Nostalgia for space (see this post by David Manheim as a nice example) is probably one of the most relevant characteristics of the techno-scientific segment of my generation. I was born in 1977 when the hangover from Apollo was fresh, and during the 1980s, while ambitious space exploration programs were already history, the space frontier narrative still had traction. Even towards the end of the 80s the idea of space cities and zero gravity factories still seemed possible in the near future.

From time to time, although with less and less conviction, the space dream is re-activated. And it is always activated in connection with rockets, space elevators and other high energy technologies. However, the essential challenge of space colonization is the construction of a self-sufficient minimal industrial economy. Or, in more economic terms, how to replace the large flows of intermediate goods and commodities on which the metabolism of an advanced economy is based with fixed capital.

Is it possible to develop a settlement capable of maintaining a reasonable standard of living for its inhabitants indefinitely without appreciable material flows with the rest of the world? To make it easier, let our colonists carry out their project in a habitat infinitely simpler than space: give them several hectares in the Mojave desert and allow them to cultivate in the open (but of course, without an external supply of fertilizers, energy, or even spare parts for their machinery). This kind of closed economy would require going from our specialized economic system (based on huge economies of scale in super-specialized factories) to a radically opposite model of flexible manufacturing.

Even the (clearly more affordable) project of a self-sustaining robotic minimal economy may still require years of development. A settlement based on autonomous or remotely operated robots capable of performing its own maintenance with minimal import of parts may already be feasible, but it is not a trivial project (and it is the natural first step in the Moon).

That's why I think NASA should not focus on rockets and engines, but on comprehensive automation and flexible manufacturing. The miniaturization and simplification of the supply chain (from the mine to the final product) is a daunting technological task, much more difficult than making rockets. 

While its final objective was intrinsically useless, the surge of research and development for the Apollo program yield an enormous social return, probably being a critical for the acceleration of the computing revolution. A similar effort for comprehensive automation and flexible manufacturing could produce a more resilient productive system, and accelerate technologies to deal with catastrophic scenarios. Additionally, a seismic change in manufacturing could erode the economic strength of some geopolitical adversaries and speed up de-carbonization.

In any case, until the closed industrial economy problem in solved on Earth, the space ships are only fireworks.

[Also posted  in Progress Forum: https://progressforum.org/posts/62XwqubkcAKNG6Wqf/space-colonization-and-the-closed-material-economy]