Merc starports are fully-automated, mobile, orbital production facilities operated by Mira Han and Mira's Marauders. During the Second Great War, Mira utilized several of these starports in a skirmish with Raynor's Raiders and the Hyperion. The Raiders destroyed the starports, much to Mira's annoyance.
Merc starports regularly manufacture griffons, valkyries, and battlecruisers to attack the Hyperion and Valerian's Space Station. They take a lot of firepower to destroy, but should be prioritized for destruction to stem the flow of enemy reinforcements.