Space Science: Solar wind might be making water on the moon, groundbreaking NASA study reveals

Constant gusts of particles from the sun may be creating water molecules on the moon, a new NASA-led experiment hints.

Scientists have detected traces of water molecules — as well as hydroxyl (OH) molecules, a component of water — on the surface of the moon through multiple space missions. The source of this water has long been a mystery, though some theories suggest volcanism, outgassing from deeper in the lunar regolith (the combination of rock and dust on the surface of the moon), and bombardment by tiny meteorites.

The new NASA experiment, described March 17 in the journal JGR Planets, tests a different idea: that solar wind is behind it all.

Solar wind is a constant gale of charged particles streaming from the sun at over 1 million mph (1.6 km/h). It bombards everything in the solar system, including Earth, and causes colorful auroras when it collides with molecules in our atmosphere. Our planet’s magnetosphere shields us from the brunt of this space weather. The moon, however, has a very weak and splotchy magnetic field, so it is less protected.

Water is made up of hydrogen and oxygen atoms. The rocks and dust making up the surface of the moon contain a lot of oxygen but not a lot of hydrogen. Solar wind is mostly made of protons, which are hydrogen atoms missing their electrons. Without a strong magnetic field to protect it, the solar wind slams into the moon’s surface every day, seeding it with protons that steal or borrow electrons from the lunar regolith to form the hydrogen needed to make water.

A topographical map of the lunar south pole. The north and south poles of the moon have frigid regions that don’t ever get sunlight, creating cold traps for water to be stored as ice. (Image credit: NASA/JPL)
According to NASA, the water that’s been detected on the moon follows an interesting pattern — it changes on a daily cycle. Areas warmed by the sun release water as vapor, while colder regions hold onto it. If the source of water was something like micrometeorite collisions, we might expect the water to keep decreasing in warm areas until more impacts occur. However, the amounts of water detected return to the same levels every day, even as some of it is lost to space. This makes it more likely that solar wind is involved.

To test this theory, the researchers simulated the effects of solar wind striking the moon using samples of lunar regolith collected by Apollo 17 astronauts in 1972. They built a tiny particle accelerator in a vacuum to launch "mock solar wind" at the samples for multiple days, simulating the effects of the real solar wind hitting the moon for 80,000 years. Then, they measured how the chemical makeup of the sample had changed — and it showed evidence of water that wasn’t there before.

"The exciting thing here is that with only lunar soil and a basic ingredient from the Sun, which is always spitting out hydrogen, there’s a possibility of creating water," study lead author Li Hsia Yeo, a planetary scientist at NASA’s Goddard Space Flight Center, said in a statement.

Understanding how water forms on the moon is important for future astronaut missions, the researchers said. Water ice stored at the lunar south pole could be an important resource for astronauts, for example.

The results also provide insight into the solar wind’s interactions beyond the moon. Other celestial bodies that don’t have much of an atmosphere or a magnetic field are also bombarded by solar wind, so studying how these environments change can help us understand celestial chemical processes that generate or strip away water, a key building block for life.

Source: https://www.livescience.com/space/astronomy/solar-wind-might-be-making-water-on-the-moon-groundbreaking-nasa-study-reveals

Space Science: How astonishing observatories could do big physics from the moon

When Michael Collins floated above the far side of the moon during the Apollo 11 mission in 1969, he knew he would be remembered as the loneliest human in history. He recalled feeling unafraid, almost exultant, thinking about everything on the other side of the moon: Neil Armstrong and Buzz Aldrin on the lunar surface and, beyond that, every creature on Earth and everything humanity had ever built. On his side, as Collins wrote in his memoir, was “one plus God only knows what”.

A half-century later, the famously empty lunar landscape is starting to get busier. Not only are NASA and other space agencies preparing to send humans to the moon for longer periods of time, researchers around the world are working on blueprints to turn it into the most powerful astrophysics laboratory in history. This could address the deepest questions we have ever asked. How did the first stars ignite? Why has the universe evolved the way it did? Is there anyone else out there?

The astrophysicist who may be about to discover how the universe began

“On the moon, we can think about concepts that, here on Earth, are completely impossible to realise,” says Jan Harms, an astronomer at the Gran Sasso Science Institute in Italy. The conditions there seem nearly purpose-built to house cutting-edge observatories that could answer some of the most perplexing questions about the cosmos. The moon’s unique peace and quiet, especially on the side that never faces Earth, could make it a portal to the history of the universe, from the first galaxies to the mysterious dark energy that stretches…

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