The ingredients for water could be made on the surface of the moon, a chemical plant


NASA scientists show how ingredients for water could be made on the surface of the moon, a chemical plant. Credit: NASA / Ernie Wright's Goddard Space Flight Center

NASA scientists have discovered that a flow of charged particles called solar wind was blowing across the moon's surface at 450 km / s (or nearly 1 million km / h) and enriching the Moon's surface. Ingredients that can produce water.

With the help of a computer program, scientists have simulated the chemistry that develops when the solar wind drives the surface of the moon. They found that the Sun was sending protons to the Moon and that these particles were interacting with electrons on the surface of the Moon, producing hydrogen atoms (H). These atoms then migrate to the surface and bind to the abundant bound oxygen (O) atoms in silica (SiO2) and other oxygen – containing molecules that make up the lunar soil, or regolith. . Together, hydrogen and oxygen make the hydroxyl molecule (OH), a component of water, or H2O.

"We think water is that special and magical compound," said William M. Farrell, a plasma physicist at NASA's Goddard Space Flight Center in Greenbelt, Maryland, who helped develop the technology. the simulation. "But here's what's amazing: every rock has the potential to produce water, especially after being irradiated by the solar wind."

Orenthal James Tucker, a physicist at Goddard, led the simulation research. It is therefore essential to understand the amount of water available on the moon or its chemical components on the moon.

"We are trying to understand the dynamics of transporting valuable resources such as hydrogen around the lunar surface and its exosphere, or a very fine atmosphere, in order to be able to know where to go to exploit these resources," Tucker said. , recently described the results of the simulation in the newspaper JGR Planets.

Several spacecraft have used infrared instruments that measure the light emitted by the moon to identify the chemistry of its surface. These include NASA's Deep Impact satellite, which has had many close encounters with the Earth-Moon system en route to the 103P / Hartley 2 comet; NASA's Cassini spacecraft, which crossed the Moon to reach Saturn; and India, Chandrayaan-1, which orbited the moon a decade ago. All found traces of water or its components (hydrogen or hydroxyl).

The sun releases a steady stream of particles and magnetic fields called the solar wind. This solar wind blows worlds into the solar system with particles and radiation – which can flow to planetary surfaces unless counteracted by an atmosphere, a magnetic field, or both. This is how these solar particles interact with some planets and other celestial bodies. Credit: NASA Goddard Space Flight Center / Mary Pat Hrybyk-Keith

But how these atoms and compounds form on the Moon remains an open question. It is possible that meteorological impacts trigger the necessary chemical reactions, but many scientists believe that the solar wind is the main factor.

Tucker's simulation, which traces the life cycle of hydrogen atoms on the Moon, supports the idea of ​​the solar wind.

"From previous research, we know how much hydrogen comes from the solar wind, we also know the amount that is in the very thin atmosphere of the moon and we have measurements of 39, hydroxyl on the surface, "said Tucker. "What we have done now is understand how these three inventories of hydrogen are physically related."

Showing the behavior of hydrogen atoms on the moon has helped to understand why spacecraft have discovered fluctuations in the amount of hydrogen in different regions of the moon. Less hydrogen accumulates in the warmer regions, like the Moon's equator, because the hydrogen atoms that are deposited there are activated by the Sun and quickly discharge from the surface in the exosphere, concluded the team. Conversely, a larger amount of hydrogen appears to accumulate in the cooler surface near the poles because solar radiation is reduced and degassing is slowed down.

Overall, Tucker's simulation shows that when the solar wind blows continuously on the Moon's surface, it breaks the links between the silicon, iron, and oxygen atoms that make up the bulk of the Earth's surface. Moon. This leaves oxygen atoms with unsatisfied bonds. When hydrogen atoms cross the Moon 's surface, they are temporarily trapped by unmoored oxygen (longer in cold regions than in warm regions). They float from O to O before spreading in the atmosphere of the Moon and finally in space. "The whole process is like a chemical plant," Farrell said.

According to Farrell, an essential consequence of the result is that every silica body exposed in space, from the moon to a small speck of dust, has the potential to create hydroxyl and thus become a chemical plant for the water.

Explore further:
The atmosphere of the Earth extends to the moon – and beyond

More information:
O. J. Tucker et al, Solar wind implantation in the lunar regolith: Monte Carlo simulations of H retention in a surface with defects and the H 2 exosphere, Journal of Geophysical Research: Planets (2018). DOI: 10.1029 / 2018JE005805

Provided by:
Goddard Space Flight Center of NASA


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