Why is Water so Valuable in Space?

Water is as valuable of a resource in space as oil is on Earth.

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Success for human space travel depends on water.

NASA’s big discovery on October 26, 2020 found more water on the Moon than previously known. This is exciting because it means lunar water resources will be easier to access and use.

Key takeaways: Uses for water in Space:

  • Propellant production
  • Radiation shielding
  • Space manufacturing
  • Space agriculture
  • Temperature control
  • Breathing

Any water source means a higher likelihood that humans will be able to sustain a longer visit, thus the goal of establishing a sustainable human presence in outer space by the end of the decade.

Water is as valuable in space as oil is on Earth. – @espressoinsight

The amount of water present on the Moon is equivalent to about 12 ounces per cubic meter of soil, and much of the water is found in the many small craters populating the lunar surface.

This was discovered by the NASA SOPHIA telescope, and other measurement instruments on board a Boeing 747. The curious part is, we don’t know for sure what created the water or how it got to the Moon, but its possible that interstellar radiation could be converting hydroxide ions, OH-, into H2O.

There are TWO articles in Nature that detail the specifics, which I’ve linked to below.

2020 Study 1: Micro cold traps on the Moon

2020 Study 2: Molecular water detected on the sunlit Moon by SOFIA

The abstract for both articles is pretty short and worth a quick glance. If you end up reading them, let me know what you thought of NASA’s discovery.

These discoveries are follow ups to the earlier discovery when scientists first realized water’s presence on the Moon at all. Before the October 2020 discovery, we only knew of water being on the north and south poles of the Moon, which are extremely cold and would be difficult and dangerous for astronauts to reach.

2018 Study: Direct evidence of surface exposed water ice in the lunar polar regions

map of water on the moon
Graphic of water located on the poles of the Moon. Source: https://www.pnas.org/content/115/36/8907

Although these studies have confirmed the presence of water on the moon this year, it isn’t a surprise. NASA evidence for this in 2009 as well, although these studies do have the benefit of solidifying the evidence.

According to the 2009 evidence, the original findings were made by NASA’s Moon Mineralogy Mapper aboard the Indian Space Research Organization’s Chandrayaan-1 spacecraft, and then confirmed NASA’s Cassini spacecraft and NASA’s Epoxi spacecraft.

What is so great about water anyways?

Why is finding water in outer space such a big deal? I mean, comparing it to oil on Earth is a little bit of an exaggeration, right? – Not quite. Water actually is like oil in because it can be used as propellant – a fuel source for rockets or other vehicles.

The Moon will effectively be a galactic gas station – @espressoinsight

How is water used in outer space?

In space, aside from drinking, H2O could be split into pure elemental components hydrogen (H2) and oxygen (O2) and used separately.

This is done through the process of electrolysis, which involves running electricity from solar panels through the water and an electrolyte with an anode and cathode attached, forming a circuit.

Water reacts at the anode to form oxygen and positively charged hydrogen ions (protons). At the cathode, hydrogen ions combine with electrons from the external circuit to form hydrogen.

electrolysis of water
Electrolysis of water. copyright Nevit Dilmen, CC BY-SA 3.0


This is important for propellant production. From pure hydrogen and oxygen, we can create rocket fuel. Since electrolysis is a relatively simple chemical process, anywhere in the universe that hosts water will serve as a galactic gas station, allowing astronauts to re-supply for additional missions.

As Saturn’s moon Titan is also a potential galactic gas station due to its vast abundance of methane and other organic material hydrocarbons, Earth’s Moon is as well for hydrogen / oxygen type rocket fuel.

rocket launch NASA
source: NASA public domain,
S82-28746

With water, fuel cells may also be used to store energy and generate electricity in the absence of sunlight, when we can’t get good solar power.

And then of course, whatever oxygen is not used for fuel can be used for breathing and saving tank space.

Water can also be used for radiation shielding to protect astronauts. We could literally put a water shield around a spacecraft.

As space manufacturing becomes more common, water will be required in a lot of these processes.

Yet another use is space agriculture. Water could often be recycled from whatever plants transpire on their leaves. And one day, when we terraform dry planets, huge amounts of water will be needed.

Temperature control on spacecrafts is also a use for water. The vacuum in space acts like a perfect insulator preventing heat transfer. Water could be used to cool spaceships to prevent overheating.

So, now we know why having access to water in space is a first step toward establishing a space economy, taking civilizations to the next level, and becoming a multi-world species.

“If we can use the resources at the Moon, then we can carry less water and more equipment to help enable new scientific discoveries.” – Jacob Bleacher, Chief Exploration scientist for NASA

Let’s not forget, however, this will be a great and noble challenge for humanity. Procuring water in space isn’t as easy as just digging a well like on Earth. Since its frozen, we have to mine and extract it from asteroids, planets, and moons.

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3 comments on “Why is Water so Valuable in Space?”

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