Nerva Beacon

The Nerva Beacon (a.ka. the Ark) was a space station located in the Sol system.

History
The Doctor thought that the station was built in the late 29th or early 30th century.

The original purpose of the space station was to act as a beacon (hence the name) to warn spacecraft about the planetoid Voga. Nerva had a transmat link to the breathable interior of the planetoid. (DW: Revenge of the Cybermen)

Some time later, the beacon had been moved to Earth orbit, where it now acted as a cryogenic storage facility, Nicknamed "the Ark". Scientists had foreseen that for 5000 years the Earth would become uninhabitable due to Solar flares, and under the leadership of the Earth High Minister had chosen Nerva as a "lifeboat". (The rest of humanity was evacuated in Thermic shelters, but they were apparently not expected to survive long enough to repopulate)
 * It is unknown exactly how long after the 30th century this occured, though the Earth high minister mentioned in a recorded revival speech that "you have slept longer than the recorded history of mankind" (supposedly refering to the planned 5000 years rather then the period really slept)

Genetic samples of Earth flora and fauna were stored on board, and the bodies of specially selected Human volunteers were placed into suspended animation. People stored were genetically screened so that the genetic pool of the survivors would be crossmatched, balanced and compact-evaluated. For this reason Regressive humans were not allowed.

The power for the station was by this time provided by solar stacks, and the transmat link now connected the station with Earth, rather than Voga.

Due to a Wirrn infestation, a massive system failure occurred and the Humans overslept, By the time they did wake up 10,000 years had passed. The awakenings had to fight of Wirnn, but eventualy managed to retake the station and start recolonising the Earth. (DW: The Ark in Space)

During those thousands of years, the Nerva Beacon became a legend, the lost ark of mankind, sleeping while the rest of humanity was expanding their empire into the rest of the galaxy and beyond. (DW: The Sontaran Experiment)