Nerva Beacon

The Nerva Beacon (also known as Space Station Nerva) was a large space station built in the 31st century. (DW: The Ark in Space)

Purpose
Its original purpose was to act as a beacon (hence the name) to warn incoming spacecraft about the planetoid Voga. (DW: Revenge of the Cybermen)

Several thousand years later it acted as a cryogenic storage facility where the bodies of the last Earth Humans were placed into suspended animation for thousands of years due to solar flares which scorched the Earth. However, due to a Wirrn infestation, the Humans overslept by many thousands of years. (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, and because of this, Sontarans used the Earth and the few who visited it for their experiments. (DW: The Sontaran Experiment)