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. We often envision filling space with vast megastructures people might live on in the future,

and mining asteroids to provide the materials for their construction.

But what would life as an asteroid miner be like?

3554-hour moon is a near-Earth asteroid a few kilometers across that orbits the sun every

351 days and gets as close to it as .7 AU and as far as 1.25 AU.

In the early 22nd century, it was one of the first-ed asteroids, and the Amun Mining Company helped

develop a number of the techniques now taken for granted by modern miners. However, most

of its materials were used up building the first O'Neil cylinder at the L5 of the Grange Point,

and workers began moving on to new prospects, but many remained, trying to convert that mined-out asteroid

into a port of Kull, one that often came near Venus, and to repurpose it to the industries

of making space-based solar panels, mirrors, and hydroponics. The same was not true of its

cousin, 1685 Toro, which was mined principally for silicon to make Earth's orbital

power grid, and when that project was done, became a ghost town almost overnight.

Although more so, because an attempt to protect the equipment still there from scavengers

till it could be retrieved or recycled, involved leaving behind prototype battle droids designed to be able to function over long, light-lagged distances.

The Toro Treaty of 2185 saw those types of machines banned, but the asteroid remains infested with them,

and the design became popular with many small prospectors for guarding their claims, and the designs

remain available through the black market. Many small prospectors disappear, likely for diverse

reasons, but homemade knockoff Torobot guardians tends to be a common suspect, and many believe

...