The wheel spins gently once a minute. It is this gentle rotation that makes this settlement different from the Lunar modules that took man for the first time to any non-terrestrial soil, because the spin produces a force that feels like gravity. Every space trip has shown that the human body needs gravity if it isn't to deteriorate, and gravity also makes normal activities possible. Nobody would want to live for long in a space settlement where everything - people and equipment and the eggs they were trying to fry - moved weightlessly around.
With gravity, life in space can be based on our experience on Earth. We can have farming and factories and houses and meeting-places that are not designed by guesswork. The need for gravity is one of the reasons for building a space colony, rather than sending settlers to an existing location such as the Moon or the planets. The Moon is inhospitable. Its gravity is tiny - and any place on the Moon has 14 days of sunlight followed by 14 of night, witch makes agriculture impossible.
In the settlement, which floats in permanent sunlight, the day-length is controlled. A gigantic mirror about a mile in diameter floats weightlessly above the ring of the settlement. It reflects sunlight on to smaller mirrors that direct it into the ring, through shutters that fix the day length.
The sunlight is constant during the 'daytime', so farming is productive to an extent which can be reached on Earth only occasionally.
