One of the primary reasons to build on the inside of the asteroid is to counter the radiation. Cosmic rays and solar flares are incredibly harsh, and need at least a couple of metres of heavy stuff like iron or rock to shield the puny meatsacks. Ditto for micro (and not so micro) meteorite impacts. So ‘a thin layer on the outside’ is probably not…[Read more]

Alan, sorry if the diagram wasn’t too clear – there are three spheres joined together by relatively thick (~200m) sections, so that it won’t tip over.

And they’re thin spheres* – high v geodesic domes with lots of triangles, primarily for their high strength to weight/material ratio, but the side effect is that they’d behave like giant  ping…[Read more]

There’s also the Ewok Holocaust 🙂

> Harve Bennett and Michael Minor came up with the most compelling concept in the grand history of Star Trek IMHO: the Genesis Device.

Pretty sure Star Trek is fantasy, not science fiction 😉

The easiest way that I can think of is to carve out a hollow with some sort of solar concentrating array, or use a concentrator like a 3d printer, to join blobs of molten rock or chunks of rubble.

You might also be able to pick a metal asteroid, which would have a far higher tensile strength (these would also allow you to sell off the rare earth…[Read more]

You don’t need the concrete itself to float — 2m walls with a 500m diameter would be roughly the proportions of a ping-pong ball (~0.5mm x 40mm), so the issue would be getting it *not* to float. That was the rationale behind filling it with fresh water (which is less dense than sea water).

I didn’t realise that seawater eroded concrete quite so…[Read more]