m. c. de marco: To invent new life and new civilizations...

Today’s Big Dumb Object (BDO) isn’t as big and dumb as some, but it forms an essential building block of several truly big yet scientifically feasible BDOs. The McKendree cylinder is the big brother of the O'Neill colony or cylinder discussed in the Rama post. In short, an O'Neill colony is a pair of cylinders 16 miles long and 4 miles wide each rotating for gravity, with half the inner surface devoted to windows running lengthwise, leaving 100 square miles of usable land per cylinder.

In 2000, Tom McKendree super-sized this classic design to 5 million square miles using a new material: carbon nanotubes. His design measured 2900 miles long by 580 miles in diameter, but only 2.5 million square miles of land due to the windows (somewhat smaller than Australia). Theoretically these dimensions could be increased to as much as 6000 miles long by 1200 miles in diameter, for an area of 24 million square miles, at least half of which would be land (so a bit larger than Africa).

These cylinders are still intended to be paired (unless incorporated into even larger structures), so the Orion’s Arm Project suggests nesting them rather than attaching them side by side, and remarks that with even more floors a McKendree cylinder can easily rival the Earth in surface area.