Hello, SFIA audio listeners. In this month's Nebula exclusive, big alien theory,

we're asked at the reason alien civilizations might be rare is because most aliens are huge.

To hear it and every episode early and ad-free, plus hours of bonus content, check out

go.nebula.tv slash Isaac Arthur and use my code, Isaac Arthur. After over half a century, it is time to return to the moon, and use its vast resources as a bridge to countless new worlds.

Welcome to Science and Futurism with Isaac Arthur, and I'm your aforementioned host, Isaac

Arthur, writer and producer of this show,

and also president of the National Space Society, an organization dedicated to a future of

space settlement. And when it comes to settling space, finding a way to set up self-supporting

bases on the Moon is necessarily always at the forefront of those efforts. After all, if

we can't make things work on the Moon, the only celestial body within real-time communication

distances of Earth, how could we ever hope to make things work on any other planet?

At its core, though, the Moon is not just a prototype place to try out space settlement,

but also the gateway to those other places, because it is very rich in resources to mine,

process, and refine, but also low in gravity and air, the two things that make the off

Earth and into space so hard.

This is why we have done so many episodes on the Moon, and we'll

doubtless do many more, and why today we will be focusing on how we get those resources,

and in the near future, with existing technologies, and it all comes down to economics and

the tyranny of the rocket equation. If I want to put a spaceship on another planet, I either need a vastly better fuel

and propellant, or I need to be willing to launch dozens of ships into space carrying a payload

of fuel just to be able to have the fuel to send one of those spaceships off to another

planet.

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