Particles from Earth’s atmosphere, carried into space by the solar wind, continue to land on the moon’s surface and mix with the moon’s soil for billions of years, according to a new study.

The study sheds new light on a mystery that has persisted for more than half a century, ever since the Apollo missions brought back lunar samples containing traces of substances such as water, carbon dioxide, helium and nitrogen embedded in the moon’s regolith.

early research They theorized that the sun was the source of some of these materials. However, in 2005, researchers at the University of Tokyo proposed It is thought that they may also have originated from the young Earth’s atmosphere, before the magnetic field developed about 3.7 billion years ago. The authors suspected that once the magnetic field was in place, it stopped the flow by trapping the particles and making it difficult or impossible for them to escape into space.

The new study overturns that assumption, suggesting that Earth’s magnetic field may have helped, rather than prevented, atmospheric particles from traveling to the moon, an assumption that continues to this day.

“This means that Earth has been supplying volatile gases such as oxygen and nitrogen to the lunar soil all along,” says Eric Blackman, a co-author of the new study and a professor in the Department of Physics and Astronomy at the University of Rochester in New York.

“It has long been thought that the moon first formed when an asteroid struck the proto-Earth, and there was a large initial mix of such volatile materials from Earth to the moon,” he added in an email. “Our results show that even after billions of years, unstable sharing still exists.”

The presence of useful elements such as oxygen and hydrogen on the moon’s surface could be interesting for lunar exploration.

“Moon exploration missions, and eventually possible lunar colonies, will require self-sustaining resources that don’t need to be transported from Earth,” Blackman said.

“For example, people are researching how to treat water from the lunar regolith and extract hydrogen and oxygen to make fuel. There is also research into ammonia-based fuels that utilize nitrogen carried by the moon or the solar wind. So this material carried by the solar wind gets into the soil and becomes part of the local resources that such innovations can tap into.”

In the new study, researchers used computer simulations to test two scenarios. One of them had a strong solar wind (a fast stream of particles coming from the Sun) and no magnetic field around the Earth. The other had a weak solar wind and a strong magnetic field around the Earth. The scenarios roughly correspond to the ancient and modern conditions of the Earth. The modern Earth scenario turned out to be the most effective at transporting debris from Earth’s atmosphere to the Moon.

The researchers then compared their results to data obtained directly from soil analysis on the Moon. previous the study.

“We used lunar samples that were brought to Earth. Apollo 14 and 17 missions Shvonkar Paramanik, a graduate student in the University of Rochester’s Department of Physics and Astronomy, is the lead author of the study, which was published in December in an academic journal. Nature Communication Earth and Environment.

“This solar wind is blowing into the Earth’s atmosphere, and then the Earth’s atmosphere is leaking out. So we tried to determine what the mixing ratio of this mixture would be, or distinguish which particles were of solar origin and which were of terrestrial origin,” he added.

Earth’s magnetic field is generated by electrical currents generated by the movement of molten iron and nickel within the planet’s liquid outer core. It extends far into space, forming a shield that deflects much of the solar wind that would eat away at the atmosphere.

When the magnetic field interacts with the solar wind, it forms the magnetosphere, a comet-like structure with a compressed front and a long tail. Auroras, also known as aurora borealis, occur when particles from the solar wind collect along lines in the magnetosphere near the poles. north and south light.

The shape of the magnetosphere explains why the solar wind can strip some of the particles from Earth’s atmosphere and channel them into space. Blackman also said it could transport more of Earth’s atmosphere to the moon than unmagnetized ancient Earth models.

“Magnetic fields are not purely protective for two reasons. One is that there is pressure in the magnetic field, which causes the Earth’s atmosphere to expand somewhat, giving the solar wind a little more access to the atmosphere,” he said. “And when the moon is in the full moon phase of its orbit, it enters a region called “.magnetic tailThe magnetic field opens a channel that allows the blown atmospheric material to take a more direct path to the moon. ”

The moon passes through its magnetic tail for several days each month, and because the moon has no atmosphere to block the particles, they land on the moon’s surface, where they become embedded in the soil.

Understanding the history of this interaction between the Moon and Earth is important, the study argues, as it provides a valuable chemical record – information about Earth’s ancient atmosphere that may be contained in the Moon’s soil. Blackman said the composition of the atmosphere is related to the evolution of life at different stages of Earth’s history.

Kentaro Terada, a professor of isotope cosmology and geochemistry at Osaka University in Japan, said he was pleased that his observations were supported theoretically. Terada led in 2017 study It showed how the solar wind and Earth’s magnetic field transported oxygen to the moon, but he was not involved in this new study.

“It has long been recognized that the Earth and Moon have physically co-evolved since their formation,” he said in an email. The discovery of lunar meteorites and observations of particle streams from Earth carried by the solar wind have revealed new perspectives. “The two bodies also interact chemically, which is a kind of material exchange,” he explained, adding that the paper is “very exciting in the comprehensive discussion of Earth’s history.”

The new study supports the idea that the moon holds clues about Earth’s history and evolution, said Simeon Barber, a senior research fellow at Britain’s Open University who was not involved in the study.

The study is timely, he added, because new samples of young lunar soil were recently obtained. China’s Chang’e 5 mission in 2020 As well as the first samples from the far side of the moon, Chang’e 6 in 2024provides an opportunity to further test the results.

Additionally, Barber said the study will help interpret results from future lunar robotic landers that can directly measure volatile elements within the lunar regolith.