Like the U.S.S. Palomino, its mission was to discover inhabitable life in outer space under the command of Captain Reinhardt. The ship and crew were recalled to return to earth however Reinhardt ignored the orders and the crew turned their trust to Frank McCrae. They tried to commit mutiny but were captured by the ship's robots and were turned into robots themselves.
For the last twenty years, the Cygnus was never heard from again and found its way to a black hole where she was finally discovered by the U.S.S. Palomino.
It turns out in the last twenty years, Reinhardt had modified his ship with anti-gravity forces to keep the Cygnus at bay. He planned to fly her through the black hole but suffered sever damage when the Palomino and asteroids collided with her. She was torn apart as she went through the black hole.