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.

The moon is barren and lifeless, but as we return to the moon and settle there permanently,

might we transform the brightest jewel in our sky into a glittering emerald full of life?

I am generally known for being a techno-optimist and upbeat about the future, but even my optimism tends to shudder a bit whenever I see my grocery bill these days. But if you think those are bad, the cost to get food up to astronauts is truly awful.

There are prestigious restaurants out there that charge a thousand bucks ahead, and they

seem like the dollar menu in a fast food joint compared to what food delivery to the moon

or Mars cost.

Those costs are coming down and sharply, but could run north of a million dollars a kilogram,

which might mean even a small permanent base on the moon, and one even a source of

water and oxygen, might still need a billion dollars' worth of food delivered to it annually.

These constant resupply costs are part of the reason why we have not returned to the

moon and set up a permanent base yet.

We really have had the technology to do that since the Apollo era, but sending a couple

people there for a few days is really quite different than shipping what is needed for semi-permanent

housing.

Needless to say, it sure would be nice if we didn't need to bring along air, food,

and water, or could recycle much of it, and this is part of our topic today. Earlier this year,

we looked at terraforming the moon and living in lunar lava tubes. This show turned 10 years

old next month, and we discussed the moon since nearly the beginning and returned

...