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

we're asking 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.nebola.tv slash Isaac Arthur and use my code, Isaac Arthur.

This episode is sponsored by Skillshare.

You might have lived in some places you thought were real holes, but for future residents

of the moon, that would actually be a good thing.

So today we are returning to the moon, something humans haven't physically done in almost

50 years since

the Apollo program.

That will be fairly important to our discussion today about setting up large-scale and

permanent facilities in craters on the moon, because when we think about going back to the

moon, a major question that always comes up is why, and what will be achieved by walking

around collecting rock samples for a few days. And the answer to that really is, not, and what will be achieved by walking around collecting rock samples

for a few days?

And the answer to that really is, not much.

Those Apollo rock samples were of great scientific worth, and more would be handy but not

enough to justify a mission there at outrageous expense and more than a bit of danger,

and why wouldn't we just send robotic sampling missions?

That's a lot of why the US hasn't gone back and nobody's worked too hard to be the second

to get there.

It's also why when we talk about returning, we tend to talk seriously about long-term or permanent

...