The artist’s concept of the moon in the Earth’s magnetic tail, the part of our magnetosphere that extends beyond our sun. The moon flows in this queue every month at full moon. Image by E. Masongsong / UCLA / EPSS / NASA / GSFC / SVS / Duluth News Tribune.
By Bob King, alias AstroBob. Originally published in Duluth News Tribune on February 16, 2021. Reprinted here with permission.
Finding water on the barren moon is one of the most remarkable discoveries of the post-Apollo era. Satellite mapping has revealed ice in permanently shaded craters at the lunar poles and more recently in Clavius, a prominent crater near the moon that rises in the sun two weeks from each month. Comets and meteoroids probably delivered water that eventually froze in ice, although water-rich lavas that erupted in the moon’s distant past may have also contributed.
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The orange soil given by Apollo 17 astronauts contained drops of glass sprayed from a volcanic fire well 3.64 billion years ago. Subsequent analyzes found water trapped inside some beads. Image via NASA / Duluth News Tribune.
Back on Earth, scientists found water trapped in glasses and volcanic rocks collected by Apollo 15 and 17 astronauts. In 2019, NASA’s LADEE mission (Lunar Atmosphere and Dust Environment Explorer) discovered that the constant flow of micrometeorites (small space rocks ) bombarding the moon creates a thin and temporary atmosphere of water vapor. When particles penetrate at least 3 inches (8 cm) into the surface, the impact shock releases water molecules attached to minerals in the deeper soil, which are not exposed to direct sunlight.
Just to be clear, the moon is far from wet, but it’s not the dry place I once thought it was. For comparison, the driest stretch of the Sahara desert has 100 times more wetlands than the moon. To fill the 16-ounce bottle of water, you will need to process about a metric ton of soil per month.
The flow of protons and electrons expelled by the sun called the solar wind affects the Earth (shown here) and the Moon alike. Protons (hydrogen) in the wind bind to oxygen in the lunar soil to make water. Image via NASA / Duluth News Tribune.
The sun also helps distill droplets and lunar water when protons from the solar wind collapse on the lunar surface and bond with oxygen atoms in the minerals to produce H2O. Protons are basically hydrogen atoms that have lost an electron. They are “H” in H2O. By the way, the same solar wind occasionally connects to the Earth’s magnetic field and provides hordes of protons and electrons that spark the northern lights.
In a new study, a team of scientists found that an “earth wind” of ionized atoms blowing from the polar regions can interact with the lunar soil and rocks to produce water molecules. H represents hydrogen; He for helium, O for oxygen and N2 for nitrogen. The plus sign means that the atoms or molecules have lost an electron and are positively charged. Image via NASA / Bob King / Duluth News Tribune.
A study published on February 1, 2021 in Astrophysical Journal Letters found that the Earth can also play a key role in creating water. Similar to the wind with electrified particles of the sun, the Earth has its own wind of ionized hydrogen, helium, oxygen and nitrogen. “Ionized” means that atoms have lost an electron and have a positive charge.
Energized by interactions with the solar wind, some of the atoms and ionized molecules in the planet’s polar atmosphere disappear into space, where they are trapped by the Earth’s magnetic field, better known as the magnetosphere.
Most of the time, the moon moves away from the magnetosphere, which moves away from the sun like a weather vane, but for 3-5 days each month it moves through it around the full moon. The magnetosphere deflects the solar wind, preventing the sun’s protons from crowding fresh water on the lunar surface. With the moon interrupted from supply, astronomers have assumed that the lunar water formed by the solar bombardment will quickly move away into space, and the moon will come out of its temporary dry shelter.
This image of the moon comes from NASA Mineralogy Mapper on the Indian spacecraft Chandrayaan-1. Small amounts of water and hydroxyl (related to water) are shown in blue. Most of the moon’s water is concentrated in the colder polar regions. Image via ISRO / NASA / JPL-Caltech / Brown University / USGS.
But no! Using data from India’s Chandrayaan-1 spacecraft, which mapped water in the polar regions of the moon, Chinese researchers made a surprising discovery. The water level remained almost the same every time the moon came out of the magnetosphere. Something had to throw protons at our satellite to keep the water coming. The Earth’s polar wind probably seemed suspicious.
Additional evidence came from the Japanese lunar orbiter Kaguya, active in the early 2000s, which detected decreases in positively charged oxygen atoms per month each time it hid in the shadow of the Earth’s magnetic tail. In addition to hydrogen, oxygen can also help create water on the moon. How amazing it is to believe that the ionic breeze on Earth can help cover the lunar surface with life-giving water potentially beneficial to future astronauts.
Bottom line: Particles transported from the Earth’s poles through our planet’s magnetosphere could interact with lunar rocks to create small amounts of water on the Moon.
Source: Earth’s wind as a possible exogenous source of hydration of the lunar surface
Via Duluth News Tribune
