Terraforming

How to Terraform the Moon

It’ll be habitable, if a lot like Florida.
By Gregory Benford
A terraformed Florida moon.
The moon: Just like Florida.


Photo illustration by Juliana Jiménez Jaramillo. Images courtesy NASA and the Florida Division of Library and Information Services.

Space fans were startled—and perhaps a little skeptical—in May when the Russians announced that they intend to build a manned moon base. The Russians think the first stage of their project will cost about $800 million, maybe assisted by private-sector investors. Their goal: to dominate “a geopolitical competition for the Moon’s natural resources in the 21st century.”

According to the Russian press release, they’ll start by analyzing the physical and chemical composition of the future home of the base, in the deep cold of the moon’s south pole. (A foolish choice, in my opinion—think how readily machinery will seize up in shadows and the cost of heating the base.) In missions between 2016 and 2025, they’ll learn how to extract minerals such as aluminum, iron, and titanium. (Maybe they can also bring back some of the helium3 we know is there. Here on Earth we’re short on helium3, which would be a key ingredient for future fusion plants.)

Russia is on the right track. To deliver vast new resources to humanity, we must pioneer and occupy the moon, Mars, and perhaps even beyond.

And inevitably, we will shape those worlds, as we have shaped our own (though not always well, of course).

Mars often gets more attention as the second Earth, since it’s larger and has thick ice buried under its sands. But its distance means it will be hard to shape and hard to reach. When it comes to remaking a celestial body in Earth’s image—“terraforming” it—the moon has clear advantages: It gets twice the sunlight of Mars. It’s a three-day trip with current technology, while getting people to Mars would take six months. Furthermore, the moon is dead and it’s small, so it needs less work and investment to build an atmosphere. Mars has slightly less than the total area of Earth's dry land; the moon has a quarter of it—a bit smaller than all Asia.

Still, engineering any planet or satellite, including Earth, is a huge job. We will probably encounter the true scale of it in this century, as we build defenses against climate change. Thinking through how we might thrive on other worlds, even in the far future, can make us reflect on how terraforming Earth or other worlds will alter the human perspectives.

So … how about the moon? With the right approach and some luck, it might make a decent place to live, so long as you enjoy Florida’s weather.

Terraforming our moon will take many decades and vast abilities. Before we can begin, we’ll have to master the resources of our solar system—especially transporting raw masses over interplanetary distances. That means nuclear thermal rockets (which we already developed by the 1970s), advanced robotics and communications, biotech, and sustainable closed environments. Once those come, we can reach higher. Here’s how the terraforming process might work.

Our moon was born too small to harbor life. It came from the collision of a Mars-sized world into the primordial Earth. From that colossal crunch spun a disk of rocks that condensed into a satellite. The sun robbed its gases, and that bully Earth slowly stole the moon’s spin, locking it so that one face always smiles at us.

Our moon can become not a replica of Earth, but an exotic realm we shape as we like.

The moon’s closeness is a huge advantage: To make it habitable, we would first have to bombard it with water-ice comets, a tricky endeavor best attempted with the many resources waiting on and near Earth. Using incoming comets will be worth the challenges, because they can deliver both an atmosphere and momentum.

The process begins by steering a comet nucleus, which some call an iceteroid, from the chilly freezer beyond Pluto. Nudge it from its slow orbit with a mile-per-second velocity change and swing it near any gas giant planet for a momentum swerve. By hooking the comet adroitly in a reverse swing-by around, say, Jupiter, we can loop it into an orbit opposite to the way that worlds orbit the sun. The grimy, mountain-size iceteroid soon will loom in the moon’s night sky.

Mere days before it strikes, scientists will have to blow it apart—brutally and carefully. Ice shards come gliding in all around the moon’s equator, small enough that they cannot free themselves from gravity’s grip. (We can’t let big chunks of comet scatter off the moon to rain down as celestial buckshot on Earth.) Within hours of the first incoming comet, the moon will have a crude atmosphere. With one-sixth of Earth's gravity, it can hold gases for tens of thousands of years.