Zeta

Mothership Zeta is an alien spaceship which appears in the Fallout 3 add-on Mothership Zeta.

About
One of two alien motherships orbiting Earth, Mothership Zeta is a rather large vessel housing a considerable number of crew members. The overall shape of the ship resembles the stereotypical "flying saucer" with another small disc-shaped section attached to the bottom. Traversing between the two sections is possible through Teleportation Matrixes on the Observation Deck and Bridge in the upper portion which connect to counterparts in the lower part's Engineering Core.

Mothership Zeta possesses both offensive and defensive capabilities. It is protected by shield technology and its main weapon is a Death Ray connected to the lower section which can be used for both orbital strikes on a planet and combat against other ships.

The ship contains various laboratories for experimentation on living beings and technology such as Biological Research, the Experimentation Lab or the Research Lab. There is also a vast number of storage facilities in which items and creatures retrieved from the planet below are stockpiled, the latter either in live or frozen state.

Aside from Living Quarters for the crew and the Bridge, the remainder of the vessel is dedicated to the ship's basic functions. The Engineering Core in the lower part of the ship provides access to most of the maintenance sections like the Maintenance Level, Engine Room or Waste Disposal. In the Mothership's Robot Assembly the various Alien Drones are produced and repaired. Death Ray Control and Death Ray Hub are dedicated to the controlling the ship's main weapon. The Mothership also features its own Hangar in which smaller vessels such as Recon Craft Theta can be stored and maintained.

Accessibility afterwards
Only Bridge, Engineering Core and Steamworks can be entered after This Galaxy Ain't Big Enough... quest.