Multiple realities
(covers information from several alternate timelines)
An orbital habitat was a facility in space where people could live. Earth had several of these habitats in its orbit.
Between the destruction of the USS Saratoga and his posting to Deep Space 9, one of Benjamin Sisko's projects was directing the construction of orbital habitats. (DS9: "The Way of the Warrior")
In 2371, Earth's orbital habitats were erased from existence after the death of Gabriel Bell in 2024. They, and the correct timeline, were restored after Sisko assumed Bell's identity and successfully brought the Bell Riots to their original conclusion. (DS9: "Past Tense, Part I")