The Space Colony ARK was a space station, formerly the home of Professor Gerald Robotnik, his granddaughter Maria, Shadow the Hedgehog and other scientists. In Silver's future, the ARK crashed on Mobius in the waters near Onyx Island, where it's been burning for many years. The ARK seemed to have a large hole on the side of it, which might have been the cause of its crash landing. (StH: #98 #124, #216)