Why Lunar water exists…


Humans have always been on a constant endeavour to discover life outside earth. Currently, we are in pursuit of exploring the toxic clouds of Venus, the devilish terrains of Mars and the Voyager probes from the 1970s have already crossed interstellar space.

But history also tells us that humans are notoriously good at exploring the unknown whilst overseeing the obvious !

So in this context, the lunar surface is naturally the closest celestial terrain that has been prodded upon but never explored.

Lunar facts

Generally, the moon is fantasized as an enchanting celestial body fixated in the lonely sky. But like most other instances in life, beauty is appreciated only from a distance. If you look closely, it exhibits a very different personality. In reality, it’s a battered chunk of space rock with a troubled past. This geologically inactive chunk of rock excels in being the “punching bag” for asteroids. For over 4.1 billion years, it has fought numerous wars and proudly beholds its scars as craters.

Battered lunar surface

What’s more interesting is that we still don’t have a concrete idea of how the moon was formed. According to NASA, the moons’ origin story dates back to 4.5 billion years ago when a Mars-sized ethereal object jarred Earth. The debris of this collision led to the moon's formation, which was locked in an orbit around the earth; nevertheless, these theories still happen to be a scholarly crux. Several years down the line, interestingly, it was discovered that even the moon seems to be losing interest on earth and is gradually moving away by 4 cm every year!

Irrespective of its history and dormant nature, the moon still is a “qualified” celestial object. Anything celestial apart from earth always holds a slim potential to support life and is worth exploring. The fundamental element required to sustain life is water, and it is generally this compound that scientists seek out in miniscule traces.

The “sweet spot” for Lunar water

There are a couple of facts that we need to acknowledge to comprehend Lunar water's existence truly.

Firstly the moon does not have a “dark side”; in reality, the entire lunar surface is dark. If you’re still wondering, take a look at the picture of the “Regolith” rock which is predominantly found on the lunar surface.

Regolith rock sample

Secondly, every 14 days, the moon experiences a transition from day to night, but unlike Earth, it is due to revolution and not a rotation about its own axis. This is the reason why we see only one phase of the moon from earth.

If you observe closely, you can visualize that the moon's poles will be engulfed either in darkness or light. This is solely due to the orientation and its motility. We also know that the moon's orbit is tilted by 5 degrees, So theoretically, the moon's South Pole is said to be permanently shaded from sunlight. Due to the South poles strategic location, it is naturally cold and is not constantly impacted by adverse calamities.

There are certain Craters in this region which is “believed” to have an ambient condition for frozen water and is also possibly the coldest place in the solar system with a freezing temperature of -297 °C

Mission findings

Naturally, interesting science is never completed with just a theoretical assumption. To verify these findings, some missions were deployed over the years from various facets of the globe.

In 2009 NASA had a mineralogy spectrometer onboard ISRO’s-Chandrayaan 1; this mission also had a “Moon impact probe” bound to crash-land on the South Pole. The massive impact caused tons of lunar minerals to be ejected into space; these were then detected by the spectrometer and studied. As anticipated, there were traces of water.

11 years down the line, in Oct 2020, NASA’s Stratospheric Observatory for Infrared Astronomy (SOFIA) confirmed the traces of water on the sunlit regions of the moon as well. We can infer that traces of water could be dispersed across the entire lunar surface. Interestingly SOFIA was a Boeing 747 aircraft with an excellent telescope mounted on its back. This setup was made to avoid errors induced by water vapour content when observing celestial objects.

SOFIA aircraft-Boeing 747

How did the water get there in the first place?

Simulation model of water distribution

All we know is that water has been spotted on the “Clavius crater” in the Southern Hemisphere. But there are no concrete explanations as to how it was formed in the first place. But naturally, there are some theories.

The existing theories are -

  • Bombardment of water containing meteors
  • Rare chemical reactions due to even scarcer volcanic activity
  • Combination of Oxygen and hydrogen under adverse conditions.

(47 % of the moon’s surface is oxygen! In the form of oxides, hydrogen comes from charged particles present in the solar wind.)

Again these theories hold good on paper and experiments conducted on earth.

One thing for sure is any phenomena above the atmosphere enjoys bending the rules of science

What lies ahead

Certainly, we know that these traces of water are huddled away in deep craters. But unfortunately, such a setup would not act as a viable resource for space applications. Furthermore, these water molecules, if exposed to the top lunar surface by any means, would only be lost forever. The potential of utilizing lunar water is quite bleak as of now, as stated below.

“This is not puddles of water but instead water molecules that are so spread apart that they do not form ice or liquid water”

Casey Honniball

So what we can conclude is that these results have definitely instilled loads of “hope” in the space community. There is active research ongoing to ascertain how water reached the lunar surface, and hopefully, it ends with it. If we go one step further to tap out lunar water as a resource, then the moon is officially a potential target for colonization!



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