Habitats vary in size and typically consist of interlinked cylinders or rings, these spin internally to generate just enough gravity to prevent long-term damage and allow for orientation. Not all sections of Habitats have gravity but key living sections typically do. It's recommended that mag boots be worn.
Artificial gravity
The cylinders and rings rotate to provide artificial gravity on their inner surface. Due to their very large radii, the habitats rotate only about forty times an hour to simulate a standard Earth gravity. At such low rotation speeds, almost no-one experiences motion sickness due to Coriolis forces acting on the inner ear. People are able to detect spinward and antispinward directions by turning their heads, and any dropped items appear to be deflected by a few centimetres. The central axis of the habitat has a zero-gravity region, and recreational facilities are located there. In smaller habitats, the cylinders are spun to 0.15G to prevent long-term damage and allow for orientation.
Atmosphere and radiation
The habitats have oxygen at partial pressures roughly similar to terrestrial air, 20% of the Earth's sea-level air pressure. Nitrogen is included to add a further 30% of the Earth's pressure. This half-pressure atmosphere saves gas and reduces the needed strength and thickness of the habitat walls.
In some of the large-scale habitats such as HAB-1, the air within the cylinder and the shell of the cylinder provide adequate shielding against cosmic rays. The internal volume of cylinder is great enough to support its own small weather systems, which may be manipulated by altering the internal atmospheric composition or the amount of reflected sunlight.
Sunlight
Large mirrors are hinged at the back of each stripe of window. The unhinged edge of the windows points toward the Sun. The purpose of the mirrors is to reflect sunlight into the cylinders through the windows. Night is simulated by opening the mirrors, letting the window view empty space; this also permits heat to radiate to space. During the day, the reflected Sun appears to move as the mirrors move, creating a natural progression of Sun angles. Although not visible to the naked eye, the Sun's image might be observed to rotate due to the cylinder's rotation. The light reflected from the mirrors is polarized, which might confuse pollinating bees.
To permit light to enter the habitat, large windows run the length of the cylinder. These are not be single panes, but would be made up of many small sections, to prevent catastrophic damage, and so the window frames can take most of the stresses of the air pressure of the habitat. Thanks to Repulsor shields meteorites are no real threat as they are pushed away.
Attitude control
The habitat and its mirrors must be perpetually aimed at the Sun to collect solar energy and light the habitat's interior. The habitat continuously turns the its 360 degrees per orbit without using rockets (which shed reaction mass). First, the pair of habitats are 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 are 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.
Habitat Ship, rather than the land running perpendicular to the habitats length they are set as a torus around the spine of the ship. However this requires an artificial light source to illuminate the rings. This design is ideal for remote locations especially where the visible light low. Such stations are in orbit around Enceladus and Gliese 667Cc.