Scientists say they have discovered water trapped inside tiny beads of glass scattered across the moon, suggesting a potential reservoir of this precious resource for future human activities on the lunar surface.

The moon was long believed to be dry, but over the last few decades, several missions have shown there is water both on the surface and trapped inside minerals.

Scientists said on Monday that an analysis of lunar soil samples retrieved in 2020 during China’s robotic Chang’e-5 mission showed that these spheres of glass – rock melted and cooled – bore within them water molecules formed through the action of the solar wind on the moon’s surface.

“The moon is constantly bombarded with impactors – for example micrometeoroids and large meteoroids – which produce impact glass beads during high-energy flash-heating events,” said planetary scientist Sen Hu of the Chinese Academy of Sciences’ Institute of Geology and Geophysics, a co-author of the study published in the journal Nature Geoscience.

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The solar wind is a stream of charged particles, primarily protons and electrons, emanating outward from the corona, the outermost part of the sun’s atmosphere, and permeating the solar system.

“Solar wind-derived water is produced by the reaction of solar hydrogen with oxygen present at the surface of the lunar glass beads,” Hu said, with these spheres then acting like a sponge for the water.

For future moon exploration, including potential long-term lunar bases staffed with astronauts, water is of vital importance not only as a drinking supply but as a fuel ingredient.

‘Heat the glass beads to free the water’

The moon lacks the bodies of liquid water that are a hallmark of Earth. But its surface is thought to harbour a fairly substantial amount of water, for example in ice patches residing in permanently shadowed locales and trapped in minerals.

“Water is the most sought-after commodity for enabling sustainable exploration of planetary surfaces. Knowing how water is produced, stored and replenished near the lunar surface would be very useful for future explorers to extract and utilise it for exploration purposes,” Hu said.

Researchers see promise in obtaining water from the glass beads, perhaps through a heating process to release vapour that would then turn into liquid through condensation.

“We can simply heat these glass beads to free the water stored in them,” said Hu.

The capsule returning the soil samples to Earth landed in the northern Chinese region of Inner Mongolia.

About 3.8 pounds (1.7 kg) of soil were collected in the Chang’e-5 mission, with 32 glass beads – tens to hundreds of micrometres wide – examined in the study from the small amount of soil made available for this research, Hu said.

The glass beads were found to hold a water content of up to about 2,000 parts per million by weight. Hu said he believes that such impact glass beads are a common part of lunar soils, found globally and spread evenly.

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The Webb Space Telescope has found no evidence of an atmosphere at one of the seven rocky, Earth-sized planets orbiting another star.

Scientists said Monday that doesn’t bode well for the rest of the planets in this solar system, some of which are in the sweet spot for harbouring water and potentially life.

“This is not necessarily a bust” for the other planets, Massachusetts Institute of Technology astrophysicist Sara Seager, who wasn’t part of the study, said in an e-mail. “But we will have to wait and see.”

The Trappist solar system – a rarity with seven planets about the size of our own – has enticed astronomers ever since they spotted it just 40 light-years away. That’s close by cosmic standards; a light-year is about 9.6 trillion kilometres. Three of the seven planets are in their star’s habitable zone, making this star system even more alluring.

The NASA-led team reported little if any atmosphere exists at the innermost planet. Results were published Monday in the journal Nature.

The lack of an atmosphere would mean no water and no protection from cosmic rays, said lead researcher Thomas Greene of NASA’s Ames Research Center.

As for the other planets orbiting the small, feeble Trappist star, “I would have been more optimistic about the others” having atmospheres if this one had, Dr. Greene said in an e-mail.

If rocky planets orbiting ultracool red dwarf stars like this one “do turn out to be a bust, we will have to wait for Earths around sun-like stars, which could be a long wait,” said MIT’s Dr. Seager.

Because the Trappist system’s innermost planet is bombarded by solar radiation – four times as much as Earth gets from our sun – it’s possible that extra energy is why there’s no atmosphere, Dr. Greene noted. His team found temperatures there hitting 230 degrees Celsius on the side of the planet constantly facing its star.

