Back in 1976, American physicist Gerard K. O’Neill proposed a revolutionary space settlement design known as the ‘O’Neill cylinder’. Here it is visualized.
In his book “The High Frontier: Human Colonies in Space” the scientist described this space colony design consisting of two counter-rotating cylinders. Those cylinders are supposed to rotate in opposite directions – to cancel out any gyroscopic effects that would otherwise make it difficult to keep them aimed toward the Sun.
Each of the O’Neill cylinders would be 5-miles in diameter and 20-miles long, connected at each end by a rod via a bearing system. Their rotation provides artificial gravity via centrifugal force on their inner surfaces.
The habitat contains mirrors directed towards the Sun to collect solar energy.
O’Neill and his students carefully worked out a method of continuously turning the colony 360° per orbit without using rockets. First, the pair of habitats can be rolled by operating the cylinders as momentum wheels. If one habitat’s rotation is slightly off, the two cylinders will rotate about each other. Once the plane formed by the two axes of rotation is perpendicular in the roll axis to the orbit, then the pair of cylinders can be yawed to aim at the Sun by exerting a force between the two sunward bearings. Pushing the cylinders away from each other will cause both cylinders to gyroscopically precess, and the system will yaw in one direction, while pushing them towards each other will cause yaw in the other direction. The counter-rotating habitats have no net gyroscopic effect, and so this slight precession can continue throughout the habitat’s orbit, keeping it aimed at the Sun.