The urge to voyage beyond what we know is at the heart of the human experience. Often, this is driven by some rare commodity—spices and silks, gold, or oil.
How about water?
The analogy may sound insane, since water is fairly plentiful here on the ground. But the unique physics of space travel means that going to the moon to get water might actually boost the space economy.
The presence of frozen water on the moon is a key motivating factor for plans to send a new wave of robotic and eventually human explorers back to the moon. That ice is one of the first real resources that humans can use in space—for drinking water, for hydroponic agriculture, and once split into its component elements, oxygen to breathe and propellant for rockets.
This week, NASA administrator Jim Bridenstine offered a hint as to how access to that water will come about, tweeting that “for the Artemis Moon base, NASA will establish a cost per ton delivered and once again let private companies innovate.”
Talk of a moon base is a ways off: NASA’s current goal is to get astronauts back on the moon for a brief visit by the end of 2024, but that is unlikely to be realized. The viability of this dream also depends on how exactly the ice, which we’ve only spotted with remote sensors, is distributed on the moon.
A series of robotic explorers expected to arrive in the next several years should help answer that question definitively. Today, NASA announced that the US company Astrobotic received a $199.5 million contract to carry a NASA rover called VIPER (Volatiles Investigating Polar Exploring Rover) to the moon in 2023.
But the water economy of space is too fascinating not to think about some more. The hinge of the whole idea is gravity. One of the most expensive things about space is getting there—escaping Earth’s gravity requires the use of chemical rockets to generate the massive energy needed to break free. That means paying a premium for anything you need to bring with you.
If those necessities were already available in space, the cost of getting the bare minimum up from Earth would go down significantly.
The chemicals behind rocket propellants are plentiful on Earth, but getting them to low-Earth orbit, where the International Space Station (ISS) lives, raises the price significantly. Going further, to geocentric orbits where satellites hang high above the Earth, is even more expensive. Take it to a Lagrange point between the Earth and the moon, a likely spot for a future space platform, or down to the moon, and the costs become astronomical.
Harvesting them on the moon, however, could be comparatively cheap, as is flying them from the moon’s low gravity to various orbits around the Earth. In theory, a market for lunar propellant could make it cheaper and more effective to operate large satellites by refueling them, instead of making them carry fifteen years’ worth of propellant up from the ground. That implies a host of benefits to life on Earth: Improved satellite internet and navigation services, better remote-sensing data about weather, climate change and economic activity, and the possibility for innovative new products manufactured in low-Earth orbit.
It could also lower the costs of operating the ISS, enable long-term stays on the moon, and make missions to Mars much cheaper, as well.
An analysis performed by the Space Resources Roundtable offers a suggestive depiction of how much it costs to produce and transport propellant—liquid oxygen and liquid hydrogen—to various points:
The challenge will be kick-starting the market—the capital investment required to create the infrastructure to extract water from lunar ice will be huge, and there’s no obvious buyer for it now.
That’s why Bridenstine’s statement is so important: If NASA follows through by saying we’ll pay $X for propellant delivered to location Y, that could give hypothetical lunar mining entrepreneurs the market they need to get off the ground, and encourage private propellant buyers to make their own plans to use these resources. (One technological wrinkle will be designing spacecraft for regular re-fueling.)
“Wow, this is extremely important!!” Elon Musk, SpaceX’s founder, tweeted in response to Bridenstine.
This is a model adapted from the commercial crew program that just saw SpaceX carry astronauts to the space station on the cheapest spacecraft the US has ever built—tell the market what you need and let it provide, rather than develop a NASA-led effort. It’s proven an effective strategy for replicating past NASA accomplishments quickly and efficiently. But when it comes to mining the moon, well, that’s a new frontier.
A version of this story was first published in Quartz’s Space Business newsletter.