By using Webb – the largest and most powerful telescope ever sent into space – the U.S. and French scientists were able to measure the change in brightness as the innermost planet moved behind its star and estimate how much infrared light was emitted from the planet.

The change in brightness was minuscule since the Trappist star is more than 1,000 times brighter than this planet, and so Webb’s detection of it “is itself a major milestone,” the European Space Agency said.

More observations are planned not only of this planet, but the others in the Trappist system. Looking at this particular planet in another wavelength could uncover an atmosphere much thinner than our own, although it seems unlikely it could survive, said Taylor Bell of the Bay Area Environmental Research Institute, who was part of the study.

Further research could still uncover an atmosphere of sorts, even if it’s not exactly like what’s seen on Earth, said Michael Gillon of the University of Liege in Belgium, who was part of the team that discovered the first three Trappist planets in 2016. He did not take part in the latest study.

“With rocky exoplanets, we are in uncharted territory” since scientists’ understanding is based on the four rocky planets of our solar system, Dr. Gillon said in an e-mail.

Launched in late 2021 to an observation post 1.6 million kilometres away, Webb is considered the successor to the Hubble Space Telescope, orbiting Earth for more than three decades.

In the past, Hubble and the Spitzer Space Telescope scoured the Trappist system for atmospheres, but without definitive results.

“It is just the beginning, and what we can learn with the inner planets is going to be different from what we can learn from the other ones,” MIT’s Julien de Wit, who was not involved in the study, said in an e-mail.

The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Science and Educational Media Group. The AP is solely responsible for all content.

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A large asteroid will safely zoom between Earth and the Moon on Saturday, a once-in-a-decade event that will be used as a training exercise for planetary defence efforts, according to the European Space Agency.

The asteroid, named 2023 DZ2, is estimated to be 40 to 70 metres (130 to 230 feet) wide, roughly the size of the Parthenon, and big enough to wipe out a large city if it hit our planet.

At 19:49 GMT on Saturday it will come within a third of the distance from the Earth to the Moon, said Richard Moissl, the head of the ESA’s planetary defence office.

Though that is “very close”, there is nothing to worry about, he told AFP.

Small asteroids fly past every day, but one of this size coming so close to Earth only happens around once every 10 years, he added.

The asteroid will pass 175,000 kilometres (109,000 miles) from Earth at a speed of 28,000 kilometres per hour (17,400 miles per hour). The moon is roughly 385,000 kilometres away.

An observatory in La Palma, one of Spain’s Canary Islands, first spotted the asteroid on February 27.

Last week, the UN-endorsed International Asteroid Warning Network decided it would take advantage of the close look, carrying out a “rapid characterisation” of 2023 DZ2, Moissl said.

That means astronomers around the world will analyse the asteroid with a range of instruments such as spectrometers and radars.

The goal is to find out just how much we can learn about such an asteroid in only a week, Moissl said.

It will also serve as training for how the network “would react to a threat” possibly heading our way in the future, he added.

‘Scientifically interesting’ 

Moissl said preliminary data suggests 2023 DZ2 is “a scientifically interesting object”, indicating it could be a somewhat unusual type of asteroid. But he added that more data was needed to determine the asteroid’s composition.

The asteroid will again swing past Earth in 2026, but poses no threat of impact for at least the next 100 years — which is how far out its trajectory has been calculated.

Earlier this month a similarly sized asteroid, 2023 DW, was briefly given a one-in-432 chance of hitting Earth on Valentine’s Day 2046.

But further calculations ruled out any chance of an impact, which is what normally happens with newly discovered asteroids. Moissl said 2023 DW was now expected to miss Earth by some 4.3 million kilometres.

Even if such an asteroid was determined to be heading our way, Earth is no longer defenceless.

Last year, NASA’s DART spacecraft deliberately slammed into the pyramid-sized asteroid Dimorphos, significantly knocking it off course in the first such test of our planetary defences.

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