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 add free, plus hours of bonus content,

check out go.nebula.tv slash Isaac Arthur and use my code, Isaac Arthur.

We dream of a destiny among the stars, but the road to the solar system starts with on-ramps in

cis-lunar space.

Why cis-luner space?

Well, we often imagine space in the next Wild West, is pushing to strange new worlds, struggling against

harsh frontiers. The truth is that real civilization shows up when logistics gets boring.

More often than not, progress is not about planting flags, it's about arguing over shipping invoices.

NASA has a lot more accountants than astronauts. So today we have a lot

to cover, and some of that is in those less glamorous but absolutely fundamental aspects of

space development, and I'll do my best to keep it interesting. If it helps, you can take a drink

every time I mention fuel arbitrage. Though I'd avoid anything

with alcohol in it, or you might not make it to the end of the episode, fundamentally,

off-earth fuel production is the key to space development, so it will come up a lot. Assuming that

hasn't scared you off, grab a drink and a snack, and let's jump in. On Earth, ports, rails,

and power lines turn wilderness into cities.

In space, the first region we can make predictable is the cis-lunel corridor,

everything from low-earth orbit, out to the moon, and the halo of useful orbits and

Lagrange points around it.

It is close enough to phone home and far enough to matter. A lot of our future in

...