[m4rtink]

Let me introduce you to the 30 km long rotating O'Neill Cylinder: https://en.wikipedia.org/wiki/O%27Neill_cylinder

Although realistically this will be built from lunar materials, you still need to lift a lot of mass to build the necessary industrial processing and mass drivers to launch it from the Moon to some Lagrange point.

And there are many other useful space megastructures that can be built in space from common materials, like giant solar arrays beaming power down via microwaves: https://en.wikipedia.org/wiki/Space-based_solar_power

Most of these proposals date from even 1980s.

[dh2022]

I guess for a trillion dollars vine can built Elysium. Generating solar power in space (vs. on the ground) makes as much sense as running AI inference in data centers in space.

[m4rtink]

Space solar power makes perfect sense once you have sufficient in-space industrial infrastructure available, so that all the actually heavy stuff (structural materials, solar panels, antennas) stuff is manufactured from local (Moon, asteroid) resources & only the most high tech stuff is launched from Earth (electronics, engineers).

The space solar arrays on geostationary orbit would get basically 24/7 sunlight with no weather effects & constant thermal environment. On the ground ad the microwave antenna level you get clean electricity to use for whatever, at any time of the day.