A starship pen is a type of large habitat intended for use as a naval base and shipyard. These were expensive in terms of resource investment, but the erratic orbits and layers of defense meant that it was hard to attack them, let alone penetrate their armor.

The Frieden constructed dozens of starship pens around Jupiter, Saturn, and the Sol Belt prior to the Interplanetary Wars, who invested huge amounts of resources into their construction. Roughly twenty of these stations survived the conflict, and they became regional centers for politics, economics, and ironically UNSC military operations. However, the effects of the Belter Exodus and the subsequent recession brought an end to their prosperity. Although some eventually found success by manufacturing colony ships and equipment, many were decommissioned and scrapped.

Because of their sturdy construction, some ex-Frieden starship pens were converted into large colony ships whose size was only eclipsed by the later Phoenix-class colony ships. At least four of these were used to colonize the Yayatsa system, and eventually they too were recycled into habitats and arcologies.