Scientists have detected water on the moon, and for the first time they can say they literally found it on the lunar surface.
A Chinese lunar lander returned more than 60 ounces of soil and rock samples from its trip to the moon in December 2020. But before Chang’E-5 returned to Earth, the spacecraft used an onboard instrument to take action on the spot. Based on the readings, scientists about 239,000 miles away on Earth knew it had likely encountered water.
Water is a scarce resource in deep space. Since it is a vital ingredient that sustains life, its scarcity beyond Earth presents an obstacle to space exploration. Scientists wondered if the moon’s small amount of water could be harnessed for astronauts to use for a long time away from the planet.
A research team, led by scientists from the Chinese Academy of Sciences’ Institute of Geology and Geophysics, saw signs of water in the probe data, identifying H2O molecules based on their reflectance distinct spectral, a measure of how well something reflects or absorbs the sun’s rays. radiation. The study was published last week in Scientists progress.
The detection of Chang’E-5 shows there may be more water on the moon than previously thought, said Matt Siegler, senior scientist at the Planetary Science Institute, a nonprofit organization based in Tucson, Arizona.
“I’m sure there are a lot of American scientists who are jealous that we didn’t have the lander on the moon to do this measurement,” said Siegler, who was not involved in the study. Siegler will be part of NASA’s Artemis team for its rover mission next year to drill ice at the moon’s south pole.
Ice near the lunar north and south poles shows a shift in the moon’s axis
People’s understanding of lunar water has increased in recent years. When the Apollo astronauts returned home in 1969, they thought the moon was completely dry.
In the late 2000s, a number of missions, including the Indian Space Research Organization’s Chandrayaan-1, found signs of hydration on the sunlit surface, but could not say for sure. whether it was H20 or hydroxyl, the close chemical relative of water. Casey Honniball, a NASA postdoctoral fellow, described the latter chemical as something akin to a drain cleaner.
Previous missions over the past two decades, such as NASA’s Lunar Crater Observation and Sensing Satellite, have found ice in hard-to-reach craters around the moon’s poles that are permanently in shadow. Scientists also reexamined the famous moon samples from Apollo in 2008 and found water molecules in glass beads and minerals within them. This discovery was somewhat controversial, however, as some were skeptical whether the water came from the moon or from moisture contamination in Houston.
Then in November 2020, a month before the Chinese lander detected water on the surface of the moon, NASA announced that it could indeed confirm that water was in a sunny part of the moon. – without going there. Flying a jet up to 45,000 feet, NASA used the Stratospheric Observatory for Infrared Astronomy, or SOFIA, to pick up the distinct wavelength signals of water molecules. The telescope’s discovery suggested water could be strewn across the moon, not just frozen at its poles.
A researcher examines the lunar soil brought back from the moon by the Chinese probe Chang’E-5.
Credit: VCG/VCG via Getty Images
Many previous measurements have seen potential water, but none of these studies have taken place on the moon itself – until now. The difference, Siegler said, is that spectral reflectance data must be corrected for the object’s temperature to determine how much water it contains. Otherwise, the heat from the moon’s surface could alter or mask the characteristics of the reflected light. But it’s difficult to know the precise temperature of a target at an extreme distance, he said.
“That’s what’s pretty big about this one on the lunar surface,” he said. “You know this (specific) rock, and they are able to measure the temperature of it, and there is no ambiguity.”
Chang’E-5 did not find any lagoons, gushing rivers or waterfalls in the previously unexplored area. Think much smaller: traces of water in the ground where he landed, a region perhaps ironically called the Oceanus Procellarum, or “ocean of storms.” The researchers believe the water was likely formed by the solar wind, gases escaping from the sun. When the solar wind, which contains hydrogen atoms, hits the oxygen in the soil and rocks of the moon, it sometimes produces water.
A moon rock from the same location held a higher concentration of water than the ground around it, suggesting it had another source of water – not just the solar wind. The pumice-like rock fragment may have broken off from older volcanic rock deep within the moon and ejected toward the landing site, the researchers said.
A figure from a new study published in Science Advances describes the water content of the Chang’E-5 landing site.
Parvathy Prem, a scientist at Johns Hopkins University’s Applied Physics Laboratory, said she was still smiling days after reading the new study.
“Just as interesting as the rock itself is that the region around it appears to be drier,” she said in an email, an observation that raises more questions about the different ways whose water forms and stays on the moon.
Despite the lander detecting water, it wasn’t much. Some of the driest places on earth, such as the Dry Valleys of Antarctica, typically have soil moisture content between 0.2 and 5 percent water, Prem said. Moon rock had about 0.018%, and nearby soil had only 0.012%, according to the study.
Chang’E-5 was the first lunar mission to collect and return material since 1976, when the Soviet Union’s Luna 24 probe returned samples. The last time NASA recovered moon rocks was 50 years ago, in 1972.
It’s much easier and more accurate to closely study a single moon rock in its surroundings than with a telescope, Siegler said.
“You’re not going to measure this from Earth,” Siegler said. “If America wants to do this kind of science, we have to be on the moon.”