What is the name of the space station in Sonic Adventure 2?

The space station in Sonic Adventure 2 is called Space Colony ARK.

The ARK is a large orbital research facility built for long-term habitation and scientific work. It was associated with Professor Gerald Robotnik, Doctor Eggman's grandfather, whose experiments there led to the creation of Shadow the Hedgehog while he searched for a way to help his terminally ill granddaughter, Maria.

In Sonic Adventure 2, Doctor Eggman travels to the abandoned colony after learning about its secret weapon, the Eclipse Cannon. Shadow and Rouge are also closely tied to the ARK's history. A recording left by Gerald ultimately reveals that the colony was programmed to collide with Earth if the Chaos Emeralds activated the cannon.

Space Colony ARK is sometimes shortened simply to “the ARK,” which can make it easy to confuse with the Eclipse Cannon, the weapon housed there. Angel Island is another major Sonic location, but it is linked to the Master Emerald and is not a space station.