Cole Habitat

Dandridge Cole and Donald Cox showed in 1964 that hollow planetoid cities, similar to the O‘Neill communities, could be constructed.

First is the erection of a lightweight solar mirror several kilometers in diameter. Next, an elongated asteroid is used, about a kilometer in diameter and two kilometers in length with a mass of about 1013 kg. The mirror is then used to bore out a hole down the central axis of the object by melting the body in stages. Water tanks are used to generate super-heated steam, causing immense pressure to blow the asteroid into a giant nickel-iron balloon about 10 km in diameter and 20 km in length.

The giant mirror is used for sunshine to the interior, and water, soil, and biology are moved in. More than 1000 km2 are available for habitation.