Mobile Shipyard

These valuable ships often travel with the fleet and are used for quick and dirty field repairs, when the fleet is far far away from the home star system. After a battle, these ships provide the necessary maintenance that allows the fleet to move to it's next engagement. Each ship can carry up to 100,000 resources.....

The airship would only return to earth—as a ship goes into dry dock—when in need of repairs.   OneLook Literature Archive