, in-situ measurements on the lunar surface have never been made.