World Water Day is March 22nd, 2019, and the theme is “leave no one behind.” In 2010, the United Nations (UN) established that access to water is a human right. Billions of people still live without safe drinking water, particularly marginalized groups around the world. Water is essential to life on Earth and other places in the solar system that we may visit at some point. Earlier in the week, I delivered a keynote lecture at Athens Academy Water Day. I ended the lecture with a picture of the dry, barren landscape of the Martian surface. I made the point that even if we go to the Moon or Mars, water will be required because it is essential to life. Ironically, I ran across a new study last night by a group of NASA scientists. They argue that our Moon may be natural “water-making” factory. Here’s why.
To explain the water-making potential of the Moon, I have to start with a definition of the solar wind. If you are scratching your head at this point, don’t worry it will make sense shortly. The solar wind is a stream of charged particles (protons and electrons mostly) flowing outward from the Sun. The Solar Physics website at NASA’s Marshall Space Flight Center says:
The solar wind streams off of the Sun in all directions at speeds of about 400 km/s (about 1 million miles per hour). The source of the solar wind is the Sun’s hot corona. The temperature of the corona is so high that the Sun’s gravity cannot hold on to it. Although we understand why this happens we do not understand the details about how and where the coronal gases are accelerated to these high velocities.
The solar wind is not uniform and varies significantly. According to NASA scientists, the solar wind that bombards the Earth and Moon could hold the key to making water. Scientists hypothesize that the solar wind enriches lunar surface ingredients that could make water. According the NASA press release,
Using a computer program, scientists simulated the chemistry that unfolds when the solar wind pelts the Moon’s surface. As the Sun streams protons to the Moon, they found, those particles interact with electrons in the lunar surface, making hydrogen (H) atoms. These atoms then migrate through the surface and latch onto the abundant oxygen (O) atoms bound in the silica (SiO2) and other oxygen-bearing molecules that make up the lunar soil, or regolith. Together, hydrogen and oxygen make the molecule hydroxyl (OH), a component of water, or H2O.
How does NASA know the chemistry of the lunar surface anyhow? The agency uses the infrared (IR) part of the electromagnetic spectrum. Virtually every object emits heat or infrared energy that can be detected by an IR sensor. You may have seen a TV cop show in which an IR sensor on a helicopter is used to find a criminal hiding in the shrubbery. Spacecraft like Deep Impact and Cassini used IR instruments to detect evidence of water or the components needed to make it.
The basic concept is simple. Every rock or speck of dust on the Moon has the potential to make water after being irradiated by the Sun, according to William M. Farrell, a plasma physicist at NASA’s Goddard Space Flight Center. His colleague Orenthal James Tucker, a physicist at NASA Goddard, adds:
From previous research, we know how much hydrogen is coming in from the solar wind, we also know how much is in the Moon’s very thin atmosphere, and we have measurements of hydroxyl in the surface….What we’ve done now is figure out how these three inventories of hydrogen are physically intertwined.”
The scientists, who recently reported these findings in the Journal of Geophysical Research, concede that determining how the compounds and atoms form on the lunar surface is still not conclusively known. Most scientists believe the solar wind is the key player, but some have speculated that meteor impacts drive the necessary chemical reactions.
Observations also reveal that the amount of hydrogen varies based on “lunar latitude.” The NASA press release went on to note:
Less hydrogen accumulates in warmer regions, like the Moon’s equator, because hydrogen atoms deposited there get energized by the Sun and quickly outgas from the surface into the exosphere, the team concluded. Conversely, more hydrogen appears to accumulate in the colder surface near the poles because there’s less Sun radiation and the outgassing is slowed.
Water is the “life blood” of Earth. Parts of humanity have likely risen and fallen because of it. It essential that every single human being has access to clean water. This new NASA study suggests that this basic need will not change as we establish our presence on other bodies of the solar system. As a told a student at Athens Academy, let’s hope that when we make or find water elsewhere, it is used more responsibly.